Denali Emerging Energy Technology Grant: Improving Cold Region Biogas Digester Efficiency Quarterly Report, Q2 - June 15, 2010

Transcription

1 Denali Emerging Energy Technology Grant: Improving Cold Region Biogas Digester Efficiency Quarterly Report, Q2 - June 15, 2010 Table of Contents i. Updated schedule and milestone information.1 i.a) Personnel.1 ii. Narrative summary of the project.3 ii.a) Project Status and Accomplishments.3 ii.b) Health and Safety.14 ii.c) Schedule of project.15 ii.d) Project budget.15 ii.e) Hurdles and solutions.16 iii. Photographs.22 Appendix 1.27 References.30

2 i. Updated schedule and milestone information as identified in the Scope of Work. The project is currently in Phase 1, as defined in the original two-year Scope of Work. In November 2009 we assembled materials and conducted a small pilot study. Phase 1 construction commenced on January 14, 2010 with the meeting of the team in Cordova. We completed the main site construction and digester setup, barring continual updates and improvements, on January 21, We have been collecting data on temperature, chemistry, and gas production since January 18, Flow meter data, quantifying gas output from each digester, has been collected since February 18 th, The project continues to closely follow the original outlined plan: - Construct Digesters for Phase 1 by December 15, 2009 DONE, January Begin Data Collection by February 1, 2010 DONE, January 18 forward - Perform mid-term Analysis of Data by July 30, 2010 continual/forthcoming - Perform Analysis of final Data (Phase 1) by December 1, 2010 forthcoming, updated according to Data Collection Plan submitted March 4, Phase 2 -Install Digester in Practical application by Sept 30, upcoming - Evaluate performance/sustainability by July 30, upcoming - Submit Final report and project close-out documents by September 30, 2011 upcoming, updated according to submitted Data Collection Plan i.a) Personnel: Cordova Electric Cooperative Clay Koplin Grant Administrator. Koplin has managed most of the financial aspects of the project thus far on behalf of the Cordova Electric Cooperative, serving as the project manager. University of Alaska, Fairbanks Katey Walter Anthony Research Director. Walter-Anthony acts as the primary investigator, and has spearheaded the scientific goals and directions of the project. She participated in the initial on-site construction efforts and provides continual scientific expertise. Laurel McFadden Research Technician. McFadden, with assistance from the rest of the project team, is responsible for the implementation of the study. McFadden was a key contributor to the project development and took the lead on organization and preparation for the initial construction and setup. She is currently working on-site in Cordova, maintaining the digester experiment, including data collection, analysis, and troubleshooting. McFadden compiled the project report with input from Walter Anthony, and Cordova team members, Koplin and Low. McFadden is also drafting a Biogas construction manual and user guide for Alaskans as part of this project. Peter Anthony Research Technician. Anthony consulted on project development, and worked on initial site construction and digester setup. Anthony continues to provide technical expertise to the maintenance and application of digesters. Cordova High School Adam Low Science Teacher. Low was integral in bringing in student involvement via classroom curriculum and extracurricular projects. He was on the construction team and continues to assist troubleshooting, construction, and maintenance. 1

3 Cordova High School Students Volunteers. The students have been highly involved with construction, feeding, maintenance, and public presentation. They include the Chemistry class students (Shannon Lindow, Craig Bailer, Taylor Kelley, Christina Morrisette, Jessica Smyke, and Danielle Hess), and the Science Club students (Craig Bailer, Danielle Hess, Ian Americus, Ben Americus, Erin Hess, Sophia Myers, Adam Zamudio, James Allen, and Keegan Irving). Ian Americus, Ben Americus, Erin Hess, James Allen, and Adam Zamudio presented at the Alaska Rural Energy Conference in Fairbanks along with Adam Low. SOLAR Cities TH Culhane Biogas Expert. With an extensive history in biogas technologies, Culhane developed the water-pressure tank design and provided extensive technical knowledge to the engineering of the project. He worked with and advised the on-site construction in January 2010 and provides expert advice from his home base in Germany. Sybille Culhane Co-founder of SOLAR Cities. S. Culhane assisted in initial construction efforts and managing financial aspects of SOLAR Cities involvement. Chena Hot Springs Bernie Carl Owner of Chena Hot Springs. Carl has been interested in deploying a digester at Chena Hot Springs, and has provided space for testing a digester in his greenhouse. Others Brandon Shaw Website Development. Shaw designed and manages the CordovaEnergyCenter.org website, where the project is hosted. He also assisted at the initial construction site, and was integral in the assembly of the flow meter system. 2

4 ii. Narrative summary of the project status and accomplishments to date, and addressing the following questions: is the project on schedule, is the project on budget, and what actions are planned to address any project problems. ii.a) Project Status and Accomplishments Phase 1 of this project is defined by experimentation with a variety of microbial communities (psychrophiles, mesophiles, and mixed communities) and temperature conditions (15 C and 25 C), and as such is the heart of the development stage for this proposal. As this is a unique approach to the development of a cold-adapted digester, we are facing a variety of interesting challenges in bringing the experimental systems to optimal gas output. The continual benefit of this process is developing an extensive database of fundamental data on the chemical processes and gas output of this biologically-based technology, while testing the physically-engineered aspects of the constructed systems. Our first pilot-experiment in November 2009 involved mixing different volumes of thermokarst (thaw) lake mud, in a series of ten 5-gallon buckets, to test the minimum mud-towater ratio required for psychrophilic biogas production as a test design for larger systems anticipated in Phase 1. Conventional biogas digesters utilizing mesophiles operate with a 50:50 ratio of manure to water. Due to the time and logistical constraints of collecting mud by hammer coring in 4.5cm width barrels, we wanted to know if a less than 50:50 ratio would work in our 1000-Liter (250 gallon) Phase 1 experiment. Our November 2009 pilot study demonstrated that a 10% concentration of thermokarst (permafrost thaw) lake mud from Fairbanks mixed with water from Lake Eyak (Cordova) was sufficient to produce a flammable biogas within 2-3 days. Flammable biogas continued to be produced, to some extent, for approximately two months. Please see Appendix 1 for a summary of the pilot study. Over the course of 3 weeks in mid-december and early January, we used a percussion corer with 4.5cm width core barrel tubes to acquire ~192 liters (48 gallons) of lake bottom sediment from Goldstream Lake, an active methane-producing, thermokarst lake near Fairbanks, to provide the source of the psychrophilic microbial community that would be the foundation of four of our 1,000-liter experimental digester systems. On January 12, 2010, we collected 240 liters (60 gallons) of fresh manure from the Northern Lights Dairy farm in Delta Junction. During January 14-19, 2010, the project team modified a Connex on site at the Cordova High School to create a temperature-controlled container for the experiment. We also constructed six digesters and filled them with mixtures of mud and manure. On January 19 th, the tanks were sealed and initial physical and chemical data on starting conditions were recorded. The experimental design is shown in Figure 1. 3

5 Psychrophiles Mesophiles Digester Temperature target ( C) Lake sediment (L) Manure (L) Inoculum concentration in tap water (% of total volume) % % % % % % Figure 1. Experimental design for Phase 1 testing of biogas production efficiency of different combinations of psychrophilic and mesophilic methanogen communities under cold and warm temperature treatments. The building team consisted of members of the research group from UAF, SOLAR Cities, CEC, and Cordova High School. System materials were based on 12 donated 1000-L HDPE tanks (six primary tanks for holding digester sludge and slurry (inoculum, feedstock, and water), and six additional tanks used in constructing half of the external water pressure systems), purchased pipe fittings and materials, and borrowed tools. Labor was directed by TH Culhane and Katey Walter Anthony with invaluable input, discussion, and active participation in design and construction from all team members. Primary site construction included insulating and heat-wiring a 40-ft metal Connex, which was evenly divided into the Cold (15 C) and Warm (25 C) rooms of the experiment. Voltage meters were installed to monitor the electrical input required to heat each room to the specified temperature, for later assessment of economic feasibility. Each tank was built to hold a slurry of microbial inoculum (manure or lake sediment) and water. The contents of each tank are detailed in Figure 1. Traditional digesters are based on a 50:50 ratio of manure to water (50% inoculum). The ratios used in this experiment are significantly lower, mainly due to time and transport constraints on the amount of material that 4

6 is required to power 6 tanks. The amounts of sediments used are within the same order of magnitude as the 10% inoculum concentration that yielded biogas in the pilot experiment described in Appendix 1. The slurry ratios used in our six tanks is significantly lower than the standard 50:50 ratio of manure to water used in traditional digesters. Although tanks with these ratios can still produce biogas, it could take longer to build a significant population of methanogens. Most methanogens have a replication turnover time of roughly 30 days (Gerardi 2003). Our tanks likely started with a low number of microbes (more on this issue in ii.d Hurdles and Solutions, 2) Low microbial population size ). Following the sealing of the tanks on January 19, 2010, baseline chemical and environmental properties were measured and recorded on a regular basis (approximately 3 times per week). Initially, we conducted daily flame tests to check the minimum methane content of produced gas (biogas is flammable at ~5% methane by volume mixed with air, in the presence of an ignition source). Chemical properties measured on subsamples of the liquid effluent mainly included: ph, oxidation-reduction potential (ORP), and dissolved oxygen; all primary indicators of the relative health of the microbial environment. In healthy anaerobic digesters, ph should be between Methanogenesis is supported at ORP readings below -300mV. Dissolved oxygen (DO) should read as close to 0% as possible, denoting the required anaerobic conditions and balance of fermentation and methanogenesis. The other main environmental variable measured is temperature, both inside and outside of the tanks. Room temperature is measured via one centrally-located temperature logger in each room, while internal tank temperatures are recorded at two levels within the digester slurry via special waterproof dataloggers (approximately 30cm above the bottom of the tank and 15cm below the surface of the slurry). Loggers were set up to log data over intervals up to 6 months, allowing the tanks to go undisturbed as long as possible. Figures 2-6 show results to date of digester chemistry, internal and external temperature. Table 1 shows results of flammability tests. 5

7 9 Tanks #1-6: ph ph Tank 1 Tank 2 Tank 3 Tank 4 Tank 5 Tank 6 1/12 1/17 1/22 1/27 2/1 2/6 2/11 2/16 2/21 2/26 3/3 3/8 3/13 3/18 3/23 3/28 4/2 4/7 4/12 4/17 4/22 4/27 5/2 5/7 5/12 5/17 5/22 5/27 6/1 6/6 6/11 Date (mm/dd) Figure 2. ph results obtained after the tanks were sealed (Jan. 19, 2010). ph declined for several months, but recently began rising in response to the alkalinity additions, which began March 22, Ideally ph should be between ph was measured with Macherey-Nagel litmus paper January 21-April 16, following which it was more accurately measured with an Oakton PC510 ph meter. 200 Tanks #1-6: Oxidation-Reduction Potential /12 1/17 1/22 1/27 2/1 2/6 2/11 2/16 2/21 2/26 3/3 3/8 3/13 3/18 3/23 3/28 4/2 4/7 4/12 4/17 4/22 4/27 5/2 5/7 5/12 5/17 5/22 5/27 6/1 6/6 ORP (mv) Tank 1 Tank 2 Tank 3 Tank 4 Tank 5 Tank 6 Date (mm/dd) Figure 3. Oxidation-reduction potential (ORP) indicates the availability of oxygen in the system. For healthy methane production, samples should have an ORP of From January 21-April 9, ORP was measured with a Xplorer GLX Pasco PS-2002 Multi-Datalogger. From May 10 forward, it was measured with an Oakton PC510 ORP meter. 6

8 10 Tanks #1-6: Dissolved Oxygen Dissolved Oxygen (ppm) Tank 1 Tank 2 Tank 3 Tank 4 Tank 5 Tank 6 1/12 1/17 1/22 1/27 2/1 2/6 2/11 2/16 2/21 2/26 3/3 3/8 3/13 3/18 3/23 3/28 4/2 4/7 4/12 4/17 4/22 4/27 5/2 5/7 5/12 5/17 5/22 5/27 6/1 6/6 Date (mm/dd) Figure 4. Dissolved oxygen (DO) readings indicate the amount of oxygen in the system. The tanks should have a DO as close to 0ppm as possible (1 ppm = 1 mg/l). Gaps in the chart above indicate periods where our DO meter was non-functioning. The high readings in early May could have been caused by opening the system during attempts to mediate ph. DO measurements were taken with a Xplorer GLX Pasco PS-2002 Multi-Datalogger until March 24, following which they have been taken by a Hanna HI9142 DO meter. 7

9 /7 1/12 1/17 1/22 1/27 2/1 2/6 2/11 2/16 2/21 2/26 3/3 3/8 3/13 3/18 3/23 3/28 4/2 4/7 4/12 4/17 4/22 4/27 5/2 5/7 5/12 5/17 5/22 5/27 6/1 6/6 6/11 6/16 Temperaature (C) Biogas Cold Room Temperatures (with Cordova Temps) Cordova Cold Room Tank 1 Btm Tank 1 Top Tank 2 Btm Tank 3 Btm Tank 3 Top Date (mm/dd/yy) Figure 5. Mean hourly temperature of the cold room and digester tanks 1-3, and mean daily temperature recorded in Cordova. The average temperature of the cold room from January 19, 2010 through June 8, 2010, was 13.7 C. Cold room temperature has been approximately 2-4 C lower than the targeted 15 C for the majority of the study period due to the difficulties of heating a metal Connex, and due to the effects of temperature stratification within the Connex (temperatures are logged approximately 3-ft from floor level). Digester tank temperatures followed the external room temperature fairly closely, while room temperatures mimicked patterns in external environment. Tank temperatures have not been downloaded since May 12 in an effort to maintain the anaerobic environment in the tanks (accessing the temperature loggers requires opening the tanks to the air). According to the patterns we have seen thus far, though, we could predict an increase in tank temperatures following the increase in room and environmental temperatures. Biogas project temperatures are measured with Hoboware U Water Temp Pro V2 loggers recording hourly. 8

10 50 Biogas Warm Room Temperatures (with Cordova Temps) /7 1/12 1/17 1/22 1/27 2/1 2/6 2/11 2/16 2/21 2/26 3/3 3/8 3/13 3/18 3/23 3/28 4/2 4/7 4/12 4/17 4/22 4/27 5/2 5/7 5/12 5/17 5/22 5/27 6/1 6/6 6/11 6/16 Temperature(C) Cordova Warm Room Tank 4 Btm Tank 4 Top Tank 5 Btm Tank 5 Top Tank 6 Btm Tank 6 Top Date (mm/dd/yy) Figure 6. Mean hourly temperature of the warm room and digester tanks 4-6, and mean daily temperature recorded in Cordova. The average temperature of the warm room from January 19, 2010 through June 8, 2010, was 25.5 C. Digester tank temperatures were approximately 5 C lower than the external room temperature. Thermal stratification in tanks was observed with warmer temperatures at the top of all tanks and colder temperatures at the bottom of the tanks. Tank temperatures lower than room temperatures are likely due to heat conduction through the poorly insulated Connex floors and wall. Tank 6, the coldest tank, touches outside walls on two sides (Fig. 1). Tank temperatures have not been downloaded since May 12 in an effort to maintain the anaerobic environment in the tanks. According to the patterns we have seen thus far, however, we could predict a general similarity in tank temperatures following the rise and fall in room and environmental temperatures. Biogas project temperatures are measured with Hoboware U Water Temp Pro V2 loggers recording hourly. Table 1. Results of produced gas flammability tests. Positive results of the flammability test indicated usable biogas. For technical and safety reasons, flame tests were not performed after flow meters were installed on 2/18/2010. Tank First positive flame Last confirmed flame 1 1/31/10 2/18/10 2 NA NA 3 1/22/10 2/1/10 4 2/1/10 2/18/10 5 1/21/10 2/9/10 6 1/26/10 1/26/10 9

11 Our most exciting result to date is the speed at which the tanks began to show flammable biogas. Tank #5 flamed after only 2 days, which was surprising considering the typical 30 day waiting period observed with most digesters post-initiation in other projects (GTZ 1999). Gas from tank #3 was flammable on the 3 rd day of the experiment. Photos in section iii) show examples of flame test results. Tanks were filled with warm (approximately 20 C) water from the high school gymnasium. The combination of initial warm temperature together with residual sugar in the tanks leftover from fish product storage served as a high-energy substrate likely facilitated the rapid response of microbes in both the manure and lake sediment to produce biogas. Despite some fluctuations in tank temperatures around the targeted 15 C and 25 C levels (Figures 5-6), all tanks except #2 showed flammable gas within two weeks. As per conventional procedure, once flammable biogas was demonstrated on all tanks (February 15, 2010), we commenced full feeding procedures. Our goals with the feeding procedure were to provide an equal volume of homogenized food-water slurry to each tank daily. In conventional biogas systems, a 1000L system is expected to digest 1kg of organic food waste daily, producing roughly 1,000L of biogas (Samuchit Enviro-Tech Pvt. Ltd.). In accordance with conventional digester protocols, we fed each tank a 2kg slurry consisting of 1kg wet food weight plus 1 kg water. The feeding procedure included collecting and blending food scraps from the high school cafeteria to produce 6 equal portions of food batch with equal 1:1 ratios of blended food and water. A 20- ml subsample of each food batch was collected and stored frozen for later carbon and nitrogen analysis. On February 18 th, Sierra Instruments Top-Trak 820 Series Mass Flow Meters were installed on all systems. Because the electronic meters were installed in line, we could no longer conduct flame tests in the same fashion on the gas discharge tube. Flow meters recorded gas output in a raw voltage format every 5 seconds. The gas flow is measured according to heat transfer and the first law of thermodynamics. The gas flows through two paths in the machine, one of which causes a small pressure drop in the other. In the sensor tube, a constant amount of heat is directed into the gas stream. The difference in the temperature between two resistance temperature detectors gives an output signal that is linearly proportional to the gas mass flow (Sierra TopTrak Manual). Due to the high volume of data and limited capacity of the data logging memory, gas flow loggers must be downloaded every 24 hours and stored on a computer. Post processing flow data includes a custom-written Visual Basic code that compiles 5-second datapoints into hourly averages, which are then more easily converted to daily output rates. Gas flow has been measured and processed continually since Feb. 18, Results to date are shown in Figure 7. 10

12 250 Tank #1-6: Gas Output Daily Total Total Daily Gas Output (L/day) Tank 1 Tank 2 Tank 3 Tank 4 Tank 5 Tank 6 2/11 2/16 2/21 2/26 3/3 3/8 3/13 3/18 3/23 3/28 4/2 4/7 4/12 4/17 4/22 4/27 5/2 5/7 5/12 5/17 5/22 5/27 6/1 6/6 6/11 6/16 Date (mm/dd) Figure 7. Mean daily gas flow rates from digesters. For an optimally operating biogas system, daily flow rates should be approximately L/day. Regular feeding began on February 15 and was stopped on March 21. Although gas is being produced, due to the low ph and high ORP levels, it is unlikely that the gas has high methane content. Spikes seen in mid-may are a result of chemical mediation. It is unknown, without analysis of gas samples, whether that increased gas output is a sign of increased biogas (high methane) production, or production of byproducts to the reaction. In mid-march a number of problems were elucidated. Digester slurry chemistry measurements indicated declining ph on all tanks, which combined with weak flow meter data (optimal tank production is on the order of 1000Lgas/day, whereas we were seeing 50Lgas/day, max) suggested that the tanks were no longer producing useable biogas. Biogas production involves fermentation reactions, through which the microbial communities produce CO 2, volatile fatty acids (VFAs), hydrogen, and other trace gases, some of which are precursors to methane. However, when fermentation reactions exceed methanogenesis, the buildup of fatty acids can lead to low ph conditions. Under conditions of low ph, redox above -300 mv, and the presence of oxygen, methanogens do not produce methane. We hypothesized that overfeeding may have led to the high production of fermentation products, including volatile fatty acids, causing the decline in ph. Although we did show positive flammability of produced gas early in the experiment, it is possible that variations in temperature, sugar content adhering to the HDPE tanks, or other variables contributed to an atypical spike in gas production immediately after sealing the tanks while ph was still close to neutral. Our initial feeding protocol was time intensive and considered by the Cordova High School students to be too gross for a lunch hour activity. The students subsequently reengineered the feeding procedure to involve a faster distribution processes. As the feeding procedure was entirely the students responsibility (as long as scientific standards were met, observed by their teacher or the on-site technician), this provided an unexpected positive highlight of the project. High school students were able to take personal role in the 11

13 engineering, leading to one student presenting their food distribution design at the Alaska State Science Fair. However, due to the acidity of the tanks, feeding was postponed as of March 21 st, and chemical mediation (adding alkalinity) to the tanks was initiated. It has been shown that a carefully mediated cocktail of baking soda, calcium carbonate (lime), and sodium hydroxide can raise the ph of biogas digesters. Table 2 shows our calculation of required alkalinity additions. Table 3 displays the schedule to date of mediation. Care has been taken to prevent tanks from going basic via this treatment, which would be a much more difficult chemical situation to fix. Measurements of ph in the sediment, manure, and mixed sediment-manure sludge at the bottoms of the tank are still around ph 7; hence we are optimistic that the methanogen population has survived this long period of low ph conditions. We are currently in the process of raising the ph, attempting to reproduce the optimal conditions for the psychro- and mesophilic methanogenic communities (ph ). As there are multiple factors that can affect ph, chemicals are being added slowly to avoid over-mediation. Table 2. Chemical mediation assessment. Slurry volumes of 500-mL were individually tested with NaOH and CaCO 3. Post-chemical ph readings are specific to the test of that particular chemical. Estimated NaOH or CaCO 3 needed to mediate an entire tank is shown in the final column. Tank Test Volume (ml) Initial ph Test NaOH (g) Test CaCO 3 (g) Final ph post-naoh Final ph post-caco 3 Estimated NaOH or CaCO 3 (g) needed to raise ph of tank to NaOH or 2000 CaCO NaOH or 1200 CaCO NaOH or 3000 CaCO NaOH or 1000 CaCO NaOH or 1000 CaCO NaOH or 1000 CaCO 3 Table 3. Schedule of chemical alkalinity treatments. ph results highlighted in blue were measured with the Oakton PC510 ph meter. All other ph measurements were determined via litmus paper readings. Date Tank ph NaOH added (g) CaCO 3 added (g) 4/8/ /9/ /10/ /12/ /13/ /14/ /15/ /16/ /23/ /14/ /5/ /7/ TOTAL /8/ /9/ /10/ /12/ /13/

14 Date Tank ph NaOH added (g) CaCO 3 added (g) 4/14/ /15/ /16/ /23/ /14/ /5/ /7/ TOTAL /8/ /9/ /10/ /12/ /13/ /14/ /15/ /16/ /23/ /14/ /5/ /7/ TOTAL /8/ /9/ /10/ /12/ /13/ /14/ /15/ /16/ /23/ /14/ /5/ /7/ TOTAL /8/ /9/ /10/ /12/ /13/ /14/ /15/ /16/ /23/ /14/ /5/ /7/ TOTAL /8/ /9/ /10/ /12/ /13/ /14/ /15/ /16/ /23/ /14/ /5/ /7/ TOTAL

15 The total amount of chemicals added to the tanks thus far is more than what was estimated in Table 2. However, ph in the tanks has not yet reached an optimal level. It is possible that acids are being continually produced by residual organic substrates in the tanks. It is also possible that the test samples used to produce the results shown in Table 2 were not representative samples for the tanks. This could be due to stratification; we have already seen thermal stratification in the tanks, we may suspect chemical stratification as well. In either case, more base addition than originally estimated may be necessary to bring ph up to desired levels. Figure 8 shows the water pressure systems designed to store and provide pressurized gas in Phase 2. As biogas is produced from the slurry in the primary tank, it is forced through the primary gas outlet into the gas storage tank, which is filled with water with a ph of 3-4 to prevent dissolution of CO 2. The pressure of the gas forces the water out through the water transport into the pump bucket. A pump then moves the water into the water storage tank. When the biogas is ready to be used, the valve between the water storage tank and the gas storage tank is opened, causing the water to flow back into the gas storage tank, forcing the biogas out at pressure from the final gas outlet. We have already assembled this water pressure system for three of the digesters (standing outside the Connex, Figure 1); however we will postpone usage of the water-pressure component of the digester system until we have higher levels of flammable biogas production (or until we have finished phase 1, where our priority is to get accurate measurements of biogas production rates, using the flow meters). Figure 8. Water pressure system for storing and dispensing pressurized biogas. System components include: 1) Feeding tube 2) Effluent pipe 3) Primary gas outlet 4) Flame tester 5) Gas inlet 6) Water transport 7) Pump bucket 8) Water inlet 9) Final gas outlet ii.b) Health and Safety Conventional biogas digesters are typically considered safe and are kept in and around homes. However, there are some safety issues that are important to be aware of, especially while conducting experiments with younger students. 14

16 Flammability/explosions: Biogas is flammable. Methane is explosive at a concentration of 5-15% in atmospheric air. It is important that the biogas digesters do not have any leaks, especially if they are in an enclosed space, as they are in the Connex. To prevent safety hazards due to flammability, our tanks are tested for leak points by immersing joints in soapy water and periodically squirting soapy water on the joints to watch for bubbling. All gas produced flows out of the Connex via the gas outlet pipes. Biogas is not allowed to be released within the Connex. Ventilation holes have been drilled into the Connex in the ceiling to allow any unintentional methane to escape (methane, being lighter than air, will rise to the ceiling). Students are not allowed to bring any ignition source (such as a lighter) into the Connex. Occasional flame tests conducted by the on-site technician are done outdoors and without students present. Students are also required to work in pairs to avoid accidents. Hydrogen Sulfide (H 2 S): Hydrogen sulfides can be produced as a side product of fermentation. The gas is flammable and toxic. At higher concentrations, or prolonged exposure to low concentrations, it is a mucus membrane irritant. Exposure can lead to headaches, nausea, and in extreme cases, pulmonary edema, heart irregularities, and unconsciousness. We have installed hydrogen sulfide detection badges in the rooms to monitor higher levels of H 2 S (at low, non-toxic levels, hydrogen sulfide can be detected by its smell of rotten eggs). Ventilation: The build-up of certain gases in an enclosed space can be toxic. Biogas digesters produce methane, carbon dioxide, hydrogen sulfide, and other gases which can be deadly at high concentrations. As with the flammability issue, tanks are tested for leaks and opened only occasionally when the Connex doors are wide open. Ventilation holes in the ceiling allow lighter gases to have an escape outlet. In addition, the Connex is flushed at least partially once a day, when the doors are opened during the flow meter download process. General safety procedures also include students being required to work in pairs, and having the Connex locked when a supervisor is not present. We are also in the process of coordinating an environmental health and safety assessment of the Connex site with the Cordova fire department. ii.c) Schedule of project The project, according to the broad outline in the proposal, is technically on schedule. Phase 1 is well underway. Construction of digesters is complete. Initial biogas was produced. Now we are working on raising ph in order to return digester conditions to those optimal for methanogenesis. When methane (biogas) production starts again, we expect to begin a more comprehensive analysis of the efficiency of psychrophilic vs. mesophilic methanogens in biogas production. ii.d) Project budget As of May 31, 2010, the project timeline is 30% complete. The UAF budget is on track with the project schedule, neither over nor under budget. This is somewhat to be expected as the UAF budget is primarily labor and is fairly predictable and manageable. Originally we planned for the UAF team to operate through part-time technical support to the project including regular site visits to Cordova; however, complications of acidification of tanks and more rigorous remediation necessitated the move of a full time UAF technician (Laurel 15

17 McFadden) to the site. On-sight full time UAF technician salary until June 2010, followed by part-time support thereafter, will require re-budgeting a fraction of the PIs salary to technician salary. UAF will also need to redirect funds within its sub-award towards contractual services. The equipment costs have been a little higher in some areas (instrumentation) and compensated in others. The grant match funds were reported as approximately on budget, the detail will be available in the next report. Lesli Walls will also submit a separate financial report to the Denali Commission. The CEC and Cordova Schools budget is approximately 10% over, but the match is over approximately 40%. The CEC budget was primarily for materials. The additional insulation, wood, and hardware necessary to create a climate controlled environment for the project negatively impacted the budget. This was compensated for by reducing the plumbing and feedstock supplies portion of the budget. Since the equipment costs represent start up costs, they are more heavily weighted on the first portion of the project, so it is appropriate that over 40% of the budget has been consumed at this time. The Cordova Schools budget is primarily for travel and dissemination of project results. Since travel and showcase events are discrete events representing most of the cost, the budget consumption has been high for the presentations to the Alaska Power Association in Juneau in February, 2010 and at the Rural Energy Conference in April, This travel represents more than half of the project related travel, but has consumed less than half the total budget. The level of effort applied to the project by both the High School teacher and the students has been much more enthusiastic than anticipated, as reflected in the matching hours. In summary, the UAF and CEC/Cordova Schools budgets are within expectations for this phase of the project. No budget overrun is expected at this time. ii.e) Hurdles and solutions Project problems and solutions were mentioned in ii.a, and are outlined in more detail here. Lack of biogas production Traditionally, biogas production requires a start-up time of 1-3 months following digester construction. Apart from the immediate production of flammable gas within days of start-up, which was most likely the result of breakdown of residual sugars in the digester tanks, we have not yet confirmed production of biogas. We speculate several causes: Cold temperature treatments. Problem: If traditional (warm climate) digesters require 1-3 months for establishment of microbial communities in digesters to produce biogas, a process that requires replication of microbial cells on the order of days to weeks, then at colder temperatures we would expect a longer start-up phase. Solution: The solution is to continue to maintain cold temperature treatments and wait for biogas production, since the response of psychrophiles to cold temperature is the purpose of the Phase 1 study. Low microbial population size. Problem: Traditional digesters are constructed with a 50:50 manure to water ratio, with manure containing a large number of microbes required for fermentation and methanogenesis. Due to logistical constraints on lake sediment acquisition by the slow method of percussion coring lake sediments in narrow tubes, our digesters contained a much lower ratio of microbial inoculum (approximately 2.5:50 sediment:water; 6:50 sediment+manure:water; and 3:50 manure:water). Beginning 16

18 with a lower concentration of microbes we would expect an even longer start-up period for cell replication and growth of the microbial population. Solution: We collected another 96L of mud and 120L of manure to re-inoculate, at a higher concentration, tanks #4 and #6 (bringing the concentrations in those tanks to a total of 7.5:50 mud:water and 9:50 manure:water, respectively). As our primary interest is the biogas production of psychrophiles versus mesophiles, we will focus on those two tanks to encourage the biogas production. We will continue to maintain the other tanks as well. Since we have introduced the increased substrate containing additional microbial populations, tank #4 has shown some increase in gas output, but tank #6 continues to show almost no activity. This could suggest that #6 continues to be overly acidic, while tank #4 has begun to recover and utilize a larger methanogenic community. Hydraulic retention/residence time. Problem: Feeding digesters involves adding a blended food/water slurry and removal of an equal volume of microbe-containing effluent. Depending on the volume of the digester tank and turnover time of microbial cells, the feeding process could lead to significant dilution of the digester slurry s microbial population by removal of effluent. Residence time is defined as the capacity of a system to hold a substance divided by the rate of flow of the substance into the system. Adding 2L of microbe-free slurry to a 1000-L tank daily results in a 500-day retention time. A slow replication rate of microbes could exacerbate the problem if low microbial retention and dilution. Solution: To prevent the removal of microbes, food can be blended with effluent instead of water. Although some effluent must still be removed to be displaced by the food mass, the microbial waste will be reduced. Feeding must also be started slowly, with small amounts, to ensure that the system can handle the amount of material and not over-produce materials to an inhibitory level. Finally, many microbes require a surface to grow their films on. On May 4, we hung socks containing mud from the top of tank 4, to increase the surface area for microbial colonization. Low ph. Problem: Methane (the flammable component of biogas), is produced by a consortium of microbes through multiple processes operating in sync with one another, including fermentation and methanogenesis. In step one, fermentation processes generate methane precursors, many which form acids (volatile fatty acids, etc.). In step 2, a separate set of microbes (methanogens) utilize precursors to produce methane, but optimally under ph conditions of Overfeeding of organic substrates can favor the first step, leading to the buildup of organic and carbonic acids and conditions of low ph. Daily feeding of a large volume of organic substrate, especially relative to the small volume of microbe-containing manure and sediment in our digesters, led to acidification of the water column in our tanks. Fortunately, subsamples of bottom-sludge revealed near-neutral ph (Table 5). Typical lake sediment ph measured in thermokarst lakes ranges between 7-8 (pers. comm. Katey Walter Anthony). Typical cattle manure ph is 7.0 (Leggett et al., 1996). 17

19 Table 4. ph results found in tank sludge. As the bottom sludge revealed a ph closer to 7 than the effluent, we believe the microbial population should still be viable. Date Tank Sludge ph 4/21/ /21/ /21/ /21/ /21/ /21/ Solution: Once we recognized that the low ph condition was not changing towards neutral on its own through microbial processes, we ceased feeding the tanks. This is the recommended solution for the problem of sour tanks in conventional biogas production procedures (Gerardi 2003). We also determined the quantity of alkalinity that needs to be added back to the tanks to raise the ph by adding alkaline chemicals to beakers containing subsamples of sludge and slurry and then scaling quantities to the volume of the digester tanks. We are in the process of restoring conditions of neutral ph by gradually increasing alkalinity and patiently waiting for organic acids in the tanks to be consumed by resident microbial communities. ph trends to date can be seen in ii.a) Fig. 4. Since initiation of chemical mediation, the ph has increased in all tanks. Except for tanks 1, 2, and 6, the ph is still below 6 in all digester effluent. We are continuing with chemical treatment.. Once we have reached the targeted ph 6.8 and observed flammable biogas, we will resume feeding tanks at a slower initial rate with the goal of building up to the targeted 2 kg per day (1 kg food + 1 kg water). Temperature fluctuation. Problem: Methanogens are sensitive not only to a general temperature range, but also to changes within their acceptable range. Most mesophiles and psychrophiles cease functioning with temperature variations of +/-2 C within an hour (Gerardi 2003). As seen in ii.a) Fig 5-6, there is some temperature variation within all six tanks. Although daily temperatures are fairly stable, there are some cases in which the temperature changes a couple degrees within a day. This is probably not enough to affect the methanogens, but it is possible with a jump of more than a few degrees the microbial communities could be negatively affected. Solution: Although temperature variability within treatments is not ideal, we hope the small changes do not have a significant effect, especially when spread over time. However, temperature fluctuation can affect the metabolic rate of bacteria. We are closely monitoring temperature with dataloggers. We can correlate increases or decreases in gas production to possible temperature variability. Lack of Mixing. Problem: Intended for construction and use by residential Alaskans, our tanks are designed to be non-technical and easy to build with minimal specialized materials or engineering experience. The digesters do not have a built-in way of internally mixing the slurry. It would be ideal to mix the contents of the primary tank, to allow food to reach the entire microbial community, prevent stratification, and prevent scum buildup. Although food does naturally migrate through layers of sludge to feed the lower microbes, it is a slower process without mixing. Our systems cannot currently be mixed without opening the tanks, which introduces atmospheric air and that can contaminate 18

20 the slurry with the introduction of oxygen. Solution: It may be possible to install a simple mechanical mixer, perhaps attached to the base of the feeding tube, which could be rotated after feeding to mix the slurry. However, considering the density of the sediments in the psychrophilic tanks, this may not be realistic until the tanks are eventually based of pure microbial inoculations (rather than sediment-based inoculation). Chlorine content. Problem: Many city water resources, including those in Cordova, are treated with chlorine to disinfect the water for drinking. As city water is the easiest available water resource for making the primary tank slurry, some chlorine was introduced to the slurry in the >900 L of tap water at initial setup and subsequently with the feeding. Chlorides can destroy microbes, which makes it dangerous and possibly detrimental to our methanogens. Solution: Although it is logistically very challenging, digester tank water could be based on local lake, stream or river water rather than city-treated chlorinated water. This may be a more viable solution for single-household units, rather than our 6-tank experimental system. Thus far, it is very difficult to say whether the chlorinated water has had a significant effect on our tanks. We tested the use of chlorinated tap water vs. non-chlorinated Lake Eyak water in the November pilot study and found that the High School tap water did not prevent biogas production. Given that we continue to observe microbial activity, we can conclude that we have not decimated the microbial community in the 1000-liter digesters either. Scum and foam. Problem: As the microbes will only digest certain materials, an overfeeding of fatty acids, combined with other environmental conditions such as under-mixing, stratification, and temperature fluctuations, can lead to the production of foam and a scum layer. Food types that lead to scum build up have high grease content or tough vegetable matter. This scum can block inlet and outlet pipes, causing problems in utilizing or measuring gas production. Solution: To prevent scum, a balanced food source should be fed to the tanks, minimizing greasy and tough (woody, fibrous) food types. If an extreme amount of scum has built up, the tank can be opened to break up the film. Feeding procedure Cordova High School students re-engineered the distribution design to shorten time commitment for preparing organic substrates and feeding digesters. (Please see section ii.a). Balance of responsibilities. Problem: The project was originally designed to be constructed by the full team on-site in Cordova in early January, and then to be maintained by Cordova High School students for the duration of the project with occasional (2-3 yearly) site visits by UAF technical staff for troubleshooting and advanced chemical monitoring. Although construction was completed as planned, a number of unanticipated problems have required the presence of a full-time onsite technician (Laurel McFadden). Chemical imbalances, discussed above, led to the failure of the systems to produce biogas. Monitoring, standard chemical measurements, mechanical maintenance, and feeding took significantly more time than anticipated. Although this was partially alleviated when Cordova High School students realized the extent of their time commitment and sought to streamline the feeding process, the chemical treatments and troubleshooting were beyond the scope of the Cordova contingent. Solution: McFadden moved to Cordova to monitor the project full-time in April. Although 19

21 solutions to many problems have either been found or are in progress, technician time represents a significant unanticipated expense to the project. It is still anticipated that, with the knowledge evolving from this extensive troubleshooting, extensive technician time should not be required for systems in community use. It is also true that we are trying to maintain certain scientific standards, and careful measurements, which are atypical of traditional digester use (contributing to increased time commitment requirements). The project consists of experiments that have not been done before, and thus has higher risk for more technical time needed for troubleshooting. It is hoped that most issues will be solved within the next month or two. As of early June, 2010, McFadden s will work on half time salary for this project. Cordova High School volunteers will be needed for feeding and maintenance for the duration of the project, as originally planned. Positive accomplishments: Proven flammability One of the primary goals of this project was to determine if the psychrophiles that produce methane in thermokarst lakes could be harnessed in an artificial environment to produce biogas. With the initial (30 days) of biogas production through which psychrophiles (and mesophiles) generated biogas using residual sugar in the digester tanks as a substrate, we proved that this is possible. The pilot study also proved longer-term biogas production by thermokarst-lake microorganisms. Student education - This project has provided an opportunity for a high level of educational enrichment across a broad group of students at Cordova Junior High and High School. The students involved can be broken into three groups: the general student body, the students in science club, and those enrolled in chemistry class. The middle school and high school students eating lunch in the cafeteria were aware of the project and its purpose each day as they made a choice to recycle their food scraps. As with many high school fads, recycling food became the cool thing to do. Students at Cordova Jr./Sr. High have gained experience about the reality of doing real science and alternative energy development as they followed the project through their friends and classmates deeper involvement. The science club is made up of high school students who volunteer for this extracurricular club. They were willing to commit to the maintenance of the digesters for the course of the two years, and volunteer to collect food, process food, and feed the digesters. As a group they worked on the various construction events, and individually they worked to make sure that the food scraps in the cafeteria were collected, processed, and fed to the digesters in a scientifically accurate manner. Three science club students were able to write up various aspects of the biogas digester project and present it at the Alaska State Science and Engineering Fair. About half of the science club students were able travel to Fairbanks to give an update on the project at the Alaska Rural Energy Conference. Students enrolled in the chemistry class had perhaps the greatest benefit from the methane digester project because of the level of buy-in and the structure of the course. Initially it was the chemistry class who researched biogas digesters, and prepared movies for presentation to the Denali commission. These students were committed to the project because they asked to be. This group played an important 20

22 role in the construction of the digesters, and in the many small engineering problems that arose. This group took many of the chemistry measurements and spent a considerable amount of time learning about the meaning of the data. They also had the opportunity to travel to Juneau to present to the Alaska Power Association and visit several members of the legislature. Community outreach We have had the opportunity to present our project ideas and preliminary results at meetings with the Alaska Power Association and Alaska state legislators in Juneau, and at a variety of conferences, including the Alaska Forum on the Environment and the Alaska Rural Energy Conference. Public response has shown community interest in and inspiration by our non-technical, low-impact, greenhouse mitigating technical development. Five Cordova High School students traveled to present at the Alaska Rural Energy Conference in Fairbanks. Titles of our project presentation at the Alaska Forum on the Environment and Alaska Rural Energy Conference were: Walter Anthony, K., Culhane, TH., Koplin, C., McFadden, L., Low, A. Improving Cold Region Biogas Digester Efficiency. McFadden, L. Alaska Forum on the Environment. Anchorage, Alaska. February 8-12, Walter Anthony, K., Culhane, TH., Koplin, C., McFadden, L., Low, A. Improving Cold Region Biogas Digester Efficiency. Low, A., Hess, E., Allen, J., Americus, I., Americus, B., Zamudio, A. Alaska Rural Energy Conference. Fairbanks, Alaska. April 27-29, Website development- Website developer Brandon Shaw designed a site ( for the Cordova Energy Center, the venue at which the biogas experiment has been conducted. The website is an online location where students and collaborators can post questions, observations, results, general information, and instructional videos. While still in development for ease of use, it is an excellent platform for public dissemination of information, global communication of observations and results among team members, and troubleshooting forums. The Cordova High School Students have produced a number of films to post on the site, detailing their involvement in the project and providing video instruction for many aspects of the project s construction and maintenance. 21

23 iii. Pictures of before and after progress, or photos that are representative of the funded activity, to the extent possible (digital format with a short description of the activity and names of those in the photos). Laurel McFadden coring for psychrophilecontaining lake sediments near Fairbanks, Nov Brandon Shaw collecting mesophile-containing cow manure at the Northern Lights Dairy in Delta Junction, Jan The Connex in first stages of construction behind CDHS, with water pressure tanks outside. TH Culhane prepares fitting pipes for the 1000-L primary digester tanks. 22

24 Peter Anthony prepares construction materials. Culhane organizes pipe fittings. McFadden and Culhane make internal fittings on a water pressure tank. Insulation panels going up inside the Connex, while McFadden and Culhane place the primary slurry tanks. 23

25 The dividing wall between cold and warm rooms goes up, while electrical wiring is installed. Students prepare insulation panels to fit around primary slurry tanks. McFadden, Shaw, and Culhane place fittings on water pressure systems. Working with water transport pipe fittings while snowing (Jan. 2010). Katey Walter Anthony distributes manure and sediments into the primary tanks. Feeding tubes are fit with internal temperature dataloggers. 24

26 First biogas flame is observed on January 21, Materials for installing flow meters. Shaw wires flow meters to a datalogger and computer. Complete digester set-up, with feeding pitcher, effluent test beaker, and running flow meter. 25 CDHS student monitors chemistry by measuring ph with litmus paper. As of April 14, ph measurements are made with an Oakton PC510 meter.

27 Food processing trailer, including sink with installed food blender (underneath bucket). CDHS student-designed food dispersal system, to insure even distribution of food batches. Testing acidic effluent for amount of mediating chemicals needed to be added. Adam Low and CDHS student re-inoculate tank with new manure. Sybille Culhane, Killian Culhane, and Peter Anthony work in the Connex. 26 Low and CDHS students visit the Fairbanks Permafrost Tunnel with Kenji Yoshikawa after presenting at the AREC.

28 Appendix 1 In November 2009, we conducted a pilot experiment to determine the minimum ratio of lake sediments to water required to sustain biogas production. The experiment consisted of ten 5-gallon buckets, with varying ratios of mud to water. Other experimental variables included temperature (warm vs. cold), water source (Lake Eyak vs. tap water), organic food stimulus (sugar at different levels, potato chips, or none), and substrate for increasing surface area for microbial growth (fish net, wood chips, or none) (Table 1). Table 1. Pilot study set-up. Ten buckets with varying mud-water ratios were tested for gas production under a variety of conditions. Bucket Treatment large M/W ratio large M/W ratio with extra sugar small M/W ratio Medium M/W ratio with no sugar Medium M/W ratio Medium M/W ratio with pine shavings (~1 L volume) as surface area for bacterial growth Temperature on 11/27/09 classroom (~25 C) classroom (~25 C) classroom (~25 C) classroom (~25 C) classroom (~25 C) classroom (~25 C) Mud (%) H2O (%) Mud (L) H2O (L) H2O source Air headspace (L) Sugar to balance O2 dissolved in water (g) Sugar to balance O2 in headspace (g) Extra 'stimulus' sugar (g) Total sugar (g) Eyak Eyak Eyak Eyak Eyak Eyak Medium M/W ratio with tap water classroom (~25 C) Cordova High School tap water Medium M/W ratio with fish net (~1 L volume) as surface area for bacterial growth Medium M/W ratio with cold temp Medium M/W ratio with 415g unsalted potato chips M/W = mud/water classroom (~25 C) energy center (~4 C)?? classroom (~25 C) Eyak Eyak Eyak g unsalte d potato chips, no sugar 27

29 Setup The lake sediments used in this pilot study were collected via piston and percussion corer from Goldstream Lake near Fairbanks on November 3-4, As it is a very slow process to collect mud, we were interested in knowing what ratio of sediments to water would be economical for a psychrophile-run digester. The buckets were designed to be glued shut and inverted (to prevent any air from entering the bucket once they were sealed), with a rubber stopper installed in the base to allow sampling of the accumulated gas in the headspace. Buckets 1-2 were based on a large mud to water ratio (9:1), bucket 3 on a very low mud:water ratio (1:99), and buckets 4-10 based on an economically mid-range estimate of a mud:water ratio (1:9). All buckets except #4 and #10 were given an amount of sugar calculated to allow the aerobic microbes to quickly digest the dissolved oxygen in the water and the oxygen in the headspace of the buckets (based on the amount of glucose needed to balance a mol or L of oxygen in water or air, respectively). Bucket #4 was used as a control and given no sugar at all, while #10 was given a comparative mass of potato chips instead of sugar to test sugar versus carbohydrates as an impetus for oxygen consumption. Bucket #2 was given extra sugar as a test stimulus for methanogens post-oyxgen consumption. Bucket #7 was mixed with tap water instead of lake water, to test if there was a noticeable difference between the two water sources to the microbe s gas production. Bucket #9 was kept at a relatively cold temperature to compare to the other warmer tanks. Buckets #6 and #8 tested two types of bacterial growth substrates: sawdust and fishnet, respectively. It has been argued that methanogens will have increased growth if given a surface area on which to colonize (Geeta et al., 1986). Results Less than 48 hours after sealing the buckets, on November 28 it was found that buckets #1 and 2 had exploded from gas pressure (Figure 1). This confirmed that the lake sediments contained a viable bacterial population, and that the large ratio of mud to water could be used. Bucket #10 was also found to be severely distended, suggesting that a medium ratio with a food source was also a usable option. This was confirmed on November 30, when buckets #7 and 10 exploded. The extreme gas production in #7 suggested that the water source did not have a significant effect on gas production. Bucket #8 was found to be distended, although the short time period in which the gas was produced suggests that at that point, the fish net growth medium had had little to no effect on the bacteria (given that the bacterial reproduction rate is on the order of 30 days, increased colonization space would have no consequence in 3 days). 28

30 Figure 1. Buckets #1-8 and 10 in the 25 C room, showing exploded buckets #1 (back left) and #2 (front) on November 28, The mud from Buckets #1 and 2 were used in a small construction experiment by Cordova High School students on December 4, as it had been proven that gas could be produced at a medium ratio (no need was seen to maintain the high-ratio buckets, considering the difficulty of obtaining the mud). All of the remaining buckets were placed in a semi-heated building (approximately 4 C) until January 18 th, 2010, when construction on the main experimental tanks began. The buckets were each punctured and the escaping gas was ignited to confirm that the gas produced was biogas. There was positive ignition on all buckets #3-10. Although by that date (2 months post-sealing) no definitive comparison could be made about the total volumetric gas production from each bucket. We concluded that a variety of sediment to water ratios could produce biogas. Based on this pilot experiment, we determined that a minimum 10% sediment ratio was sufficient to power a 1,000L digester system. Problems Although the buckets did show positive biogas production, an error in the sugar calculations may have skewed our results. Due to an extreme over-estimate of the amount of sugar it would take to consume the oxygen in the water and the air headspace, it is possible that the explosions seen in buckets #1, 2, and 10 could be attributed to an overabundance of glucose, and such an immediate gas production would not normally be expected. It is interesting to note that although left alone for 2 months, without being fed, the buckets continued to produce biogas. This could suggest that over-fed digesters will eventually recover, if left alone. 29

31 References: Geeta, G.S., Raghevendra, S., and Reddy, T. K. R. Increase in biogas production from bovine excreta by addition of various inert materials. Agricultural Wastes 17 (2), 1986: Gerardi, Michael. The Microbiology of Anaerobic Digesters (New Jersey: John Wiley & Sons, Inc., 2003), 23. Germany: Information and Advisory Service on Appropriate Technology (ISAT) and Gesellschaft für Technische Zusammenarbeit (GTZ), Biogas Digest: Volume 1, Biogas Basics, Leggett, J., Lanyon, L., and Graves, R. Biological Manipulation of Manure: Getting What You Want from Animal Manure. Pennsylvania State Agricultural and Biological Engineering Extension. Fact sheet: G

32 Denali Emerging Energy Technology Grant: Improving Cold Region Biogas Digester Efficiency Year 1 Quarterly Report, Q3 September 30, 2010 Table of Contents i. Y1Q3 Summary.1 ii. Schedule and milestone information.2 ii.a) Personnel.2-3 iii. Narrative summary of the project.4 iii.a) Project Status and Accomplishments.4-14 iii.b) Health and Safety iii.c) Schedule of project.16 iii.d) Project budget.16 iii.e) Hurdles and solutions iii.f) Positive Accomplishments References.23 Appendix Appendix Appendix 3. (Photographs) 28-29

33 i. Y1Q3 Summary The project is on target with regards to progress in Phase 1. Phase 1 commenced January The entire project team met on site in Cordova in Nov to conduct a pilot study, in January 2010 to start Phase 1, and in June 2010 for a mid-phase project meeting. The most exciting result since the Y1Q2 report is that we have achieved healthy biogas production in our phsychrophile-only tanks in both the warm and cold rooms and in the mesophile tank in the warm room. These results support our original hypothesis that psychrophilic organisms extracted from permafrost thaw lakes are capable of producing biogas at low temperatures (15-25 C), whereas conventional mesophile methane production would be limited to warm temperature conditions ( 25 C). Methane concentrations in the biogas reactors reached a maximum of 82% CH 4 by volume, which is 22% higher than conventional biogas digesters. During the remainder of Phase 1 we will make improvements to our gas collection system and raise the feeding rate of the digesters to determine their maximum biogas production rate. Our production target is 1,000 liters per day on a 2kg per day feeding regime, comparable to warm climate digesters of the same household scale. This information will be necessary for commencement of Phase 2, demonstrating the use of biogas to power gaspowered technologies. 1

34 ii. Schedule and milestone information The project continues to closely follow the original outlined plan: - Construct Digesters for Phase 1 by December 15, 2009 Completed January Begin Data Collection by February 1, 2010 Ongoing, commenced January 18, June 25-27, 2010, project meeting onsite in Cordova (all team members present); High school student presentations - Perform mid-term Analysis of Data by July 30, 2010 Completed informally internally as a project team, and formally in Quarterly reports 2 and 3. - Year 1 Q4 Report due December 15, Phase II Scoping Deadline January 25th Phase I Report, including analysis of all Phase I data, due February 28, Year 2, Q1 Report due March 15, Year 2, Q2 Report due June 15 - Year 2, Q3 Report due September 15 - Final project report due September 30, 2011 ii.a) Personnel: Cordova Electric Cooperative Clay Koplin Grant Administrator. Koplin has managed most of the financial aspects of the project thus far on behalf of the Cordova Electric Cooperative, serving as the project manager. Koplin serves as a technical advisor to the project. University of Alaska, Fairbanks Katey Walter Anthony Research Director. Walter-Anthony acts as the primary investigator, and has spearheaded the scientific goals and directions of the project. She provides continual scientific expertise and project management. She contributed to the data analysis, interpretation and writing of this report. Casey Pape Research Technician. Pape joined the project in early September, 2010, to replace Laurel McFadden as the primary project technician. Pape is currently working on-site in Cordova, maintaining the digester experiment, including data collection, analysis, and troubleshooting. Pape led the preparation of the current quarterly report with assistance from other team members. A recent graduate of Western Washington University, Pape has a long history of experience with small scale (<1 MW) alternative energy projects including biogas digesters and is excited to be working on this project. Due to prior work commitments, Pape will be away from the project Oct. 15 Dec. 5, In his absence, Adam Low and Clay Coplin will maintain feeding and measurements in Cordova. They will work with Pape to collect data in preparation for the Y1Q4 Report. Pape will lead the assembly and writing of the report upon his return to Cordova on Dec. 5. Pape plans to remain with the project until its completion in September Dane McFadden Project Intern. Currently an undergraduate at Stanford University, Dane McFadden helped maintain digester performance over the summer. Job responsibilities included: maintaining daily gas data collection, feeding, chemistry measurements and gas sampling. McFadden will be using his experience here in Cordova as his required internship at Stanford University and will generate an intern project report which will be submitted to the PI, the Denali Commission, and to Stanford University. 2

35 Laurel McFadden Research Technician. McFadden, having begun a graduate program at UAA in mid August 2010, now consults on the project and has provided invaluable training of new project team members (i.e. Dane McFadden and Casey Pape). She provided feedback and assistance with the writing of this report. McFadden was a key contributor to the project development and took the lead on organization and preparation for the initial construction and setup. McFadden completed the first draft of a Biogas Handbook for Alaskans, which will be submitted as a deliverable in final form to the Denali Commission by the end of the project. Peter Anthony Research Technician. Anthony consults on the project and continues to provide technical expertise to the maintenance and application of digesters. He participated in the on-site project meeting in June 2010 and provided recommendations for simplification and winterization of the gas collection system in preparation for Phase 2. Anthony conducted the gas chromatography analyses of biogas composition for this report. Jeffrey Werner State FFA Director. Werner is looking into using the effluent from anaerobic digesters as a liquid fertilizer for agricultural crops. Located at the horticultural center at UAF, Werner remains enthusiastic about the possibilities of the potential uses of the once thought of waste product. Cordova High School Adam Low Science Teacher. Low was integral in bringing in student involvement via classroom curriculum and extracurricular projects. He was on the construction team and continues to assist troubleshooting, construction, and maintenance. Cordova High School Students Volunteers. The students have been highly involved with construction, feeding, maintenance, and public presentation. They include the seventeen Chemistry class students and Science Club students (Craig Bailer, Ben Americus, Adam Zamudio, Sophia Myers, James Allen, Eli Beedle, Josh Hamberger, Keegan Crowley, Kris Ranney, and Carl Ranney). Ian Americus, Ben Americus, Erin Hess, James Allen, and Adam Zamudio presented at the Alaska Rural Energy Conference in Fairbanks along with Adam Low. SOLAR Cities TH Culhane Biogas Expert. With an extensive history in biogas technologies, Culhane developed the water-pressure tank design and provided extensive technical knowledge to the engineering of the project. He worked with and advised the on-site construction in January 2010 and provides expert advice from his home base in Germany. Sybille Culhane Co-founder of SOLAR Cities. S. Culhane assisted in initial construction efforts and managing financial aspects of SOLAR Cities involvement. Chena Hot Springs Bernie Carl Owner of Chena Hot Springs. Carl has expressed interest in deploying a digester at Chena Hot Springs, and has offered space for testing a digester in his greenhouse. Others Brandon Shaw Website Development. Shaw designed and manages the CordovaEnergyCenter.org website, where the project is hosted. He also assisted at the initial construction site, and was integral in the assembly of the flow meter system. 3

36 Keywords: Biogas, anaerobic digester, reactor, phsychrophiles, mesophiles, methane, etc. iii. Narrative summary of the project status and accomplishments to date, and addressing the following questions: is the project on schedule, is the project on budget, and what actions are planned to address any project problems. iii.a) Project Status and Accomplishments The project is on target in Phase I of the original research proposal. Phase I involves the testing of several different blends of methanogenic microbial populations (mesophilic and psychrolphilic) in order to examine different characteristics of digesters that operate in cold environments. The primary goal of Phase I experiments are to construct and monitor six different anaerobic digesters and to try to maximize the amount of gas that can be produced in depressed temperature climates (see original research proposal for more details on Phase I goals and objectives). We have achieved substantial improvements in biogas production during the past few months following resolution of challenges experienced during the previous quarter (see Y1Q2 report). All of the complications encountered are common among new biogas start-up efforts (Gerardi 2003). Our gradual chemical amendments to raise the ph in digesters to have been largely successful. In response to our concern about the possibility of low microbial population sizes, we added additional fresh manure to Tank 6 (mesophiles, 25 C) and additional fresh thaw-lake lake mud to Tank 4 (psychrophiles, 25 C). The microbial additions could not have hurt the biogas production progress in these tanks; however, since we have since observed successful biogas production not only in Tanks 4 and 6, but also in Tanks 1 (psychrophiles, 15 C) and most recently also in Tank 5 (mixed phsychrophile/mesophile), it is possible that the microbial amendments were not necessary. Preliminary analysis of recent gas samples shows that tanks are producing methane in high concentrations (as high as 50-82% in some cases). This is a very encouraging finding as it illustrates that not only are tanks supporting microbial populations, but that those communities are healthy and supporting active methanogenesis. At this time it is the researchers intention to begin pilot-level experiments for Phase II (-finding usable applications for biogas produced from the anaerobic digesters), while at the same time maintaining the Phase I study through completion in effort to improve yield and efficiency. Phase II will also incorporate data collection and monitoring of time and effort required to build and maintain biogas digesters to provide economic assessment as part of our assessment of biogas technology in Alaska. Successful remediation of digester ph Several setbacks occurred during the initial Phase I study that resulted in the delay of biogas production. The greatest setback was the early issues encountered with over-feeding the digesters causing the tanks to accumulate high concentrations of volatile fatty acids (VFAs) and acidify. The methane fermentation pathway involves several steps and multiple species of bacteria and archea in order to produce biogas (Weiland 2010). Prior to microbial synthesis of methane, acetogenic and other bacteria must first break down complex volatile organic matter to form simpler VFAs. Those VFAs can be further decomposed by methanogens in order to form 4

37 methane and other trace gases. Often times, however, acetogenic microbial metabolic rate can exceed other microorganism activity and result in a buildup of the concentration of acids within the system (Gerardi 2003). Early in our experiment we suspect this acidification to have occurred in our digesters and resulted in minimal amounts of biogas production and decreased methanogen activity. Chemical remediation was then considered as a means to restore system ph. Soon after sealing the tanks and beginning our initial feeding schedule in January of this year a marked drop in ph was noted among all six digesters. In subsequent months the declining ph became too great an issue to be ignored and it became clear that remediation steps would have to be taken in order to maintain the integrity of methanogen communities (Table 1). As of March 22, 2010, all feeding was stopped and chemical remediation was set to begin restoring optimal ph conditions for psychro- and mesophilic methanogenic communities (ph ). This required the sending of a full-time UAF technician (Laurel McFadden) to Cordova in order to preserve accurate measurements and perform the necessary chemical treatments to restore digester ph. McFadden s schedule of chemical treatment involved the careful additions of calcium carbonate, calcium oxide (lime), and sodium hydroxide to all six tanks (information regarding treatment schedule can be found in the Y1Q2 R report). The last treatment of alkaline chemicals was performed on June 6, 2010 and ph values have since stabilized at their desired range (Figure 1) with the exception of tank 3 which continues to remain at a very low ph (4.9 as of 9/21/10). Probing of different areas of the tanks during the acidification period revealed that only the liquid water columns of the digesters were acidified, and that methanogens may have still been viable in the neutral-ph of the sediment and manure sludges at the tank bottoms. After successful remediation of water column ph and demonstrated flammability of produced biogas, we resumed feeding of digesters, but at a lowered rate to allow all stages of microbial metabolism (fermentation and methanogenesis) to increase slowly together. Table 1. Tank acidity recorded at their lowest ph values in April 2010 and at their current, largely restored, values in September Active methanogenesis does not occur efficiently at ph values < 6.5. Cessation of feeding and chemical remediation resulted in higher ph, conditions favorable to biogas production. Tank Date of lowest recorded ph ph value Date of last sample ph Value 1 3/31/ /21/ /29/10 5 9/21/ /29/ /21/ /19/ /21/ /19/ /21/ /17/10 4 9/21/

38 Figure 1. ph results indicate that the acidity of the tanks is declining and optimal ph values (ideally ) have been restored. Despite of multiple additions of Calcium carbonate, Lime, and Sodium hydroxide Tank 3 has shown little response chemical treatments. Tank 3 remains as low ph of 4.9 and is unlikely to support methane production at this time. ph was measured with Macherey-Nagel litmus paper January 21-April 16, following which it was more precisely measured with an Oakton PC510 ph meter. In accordance with restoration of biogas digester conditions, we also observed changes in dissolved oxygen and redox within tanks. Both dissolved oxygen and redox levels declined to anaerobic levels favorable to methanogenesis (See data figures in Appendix 1). Flammable biogas restored Flammable biogas is once again being observed in many of the original six digesters. We interpret this as an indication that the digesters contain healthy microbial communities of fermenters and methanogens working synergistically. Due to low feeding rates, biogas production rates are also still relatively low; however, recent analysis of gas composition on a Shimadzu 2014 gas chromatograph equipped with a flame ionization detector revealed that CH 4 concentrations in gas flowing from the digester tanks is up to 82% by volume (Figure 2). Typically conventional biogas reported in the literature is 40-60% by volume. It is possible that as we increase feeding rates to increase gas production rates, we will observe a decline in CH 4 content associated with rebalancing of fermentation and methanogenesis and in variation with feedstock quality. 6

39 90 80 Methane (CH 4 ) Concentration (%) Concentration (%) Concentration (%) Dec Jan Mar-10 2-May Jun-10 Carbon dioxide (CO 2 ) 10-Aug Sep Sample collection date Dec Jan Mar-10 2-May-10 Oxygen (O 2 ) 21-Jun Aug Sep Sample collection date Dec Jan Mar-10 2-May Jun-10 Nitrogen (N 2 ) 10-Aug Sep-10 Sample collection date 50 Tank 1 Tank 3 Tank 4 Tank 5 Tank 6 Tank 1 Tank 3 Tank 4 Tank 5 Tank 6 Tank 1 Tank 3 Tank 4 Tank 5 Tank 6 Concentration (%) Tank 1 Tank 3 Tank 4 Tank 5 Tank Dec Jan Mar-10 2-May Jun Aug Sep-10 Sample collection date 7

40 Figure 2. Gas composition results determined by measuring concentrations of methane, CO2, oxygen and nitrogen on a Shimadzu 2014 gas chromatograph equipped with FID and TCD. Concentration of gases are presented as percent by volume. It should be noted that 70% CH4 in Tank 4 shown for Aug. 28 and Sep. 5 was calculated as a correction to lower concentrations measured in samples due to a leak in the sampling system. Both the samples from August/September Tank 4 had the same methane/carbon dioxide ratio - =4.4 Based on a review of the other biogas samples, this should put the methane level of the biogas at ~65-70%, after correcting for presumed dilution from air contamination. The fact that the two samples had the same ratio of these gases, despite a two-fold difference in the methane level, is a good indication that the low reading is due to dilution by atmospheric air in the sample collection stage. Additional gas analyses will be performed to complete the time series of gas composition for assessment of digester behavior over time; however, these preliminary results look good and give invaluable insight into the current health of our digesters. Flame tests show that Tanks 1, 4, 5, 6 have been producing flammable gas (Table 2); however, methane-rich gas from Tank 4 is being diluted by air through a discovered leak in the in the secondary holding tank (water-pressure system). Due to too low of gas flow rates, gas from tanks 2 and 3 is not being collected and we have no data on its composition. Table 2. Results of produced gas flammability tests. Positive results of the flammability test indicated usable biogas. For technical and safety reasons, flame tests were not performed directly from the tanks after flow meters were installed on 2/18/2010. Flame tests are still conducted on Tanks 1, 4, 5, and 6 as they are connected to water-pressure tanks that may be isolated from the flow meters. Tank 4, which is producing 60-70% CH 4, is no longer showing positive flame tests due to a leak identified in the secondary gas holding tank. Tank First positive flame Last confirmed flame 1 1/31/10 9/18/10 2 NA NA 3 1/22/10 2/1/10 4 2/1/10 2/18/10 5 1/21/10 9/18/10 6 1/26/10 9/18/10 GC analysis provides valuable information about digester integrity and microbial fitness. For a digester to be producing gas that is of such high methane content as we have observed recently is a very good thing, regardless of the amount, as it shows we have active methanogens within several tanks and to some extent indicates the health of the microbial communities inside. Since our digesters are now producing high concentrations of methane within the biogas we can determine that these methanogenic archea are now more prevalent in our tanks than they were once before. The time series GC results show that methane concentrations have increased since chemical remediation (Figure 2). Low oxygen levels and 8

41 declining CO2 concentrations are also indicators of healthy biogas conditions in the tanks. More work will have to be done with current and future samples, but our preliminary assessment is that several tanks are producing proportionally high amounts of methane and that this is an indication that methanogens are active and in healthy proportions within the tanks. We expect that an increase in feeding will increase absolute number of moles of CH 4 produced by the digesters throughout the remainder of Phase 1. Resuming feeding of digesters to increase gas production The digesters have not been feed on a consistent basis since the decision to stop feeding them as part of ph remediation on March 22, No feeding took place from March 22 to June 22, The tanks were sealed following chemical treatments, and then feeding was resumed at low levels by Laurel and Dane McFadden. Since the feeding protocols and responsibilities were initially designed by and for the Cordova High School chemistry and science club students, lack of student participation over the summer has hampered the ability to feed digesters. Following protocols for a precise feeding plan (for the purpose of scientific data analysis) requires considerable time inputs, and is the type of activity that the project depends on student volunteers to perform. Engineers and technicians funded by the grant are better used to collect and analyze data, trouble shoot problems, and design and implement technical aspects of biogas production and use. We anticipate that biogas production rates will increase once feeding resumes at a regular rate of acceleration. With the start of the new school year students have begun collecting food once again. Student participation is likely to increase this fall and will be welcomed to the project. New techniques are being implemented in order to streamline the feeding process as well as improve its sanitation and minimize variability between feeds (Appendix 1). In order to return to the initial feeding schedule as defined by the original project proposal (1kg food + 1kg water), careful attention will have to be paid to prevent tank reacidification. As of September 27, 2010, we have begun to feed the digesters on a strict and consistent feeding schedule. For one week the digesters will be fed equal parts (1:1) totaling 500g of food combined with 500g water at every other day intervals. The following week the same amount of food and water will be added at every day intervals. Assuming no detectable decrease in ph or other chemistry is noted, the digesters will begin to resume our original feeding proposal of 1kg food and 1kg water on daily intervals the following week (October 11 17th). Chemistry and gas measurements will be closely monitored in order to detect any changes that result from increased feeding. Careful measurements of gas flow output should provide insight into whether increased feeding results in measurable increases in gas production. Gas flow measurements In order to improve our confidence in measurements of gas production, we will look into an independent means of measuring gas flow for cross-checking of the currently employed in-line gas flow meters. Gas flow is at this time measured on all tanks with Sierra Instruments Top-Trak 820 Series Mass Flow Meters. These meters were installed on February 18, They measure gas flow based on a pressure differential between two fluid reservoirs (Sierra TopTrak 9

42 Manual). The output measurement is rated in Volts and must be converted in order to obtain standard liters per minute (SLPM). One concern is that the measurement is only of an average flow rate and not of the total cumulative amount of biogas moving through the meter. Each instrument has its own distinctive characteristics and error factor which is also a cause for concern, it is suspected at this time that the flow meter on tank 3 is miss calibrated and will need an appropriate correction factor after contacting the manufacturer. During the next quarter, Casey Pape will investigate the principle of data collection through the Sierra Mass Flow Meters and determine the best way of analyzing and presenting the data. Figure 3. Mean daily gas flow rates from digesters. The flow meters averaged flow over a defined unit of time (hours in this case) rather than totaling the gas moving across the meter. We suspect that the represented data in Figure 3 underestimate total gas production. We aim to resolve this uncertainty during the next quarter. For an optimally operating biogas system, daily flow rates should be approximately 800-1,000 L/day. Regular feeding began on February 15 and was stopped on March 21. Spikes seen in mid-may are a result of chemical mediation. Lower rates of feeding resumed June 22, Feeding rates are scheduled to increase during the remainder of Phase 1 to increase production rate towards the optimal target of 800-1,000 L/day. Measurements were obtained with Sierra Instruments Top-Trak 820 Series Mass Flow Meters and were calibrated by the manufacturer. It should be noted that the flow-meter on Tank 3 was apparently miscalibrated. Data from Tank 3 need to be corrected. Tank 3 actually produces minimal volumes of gas. In the immediate future, in order to achieve a secondary form of control of our gas measurements we propose installing tipping cup gas flux traps further down line from the Sierra Top-Trak instruments in order to obtain total gas output for each of the anaerobic digesters. The addition of tipping cups, built to the standard of those used to quantify gas flux in previous ecosystem methane flux studies (Walter Anthony et al. 2010), will be used in order 10

43 to check and correct for any error seen among the Sierra Top-Trak meters. It is possible that at such low pressures and flow rate the Sierra flow meters will not be accurately detecting the amount of gas that is flowing through them. That is not to say that they are not appropriate at higher rates of flow or that they are not working properly now, but at this time we would like to double check our numbers. The installation of tipping cups will implement the use of liquidfilled five gallon buckets which are to be sealed and have the added barrier of a water-trap bubbler to ensure no air is entering back into our tanks. These measurement devices will be installed in line with the Sierra instruments and will not require stopping any of the loggers, thusly preserving the continuity of our data set. Temperature control in the Connex Several important factors in biogas production are microbial community, substrate availaibility for methanogenesis, and temperature. Because the goal of Phase 1 is to test microbial community capacity for biogas production at two different temperatures, it is important to control feeding and temperature according to the experimental design. The Connex was built by the project team to maintain digesters in two separate rooms at cold (15 C) and warm (25 C) temperatures. Dataloggers record temperature in these rooms as well as inside each digester. Several digesters have multiple dataloggers suspendted at different height locations in order to better understand temperature stratification within the tanks. Figure 5 shows the summary data from all tempertature loggers over the course of the experiment. One of the goals of this study was to precisely control the temperature range in which the microbial communities were exposed to. Daily fluctuations occur as a result of opening the Connex to download flow meter data, but overall stays generally consistant (Figure 4). Average temperature of the Cold Room Connex since June 15, 2010 was C. This would seem to indicate that Connex temperature flucuates with the local Cordova weather as winter temperatures averaged 2-4 C below our intended 15 C controlled environment. Average Warm Room temperature was recorded at C for the same period. Cold room variation is expected to be greater than the warm room as the cold room is disturbed daily in order to download our gas flow data. A slight variation can be dectect between winter cooler and summer warmer months, but we are not concerned this is a major issue at this time. Also, in-tank temperatures recorded from January-May 2010 show that the large volume of liquid in the tanks buffers the tanks against the rapid temperature flucutations occuring in the room air. Temperate loggers continue to record temperatures inside all of the tanks; however, we plan to download them at the end of Phase 1 so as not to open the tanks and disturb the anaerobic conditions in there now. 11

44 50 All Temperatures Temperature (C) Cordova Temp Cold Room Temp Tank 1 Tank 2 Tank 3 Warm Room Temp Tank 4 Tank 5 Tank /12/10 2/11/10 3/13/10 4/12/10 5/12/10 6/11/10 7/11/10 8/10/10 9/9/10 10/9/10-20 Date (mm/dd/yy) Figure 4. Mean hourly temperature of the data loggers in the Connex cold and warm room, and mean daily temperature recorded in Cordova. Tank temperatures have not been downloaded since May 12 in an effort to maintain the anaerobic environment in the tanks (accessing the temperature loggers requires opening the tanks to the air). According to the patterns we have seen thus far, though, we could predict an increase in tank temperatures following the increase in room and environmental temperatures. Biogas project temperatures are measured with Hoboware U Water Temp Pro V2 loggers recording hourly. 12

45 Removal of the outdoor water pressure system Figure 5. The diagram above illustrates the current layout of Phase 1 testing of biogas production efficiency of different combinations of psychrophilic and mesophilic methanogen communities under cold and warm temperature treatments. Tank 2 and 3 are not currently attached to any water-pressure system and exhaust gases are simply vented to the outside. The remaining tanks closely mimic this initial design though noticeable flexion and deformation is observed due to the large volume of liquids contained within each tank. Adding additional lateral support could help to address this issue as any distension among the containers puts considerable stress on joints and brings to question the integrity of the system. Figure 5 illustrates the current configuration of all six digesters in the temperature controlled Connex and their outdoor secondary gas collection containers. The ability to store and pressurize biogas is outside the scope of the phase I study. Gas collection is relevant to Phase II. The outdoor water-pressure system was installed in January 2010 by T.H. Culhane to show the Alaska project team members the design he has built in other warm-climate regions. Unfortunately, these water pressure systems, if stored outdoors, are not appropriate for Alaskan environments (i.e. seasonal rain, snow, ice and wind). Their effectiveness for use in biogas technology is questionable altogether. Electric pumps are required to move the water intended to generate the necessary water pressure in order to operate the system (Figure 6). These pumps do not aid our attempts to minimize electrical inputs nor does the system have pipes big enough to sustain a high enough flow in order to maintain a steady pressure on the stored biogas. Finally, the use of water to this extent is not practical for the project s intended users, rural Alaskans who live in freezing winter conditions. As a result these tanks are now to be dismantled and their parts inventoried for future use. Ideally liquid-free gas containment systems would be most useful to the current system design. We hope to design a successful gas containment system intended for widespread use in Alaska. Design ideas will be developed between now and the next quarterly report with prototypes hopefully being constructed and tested at the beginning of next year. 13

46 Figure 6. T.H. Culhane s water pressure system for storing and dispensing pressurized biogas. System components include: 1) Feeding tube 2) Effluent pipe 3) Primary gas outlet 4) Flame tester 5) Gas inlet 6) Water transport 7) Pump bucket 8) Water inlet 9) Final gas outlet. This system is deemed to be inadequate for our needs in Alaska and for the purposes of this study. Cordova High School students brainstorming for Phase II During the fourth quarter, this project would like to begin aspects of the Phase II study to develop practical applications of these small-scale anaerobic digesters. Currently (due to low feeding rates over summer) biogas production rates are insufficient to make use of conventional combustion applications of the gas feasible. During the remainder of Phase I we aim to increase gas production rates through enhanced feeding, in order to generate sufficient gas to power gas-powered technologies. In the immediate term, creative alternatives will be considered. Students and community members should be encouraged to design useful applications of biogas. Recent interest has been expressed in using anaerobic digesters for use in improving greenhouse efficiency as biogas could be used as a source of heat and carbon dioxide (CO 2 ) for plants. Cordova science teacher Adam Low has recently obtained two large collapsible green houses. Science club students will be encouraged to perform experiments with growing agricultural crops that may be enriched with high levels of CO 2 from burned biogas as well as fertilized with effluent material. All these options will be explored as we begin to look into practical applications of the anaerobic digesters we have at the Cordova site. iii.b) Health and Safety Conventional small-scale anaerobic digesters are generally considered to be nonhazardous when given proper ventilation and maintenance. Still anaerobic digesters are used for the synthesis of combustible gases and have some safety concerns associated with them. 14

47 Flammability/explosions: Biogas is flammable. Methane is explosive at a concentration of 5-15% in atmospheric air. It is important that the biogas digesters do not have any leaks, especially if they are in an enclosed space, as they are in the Connex. In order to prevent potential sources of flammability, the digesters should be checked for leaks regularly. The use of soapy water can help to positively identify leaks at seems and joints where small leaks may not be audible or visible to the naked eye. These checks should be preformed fairly regularly as the tanks are constantly experiencing stresses from both operation and the varying weather of Cordova. Periodic room air will be sampled and analyzed on the gas chromatograph in the Anthony lab at UAF for quantification of background levels in the Connex. We will investigate options for acquiring gas detection alarm systems for the Connex. Signs are clearly posted inside of the Connex that explain(s) the presence of flammable gas and expressly prohibits the use of open flames inside. More signs should be visible from the outside, however, both to warn the general public of the danger, but also to encourage curiosity about the study. All students and researchers should wear proper safety glasses when conducting flame tests or working with pressurized digesters. There are several options available for the detection and alarm of dangerous concentrations of flammable gases. Current detectors can sample gases for flammable elements through either use of catalytic beads or infrared technology. For our purposes it would probably be best to investigate infrared options as they would be less likely to experience failure due to potential catalyst poisoning. Several companies make detectors that measure the lower explosive limit (LEL) of flammable gas mixtures. These detectors measure a range of different gases and are not selective to just methane. We will explore possibilities of acquiring a flammable gas detector for the Connex. Hydrogen Sulfide (H 2 S): Hydrogen sulfides can be produced as a side product of fermentation. The gas is flammable and toxic. At higher concentrations, or prolonged exposure to low concentrations, it is a mucus membrane irritant and is considered a broadspectrum poison. Exposure can lead to headaches, nausea, and in extreme cases, pulmonary edema, heart irregularities, and unconsciousness. We have installed hydrogen sulfide detection badges in the rooms to monitor higher levels of H 2 S (at low, non-toxic levels, hydrogen sulfide can be detected by its smell of rotten eggs). Carbon Monoxide (CO): There is no mechanism for the formation of CO gas within the methane fermentation pathway and is not of major concern in this study. Carbon monoxide can be formed through improper combustion and should be taken into consideration whenever combusting biogas in a poorly ventilated area. Ventilation: The build-up of certain gases in an enclosed space can be toxic. Biogas digesters produce methane, carbon dioxide, hydrogen sulfide, and other gases which can be deadly at high concentrations. Though the tanks are checked often for leaks, the inside of the Connex container has a very noticeable smell reminiscent of manure. The air is cycled daily to a certain extent when the Connex container is opened for daily download of the gas flow data. Tubes are connected to the tanks to allow lighter than air constituents escape the container. The Cordova fire department has visited the site and tested it for noxious gases. The results of the fire departments testing came up negative for any toxic gases. 15

48 iii.c) Schedule of project The project is still on schedule as defined by the original project outline. Phase I of the study is still of major importance to the project and should be continued, possibly through until the project s completion. We plan efforts to begin Phase II of the study at the start of 2011 to incorporate the practical use of digester biogas and effluent waste products. Attempts to produce large quantities of biogas have not been successful up to date. This has been due to many factors including a significant acidification of the tanks that had to be remedied for several months during the projects first year of study and subsequent low feeding rates. Preliminary GC analysis provides encouraging evidence as to digester health and productivity. It is suspected at this time that an increased regiment of food inputs will likely result in more biogas output. iii.d) Project budget The UAF budget is on track with the project schedule, neither over nor under budget. This is somewhat to be expected as the UAF budget is primarily labor and is fairly predictable and manageable. Originally we planned for the UAF team to operate through part-time technical support to the project including regular site visits to Cordova; however, complications of acidification of tanks and more rigorous remediation necessitated the move of a full time UAF technician (Laurel McFadden) to the site. On-sight full time UAF technician salary until June 2010, followed by part-time support thereafter, required re-budgeting a fraction of the PIs salary to technician salary. Casey Pape replaced Laurel in September, and is working full time on the project. The grant match funds were reported as approximately on budget, the detail will be available in the next report. Lesli Walls will also submit a separate financial report to the Denali Commission. The CEC and Cordova Schools budget is slightly over, but the match is over approximately 40%. The CEC budget was primarily for materials. The Cordova Schools budget is primarily for travel and dissemination of project results. Since travel and showcase events are discrete events representing most of the cost, the budget consumption has been high for the presentations to the Alaska Power Association in Juneau in February, 2010 and at the Rural Energy Conference in April, This travel represents more than half of the project related travel, but has consumed less than half the total budget. The level of effort applied to the project by both the High School teacher and the students has been much more enthusiastic than anticipated, as reflected in the matching hours. A portion of the travel funds have been redirected to pay for Adam Low s additional new time on the biogas project and the development of the website. In summary, the UAF and CEC/Cordova Schools budgets are within expectations for this phase of the project. No budget overrun is expected at this time. ii.e) Hurdles and solutions Project problems and solutions were mentioned in iii.a, and are outlined in more detail here. Low biogas production In order to be of any practical use to the general public - a major goal of the study - an anaerobic digester would have to consistently produce relatively high 16

49 amounts of methane (on the order of 1000 L/day). So far, our digesters have been unsuccessful in this effort. We speculate two causes. The most plausible explanations were that initially low ph in the tanks inhibited methanogenesis, and more currently, now that we have neutral ph and otherwise good tank conditions, our feeding rates are too low. (1) Low ph. Problem: The low ph problem has, for the most part, been solved. Initially, all digesters were scheduled to be feed on a daily basis of about 1kg food + 1kg water. Beginning in January, feeding in this manor was continued until March 21, 2010 when overfeeding was suspected to be the cause of an observed decline in ph. Since that time, efforts to restore initial ph chemistry within the tanks has proven very successful with the exception of Tank 3 (Table 1). Probing conducted among the sludge of the digesters revealed that acidic conditions were not consistent throughout the tank and that microbial viability may have been preserved in the sludge, which measured near neutral ph. Tank 3 has not recovered even with the addition of alkaline chemicals and is suspected to have fully crashed. Solution: We are currently pleased with ph levels in all but Tank 3. Additional probing in Tank 3 may reveal more about the current status of ph stratification within this digester and sludge. This information would indicate the probability of a viable methanogen community remaining in the sludge if it has a neutral ph. However, raising the ph of tanks through chemical remediation is time consuming and requires an adult technician. Given time constraints and other priorities, it may not be possible to remediate Tank 3. Tank 3 is currently suspected to no longer be performing; any gas readings that are observed are thought to be the result of improper flow reader calibration and variations in atmospheric pressure. (2) Feeding procedure. Problem: Following the observation of acidification within each of the digesters by Laurel McFadden and PI Walter Anthony, a teleconference meeting was held among project participants including also Adam Low, Clay Koplin and Peter Anthony, to concur on steps mediating digester chemistry. It was determined at that time that feeding should be stopped and remediation using alkaline chemicals should take place. As of March 21, 2010, daily feeding in all digesters was halted. This proved to be a major disappointment to the students of Cordova High School as feeding was not only their main responsibility and contribution to the project, but also discouraged them in that collected food scraps were now no longer of any use to the project and simply were discarded after intense effort to convince the school and students of the importance of recycling. After the alkalinity of the tanks was restored partial feeding was maintained by Laurel McFadden and Dane McFadden over the summer of Digesters # 1, 4, 5, 6 were feed periodically, but lower rates than originally projected. Low feeding rates with gradual increases are important to maintain concomitant growth of synergistic microbial processes required for methane production. Current feeding procedures are inadequate and unsanitary as food overflow and clogging are of constant issue (Appendix 1). Food stratification as a result of mixing slurry also presents a problem to researches who would like to maintain constant measurements of the exact amount of food + water that is added to each tank. Solution: Since this project is both a scientific study as well as a community outreach 17

50 program it is important that both interests are met throughout the course of the study. Students gain much from being involved in a primary research study, but also from the educational aspects it provides for sustainability and conservation. Food preparation to date has been somewhat of an ad hoc procedure and leaves potential for falsifying the results of the experiment as well as contaminating the digesters with foreign pathogens and materials. It would be ideal to stabilize this variable in our study. One means for accomplishing this while also involving the students would be to collect large amounts of food and freeze it prior to mixing. This way food could be combined in large batches that are more homogenous and pathogen free. In addition, other forms of digesters could be built (i.e. aerobic composters) that could compost the remaining food if not needed for the anaerobic digesters. Students could then use the composted products for other experiments. More thought and design needs to be put into correcting the current feeding procedure as it is currently not serving the project in an effective and safe way. Other potential considerations: The following factors are important considerations that generally can lead to problems in biogas technology. While we have no reason to think that any of these factors is causing a problem in our systems, for the sake of thoroughness, here we evaluate each as a potential problem in the context of our study. Lack of ability to quantify total gas output. Problem: Gas output is currently being measured by six Sierra Instruments Top-Trak 820 Series Mass Flow Meters. These meters take instantaneous readings of pressure differences between two tubes that are internal to the meter. Based on the pressure difference, the meter measures the rate of gas flow that must be traveling through the meter. The reading is generated in Volts, but can be easily converted to standard Liters per minute (SLPM). These SLPM readings are then averaged and multiplied in order to obtain daily total liters that traveled through the meter. We are concerned that this is not a true reading; however, because the data averaging may include zero and low-flux values, which would serve to lower the average flow rate. We are interested in the cumulative volume of gas produced per unit time. Solution: Casey Pape will gain a better working knowledge of the Mass Flow principle and data analysis to provide accurate gas flow determinations from these instruments. An independent method for measuring total gas flow will also be employed (see main text). Temperature fluctuation. Problem: Methanogens are sensitive not only to a general temperature range, but also to changes within their acceptable range. Most mesophiles and psychrophiles cease functioning with temperature variations of +/-2 C within an hour (Gerardi 2003). As seen in iii.a) Fig 5, there is some temperature variation within all six tanks. Although daily temperatures are fairly stable, there are some cases in which the temperature changes a couple degrees within a day. This is probably not enough to affect the methanogens, but it is possible with a jump of more than a few degrees the microbial communities could be negatively affected. Solution: Although temperature variability within treatments is not ideal, we hope the small changes do not have a significant effect, especially when spread over time. However, temperature 18

51 fluctuation can affect the metabolic rate of bacteria. We are closely monitoring temperature with dataloggers. We can correlate increases or decreases in gas production to possible temperature variability. Hydraulic retention/residence time. We do not suspect any problems with residence time in our digesters. Feeding rates are too low relative to the digester tank volume to be a concern for dilution of microbial populations. Lack of Mixing. Problem: Most large-scale biogas digesters, within the scientific and industrial setting, benefit greatly from being mixed. Even occasional turnover of materials would periodically expose different microbial communities to new sources of food and cycle nutrients and waste. Digester tanks in this study were intended for use by residential and rural Alaskans. The digesters were built to be very cost effective and simple to operate. In order to cut down cost the digester tanks were not built with any means to mix the solution inside. Once sealed, the digesters have no simple way of being mixed and there is observed stratification of particles and chemical concentrations within the tank. For small-scale digesters, it has been deemed not to be cost effective to mix digesters (House 1978). Solution: Mechanical mixing could be as simple as installing a gearing system that could be attached to a bicycle gear. This option would be cost effective and have the added benefit of not decreasing digester efficiency as other means of mixing (i.e. electric pump) would. Chlorine content. Problem: It is unknown at this point whether digester efficiency is retarded by use of Chlorinated tap water. As this is the most easily attainable source of water for most Alaskan communities (as well as for this study) it was chosen to be used in all six tanks. Solution: We tested the use of chlorinated tap water vs. non-chlorinated Lake Eyak water in the November pilot study and found that the High School tap water did not prevent biogas production. More research should be done to consult the scientific literature and see whether Chlorinated tap water has any effect on hampering microbial activity. Scum and foam. Problem: It is not believed that there is a significant issue with scum or foam buildup to merit taking any additional action at this time. As feeding increases again in the future we may observe foaming to become more prevalent and will address it at that time. Cold temperature(s). Problem: Due to limited resources and a priority for allocating resources to low-temperature digestion, there is no extremely-warm-temperature control currently designed into this experiment. Typical digesters of proven replication and reliability claim to be operated at much warmer temperatures than that observed in this experiment (35-50 C). Solution: The students at Cordova High School and members of the science club propose that smaller digester reactors be built in controlled hot and cold environments in order to determine whether or not the lack of hot temperature is playing a significant role in our digesters. Any and all experiments would be conducted under supervision of Cordova High School science teacher Adam Low. Little knowledge of microbial population and size. Problem: While outside the original scope of this project, there has been little effort to examine the microbiological populations within the tanks. Efforts to understand microbial communities within anaerobic digesters are an important step because digester efficiency is dependent on both microbial activity (metabolism) and microbial abundance (population size). Solution: 19

52 Simple efforts to look at effluent samples under dissecting microscope could reveal much about population dynamics within individual tanks. Simple live or dead counts of bacteria could give insight into relative reactor activity and be used to compare microbial activity between tanks. This could be a good activity for high school science students. Since there are multiple types of bacteria involve in the methane fermentation process, efforts to examine effluent bacteria could provide insight into possible favoring (e.g. abundance of acetogens compared with other pathway contributors). More advanced Gram-staining identification techniques could be used if further information about taxonomy were determined to be desired. For example dominant forms of methane forming microbes for mesophilic systems are Methanobacterium formicium and Mehtanobrevibacter arboriphilus and positive identification (or lack thereof) could be of importance to our study (Gerardi 2003). Logistical and management concerns: Digester/tank and fittings integrity. Problem: Initially, digester tank design was based on commonly available and recycled materials that were in abundance to the people of Cordova. The intention being that once a design was proven effective, that design could easily be replicated throughout other Alaskan communities. Unfortunately, the materials being used for the project were not designed for their current use and have proven inadequate given their condition. Each of the main 1000-L HDPE containers used for the digester reactor as well as water-pressure systems (Figure 6) has experienced significant flexing and distension over the course of the experiment. The tanks have not yet been provided with adequate lateral support and as a result deform whenever internal water volumes or gas pressure is fluctuated (See Pictures at end of the report). Any distension of the tanks results in unwanted joint stress that leads us to question joint integrity. Every additional fitting used on the tanks is a possible point of failure and several leaks have already been uncovered as mentioned in section iii.a). Solution: Soapy water may be used to uncover additional leaks in the system. It is recommended that these be conducted biweekly on all tanks to ensure system integrity. Reactor tanks should be installed with proper lateral and vertical support. Properly reinforced containers are available (Appendix 3); however, if cost and feasibility determine that these tanks cannot be obtained, then retrofitting our existing system is still of importance. Lateral support can be provided through use of horizontal tie-down straps. Tie-down straps have the additional benefit of being cheap, easily adjustable and could have vertical supports associated with them. Water-pressure System. Problem: Pressurization of produced biogas can be advantageous for running certain types of gas-powered appliances or an electrical generator. The current system in place uses elevated tanks with aid of a pump bucket in order to provide a means to pressurize the biogas (Figure 6). This system has several disadvantages; however, and is not thought to be working as initially desired by TH Culhane. The pump bucket also presents a problem as it is ultimately consuming more energy than the digesters are currently producing. Only one water-pressure system is working as is designed (Tank 4) and that is suspected to be because of a known air leak found in the gas holding tank (current flames tests of Tank 4 prove negative) which would allow 20

53 siphon to be generated between the pump bucket and the gas holding tank. All other systems are poorly or non-functioning. Water-pressure systems are not necessarily feasible for the given climate as water used to pressurize the gas will freeze this upcoming winter. Additions of propylene glycol or natural anti-freezes are not practical for rural use and may react adversely with the electric pump. Solution: All waterpressure systems are advised to be taken out at this time. They have not been shown to work, nor are they designed for winter conditions in Cordova. New designs should be entertained at this time that incorporate low cost materials and ideally non-liquid containment systems (i.e. pressurizing inflatable bags or covered piston configurations). Balance of responsibilities. Problem: The project was originally designed to be constructed by the full team on-site in Cordova in early January, and then to be maintained by Cordova High School students for the duration of the project with occasional (2-3 yearly) site visits by UAF technical staff for troubleshooting and advanced chemical monitoring. Although construction was completed as planned, a number of unanticipated problems have required the presence of a full-time onsite technician (Laurel McFadden and later Casey Pape). Chemical imbalances, discussed above, led to the failure of the systems to produce biogas. Monitoring, standard chemical measurements, mechanical maintenance, and feeding took significantly more time than anticipated. Although this was partially alleviated when Cordova High School students realized the extent of their time commitment and sought to streamline the feeding process, the chemical treatments and troubleshooting were beyond the scope of the Cordova contingent. Solution: The project now employs a full-time technician (Casey Pape) as well as dedicates partial salary of Cordova High School teacher Adam Low to work on the project. There is time allowed for continual research in how to improve digester output as well as ample enthusiasm to see its success. Additional student participation will likely increase over the coming months with the onset of the current school year. Student involvement will also provide valuable creativity and energy to move the project forward. iii.e) Positive accomplishments: Biogas production- high methane and proven flammability One of the primary goals of this project was to determine if the psychrophiles that produce methane in thermokarst lakes could be harnessed in an artificial environment to produce biogas. With the initial production of biogas from both psychrophilic and mesophilic microbes we proved flammability possible (refer to Y1Q2 report). Biogas from conventional anaerobic digests typically contains methane content between 40-60%. Recently it has been discovered that our biogas contains increasingly high concentrations of methane (50-82%). We suspect that the increased methane concentration(s) observed in our tanks are the result of using psychrophilic methanogens whereas typical anaerobic digesters commonly use mesophilic bacteria and archea found in bovine and animal manure. This is an important finding as it implicates the use of psychrophilic methanogens for improving the energy content of biogas as opposed to more common mesophilic anaerobic digester systems. Successful Chemical Remediation of Digester Tanks As mentioned before in section iii.a) early in the experiment, observed declining ph was foreseen as a potential threat to the 21

54 digester(s) microbial health and action was taken to restore ph to previous levels. Ideally, digester psychrophilic and mesophilic-communities perform under optimal conditions at a ph of around , observing tank ph(s) much lower than this (ph 3.5 6) was an indication that the tanks were acidifying and VFA s were likely being produced in large quantities. From this point chemical remediation was determined necessary to stop the digesters from potentially crashing or souring from prolonged exposure to low ph. Remediation was performed in two steps. The first step involved stoppage of the initial feeding schedule as specified in the project proposal. Stopping feeding was a necessary step as it was essential to minimize the amount of variability in the tanks while alkalinity was restored. The second step entailed adding calculated quantities of Calcium Carbonate, Lime, and Sodium Hydroxide in order to bring the ph back to the initial conditions. Care had to be taken to restore the ph in a gradual manner as to not shock the microbial communities. Slow remediation was also essential as over treating the tanks could cause them to become too basic, as anaerobic digester bacteria are particularly sensitive to increased ammonium concentration and this is to be avoided as even slightly basic tanks can cause total failure of mesophilic communities (comm. TH Culhane). All digesters are now at relatively stable ph values with the exception of Tank 3. Proven High Methane Content of Biogas Recent GC analysis of gas samples collected from tanks 1, 4, 5, and 6 shows high levels of detected methane in most cases. Preliminary analysis shows that methane concentrations have increased since the onset of Phase I research. To some extent this is an indication that we are observing healthy proportions of microbes in several tanks enough to support active methanogenesis. More work will have to be performed on the GC in order to understand long term trends and behavior of our tanks, but at first look the results seem promising. Student education This project has the fortunate opportunity of involving High School students in a primary scientific study. Cordova High School students have the unique ability to see some of the technical aspects and complications that go along with scientific research. The science club and chemistry class provide an excellent platform to organize student involvement. Previously, students have had the opportunity to troubleshoot and take the lead on feeding procedures for the project resulting in several very clever and innovative ideas being implemented. Students were disappointed last year when tank acidification resulted in decreased feeding of the digesters. Despite the necessary remediation of the tanks, students were given little responsibility and direction once they were told to stop feeding. It is important to maintain a high level of enthusiasm in order to build morale among the students. If in the future, we should determine it necessary to halt a certain student experiment it is important that they be provided with other avenues in order to participate in the project. Their creativity and energy is welcomed to the project as student ideas bring new perspective to current issues found in the experiment. Community outreach We have had the opportunity to present our project ideas and preliminary results at meetings with the Alaska Power Association and Alaska state legislators in Juneau, and at a variety of conferences, including the Alaska Forum on the Environment and the Alaska Rural Energy Conference. Five Cordova High School 22

55 students traveled to present at the Alaska Rural Energy Conference in Fairbanks. Titles of our project presentation at the Alaska Forum on the Environment and Alaska Rural Energy Conference were: Walter Anthony, K., Culhane, TH., Koplin, C., McFadden, L., Low, A. Improving Cold Region Biogas Digester Efficiency. McFadden, L. Alaska Forum on the Environment. Anchorage, Alaska. February 8-12, Walter Anthony, K., Culhane, TH., Koplin, C., McFadden, L., Low, A. Improving Cold Region Biogas Digester Efficiency. Low, A., Hess, E., Allen, J., Americus, I., Americus, B., Zamudio, A. Alaska Rural Energy Conference. Fairbanks, Alaska. April 27-29, Biogas Handbook for Alaskans- McFadden completed the first draft of a Biogas Handbook for Alaskans, an instructional booklet specific to biogas production and applications for Alaskan communities. The Handbook will continue to be revised, and submitted as a deliverable in final form to the Denali Commission by the end of the project. Website development- Website developer Brandon Shaw designed a site ( for the Cordova Energy Center, the venue at which the biogas experiment has been conducted. The website provides a venue for students and community members to obtain information about the project and how to get involved. It is important to update the website often as a means to show visitors that the project is still underway, that is still producing results and that people are still encouraged to get involved. References: Gerardi, Michael. The Microbiology of Anaerobic Digesters (New Jersey: John Wiley & Sons, Inc., 2003), House, David. (1978) The Complete Biogas Handbook. (Alternative House Information, United States), 52. Walter Anthony, K. M., D. A. Vas, L. Brosius, F. S. Chapin III, S. A. Zimov, Q. Zhuang (2010) Estimating methane emissions from northern lakes using ice-bubble surveys. Limnology and Oceanography: Methods, in press. Weiland, P. (2010) Biogas production: current state and perspective. Applied Microbiology Biotechnology. 85:

56 Appendix 1. Problems and solutions to managing digester feeding Figure 7. Common overflows following a typical feeding regiment of 1kg food + 1kg water. The PVC inlet tube does not allow for easy use of a funnel and it is hard (especially for students) to observe an overflow prior to it occurring. Issues with sanitation result as many of the digesters exhibit this problem. Clogging continues to slow the feeding process and will need to be improved in the project future. In the past, students complained that feeding the digesters was an inherently gross process, often messy, smelly and unsanitary. Digester feeding inlet tubes often clog leading to unsightly backups in the system and overflows (Figure 7). This is both undesired from a research perspective to measure the amount of input into the tanks as well as from a public health perspective to provide a safe environment for student education. As a result, preparation of food slurry mixtures to be added to the tanks will be performed in the following way: Food will be collected from the Cordova High School lunch room and be placed in an industrial freezer in order to sterilize prior to being blended. Once a large amount of food has been accumulated, individual collections will be thawed and combined into larger, more uniform batches. These large batches of food will be blended, separated into individual digester portions and labeled. Labels will include the date, the sample size (mass), notes describing the food contents within the sample, and initials of quality control from either science teacher Adam Low or Casey Pape. No sample will be fed to any digester should it be missing an approved initial as both Low and Pape will be responsible for making sure all samples were prepared and cataloged properly. The individual slurry will be placed back into the freezer for storage. The day prior to a feeding, the individual samples will be removed and mixed with the appropriate equivalent of water to assist in thawing the frozen slurry. The mixture can then be pulverized one last time prior to being added to the digesters. Final measurements will be recorded on the day of the feeding 24

57 confirming the wet weight of: total solid, total water added, combined solid plus water. In addition, students will be required to wear gloves, apron and appropriate eye protection while feeding. Methods for preventing overflow and spill will still have to be developed as there is currently no easy solution given digester design. During the summer when students were gone and turnover in technicians was occurring, Pape arrived to the project grounds to find containers, glassware and funnels left out after chemical treatments and feedings with the buildup of mold and potentially noxious bacteria (Figure 8). In the future all materials used in the preparation of feeding will be required to be cleaned and sanitized immediately following feeding. The use of bleach will help to ensure that pathogens are not exposed to students or food material. With careful controls such as these we can begin to feed the digesters on a more consistent basis as well as maintain high levels of student morale. Our intention is to eventually get feeding back up to the original schedule as defined in the initial project proposal. Figure 8. Dirty glassware and feeding containers found within the Connex. From now on any beakers or containers used to feed or remediate the chemistry of the primary digesters will be cleaned expressly after use. Cordova High School does not have any access to distilled or deionized water at this time. The use of non-chlorinated water, though not of practical necessity to the project, could be purchased and stored in a hand-pump reservoir available on site. 25

58 Appendix 2. Figure 9. Dissolved oxygen (DO) readings indicate the amount of oxygen in the system. The tanks should have a DO as close to 0ppm as possible (1 ppm = 1 mg/l). Gaps in the chart above indicate periods where DO could not be measured due to improperly functioning equipment. The high readings in early May could have been caused by exposure of the tanks to air in our attempts to mediate low ph concerns. DO measurements were taken with a Xplorer GLX Pasco PS-2002 Multi-Datalogger until March 24, following which they have been taken by a Hanna HI9142 DO meter. 26

59 Figure 10. Oxidation-reduction potential (ORP) indicates the availability of oxidative molecules and ions in the system. ORP is a valuable measure as it determines the likelihood that bacteria will follow the methane fermentation pathway. For healthy methane production, samples should have an ORP of From January 21-April 9, ORP was measured with a Xplorer GLX Pasco PS-2002 Multi-Datalogger. From May 10 forward, it was measured with an Oakton PC510 ORP meter. 27

60 Appendix 3. Pictures of project since Y1Q2 report (digital format with a short description of the activity and names of those in the photos). Mr. Low s 2010 Science Club students after one of their weekly meetings. (In this picture: Craig Bailer, Ben Americus, Adam Zamudio, Sophia Myers, James Allen, Eli Beedle, Josh Hamberger, Keegan Crowley, Kris Ranney, and Carl Ranney) 1,000 L HDPE reinforced containers used for storing Phosphoric acid at the local fish oil plant in Cordova. These containers could be used in order to improve digester support. Casey Pape observed enthusiastically washing glassware after feeding the tanks. 28

61 Current configuration of secondary water-pressure tanks with attached pump buckets. Weathering on the tanks has caused considerable lead and distention. Small leaks caused by joint stress due to flexion of secondary tanks. Current layout of the Connex container and project site. More signs might spark public interest in the project research and grant stakeholders. Cordova High School senior Craig Bailer along with science teacher Adam Low preparing food samples prior to feeding. Senior Craig Bailer, observed taking effluent samples for chemistry measurements. 29

62 Denali Emerging Energy Technology Grant: Improving Cold Region Biogas Digester Efficiency Year 1 Quarterly Report, Q4 December 12, 2010 Table of Contents i. Y1Q4 Summary.1 ii. Schedule and milestone information.2 ii.a) Personnel.2-4 iii. Narrative summary of the project.4 iii.a) Project Status and Accomplishments.4-13 iii.b) Health and Safety iii.c) Schedule of project iii.d) Project budget.15 iii.e) Hurdles and solutions iii.f) Positive Accomplishments References.20 Appendix 1.21 Appendix 2. (bubble trap)..22 Appendix 3. (Photographs) 23-24

63 i. Y1Q4 Summary The project is on target with regards to progress in Phase 1. Since the Y1Q3 report, the project has been focused on resuming and improving a consistent and regimented feeding schedule in efforts to closely track changes in gas production and efficiency of conversion of food-to-biogas. We are pleased to report that we still observe healthy, flammable biogas production in our psychrophile-only tanks in both the 25 C (tepid) and 15 C (cold) rooms and in the mesophile+psychrophile tank in the 25 C room. Currently, we do not see any activity among either of the mesophile-only tanks though nominal amounts of gases are still reported flammable. These findings support our initial hypothesis very well, that the psychrophile and mixed cultures would produce more biogas than the conventional manure-cultures at the relatively cool temperatures of 15 C and 25 C. Recent installation of several water traps downstream of the gas flow meters provided a useful visual reference for project observers. They serve additional purposes of (1) aiding in gas sample collection for CH 4 concentration analysis and (2) aiding in smoothing out flow-data measurements. These traps, outfitted with tipping cups and data loggers were also intended to serve a third purpose as a secondary gas-flux monitor in efforts to serve as a check on the Sierra instruments. The data loggers failed shortly after weather conditions in Cordova began to deteriorate. While it was unfortunate to lose the tipping-cup logger data, we nonetheless found other ways to obtain the desired information on gas production rate. One of the strongest achievements of this quarter was achieving a good understanding of digester daily gas production (see results below). The internal chemistry of the digesters has remained for the most part stable, though Tank 1 has exhibited a noticeable drop in ph (currently 6.2). In response, we have temporarily ceased feeding Tank 1 in effort to allow the tank time for metabolic recovery. For the remainder of Phase 1 we will continue to raise the feeding rate of the digesters (with the exception of Tank 1) to determine their maximum biogas production rates. Our goal is to determine how close our cold-adapted systems (15-25 deg C) can come to reaching the same gas production rates of conventional (warm C) biogas systems of the same household scale. The production target is 1,000 liters per day on a 2kg per day feeding regime, comparable to warm climate digesters of the same household scale. Currently, we are feeding the digesters on a 1kg per day regime and are observing a maximum gas production of around 130L/day for any one given digester. The project team is eager to see if increased feeding will improve total daily gas output. This information will be necessary for commencement of Phase 2, demonstrating the use of biogas to power gas-powered technologies. New components of Cordova High School student participation involve construction of a greenhouse to test the potential use of biogas slurry as a liquid fertilizer for food production and Student Craig Bailer s science fair project on a heat exchanger for use to the digester project during Phase II. Bailer also maintained chemistry and flow meter measurements while the UAF-technician Casey Pape was away from the project, showing enthusiasm and determination in order to preserve the integrity of the experiment while Pape was away. Both Bailer and Cordova High School teacher Adam Low exceeded expectations in their ability to maintain the project and in demonstrating the school s interest in the projects success. The project was recently featured by New Scientist Magazine in an article entitled, Cold climates no bar to biogas production. November 4,

64 ii. Schedule and milestone information The project continues to closely follow the original outlined plan: - Construct Digesters for Phase 1 by December 15, 2009 Completed January Begin Data Collection by February 1, 2010 Ongoing, commenced January 18, June 25-27, 2010, project meeting onsite in Cordova (all team members present); High school student presentations - Perform mid-term Analysis of Data by July 30, 2010 Completed informally internally as a project team, and formally in Quarterly reports 2 and 3. - Year 1 Q4 Report due December 15, Phase II Scoping Deadline January 25th Phase I Report, including analysis of all Phase I data, due February 28, Year 2, Q1 Report due March 15, Year 2, Q2 Report due June 15 - Year 2, Q3 Report due September 15 - Final project report due September 30, 2011 ii.a) Personnel: Cordova Electric Cooperative Clay Koplin Grant Administrator. Koplin has managed most of the financial aspects of the project thus far on behalf of the Cordova Electric Cooperative, serving as the project manager. Koplin serves as a technical advisor to the project. University of Alaska, Fairbanks Katey Walter Anthony Research Director. Walter-Anthony acts as the primary investigator, and has spearheaded the scientific goals and directions of the project. She provides continual scientific expertise and project management. She contributed to the data analysis, interpretation and writing of this and previous reports. Casey Pape Research Technician. Pape joined the project in early September, 2010, to replace Laurel McFadden as the primary project technician. Pape is currently working on-site in Cordova, maintaining the digester experiment, including data collection, analysis, and troubleshooting. After returning to the project on December 6, 2010, Pape led the preparation of the current quarterly report with assistance from other team members. In his absence, Adam Low, along with help from Cordova High School science club students were able to maintain feeding and measurements at the Cordova site. Pape plans to remain with the project until its completion in September Dane McFadden Project Intern. Currently an undergraduate at Stanford University, Dane McFadden helped maintain digester performance over the summer. Job responsibilities included: maintaining daily gas data collection, feeding, chemistry measurements and gas sampling. McFadden will be using his experience here in Cordova as his required internship at Stanford University and will generate an intern project report which will be submitted to the PI, the Denali Commission, and to Stanford University. Laurel McFadden Research Technician. McFadden, having begun a graduate program at UAA in mid August 2010, now consults on the project. McFadden was a key contributor to 2

65 the project development and took the lead on organization and preparation for the initial construction and setup. McFadden completed the first draft of a Biogas Handbook for Alaskans, which will be submitted as a deliverable in final form to the Denali Commission by the end of the project. Peter Anthony Research Technician. Anthony consults on the project and continues to provide technical expertise to the maintenance and application of digesters. He participated in the on-site project meeting in June 2010 and provided recommendations for simplification and winterization of the gas collection system in preparation for Phase 2. Anthony conducted the gas chromatography analyses of biogas composition for this report. Jeffrey Werner State FFA Director. Werner is looking into using the effluent from anaerobic digesters as a liquid fertilizer for agricultural crops. Located at the horticultural center at UAF, Werner remains enthusiastic about the possibilities of the potential uses of the once thought of waste product. Cordova High School Adam Low Science Teacher. Low was integral in bringing in student involvement via classroom curriculum and extracurricular projects. Low has been in charge of maintaining a consistent feeding regime and guiding student involvement with the project. While Pape was away from the project, Low had the added responsibility of maintaining gas flow and chemistry measurements as well as general troubleshooting. Additionally, Low has been working with science club students to set up a greenhouse experiment in which to test effluent samples for their potential use as a liquid fertilizer. Low also assisted in collecting and shipping effluent samples to other project colleagues in Germany in efforts to greater proliferate psychrophilic digester technology. Cordova High School Students Volunteers. The students of Cordova High School have been highly involved with construction, feeding, maintenance, and public presentations for the project. They include the seventeen Chemistry class students and Science Club students (Craig Bailer, Ben Americus, Adam Zamudio, Sophia Myers, James Allen, Eli Beedle, Josh Hamberger, Keegan Crowley, Kris Ranney, and Carl Ranney). Ten students now share the responsibility of feeding the digesters on a daily schedule. Student Craig Bailer in particular has been of great help to the project. Bailer maintained chemistry measurements while the UAF-technician (Pape) was away and proved to be more than competent at updating records as well as downloading flow data. In addition, Bailer has been assisting Low with other experiments in the Cordova Energy Center in preparations for Phase II of the project. In particular, Bailer has been working on a type of heat exchanger as part of a potential science fair project with the aim that it may be of use to the digester project during Phase II. SOLAR Cities TH Culhane Biogas Expert. With an extensive history in biogas technologies, Culhane developed the water-pressure tank design and provided extensive technical knowledge to the engineering of the project. He worked with and advised the on-site construction in January 2010 and provides expert advice from his home base in Germany. Recently, Culhane has asked to acquire a 2 L sample of psychrophilic effluent in efforts to test the success of psychrophilic digesters in different locations in Europe, Asia and Africa with different weather patterns and 3

66 climate regimes as part of a tangential outreach project that Culhane and Walter Anthony have, funded by the National Geographic Society and Blackstone Ranch. Sybille Culhane Co-founder of SOLAR Cities. S. Culhane assisted in initial construction efforts and managing financial aspects of SOLAR Cities involvement. Chena Hot Springs Bernie Carl Owner of Chena Hot Springs. Carl has expressed interest in deploying a digester at Chena Hot Springs, and has offered space for testing a digester in his greenhouse. Others Brandon Shaw Website Development. Shaw designed and manages the CordovaEnergyCenter.org website, where the project is hosted. He also assisted at the initial construction site, and was integral in the assembly of the flow meter system. Keywords: Biogas, anaerobic digester, reactor, psychrophiles, mesophiles, methane, etc. iii. Narrative summary of the project status and accomplishments to date, and addressing the following questions: is the project on schedule, is the project on budget, and what actions are planned to address any project problems. iii.a) Project Status and Accomplishments The project is on target in Phase I of the original research proposal. Phase I involves the testing of several different blends of methanogenic microbial populations (mesophilic and psychrolphilic) in order to examine different characteristics of digesters that operate in cold environments. The primary goal of Phase I experiments are to construct and monitor six different anaerobic digesters and to try to maximize the amount of gas that can be produced in depressed temperature climates (see original research proposal for more details on Phase I goals and objectives). We are pleased to report that several of the tanks are producing biogas from food waste material at high levels. Currently, we are observing flammable biogas production in Tanks 1, 4 and 5 in large quantities (up to 130 L/day). Only Tank 6 is no longer observed to be producing biogas at observable levels, despite no change in ph. Tanks 2 and 3 have not been producing gas in previous quarters and are no longer being fed. Gas contained in the headspace of Tank 6 may contain methane, but gas production in this tank is nominal (<1L/day). We have remediated many of the problems elucidated in the last quarterly report (see Y1Q3 report). In the fourth quarter we have begun pilot-level experiments for Phase II, while at the same time maintaining the Phase I study through completion in effort to improve yield and efficiency. The Cordova High School students have taken the lead on a greenhouse pilot study to test the potential for digester effluent to serve as a liquid fertilizer in food production. Casey Pape is leading the project team in preparations for Phase II, to find usable applications for biogas produced from the anaerobic digesters. In the second year of the project, Phase II research will also incorporate data collection on the time and effort required to build and maintain biogas digesters; provide data to inform economic assessment of biogas technology in Alaska; and produce a Do-it-Yourself Biogas Handbook for Alaskans. 4

67 Flammable biogas Previous analysis of gas composition on a Shimadzu 2014 gas chromatograph equipped with a flame ionization detector revealed that CH 4 concentrations in gas flowing from the digester tanks is up to 82% by volume (see Y1Q3 report). Composition data does not exists for current or catalogued biogas samples since the third quarter, but biogas from all producing tanks demonstrates positive flame test (Table 1.). Typically, conventional biogas reported in the literature is 40-60% CH 4 by volume. It is possible that with our increase feeding rates and increased gas production rates, we will observe among collected samples a decline in CH 4 content associated with rebalancing of fermentation and methanogenesis and in variation with feedstock quality. Future gas analyses will need to be performed to complete a time series of gas composition for assessment of digester behavior over time; however, these analyses will most likely be held off until the Phase I Report. Flame tests show that Tanks 1, 4, 5, 6 has been producing flammable gas (Table 1). Methane-rich gas from Tank 4 was previously being diluted by air through a discovered leak in the in the secondary holding tank (water-pressure system). The secondary tank was removed and biogas began showing positive flame once again. Due to too low of gas flow rates, gas from tanks 2, 3 and recently 6 is not being collected and we have little or no data on its composition. Table 1. Results of produced gas flammability tests. Positive results of the flammability test indicated usable biogas. Flame tests are still conducted on Tanks 1, 4, and 5. Tank 4, which was not showing positive flame tests at the time of the last quarterly report (probably due to a leak identified in the secondary gas holding tank), is now demonstrating positive flame. Tank First positive flame Last confirmed flame 1 1/31/10 12/10/10 2 NA NA 3 1/22/10 2/1/10 4 2/1/10 12/10/10 5 1/21/10 12/10/10 6 1/26/10 9/18/10 For more information about GC analysis and this project please refer to Project Status and Accomplishments of the Y1Q3 report (section iii.a)). Resumed feeding of digesters to increase gas production As of September 27, 2010 the digesters have been fed on a consistent basis for the first time since the decision to stop feeding them on March 22, 2010 as part of ph remediation. Today, the time required to perform feeding has been greatly reduced due to the methods specified in the Y1Q3 report (see Y1Q3, Appendix 1). Using pre-printed labels for 1 gallon Ziploc bags, a 2 person team is able to process five to six days of food in under 2 hours using the 5

68 before mentioned protocol. The bags are then weighed, sampled and stored in a large industrial freezer in the science classroom to be brought out the day prior to feeding. Once a team has fed the digesters, the next day s frozen food slurry is placed inside the Connex 25 C-room to thaw. Actual feeding of the digesters takes less than five minutes and students have been asked to note that all valves and doors are open/shut properly prior to exiting. The benefit of processing large batches of food using this method as opposed to daily collection and processing is not only good from a scientific perspective as there is more consistency between batches, but has also resulted in saving Low and students considerable amounts of time as well as improved student and teacher moral (ref. Adam Low). The project now feeds almost entirely in accordance with the original project proposed rate (1kg food + 1kg water). Only Tanks 1, 4, 5, and 6 are being fed currently as these tanks are the only ones to demonstrate active methanogenesis. At the end of September, for one week the digesters were fed in equal parts (1:1), totaling 500g of food combined with 500g water at every other day intervals. The following week the same amount of food and water was added at every day intervals. During the week of October th, the tanks once again resumed a conventional feeding regime according to the original project proposal (1kg food + 1kg water). Chemistry and gas measurements were closely monitored in order to detect any changes that result from increased feeding. By mid-november it became apparent that Tank 1 was beginning to exhibit a decline in ph once again despite other tanks maintaining consistent ph. Once the ph dropped below 6.5 it was recommended that Tank 1 feeding cease all together in order to prevent digester crash and has remained that way until it can recover on its own (currently 6.2, as of 12/07/10) (Figure 1.). It is probable that the drop in ph occurred because acetogenic activity had been exceeding methanogenic activity. This effect could be accelerated by the lower temperature and slower metabolism of Tank 1 compared to other tanks 25 C -room tanks which have had more stable ph. All tanks which are currently or were (Tank 1) on a feeding regime continue to produce measurable quantities of biogas with the exception of Tank 6. Feeding of Tank 1 will resume once its ph has returned to a desirable level ( 6.5) (Gerardi 2003). 6

69 Figure 1. ph results indicate that Tank 1 has been becoming slightly acidic since the last quarterly report (currently 6.2). Daily feeding has been halted to allow the ph to on its own without seeking chemical remediation treatments. ph was measured with Macherey-Nagel litmus paper January 21-April , following which it was more precisely measured with an Oakton PC510 ph meter. In accordance with restoration of biogas digester conditions, we also observed changes in dissolved oxygen and redox within tanks. Both dissolved oxygen (DO) and redox levels declined to anaerobic levels favorable to methanogenesis although recent DO measurements appear to be off due to instrument error (See data figures in Appendix 1). Gas flow measurements At the time of the last quarterly report, it was not known with certainty whether or not the project s Sierra Instruments Top-Trak 820 Series Mass Flow Meters (installed February 18, 2010 to maintain continuous mass flow measurements of each tank), were recording properly. Due to the low reported flow rates and inconsistency in the data record (Figure 2), researchers suspected that either the flow meters were not recording accurately or that methodology for summarizing the raw data was inaccurate, leading to false low values. The information presented in Figure 2 was derived from the product of averaging daily flow rates which were then multiplied to obtain daily totals. Though generally this is an acceptable method and is appropriate for obtaining estimates of daily gas totals it does not represent the actual total sum or quantity of gas produced by the digesters and recorded by the flow meters. Additionally, the metabolic rate of each digester appeared to be too low to regisgter gas flows accurately by the 7

70 Sierra flow meters. The flow meters were calibrated by the manufacturer for a faster flow rate than our real-time biogas production. Finally, it was feared that data may be lost while the project technician was away over the course of the quarter as flow data required daily downloading and monitoring. In order to resolve this issue and settle any further concerns regarding gas production, the project team constructed a series of tipping cup bubble traps with event data loggers that were intended to serve as a secondary measure of gas produced and act as a water trap ensuring unidirectional gas flow. Unfortunately, flow dynamics and weather conditions prevented these traps from working as they were intended, but still aided the research team in developing an understanding of total gas flux amounts. Figure 2. Mean daily gas flow rates from digesters. The flow meters averaged flow over a defined unit of time (hours in this case) rather than totaling the gas moving across the meter. The noticeable drop in gas flow on Oct. 15, 2010 and subsequent consistency of the data corresponds to the installment of water/gas traps which serve both as a secondary measure of the gas and as a passive one-way check valve. Measurements were obtained with Sierra Instruments Top-Trak 820 Series Mass Flow Meters and were calibrated by the manufacturer. It should be noted that the flow-meter on Tank 3 was apparently miscalibrated, a correction factor has been applied to report observed values. Pape constructed four tipping-cup gas traps following the design used in lakes by researchers in the Walter-Anthony lab (Walter Anthony et al. 2010). The devices operate by recording tipping events of gas flux using falling edge magnetic-trigger switches. Essentially, gas from each one of the tanks would be diverted into an inverted cup, once the cup filled to a calibrated level it would tip, releasing the gases to the atmosphere (Appendix 2). If the amount of gas flux from a tank is low enough, the cup should tip episodically, only when the cup has filled to the calibrated level. As the tipping event occurs the motion of the cup passes by a magnetic switch which closes momentarily, causing a logger device to record the event. The devices were constructed in a glass 30Gal aquarium to allow for easy maintenance and public viewing (Appendix 2). The water used to maintain the tipping cups also served as a type of passive check valve, only allowing gases to travel out of the tanks inside the Connex. Therefore, 8

71 any measurement recorded on a Sierra flow meter that that did not correspond directly with a bubbling event or reported a negative number could thrown out or ignored as a misread on the flow meter. The traps were calibrated and deployed on October 15, 2010 and are marked by a noticeable drop in gas flow as the pressure in the tanks had to build to overcome the hydrostatic pressure of the aquarium (Figure 2). Once the pressure inside the tanks accumulated enough to overcome the height of the water column, the tanks began bubbling biogas into the automated tipping cups. One of these events was witnessed by CHS student Craig Bailer and documented in the project notebook. The observer noted that the bubbling event was from Tank 4 in which bubbles were seen filling the tipping cup, over powering it and causing it to remain in the open position for the duration of the event. This phenomenon was not anticipated by the trap designer and future note should be taken before attempts to build additional traps are made. Additionally, it was discovered that moisture had penetrated the Hobo pendant loggers intended to record tipping events and rendered them unreadable. This came as a surprise to the project team as the devices are used commonly within the scientific community and should not have failed in this or any similar application. The loggers are now being sent into Onset in an effort to uncover why they failed during their time of deployment. Though the information could not be gathered from the tipping cups as anticipated, the project team developed an alternative approach to measuring biogas flux using both the Sierra flow meters and the installed bubble traps which served to validate our measurements of biogas production. Upon returning to the project on December 6, 2010, project technician Casey Pape contacted Sierra instruments about some of the difficulties encountered from using the Top- Trak Mass Flow meters. Jack, from technical services was very helpful in identifying what intended flow rate our units had been calibrated to as well as provide useful information about possible problems that may encountered from measuring gases with high water vapor content like that found in biogas. Jack explained that the flow meters employed at the site had been calibrated at a gas flow level at best around 3 std. L (that is, as if it was an ideal gas at 1 bar, K) per minute. Once it was realized that the biologic/ metabolic rate would be much lower than the calibrated level, Jack agreed that measuring flow rates that low with instruments calibrated for 3 std. L/min (SLPM) would be a challenge. It was therefore determined of great interest to increase the flow rate through the tanks and subsequently the flow meters. No advice was given on how to fix the miscalibrated devices aside from sending them in. Once it became known that increasing the flow rate may provide more accurate measurements Pape considered closing each of the tanks and letting them build pressure, then opening the tanks to release pressure may provide more definite measurements of gas production. Preliminary tests have been promising as tank pressure is being released four times a day (every six hours) shows very strongly in the flow data (Figures 3 and 4). This technique has been very helpful also in providing a visual representation of tank metabolic rates. The tanks that have the highest production rate demonstrated visually more biogas both through the increased duration of the pressure release and through observed bubbles witnessed from outside the Connex (Appendix 2). Bleeding the tanks on a regimented schedule as described above has aided researchers in both reducing the size of data files necessary for performing data translations and serving as a check against improperly calibrated meters. The Sierra flow meters record upwards of 16,000 9

72 measurements in a day and it is of great interest to be able to reduce the size of data files in order to reduce the number of unnecessary computations. By releasing all of the gas accumulated over the course of a day in short bursts like those observed in Figure 5 it was much easier to perform summary statistics and integrate the data to obtain the total amount of gas that traveled through the flow meter over a given period of time. By integrating the data we hope to check our data against the previous method for obtaining daily gas totals (Figure 2) to assure consistency and validity of the method. All data results will be included in the final Phase I Report as there was not enough time to include within the timeframe of this report. Table 2. Total amount of biogas produced on 12/10/2010. According to the information below, Tank 5 (25 C room, psychrophiles+mesophiles) is currently producing the greatest amount of biogas at L/day though it is suspected Tank 4 (psychrophiles only) was producing the most at one time. Tank 4 has been the most bloated of all the tanks and it is believed to have recently begun to leak. The leak was located and fixed December 13, 2010 as of 3:05pm and we would expect to see a slight increase in the amount of biogas observed. All valves were closed on Tanks 2 and 3. Total L/day (Data from 12/10/2010) Tank 1 Tank 2 Tank 3 Tank 4 Tank 5 Tank Figure 3. Flow rate data for all tanks taken from Top-Trak 820 Series Mass Flow Meters on 12/11/2010. The peaks correspond to moments when the tank valves were opened and gas was allowed to bubble through the water traps located outside of the Connex. The pressure in each of the tanks was bleed intentionally every 6 hours to release pressure build up though there is fifth peak which corresponds to CHS students opening the tanks briefly to perform the day s feeding. Values are recorded in SLPM. 10

73 Figure 4. Example of an individual pressure release event. The shape of the curve generated generally follows the shape of an isotherm as would be expected of an ideal gas. The area under the curve corresponds to the total amount of biogas that passed through the flow meter. Data was obtained from Top-Trak 820 Series Mass Flow Meters on 12/10/2010 and is presented in Volts. The second peaks found among Tank 4 and Tank 5 correspond to the technician opening the valve again in effort release all of the excess pressure in the tank. More analysis needs to be done in order to determine if previous data can be improved through integration and if water traps stabilize the data without causing any negative effects. Temperature control in the Connex Temperature remains one of the most imporant factors that influences methanogenic metabolic rate (House 1978). The Connex used to house the digesters was designed by the project team to maintain two rooms at separate cold (15 C) and tepid (25 C) temperatures (as opposed to conventional biogas deg C, warm temperatures). The temperature is visually monitored by digital thermometers (less accurate) and recorded by (more accurate +/-0.47 C, Drift +/-0.1 C/yr) dataloggers suspended in both rooms as well as inside the slurry of each digester. Several dataloggers, suspended at different depths within some of the tanks, have not been downloaded since May 12, 2010 in an effort avoid opening the lids of the tanks and preserve the current anaerobic conditions of the experiment. Summary data from all tempertature loggers over the course of the experiment are illustrated in Figure 5. A major goal of this study is to control a narrow temperature range in which the microbial communities were exposed to. Daily fluctuations occur as a result of opening the Connex to download flow meter data, but is not considered to be of major concern to tank health as the large volumes of water in the tanks makes them relatively thermally stable. Of greater concern is the tendency of the Connex temperature drift with changes in local environmental conditions and Cordova weather (Figure 5). As temperatures in Cordova have 11

74 dropped to wintertime values so too has the average temperature of the Connex and hense the digesters as well. Average temperature of the Cold Room Connex since Sept 30, 2010 was 10.8 C. Average Tepid Room temperature was recorded at 23.1 C for the same period. Cold room variation is expected to be greater than the tepid room as the cold room is disturbed daily in order to download our gas flow data. Due to the thermal mass of the tanks and water s high heat potential, the digesters tend to resist daily changes in temperature; however, if temperatures remain on average at low values (Figure 5) then it is likely that the temperatures of the digesters have also dropped below set targets. Currently the project obtains it s energy and electricity needs through use of extension cables run from the school to the Connex. Unfortunately, high exposure to student traffic sometimes results in these connections becoming severed and Connex temperature declines as a consequence. The most recent case discovered by the project team was on December 13, Signs have been replaced in an effort to detract passers by from possibly disconnecting experiment power cables. More analysis will need to be done to tract the changes in gas production as related to changes in digester temperature. Figure 5. Mean hourly temperature of the data loggers in the Connex cold and tepid room, and mean daily temperature recorded in Cordova. As the temperatures in Cordova began to drop from temperate summer conditions, the Connex experienced a noticeable and unfavorable drop in temperature. Temperatures are still below their set values (of 15 C and 25 C respectfully), both rooms will need further heating inputs to meet project targets. Individual tank temperatures have not been downloaded since May 12 in an effort to maintain the anaerobic environment in the tanks (accessing the temperature loggers requires opening the tanks to the air). Biogas project temperatures are measured with Hoboware U Water Temp Pro V2 loggers recording hourly. Removal of the outdoor water pressure system 12

75 Appendix 2 depicts the site in its current state. The outdoor water-pressure system that was installed at the project in January 2010 by T.H. Culhane was adapted by the Alaska team members from other versions built in tepid-climate regions. At the time of the last quarterly report it was determined that these secondary containment systems did not meet the needs of project nor were they appropriate for the given conditions found here in Cordova. The average temperature in Cordova since September 30, 2010 has been 2.3 C, with freezing events occurring often. The use of water in the old containment system would have presented a significant problem in case of a freezing event as joint stress caused from the expansion of freezing water was known to cause leaks in the past and would further bring to tank integrity into question. All outside tanks have been removed as of October 12, Remaining salvageable parts have been inventoried and stored inside of the Cordova energy center to possibly be used again during the Phase II study. The LDPE tanks that were once used for the containment system are now stacked near the Connex with the exception of the Tank 1 floating barrel system which is still located in its original position against the Connex. None of the tanks are currently connected with any type of gas containment system and all gases are simply being vented to the atmosphere at this time. We will once again pursue a suitable containment system with the goal of utilizing the biogas to fuel a gas-powered technology in Phase II. Cordova High School students brainstorming for Phase II During the third quarter, it became of interest to team members to test digester effluent for its use as a nutrient-rich liquid fertilizer. Since the last report, Cordova High School teacher Adam Low spearheaded efforts with students to test effluent samples in a controlled greenhouse experiment (Appendix 3). The greenhouse experiment is currently set up within the Cordova Energy Center and employs the use of heaters and florescent lighting in order to support plant growth despite the local weather conditions of Cordova. Students worked with Clay Koplin and Adam Low to set up experiments testing effluent from Tank 4 as an organic plant fertilizer. Students are currently growing lilies, carrots, lettuce, radishes and cilantro. By planting these food crops in both nutrient enriched and poor soil(s) students are hoping to identify a difference in responsiveness to the nutrient rich effluent. Additionally, the students in CHS Science club have also taken home dropper bottles of effluent from Tank 4 and are using this as a concentrated plant food on various house plants in their homes. In the next quarter, as the project begins to move into Phase II, more research will be conducted around potential use of biogas for increasing greenhouse efficiency. Namely, it is of interest to see whether or not current digesters can produce enough biogas that can be burned or flared in order to sustain elevated temperatures and CO 2 concentrations within the greenhouse. iii.b) Health and Safety Conventional small-scale anaerobic digesters are generally considered to be nonhazardous when given proper ventilation and maintenance. Still anaerobic digesters are used for the synthesis of combustible gases and have some safety concerns associated with them. Flammability/explosions: Biogas is flammable. Methane is explosive at a concentration of 5-15% in atmospheric air. It is important that the biogas digesters do not have any leaks, especially if they are in an enclosed space, as they are in the Connex. 13

76 In order to prevent potential sources of flammability, the digesters should be checked for leaks regularly. The use of soapy water can help to positively identify leaks at seems and joints where small leaks may not be audible or visible to the naked eye. These checks should be preformed fairly regularly as the tanks are constantly experiencing stresses from both operation and the varying weather of Cordova. Periodic room air will be sampled and analyzed on the gas chromatograph in the Anthony lab at UAF for quantification of background levels in the Connex. We will investigate options for acquiring gas detection alarm systems for the Connex. Signs are clearly posted inside of the Connex that explain(s) the presence of flammable gas and expressly prohibits the use of open flames inside. More signs should be visible from the outside, however, both to warn the general public of the danger, but also to encourage curiosity about the study. All students and researchers should wear proper safety glasses when conducting flame tests or working with pressurized digesters. There are several options available for the detection and alarm of dangerous concentrations of flammable gases. Current detectors can sample gases for flammable elements through either use of catalytic beads or infrared technology. For our purposes it would probably be best to investigate infrared options as they would be less likely to experience failure due to potential catalyst poisoning. Several companies make detectors that measure the lower explosive limit (LEL) of flammable gas mixtures. These detectors measure a range of different gases and are not selective to just methane. We will explore possibilities of acquiring a flammable gas detector for the Connex. Hydrogen Sulfide (H 2 S): Hydrogen sulfides can be produced as a side product of fermentation. The gas is flammable and toxic. At higher concentrations, or prolonged exposure to low concentrations, it is a mucus membrane irritant and is considered a broadspectrum poison. Exposure can lead to headaches, nausea, and in extreme cases, pulmonary edema, heart irregularities, and unconsciousness. We have installed hydrogen sulfide detection badges in the rooms to monitor higher levels of H 2 S ( 10ppm). So far all badges indicate the rooms contain nominal H 2 S levels. Carbon Monoxide (CO): There is no mechanism for the formation of CO gas within the methane fermentation pathway and is not of major concern in this study. Carbon monoxide can be formed through improper combustion and should be taken into consideration whenever combusting biogas in a poorly ventilated area. Ventilation: The build-up of certain gases in an enclosed space can be toxic. Biogas digesters produce methane, carbon dioxide, hydrogen sulfide, and other gases which can be deadly at high concentrations. Though the tanks are checked often for leaks, the inside of the Connex container has a very noticeable smell reminiscent of manure. The air is cycled daily to a certain extent when the Connex container is opened for daily download of the gas flow data. Tubes are connected to the tanks to allow lighter than air constituents escape the container. The Cordova fire department has visited the site and tested it for noxious gases. The results of the fire departments testing came up negative for any toxic gases. iii.c) Schedule of project The project is still on schedule as defined by the original project outline. Phase I of the study is still of major importance to the project and should be continued, possibly through until 14

77 the project s completion. We plan efforts to begin Phase II of the study at the start of 2011 to incorporate the practical use of digester biogas and effluent waste products. iii.d) Project budget Project costs as of Oct. 30, 2010 for the project are $110, This represents 40% of the $250,910 budget. As of Oct. 30, 2010, the project timeline is approximately 50% consumed. The project is running just below budget through Q4 of The CEC match portion of the project is $15, as of Oct. 30, Cordova Schools match have not been computed recently, but had exceeded $50,000 as of June UAF match has not been computed recently, but had exceeded $3,000 as of June The Cordova Schools expended a large number of labor hours during this quarter, but total match as of Oct. 30, 2010 was in excess of $69,000 or 70% of the $98,500 match requirement even without recent Cordova Schools and UAF grant matching activities included. In summary, grants costs are slightly under budget as of October 30, 2010, and matching requirements have met 70% of the project requirements through 50% of grant completion. At this time, the budget is not expected to exceed the grant, and the matching contribution is expected to significantly exceed the grant requirement. iii.e) Hurdles and solutions Project problems and solutions were mentioned in iii.a, and are outlined in more detail here. Lack of confidence in biogas measurements: Due to offsets between the flow meter calibration levels and our gas production rates, we were not able, until this report, to provide the true values of biogas produced. Previous values represented averaged daily flow rates as opposed to cumulative daily gas production. Though this is generally an acceptable method for smoothing out noise in any data set, the true biogas production rates were underestimated. Solution: Casey Pape determined a new method to achieve our goal of daily gas production determinations by closing tanks, allowing them to swell with produced gas, opening the valves over a short period of time to allow high rates of gas flow within the level of the flow meter calibration. We will now start reporting total values of gas produced and make an effort to correct errors in the data that may be attributed to false readings on the Sierra instruments rather than actual biogas being produced. Low biogas production: In order to be of any practical use to the general public - a major goal of the study - an anaerobic digester would have to consistently produce relatively high amounts of methane (on the order of 1000 L/day). Since we began consistently feeding in September, there has been a greatly noticed increase in the amount of biogas produced, though perhaps not noted in the flow data. As of 12/11/2010, Tank 1 reported producing 30 L/day, Tank 4 about 125 L/day and Tank 5 at about 130 L/day. These numbers are still below target values; however, we are excited to be once again seeing flammable biogas in any significant quantity. It is possible that increased feeding could aid the digesters more, but this is so far untested as we are currently feeding at the original proposed rate, which is half the rate used in warm temperature conventional biogas systems. 15

78 (1) Low ph. Problem: ph has stabilized in all tanks except Tanks 1 (6.2, Figure 1) and 3, which are currently lower than that which is ideal for supporting active healthy methanogenesis (Gerardi, 2003). It is probable that acetogens out-produced methanogens once the temperature began to drop within the cold room of the Connex. It is very important that team members do not to allow tanks to drop too far below their marginal ph values as it can result in needing chemical remediation which is time intensive in both labor inputs as well as time taken by the digester to recover. Solution: Feeding has been halted on Tank 1 in the short-term in order to asses if the ph can be restored on its own as methanogens begin to consume the VFA s and acetate within the digester which are responsible for its lowered ph. Tanks 2 and 3 have not been feed for the duration of the quarter. If the digester can recover on its own that is a very important finding as it indicates the microbial consortium functions a type of biological buffer and are able to sustain their own chemistries if caught early enough and given enough time to recover. Tank 1 is still producing measureable amounts of biogas and it will be interesting to observe how the production rate changes in the near future as it could be due to changing ph or to relative nutrient availability. Other potential considerations: The following factors are important considerations that generally can lead to problems in biogas technology. While we have no reason to think that any of these factors is causing a problem in our systems, for the sake of thoroughness, here we evaluate each as a potential problem in the context of our study. Temperature fluctuation. Problem: It is a major goal of this study to preserve the cold (15 C) and tepid (25 C) conditions as was defined in the original project proposal for the purpose of incubation of microbes. The Connex constructed for the project is insulated with R-10 pink foam insulation, but has poor seals and air spaces that cause it to have a heat/cooling regime that mimics that of the local environment of Cordova. Over the course of this quarter, average temperatures for both cold and tepid rooms was 4.2 C and 1.9 C below target values respectively. This is not ideal and will need to be better monitored in the future as our impression of the day to day gas production is that it should be consistent if temperature and food inputs are maintained at a constant level. Solution: Although temperature variability is undesirable, we have tried to correct it each time it comes to the team s attention that it may be an issue. Currently there are no outdoor outlets for the project to plug into and makes getting needed power out to the Connex an arduous process. Circuit overload is of great concern as the temperatures have become colder. The projects heating needs are entirely met by electrical heaters and the project currently employs the use of 5 electric radiant heaters. The project team will have to be more careful in the future to make sure heaters are working properly or have not been unplugged by curious passersby or malcontent youth. Logistical and management concerns: Digester/tank and fittings integrity. Problem: Generally speaking, the more holes and fittings installed on a digester or any gas-holding container increases the chance for a leak to 16

79 develop. When designing systems intending to carry gas (especially flammable gas), it is important to try and build them with as few joints and failure points as possible. Each joint or threaded fitting is a possible leak point equivalent to the circumference of the circular fitting. Summing the total linear area of all these fittings reveals the total area of open holes in the system that now have to be filled with some sort of compound or sealant in order to prevent the vessel from leaking. In this experiment, leaks have already been uncovered among the secondary gas containment systems and resulted in biogas no longer being flammable in air. Inside the Connex, this is less of a concern, but still cannot be ruled out. There are somewhere between fittings located on each tank that must all be air tight in order for the researchers to conclude that ever mole of gas is being measured. Additional fittings exist on each tank, but aren t necessarily exposed to an air-gas boundary. This is an issue, but for the most part tanks demonstrate the ability to maintain positive pressure and are thought to be mostly air tight, though minute leaks have been discovered on Tank 4. Tank 6 is not producing biogas that we can record, but we are not sure as to whether or not it can maintain positive pressure. Solution: Soapy water does help to uncover leaks where they are suspected; however, small leaks may still exist that are simply too small to notice. For example Tank 4 was found to have a leak, but it was less significant than the metabolic rate of its methanogens and continued to exude positive pressure. If a tank can t exert positive pressure then it is unlikely that soapy water would uncover a leak as there has to be some significant Δ in pressure in order to observe gas exchange between the tank and the atmosphere. In this case, increased pressure is the best way to uncover if there is a leak or not. In the last remaining part of Phase Pape we will try and demonstrate that all tanks have the ability to maintain positive pressure and therefore lack of biogas can be attributed to the chemistry of the tanks and not tank fitting soundness. Balance of responsibilities. Problem: The project is designed to be conducted in tandem between Cordova High School students and staff as well as the University of Alaska, Fairbanks. Collective effort between both parties is necessary in order to maintain the project and pursue additional research and development during the Phase II study. Students are very capable of feeding and maintain digesters from day to day, but both students and staff are ill-equipped to combat many of the more technical problems that arise due to the nature of an experiment of this type. Solution: The project full-time technician (Casey Pape) has recently returned from prior work commitments will now be solely committed to this project both in research and practical development. Adam Low and CHS students have done a wonderful job filling in for Pape while away. Students are eager to learn more from the project and help in any way they can. It will be an educator s challenge to come up with more challenging and constructive projects for students to include themselves in during the next phase of the project. iii.f) Positive accomplishments: Biogas production- high methane and proven flammability One of the primary goals of this project was to determine if the psychrophiles that produce methane in thermokarst lakes could be harnessed in an artificial environment to produce biogas. With the initial production of biogas from both psychrophilic and mesophilic microbes we proved flammability possible (refer to Y1Q2 report). 17

80 Biogas from conventional anaerobic digests typically contains methane content between 40-60%. Recently it has been discovered that our biogas contains increasingly high concentrations of methane (50-82%). We suspect that the increased methane concentration(s) observed in our tanks are the result of using psychrophilic methanogens whereas typical anaerobic digesters commonly use mesophilic bacteria and archea found in bovine and animal manure. Additional measurements of gas content are needed to confirm consistency in this trend. Stable isotope analysis could also help distinguish pathways of methanogenesis in the manure-vs.-psychrophile tanks. If this high CH 4 -content of psychrophilic biogags holds constant, then this is an important finding as it implicates the use of psychrophilic methanogens for improving the energy content of biogas as opposed to more common mesophilic anaerobic digester systems. Successful Chemical Remediation of Digester Tanks As mentioned before in section iii.a) early in the experiment, observed declining ph was foreseen as a potential threat to the digester(s) microbial health and action was taken to restore ph to previous levels. Ideally, digester psychrophilic and mesophilic-communities perform under optimal conditions at a ph of around , observing tank ph(s) much lower than this (ph 3.5 6) was an indication that the tanks were acidifying and VFA s were likely being produced in large quantities. From this point chemical remediation was determined necessary to stop the digesters from potentially crashing or souring from prolonged exposure to low ph. Remediation was performed in two steps. The first step involved stoppage of the initial feeding schedule as specified in the project proposal. Stopping feeding was a necessary step as it was essential to minimize the amount of variability in the tanks while alkalinity was restored. The second step entailed adding calculated quantities of Calcium Carbonate, Lime, and Sodium Hydroxide in order to bring the ph back to the initial conditions. Care had to be taken to restore the ph in a gradual manner as to not shock the microbial communities. Slow remediation was also essential as over treating the tanks could cause them to become too basic, as anaerobic digester bacteria are particularly sensitive to increased ammonium concentration and this is to be avoided as even slightly basic tanks can cause total failure of mesophilic communities (comm. TH Culhane). All digesters are now at relatively stable ph values with the exception of Tank 3. Proven High Methane Content of Biogas Recent GC analysis of gas samples collected from tanks 1, 4, 5, and 6 shows high levels of detected methane in most cases. Preliminary analysis shows that methane concentrations have increased since the onset of Phase I research. To some extent this is an indication that we are observing healthy proportions of microbes in several tanks enough to support active methanogenesis. More work will have to be performed on the GC in order to understand long term trends and behavior of our tanks, but at first look the results seem promising. Student education This project has the fortunate opportunity of involving High School students in a primary scientific study. Cordova High School students have the unique ability to see some of the technical aspects and complications that go along with scientific research. The science club and chemistry class provide an excellent platform to 18

81 organize student involvement. Previously, students have had the opportunity to troubleshoot and take the lead on feeding procedures for the project resulting in several very clever and innovative ideas being implemented. Community outreach We have had the opportunity to present our project ideas and preliminary results at meetings with the Alaska Power Association and Alaska state legislators in Juneau, and at a variety of conferences, including the Alaska Forum on the Environment and the Alaska Rural Energy Conference. Five Cordova High School students traveled to present at the Alaska Rural Energy Conference in Fairbanks. Titles of our project presentation at the Alaska Forum on the Environment and Alaska Rural Energy Conference were: Walter Anthony, K., Culhane, TH., Koplin, C., McFadden, L., Low, A. Improving Cold Region Biogas Digester Efficiency. McFadden, L. Alaska Forum on the Environment. Anchorage, Alaska. February 8-12, Walter Anthony, K., Culhane, TH., Koplin, C., McFadden, L., Low, A. Improving Cold Region Biogas Digester Efficiency. Low, A., Hess, E., Allen, J., Americus, I., Americus, B., Zamudio, A. Alaska Rural Energy Conference. Fairbanks, Alaska. April 27-29, New Scientist article featuring this project: Cold climates no bar to biogas production. November 4, Unfortunately no final reference was made to the Denali Commission as the funders of this research. Interviewees informed the writer of the funding source, but did not have the opportunity to ensure that the information was included in the printed article. We are pleased to announce that we will be presenting this research at the 2011 Alaskan Forum for the Environment. Pape will be presenting on the project along with aid and support from Science club students. Held in Anchorage from Feb. 7-11, 2011, our presentation will revolve around technical aspects of the project as well as student involvement. CHS Students were not at first able to attend the conference due to lack of funding from the Cordova School District; however, have recently been invited by the Forum as part of the Youth Track. The Forum has provided funding for air travel and lodging for two students and one adult chaperone. Last year the chemistry students took a class trip to the Alaska Power Association in Feb Students C. Bailler, D. Hess, C. Morrissett, J. Smyke, S. Lindow, and T. Kelley presented on the project and it was received well among those who attended the meeting. The project teams intends to present at next years Alaska Rural Energy Conference in Juneau, Sept , Biogas Handbook for Alaskans- McFadden completed the first draft of a Biogas Handbook for Alaskans, an instructional booklet specific to biogas production and applications for Alaskan communities. The Handbook will continue to be revised, and submitted as a deliverable in final form to the Denali Commission by the end of the project. 19

82 Website development- Website developer Brandon Shaw designed a site ( for the Cordova Energy Center, the venue at which the biogas experiment has been conducted. The website provides a venue for students and community members to obtain information about the project and how to get involved. It is important to update the website often as a means to show visitors that the project is still underway, that is still producing results and that people are still encouraged to get involved. References: Gerardi, Michael. The Microbiology of Anaerobic Digesters (New Jersey: John Wiley & Sons, Inc., 2003), House, David. (1978) The Complete Biogas Handbook. (Alternative House Information, United States), 52. Walter Anthony, K. M., D. A. Vas, L. Brosius, F. S. Chapin III, S. A. Zimov, Q. Zhuang (2010) Estimating methane emissions from northern lakes using ice-bubble surveys. Limnology and Oceanography: Methods, in press. 20

83 Appendix 1. Figure. DO measurements were taken with a Xplorer GLX Pasco PS-2002 Multi-Datalogger until March 24, following which they have been taken by a Hanna HI9142 DO meter. As of October 1, 2010, the Hanna instrument could no longer be calibrated properly. All DO measurements from 10/1/2010 until present are suspected to be inaccurate due the malfunctioning instrument. Methods/steps to restore proper function to the Hanna HI9142 DO meter is/are discussed in the Hurdles and Solutions portion of the report (section ii.e)). Figure. Oxidation-reduction potential (ORP) indicates the availability of oxidative molecules and ions in the system. ORP is a valuable measure as it determines the likelihood that bacteria will follow the methane fermentation pathway. For healthy methane production, samples should have an ORP of From January 21-April 9, ORP was measured with a Xplorer GLX Pasco PS-2002 Multi-Datalogger. From May 10 forward, it was measured with an Oakton PC510 ORP meter. 21

84 Appendix 2. Automated bubble traps were installed on 10/15/2010 in an effort to monitor total gas flux from digesters 1, 4, 5, and 6 in a to the Sierra Top-Trak Mass Flow meters Student Craig Bailer working with CHS teacher Adam Low to try and obtain gas samples from the aquarium in mid- November. Despite being almost completely frozen, a very distinct bulge was observed to contain flammable gas. Aquarium pictured here with a car battery jacket in an effort to thaw out the tank. The jacket worked very well and is now used periodically to prevent freeze up. Here the water traps are observed in action during one of the four daily pressure releases of tanks 1, 4, and 5. Tank 6 (on the right) has not demonstrated gas production since the water trap was installed. 22 Teacher Adam Low is pictured obtaining a sample of gas from Tank 4 in order to demonstrate its flammability to students in his Chemistry class.

85 Appendix 3. Student Craig Bailer is pictured preparing a weeks worth of food for the digesters. The apron and eye protection are more so as a precaution rather than a necessity though the process can be messy sometimes. The new greenhouse experiment is currently up and running inside of the Cordova Energy Center. Inside are the starts of several experiments which use effluent samples to test its possible use as a liquid fertilizer product Lilly starts contained within the greenhouse aim to see if effluent samples grow faster or slower given the same conditions as starts with only light and water inputs with minimal nutrient content 23

86 Effluent samples taken from Tank 4 have been disseminated among Science club students to be used for their own experiments with the anaerobes. Students now have the ability to test the nutrient potential of the effluent as well as pursue individual experiments. Samples contain active cultures as demonstrated in the picture (right) Student Craig Bailer s heat exchanger experiment to be presented in the annual Alaska State Science Fair. The heat exchanger idea is being explored as it may be of use to the biogas project during Phase II. Tank 5 with active methanogenesis Tank 6 with no positive pressure, an indication of decreased methanogenic activity 25 C room showing active (Tank 4 and 5) and inactive (Tank 6) tanks. Outside the Connex, a water trap allows for a constant pressure to exist within the tanks (approx 0.65 psi). Active tanks can be identified by their tendency to bloat due to the positive pressure exerted by gas produced during methanogenesis. 24

87 Denali Emerging Energy Technology Grant: Improving Cold Region Biogas Digestor Efficiency Year 2 Quarterly Report, Y2Q1 March 15, 2011 Table of Contents i. Y2Q1 Summary.1-2 ii. Schedule and milestone information.2 ii.a) Personnel.2-4 iii. Narrative summary of the project.4 iii.a) Accomplishments..4-7 iii.b) Project Status.7-16 iii.c) Health and Safety.16 iii.d) Schedule of project.17 iii.e) Project budget.17 iii.f) Hurdles and solutions References.20 Appendix I. (Chemical Data Supplement) Appendix II. (Joint and Electrical Retrofit) Appendix III. (Pictures) 28-31

88 i. Y2Q1 Summary The project is transitioning into Phase 2. Research has commenced in order to apply small-scale anaerobic digestors in various applications that may benefit peoples in Alaska who are interested in biogas technology. During the past quarter, the project focused on resuming and improving a consistent and regimented feeding schedule in efforts to closely track changes in gas production and efficiency of conversion of food-to-biogas. This involved stringent daily protocols for obtaining gas measurements and accurate monitoring of tank activity. Currently, high rates of daily activity (i.e. production of biogas) are being recorded among all tanks within the 25 C room. We observe lower activity in Tank 1 in the 15 C room. Though biogas production occurred throughout much of the Phase 1 period, data collected on site remained inconclusive until only recently. The most recent assessment of gas production among the 15 C and 25 C rooms reveals almost all tanks containing psychrophilic cultures are active producers of biogas. Between the mesophile-only tanks, only the 25 C tank produces gas. The cold room mesophileonly tank does not. These findings support our initial hypothesis very well, that the psychrophile and mixed cultures would produce more biogas than the conventional manurecultures at the relatively cool temperatures of 15 C and 25 C. Several design elements were changed on the tanks to solve problems related to observed gas leaks when tanks were under positive pressure. Namely, the number of fittings and joints involved with the gas outflow system was initially very high and designed in such a way that repairs would be costly and time consuming in cases where fitting integrity was lost. Recurring issues with the gas outflow system resulted in several retrofits in order to reduce the likelihood of future leaks occurring among the tanks. Currently, the gas outflow system has been remodeled and the number of joints has been cut by more than half. Once completed, noticeable gas production was observed among tanks previously thought to be inactive. Now in its second year of study, the project is starting to switch its focus away from intensive hypothesis-testing data collection efforts into more application-based research. The overarching goal of the Phase II research effort is to simulate a fully-functioning small-scale anaerobic digestor and test various applications that may serve Alaskans interested in the technology. To date, we have already demonstrated the ability to collect biogas for use in conventional combustion applications. Throughout the remainder to the project, efforts will focus on developing better gas collection systems and further demonstration/analysis of smallscale anaerobic digestor technology for Alaskan individual homes. Finally, the project team along with Cordova High School (CHS) students made multiple appearances at various Alaskan State conferences during the last quarter. February 6-10, 2011 team members Casey Pape, Adam Low, and students from CHS science club traveled to Anchorage to present the project at the Alaskan Forum on the Environment (AFE). On February 14, 2011 the students again presented the project at the Emerging Energy Technology Grant meeting in Juneau. The project was received at AFE and in Juneau with excitement and enthusiasm. Following the meeting on February 14, 2011, students were invited to again present the project before the Alaska State Legislature and in a private meeting with Senator Lesil McGuire s office. The project was recently featured by Alaskan Dispatch Magazine in an article on rural Alaska entitled, Biogas could bring new energy to rural Alaska. January 17,

89 The project was also mentioned in Senator Lesil McGuire s recent press release on the Deadline for Emerging Energy Technology Fund Grant Applications Approaching. Released March 3, ii. Schedule and milestone information The project continues to closely follow the original outlined plan: - Construct Digestors for Phase 1 by December 15, 2009 Completed January Commence Data Collection by February 1, 2010 Achieved January 18, June 25-27, 2010, project meeting onsite in Cordova (all team members present); High school student presentations - Perform mid-term Analysis of Data by July 30, 2010 Completed informally internally as a project team, and formally in Quarterly reports 2 and 3. - Year 1 Q4 Report, December 15, Phase II Scoping, deadline for revised report: March 15, Phase I Report, including analysis of all Phase I data: March 15, Year 2, Q1 Report: March 15, 2011 (this report) - Year 2, Q2 Report due June 15 - Year 2, Q3 Report due September 15 - Final project report due September 30, 2011 ii.a) Personnel: Cordova Electric Cooperative Clay Koplin Grant Administrator. Koplin has managed most of the financial aspects of the project thus far on behalf of the Cordova Electric Cooperative, serving as the project manager. Koplin serves as a technical advisor to the project. University of Alaska, Fairbanks Katey Walter Anthony Research Director. Walter-Anthony acts as the primary investigator, and has spearheaded the scientific goals and directions of the project. She provides continual scientific expertise and project management. She contributed to the data analysis, interpretation and writing of this and all reports. Casey Pape Research Technician. Pape joined the project in early September, 2010, to replace Laurel McFadden as the primary project technician. Pape worked on-site in Cordova during the past quarter, maintaining the digestor experiment, including data collection, analysis, and troubleshooting. Pape led the preparation of the current quarterly report with assistance from other team members. Pape anticipates relocating to Fairbanks in March 2011, to continue working on the project with closer access to lab instruments, consultation with Walter Anthony and ACEP. Pape will travel intermittently to Cordova. Pape plans to remain with the project until its completion in September Dane McFadden Project Intern. Currently an undergraduate at Stanford University, Dane McFadden helped maintain digestor performance during August Job responsibilities included: maintaining daily gas data collection, feeding, chemistry measurements and gas sampling. McFadden will be using his experience here in Cordova as his required internship at 2

90 Stanford University and will generate an intern project report which will be submitted to the PI, the Denali Commission, and to Stanford University. Laurel McFadden previous Research Technician. McFadden, left the project and began graduate school at UAA in mid August McFadden was a key contributor to the project development and took the lead on organization and preparation for the initial construction and setup. McFadden completed the first draft of a Biogas Handbook for Alaskans, which will be submitted as a deliverable in final form to the Denali Commission by the end of the project. Peter Anthony Research Technician. Anthony consults on the project and continues to provide technical expertise to the maintenance and application of digestors. He participated in all on-site project meetings in Cordova and provided recommendations for simplification and winterization of the gas collection system in preparation for Phase 2. Anthony conducted the gas chromatography analyses of biogas composition for this report. Jeffrey Werner State FFA Director. Werner is interested in using the effluent from anaerobic digestors as a liquid fertilizer for agricultural crops. Located at the horticultural center at UAF, Werner remains enthusiastic about the possibilities of the potential uses of the once thought of waste product. Cordova High School Adam Low Science Teacher. Low was integral in bringing in student involvement via classroom curriculum and extracurricular projects. Low has been in charge of maintaining a consistent feeding regime and guiding student involvement with the project. While Pape was away from the project over Christmas vacation, Low had the added responsibility of maintaining gas flow and chemistry measurements as well as general troubleshooting. Additionally, Low has been working with science club students to set up a greenhouse experiment in which to test effluent samples for their potential use as a liquid fertilizer. Low also assisted in collecting and shipping effluent samples to other project colleagues in Germany in efforts to greater proliferate psychrophilic digestor technology. Cordova High School Students Volunteers. The students of Cordova High School have been highly involved with construction, feeding, maintenance, and public presentations for the project. They include the seventeen Chemistry class students and Science Club students (Craig Bailer, Ben Americus, Adam Zamudio, Sophia Myers, James Allen, Eli Beedle, Josh Hamberger, Keegan Crowley, Kris Ranney, and Carl Ranney). Ten students now share the responsibility of feeding the digestors on a daily schedule. Student Craig Bailer in particular has been of great help to the project. Bailer maintained chemistry measurements while the UAF-technician (Pape) was away and proved to be more than competent at updating records as well as downloading flow data. In addition, Bailer has been assisting Low with other experiments in the Cordova Energy Center in preparations for Phase II of the project. In particular, Bailer has been working on a type of heat exchanger as part of a potential science fair project with the aim that it may be of use to the digestor project during Phase II. SOLAR Cities TH Culhane Biogas Expert. With an extensive history in biogas technologies, Culhane developed the water-pressure tank design and provided extensive technical knowledge to the engineering of the project at its outset. He worked with and advised the on-site construction in 3

91 January 2010 and provides expert advice from his home base in Germany. Recently, Culhane requested a 1-L sample of psychrophilic effluent in efforts to test the success of psychrophilic digestors in different locations in Europe, Asia and Africa with different weather patterns and climate regimes as part of a tangential outreach project that Culhane and Walter Anthony have, funded by the National Geographic Society and Blackstone Ranch. Sybille Culhane Co-founder of SOLAR Cities. S. Culhane assisted in initial construction efforts and managing financial aspects of SOLAR Cities involvement. Chena Hot Springs Bernie Carl Owner of Chena Hot Springs. Carl has expressed interest in deploying a digestor at Chena Hot Springs, and has offered space for testing a digestor in his greenhouse. Others Brandon Shaw Website Development. Shaw designed the CordovaEnergyCenter.org website, where the project is hosted. He also assisted at the initial construction site, and was integral in the assembly of the flow meter system. Keywords: Biogas, anaerobic digestor, reactor, psychrophiles, mesophiles, methane, methanogens, Alaska, cold-climate, thermokarst lakes, etc. iii. Narrative summary of the project status and accomplishments to date, and addressing the following questions: is the project on schedule, is the project on budget, and what actions are planned to address any project problems. iii.a) Notable Accomplishments: Biogas production Thorough understanding of variables that limit biogas We now have an extensive dataset of daily biogas production from each of the tanks in the experiment. Currently we are producing high quantities of flammable gas (between L/day per 1000L tank). The gas produced is being release for the most part to the atmosphere which is undesirable due to the radiative and heat trapping properties of the gas. Our focus now is to capture the biogas being produce and begin experiments testing the flammability and applicability of the gas. Proven flammability One of the primary goals of this project was to determine if the psychrophiles that produce methane in thermokarst lakes could be harnessed in an artificial environment to produce biogas. With the initial production of biogas from both psychrophilic and mesophilic microbes we proved flammability possible (refer to Y1Q2 report). Biogas from conventional anaerobic digests typically contains methane content between 40-60%. Recently it has been discovered that our biogas contains increasingly high concentrations of methane (50-82%). It is possible that the increased methane concentration(s) observed in our tanks are the result of using psychrophilic methanogens whereas typical anaerobic digestors commonly use mesophilic bacteria and archea found in bovine and animal manure. Additional measurements of gas content are needed to confirm consistency in this trend. Stable isotope analysis could 4

92 also help distinguish pathways of methanogenesis in the manure-vs.-psychrophile tanks. If this high CH 4 -content of psychrophilic biogags holds constant, then this is an important finding as it implicates the use of psychrophilic methanogens for improving the energy content of biogas as opposed to more common mesophilic anaerobic digestor systems. Successful Chemical Remediation of Digestor Tanks As mentioned before in section iii.a) early in the experiment, observed declining ph was foreseen as a potential threat to the digestor(s) microbial health and action was taken to restore ph to previous levels. Ideally, digestor psychrophilic and mesophilic-communities perform under optimal conditions at a ph of around , observing tank ph(s) much lower than this (ph 3.5 6) was an indication that the tanks were acidifying and VFA s were likely being produced in large quantities. From this point chemical remediation was determined necessary to stop the digestors from potentially crashing or souring from prolonged exposure to low ph. Remediation was performed in two steps. The first step involved stoppage of the initial feeding schedule as specified in the project proposal. Stopping feeding was a necessary step as it was essential to minimize the amount of variability in the tanks while alkalinity was restored. The second step entailed adding calculated quantities of Calcium Carbonate, Lime, and Sodium Hydroxide in order to bring the ph back to the initial conditions. Care had to be taken to restore the ph in a gradual manner as to not shock the microbial communities. Slow remediation was also essential as over treating the tanks could cause them to become too basic, as anaerobic digestor bacteria are particularly sensitive to increased ammonium concentration and this is to be avoided as even slightly basic tanks can cause total failure of mesophilic communities (pers. com. TH Culhane). All digestors are now at relatively stable ph values with the exception of Tank 3. Proven High Methane Content of Biogas GC analysis of gas samples collected from tanks 1, 4, 5, and 6 shows high levels of detected methane in most cases. Preliminary analysis shows that methane concentrations have increased since the onset of Phase I research. To some extent this is an indication that we are observing healthy proportions of microbes in several tanks enough to support active methanogenesis. More work will have to be performed on the GC in order to understand long term trends and behavior of our tanks, but the initial results seem promising. Student education This project has the fortunate opportunity of involving High School students in a primary scientific study. Cordova High School students have the unique ability to see some of the technical aspects and complications that go along with scientific research. The science club and chemistry class provide an excellent platform to organize student involvement. Previously, students have had the opportunity to troubleshoot and take the lead on feeding procedures for the project resulting in several very clever and innovative ideas being implemented. The students of Cordova High School have presented on the project several times now and have been received well with each new appearance. The students demonstrate a thorough understanding of the issues involved with conducting new technology research as well as the factors that contributed to lessons learned during this project. CHS students and teacher Low are presently preparing projects for the 5

93 Alaska State science fair in which many are using biogas-inspired projects. More will be reported after the students have attended, but generally the project can be thought of as very successful in its educational aspects for local students. Community outreach We have had the opportunity to present our project ideas and preliminary results at meetings with the Alaska Power Association and Alaska state legislators in Juneau, and at a variety of conferences, including the Alaska Forum on the Environment and the Alaska Rural Energy Conference. Five Cordova High School students traveled to present at the Alaska Rural Energy Conference in Fairbanks. Titles of our project presentation at the Alaska Forum on the Environment and Alaska Rural Energy Conference were: Walter Anthony, K., Culhane, TH., Koplin, C., McFadden, L., Low, A. Improving Cold Region Biogas Digestor Efficiency. McFadden, L. Alaska Forum on the Environment. Anchorage, Alaska. February 8-12, Walter Anthony, K., Culhane, TH., Koplin, C., McFadden, L., Low, A. Improving Cold Region Biogas Digestor Efficiency. Low, A., Hess, E., Allen, J., Americus, I., Americus, B., Zamudio, A. Alaska Rural Energy Conference. Fairbanks, Alaska. April 27-29, New Scientist article featuring this project: Cold climates no bar to biogas production. November 4, Unfortunately no final reference was made to the Denali Commission as the funders of this research. Interviewees informed the writer of the funding source, but did not have the opportunity to ensure that the information was included in the printed article. The project was recently featured by Alaskan Dispatch Magazine in an article on rural Alaska entitled, Biogas could bring new energy to rural Alaska. January 17, Low, A. Youth Participation: Improving Cold Region Biogas Digestor Efficiency. Low, A., Bailer, C., Allen, J., Americus, B., Zamudio, A. Alaska Forum on the Environment. Anchorage, Alaska. February 8, Walter Anthony, K., Culhane, TH., Koplin, C., Low, A., Pape, C. Improving Cold Region Biogas Digestor Efficiency. Low, A., Bailer, C., Allen, J., Americus, B., Zamudio, A. Denali Commission Public Forum on the Emerging Energy Technology Grant. Juneau, Alaska. February 14-15, The project was also mentioned in Senator Lesil McGuire s recent press release on the Deadline for Emerging Energy Technology Fund Grant Applications Approaching. Released March 3,

94 Last year the chemistry students took a class trip to the Alaska Power Association in Feb Students C. Bailler, D. Hess, C. Morrissett, J. Smyke, S. Lindow, and T. Kelley presented on the project and it was received well among those who attended the meeting. The project team intends to present at next years Alaska Rural Energy Conference in Juneau, Sept , Biogas Handbook for Alaskans- McFadden completed the first draft of a Biogas Handbook for Alaskans, an instructional booklet specific to biogas production and applications for Alaskan communities. The Handbook will continue to be revised, and submitted as a deliverable in final form to the Denali Commission by the end of the project. Website development- Website developer Brandon Shaw designed a site ( for the Cordova Energy Center, the venue at which the biogas experiment has been conducted. The website provides a venue for students and community members to obtain information about the project and how to get involved. It is important to update the website often as a means to show visitors that the project is still underway, that is still producing results and that people are still encouraged to get involved. iii.b) Project Status The project is in the final wrap up stages of Phase I and research efforts are now turning towards applications of biogas according to Phase II of the original research proposal. Phase I involved the testing of several different blends of methanogenic microbial populations (mesophilic and psychrolphilic) in order to examine different characteristics of digestors that operate in cold environments. The primary goal of Phase I experiments were to construct and monitor six different anaerobic digestors and to try to maximize the amount of gas that can be produced in depressed temperature climates (please refer to the original research proposal for more details on Phase I goals and objectives). Researchers feel confident at this time that Phase I should wrap up as the current data set has satisfied interests to understand biogas production in depressed temperature environments (see Phase I Data Report for details). We are pleased to report that many of the tanks are producing biogas from food waste material at high levels. Currently, we are observing flammable biogas production in Tanks 1, 4, 5 and 6 in large quantities (up to 345 L/day). Tanks 2 and 3 have not been producing gas in previous quarters and are not presently active despite increase feeding in Tank 2. Both tanks are suspected to be inactive at this time. We have remediated many of the problems elucidated in the last quarterly report (see Y1Q4 report). During the past quarter, we began pilot-level experiments for Phase II, while at the same time maintained the Phase I and Phase 1.5 study to completion in effort to better understand yield and efficiency. The Cordova High School students took the lead on a greenhouse pilot study to test the potential for digestor effluent to serve as a liquid fertilizer in food production. In addition, the team demonstrated use of biogas in conventional applications at various conferences this quarter. UAF research technician Casey Pape is leading the project team in preparations for Phase II, to find usable applications for biogas produced from the anaerobic digestors. In the following months of this project, Phase II research will begin to incorporate data collection on the time and effort required to build and maintain 7

95 biogas digestors; provide data to inform economic assessment of biogas technology in Alaska; and produce a Do-it-Yourself Biogas Handbook for Alaskans. Phase 1.5: Gas flow measurements At the time of the last quarterly report, it determined that the project s Sierra Instruments Top-Trak 820 Series Mass Flow Meters (installed February 18, 2010 to maintain continuous mass flow measurements of each tank), were not recording gas flow properly. The issue was remedied for the most part when gas flow through the meters was limited to specific times of day. The tanks therefore could build pressure in order to achieve higher rates of flow necessary for the flow meters to record biogas production accurately. This method has been demonstrated to be very effective and was used throughout the quarter to obtain daily total production of biogas. By the time this method was developed, Phase I efforts were in large part beginning final stages as research focus was shifting towards Phase II - implementing the produced biogas. Due to the lack of an extensive dataset that accurately demonstrated biogas production among all tanks, the research team proposed an intermediate phase in the second year first quarter to obtain a solid data set for hypothesis testing. At the same time we started planning Phase II research. The proposed study was entitled Phase 1.5 as it contained both elements of Phase I and Phase II (see Phase I Final Report for details regarding Phase 1.5). The methodology used during Phase 1.5 was simple for the most part. Each of the tanks gas outlet valves were closed for a period of several hours, allowing all biogas produced inside to accumulate within the headspace of each tank or remain dissolved in solution. As biogas began to accumulate within the vessel, the tanks would begin to distend in response to the accumulation of gas positive pressure within the tanks. After a period of about 6-8 hours, each tank valve was turning to the open position and the gas was allowed to vent to the outside atmosphere. The large difference in pressure between the tank and ambient air (high ΔP) meant that a greater quantity of gas would flow through the mass flow meters in a shorter period of time. Within the range of three standard liters per minute ( 3 SLPM) the meters record mass flow rate with a high levels of precision so researchers aimed to vent the tanks within this set range. Once the tank achieved a pressure similar to that of the ambient air the tanks were closed and the cycle was repeated (for more information about the protocols mentioned here please refer to Y1Q4 report). This method proved highly effective at determining daily gas output with relatively few drawbacks. The main disadvantage associated with venting according the method mentioned above is that it is very labor intensive. Venting every 6-8 hours meant that a researcher had to be near enough to the project in order to tend to and vent each tank three or four times a day. In addition, the tight range of flow in which the meters were calibrated meant that venting events had to be highly controlled, making it difficult to allow multiple project team members to vent each tank as this may result in highly variable interpretations of the data in a given day. As a result, the burden of responsibility to maintaining flow measurements was entrusted to the onsite technician (Pape). Therefore data could only be collected when researcher time could be dedicated to tending the tanks and the resulting dataset could not be maintained continuously throughout the quarter. However, recording biogas production using this method proved to be very effective and the project team was able to get very reliable estimates of daily gas production among each tank (Figure 1). 8

96 Table 1. Biogas summary data for Phase 1.5. The numbers present average gas production within a 24hr period for each tank. Data are not normalized by the volume of slurry inside each tank. Normalized data are presented in the Phase I Final Report. On several occasions, gas pressure contained in the headspace of the reactors caused tanks to expel some of their liquid contents from the tanks. Dates of occurrences of tanks spills are both documented and undocumented as students may not have reported a spill during several instances when researcher and teacher support was not available. Gas Production Summary Data (Raw Data) 15 C Room 25 C Room Tank Tank Date Tank Tank 4 Tank 5 Tank 6 12/11/ /17/ /18/ /19/ /20/ /21/ /22/ /23/ /24/ /26/ /29/ * /30/ /31/ * /1/ /2/ /3/ * * 2/4/ /25/ * /26/ * /27/ /28/ /1/ /2/ /3/ /4/ * 163.3* /5/ /6/

97 3/7/ /8/ * 3/9/ /10/ Average Standard Dev Total * Days in which a documented leaks occurred (volume released is not known) Figure 1. Current flow measurements from Phase 1.5 and graphical representation of unnormalized data presented in Table 1. Biogas production shows marked increase from the beginning of the week (01/17/11) and the end (01/23/11). Tank(s) # 2 and 3 valves were closed and were not observed to have produced gas above nominal levels for the entire period. Any noise recorded by the Serria Top-Track 820 mass flow meters was given a value of zero. Data gaps may exist during times where either no flow data was being recorded or data collected did not align with the above mentioned protocol(s). Another drawback associated with sampling biogas on an hourly-based schedule is the increased potential for pressure buildup to cause a spill or seepage from the tanks. This mainly occurred when the pressure within the tanks increased to the point that effluent would rise to the top of the inlet tube - where food is typically put into the tanks - and spill onto the ground. In order for this to occur, the pressure of the gas within the tanks would have to exceed about two pounds of pressure ( 2 psi) (Equation 1). Several spills were documented from tanks in the 25 C room as they were the tanks with the greatest amount of activity. Though efforts were made to vent tanks in time to avoid spills, some inevitably occurred when the time between venting was too long. The primary negative result of a seeping tank was loss of viable bacteria and food media from which biogas can be produced, not inoculants exposure to air. Though any seepage of material from the tank was undesirable, any loss of biogas production could be directly attributed to loss of tank inoculants and ultimately be readjusted to the new tank 10

98 volume. Still it is important to observe that the issues were known to have occurred on multiple occasions among all 25 C room tanks. More information on this issue will be presented later on in section iii.f) Hurdles and Solutions. Equation 1. Hydrostatic pressure for a (non-moving) fluid in pounds per square inch. The height of the top of the tanks is about 3-4 ft above the waterline within the reactor. At this time the project team is confident in the results obtained during Phase 1.5. We have answered many of the questions charged to the Phase I research. We are satisfied with the result of Phase I and are ready to begin research into Phase II. For more information regarding data collected during Phase I please refer to the Phase I Data Report submitted March 15, Supplemental chemistry data is provided at the end of this report (See Appendix I) Tank Fitting and Joint Retrofit In order to ensure that biogas production data was accurate among each of the tanks, researchers had to be confident that all gas leaving the tanks flowed exclusively through the flow meters installed on sight. At several points during the quarter seal integrity was elucidated to be an issue that ultimately compromised the observed trends among all of the tanks in the experiment. It was reported that at the beginning of the school year, over 15 joints were noted to be upstream of the Sierra Top-Track 820 Mass Flow meters, of which all were required to be air tight. In addition, each of these tank gas outlets were assembled in such a way that repairs could not be made easily if a leak were to develop. Ultimately, each of the tanks had weaknesses associated with joint and gas fittings which had to be addressed before results on Phase I could be deemed definitive or conclusive. In the past, soapy water had uncovered several minute leaks among tanks 4 and 5 in the 25 C room. This method works well in cases where the leak is small enough that the amount of gas release is less than the amount of pressure buildup (or biologic rate in this case) within the tank. In this instance soapy bubbles would form around the leaking area as gas escaped to the atmosphere. Small leaks like these were discovered and usually remedied when fittings were tightened; however, large leaks could not be uncovered this way as the exchange of gases between the tanks an atmosphere would appear ubiquitous to the point that soap water would have no effect. This was suspected to be the case among Tank 6 in the 25 C room. In the last report (Y1Q4), decreased activity observed in Tank 6 was assumed to be due to the temperature threshold not being met for mesophilic bacteria to be active, though this seemed peculiar considering the activity of each of the other tanks within the 25 C room (Appendix I). The team met on January 9, 2011 via teleconference to discuss the project status and upcoming transition to Phase II. Addressed in that meeting was the current concern that joints 11

99 and fitting among the tanks may not be structurally sound. This was both a primary research interest in that leaks possibly compromised the findings of Phase I and also because the final project booklet intends to present a robust digestor design for ordinary Alaskan households to duplicate with high rates of success. The team concluded at that time that all leaks should be assessed at that time and any retrofits necessary be made in order to correct any issue with leaking tanks. Alternative testing methods later revealed several leaks present on Tank 6 and steps were taken in order to improve fittings on all tanks (Appendix II). Shortly after the repair was made on January 15, 2011, Tank 6 s flow meter was reinstalled the tank started showing high levels of biogas production (Figure 2). Figure 2. Flow data from Tank # 6 from Jan , Leaks were uncovered and repaired on January 15, 2011 and biogas production was recorded shortly after. All biogas data measurements were recorded using Sierra Top-Track 820 Mass Flow meters which were installed on site since February 18, It is not known at this time how long the leaks uncovered where present within the system. All tanks have received a complete retrofit and no leaks have been reported since February 25, Several additional leaks were uncovered among all producing tanks in the weeks that followed the first discovery in January. As the tanks were now experiencing elevated pressures associated with daily flow measurements the tanks were demonstrating leaks due to the increased positive pressure within each reactor vessel. Researchers were therefore convinced that an overhaul of all gas outlet systems was merited before Phase I research could reach any final conclusions. The last of the proposed retrofits was completed on February 25, 2011 and no leaks have been uncovered since. The new system improves on the old design by reducing the number of joint fittings and components by more than half. The new improvements will be used in the final handbook for Alaskans as the likelihood of leaks to develop has been greatly reduced using this design as well the cost and difficulty involved with installation and repair should a leak develop in the future (Appendix II). 12

100 As a result of the system repair, we now see flammable gas being produced in large quantities from tanks 1, 4, 5, and 6. We have carefully monitored the rates in production of biogas between these tanks and feel satisfied to make conclusive statements about the Phase I research. Flammable biogas Previous analysis of gas composition on a Shimadzu 2014 gas chromatograph equipped with a flame ionization detector revealed that CH 4 concentrations in gas flowing from the digestor tanks is up to 82% by volume (see Y1Q3 report). Composition data does not exists for current or catalogued biogas samples since the third quarter, but biogas from all producing tanks demonstrates positive flame test (Table 2). Weekly samples are now being collected from all producing tanks and will be analyzed when Pape returns to Fairbanks later in March (Appendix II). We expect to have an updated GC analysis of gas composition by the next quarterly report. Currently, we are observing flammable biogas among four of the original six tanks. Tank 2 and 3 are not observed to be producing biogas and therefore no gas record exists. Though we are not able to say definitely at this time what the concentration of gases is or the percent methane content (% CH 4 ), the biogas produced on site has demonstrated flammability and applicability in many conventional gas applications (see Phase II Progress). Table 2. Results of produced gas flammability tests. Positive results of the flammability test indicated usable biogas. Flame tests are now being conducted on Tanks 1, 4, 5 and 6. Last demonstration was conducted on March 10, Tank First positive flame Last confirmed flame 1 1/31/10 03/10/11 2 NA NA 3 1/22/10 2/1/10 4 2/1/10 03/10/11 5 1/21/10 03/10/11 6 1/26/10 03/10/11 For more information about GC analysis and this project please refer to Project Status and Accomplishments of the Y1Q3 report (section iii.a)). Temperature control in the Connex Temperature remains one of the most imporant factors that influences methanogenic metabolic rate (House 1978). The Connex used to house the digestors was designed by the project team to maintain two rooms at separate cold (15 C) and tepid (25 C) temperatures (as opposed to conventional biogas deg C, warm temperatures). The temperature is visually monitored by digital thermometers (less accurate) and recorded by (more accurate +/-0.47 C, Drift +/-0.1 C/yr) dataloggers suspended in both rooms as well as inside the slurry of each 13

101 digestor. Several dataloggers, suspended at different depths within some of the tanks, have not been downloaded since May 12, 2010 in an effort avoid opening the lids of the tanks and preserve the current anaerobic conditions of the experiment. Summary data from all tempertature loggers over the course of the experiment are illustrated in Figure 3. Over the last quarter temperature conditions in Cordova reached unexpected lows that translated into decreased temperatures within the rooms inside the Connex. From December to March 15, 2011 average temperatures for the 15 C and 25 C rooms were C and C respectively, well below target values. Temperature regulation is presently controlled by researchers by checking on the experiment daily. If the temperature drops or climbs above the desired level, researchers reduce or increase the amount of heating by adjusting the radiator heating units in each room. This method has not proven affective at keeping the temperature constant as average hourly temperature for this quarter was 4.27 C and 2.85 C degrees cooler than the targets set in the Phase I study. Figure 3. Mean hourly temperature of the data loggers in the Connex cold and tepid room, and mean daily temperature recorded in Cordova. As the temperatures in Cordova began to drop from temperate summer conditions, the Connex experienced a noticeable and unfavorable drop in temperature. Temperatures are still below their set values (of 15 C and 25 C respectfully), both rooms will need further heating inputs to meet project targets. Individual tank temperatures have not been downloaded since May 12 in an effort to maintain the anaerobic environment in the tanks (accessing the temperature loggers requires opening the tanks to the air). Biogas project temperatures are measured with Hoboware U Water Temp Pro V2 loggers recording hourly. Cordova temperature data was obtained from online sources (source: wunderground.com) The project team has expressed concern with the electrical system currently being used to supply the Connex experiment with heat and power. With the help of Cordova Electric 14

102 Cooperative (CEC), the project is installing an updated electrical system that will help to regulate temperature more effectively as well as improve project safety. CEC linemen visiting the site also showed large areas of radiative heat loss throughout the Connex, demonstrating areas where insulation was inadequate. Currently, steps are being taken in to route additional power to the Connex which will reduce the amount of school liability as well as make efforts to regulate temperature easier in the future (Appendix III). Tentative completion date is set for the end of the second quarter of this year. Phase II Progress Phase I is drawing to a close and research interests are transitioning to the Phase II applications of biogas. The project team has detailed where emphasis will be placed in the coming months as work begins to demonstrate what small-scale anaerobic digestor technology will likely look like in Alaska (see Phase II Scoping report). These projects will be tested over the coming months and will be reported in the next quarter. For now Cordova High School teacher Adam Low, along with students from the school s science club are heading efforts to collect and test the gas. The students at CHS have already demonstrated the use of biogas for conventional applications such as boiling 100mL of water, powering a combustion engine (lawn mower) and have presented these findings at conferences in Anchorage and Juneau as well at the upcoming State Science Fair (Appendix III). Through the remainder of the project, Cordova High School will likely take the lead on demonstrating applications of biogas. CEC interests at this time are in providing technical support as well as updating equipment located on site in order to conform to school and state regulations. At this time UAF researchers are will continue to focus on data acquisition involving more technical analysis of catalogued samples collected at the Cordova site. On March 25, 2011, UAF researcher Pape will be relocating back to Fairbanks in order to conduct said analyses. Pape will also begin to work closely with the Alaska Center for Energy and Power (ACEP) in the coming months in order to provide an economic assessment of the time and resources required to replicate projects like this one on the broader scale. Of immediate research concern and interest is that of collecting biogas. Currently we are producing more gas than at any other point during the project, but are no longer attempting to collect it once measured. For now, collecting biogas so as to be used in applications is a primary research interest in the beginning of Phase II. Gas Collection: Proof of Concept As research interests to understand psychrophilic biogas production on the small-scale have been mostly satisfied at this time, the project team will now begin switching efforts into Phase II efforts with the issue of gas collection and storage being of primary focus in the days ahead. At the time of the last quarterly report it was determined that a bladder or waterless gas collection and pressurization system was the most likely candidate for taking hold in Alaska (refer to Y1Q4 report). For Alaskans requiring a low-tech solution to both collect and pressurize stored gas for usage, a bladder-type system has the most appeal for its simple use and maintenance requirements. Preliminary research into bladder collectors has proven the idea is effective in Alaska. Students at CHS have been using car tire inner tubes to demonstrate this 15

103 idea (Appendix III). The inner tubes serve as a practical demonstration of how bladder storage containers could work for Alaskan residents; they are light, easily transportable and can be pressurized easily. To date, the CHS students have used inner tubes containing biogas for all science experiments and demonstration projects. Further work will now be conducted to find bladder-type gas containers that can be applied on a larger household scale. The research team anticipates having a full-scale bladder gas container or alternative gas collection system operating at the Cordova site by June 30, From there, Phase II research efforts can continue to further pressurize and demonstrate biogas usage. iii.c) Health and Safety Conventional small-scale anaerobic digestors are generally considered to be nonhazardous when given proper ventilation and maintenance. Still anaerobic digestors are used for the synthesis of combustible gases and have some safety concerns associated with them. Electrical and Power: The project site is maintained by electrical heat and power supply. At present, that electricity has been provided by extension cords that run from inside the school and out to Connex. The cords draw power from multiple outlets and run underneath doors from the back of the school gymnasium which is not allowed according to state electrical codes. These wires are exposed to the elements as well as encounter significant resistance from the amount and length of cords being used. During peak demand the breaker has been known to trip if the cords are not distributed properly between the devices and the school. We are currently trying to update the electrical system associated with the Connex in order to reduce an liability as well as improve the project electrical consumption efficiency. Flammability: Biogas is very flammable and it is important that measures be taken to prevent any undesirable fires that may cause explosion. Currently no open flame is allowed within the Connex and students handling biogas are advised to wear appropriate eye protection at all times. Students conducting experiments with biogas are required to wear eye safety glasses and proceed under adult or teacher supervision. No injuries due to fire or explosions have been reported during this project though several fire alarms have been triggered when demonstrating biogas flammability was conducted without proper ventilation. Ventilation: The build-up of certain gases in an enclosed space can be toxic. Biogas digestors produce methane, carbon dioxide, hydrogen sulfide, and other gases which can be deadly at high concentrations. It is apparent to anyone entering the Connex which houses the experiment that a very noticeable barn-like smell can be detected. This smell was significantly reduced once the new tank gas outlets were installed, but still the smell remains. It is thought at this time that current smells are from effluent reservoirs stored inside the Connex and not due to any leaks among the tanks. Tanks are monitored daily and do not pose any threat to human health. Though the tanks are checked often for leaks, the inside of the Connex container has a very noticeable smell reminiscent of manure. The air is cycled daily to a certain extent when the Connex container is opened for daily download of the gas flow data. Tubes are connected to the tanks to allow lighter than air constituents escape the container. The Cordova fire department has visited the site and tested it for noxious gases. The results of the fire departments testing came up negative for any toxic gases. 16

104 iii.d) Schedule of project The project is still on schedule as defined by the original project outline. Phase I is drawing to a close and research efforts are beginning to focus on Phase II. Throughout the rest of the project research efforts will focus on applying biogas in a series of demonstration projects design to show biogas versatility as well as chemical and cost feasibility analysis to assess the practicality of small-scale digestors in Alaska. The final project report will be completed and submitted on September 15, 2011 including all the findings of Phase II research. iii.e) Project budget We anticipate that the budget is on target. At this time, the budget is not expected to exceed the grant, and the matching contribution is expected to significantly exceed the grant requirement. Clay Koplin will provide more details on the budget when he returns from out-ofstate travel. iii.f) Hurdles and solutions Project problems and solutions were mentioned in iii.a, and are outlined in more detail here. Confidence in biogas measurements: Due to offsets between the flow meter calibration levels and our gas production rates, we were not able, until this report, to provide the true values of biogas produced. Previous values represented averaged daily flow rates as opposed to cumulative daily gas production. Though this is generally an acceptable method for smoothing out noise in any data set, the true biogas production rates was underestimated. Solution: Casey Pape determined a new method to achieve our goal of daily gas production determinations by closing tanks, allowing them to swell with produced gas, opening the valves over a short period of time to allow high rates of gas flow within the level of the flow meter calibration. We now have an extensive dataset on the biogas production among tanks in the experiment and can make clear predictions about the future of biogas small-scale technology in Alaska. Data collection was completed on March 10, 2011 and the project report was submitted in the Phase I Data report. Date submitted March 15, Other potential considerations: The following factors are important considerations that generally can lead to problems in biogas technology. While we have no reason to think that any of these factors is causing a problem in our systems, for the sake of thoroughness, here we evaluate each as a potential problem in the context of our study. Temperature fluctuation. Problem: It is a major goal of this study to preserve the cold (15 C) and tepid (25 C) conditions as was defined in the original project proposal for the purpose of incubation of microbes. The Connex constructed for the project is insulated with R-10 pink foam insulation, but has poor seals and air spaces that cause it to have a heat/cooling regime that mimics that of the local environment of Cordova. Over the course of this quarter, average temperatures for both cold and tepid rooms was 4.2 C and 1.9 C below target values respectively. This is not ideal and will need to be better 17

105 monitored in the future as our impression of the day to day gas production is that it should be consistent if temperature and food inputs are maintained at a constant level. Solution: Although temperature variability is undesirable, we have tried to correct it each time it comes to the team s attention that it may be an issue. Currently there is interest to install power to the Connex container and will likely materialize in the coming weeks (Appendix II). CEC linemen have been dedicated to completing installation and work will likely be completed in time to be reported in the next quarterly report. Logistical and management concerns: Digestor/tank and fittings integrity. Problem: Generally speaking, the more holes and fittings installed on a digestor or any gas-holding container increases the chance for a leak to develop. At the beginning of the scholastic year, the project gas outlet system installed on each of the tanks were known to have as many as separate joints and fittings. This many fittings can make it very difficult to ensure the vessels remain anaerobic. In this experiment, leaks have already been uncovered among the secondary gas containment systems and resulted in biogas no longer being flammable in air. Simple tests of pressurizing the tanks revealed that many contained significant leaks that compromised researcher efforts to record gas flow. Much of the data may have been skewed during the Phase I study as tanks showing no signs of biogas production have been demonstrated to be active after leaks were repaired. Recurring issues continually compromised research efforts to understand gas production as multiple leaks were continually discovered among several tanks and within different joints throughout the gas outlet system. Solution: A meeting between team members via teleconference back in January 2011 resulted in a group decision to retrofit or repair any leaks that were thought to be obscuring Phase I results. Initially faulty joints were repaired with sealants and other compounds in effort the patch the existing system. This could be likened to a Band-Aid-type approach and was not ideal in the longer term. In the weeks that followed, positive pressure experiments revealed that many of the tanks had significant weak points and that ultimately the most effective way to resolve any issue was by retrofitting the entire gas outlet system on each of the tanks. The flow meters were properly mounted to the wall of the Connex and fitted with standard pipe thread fittings in order to allow for proper flow readings to take place. New valves and reinforced hose were installed in order to reduce the number of joints within the system by more than half. The new systems are generally cleaner and easier to maintain than previous designs and have demonstrated the ability to maintain pressure since the installation was completed (Appendix II). As of February 25, 2011 the last of the tank retrofits were completed and no leaks have been reported since. All tanks expected to be producing biogas exhibit the ability to maintain a positive pressure at this time. Soapy water test have not revealed any additional leaks and the problem is thought to be solved for the most part. Balance of responsibilities. Problem: The project is designed to be conducted in joint partnership between Cordova High School, a public utility (CEC) and the University of Alaska, Fairbanks. Collective effort between these parties is necessary in order to 18

106 maintain the project and pursue additional research development during the Phase II study. Students are very capable of feeding and maintain digestors from day to day, but both students and staff are ill-equipped to combat many of the more technical problems that arise due to the nature of an experiment of this type; however, as the project switches focus in its second year to less technical interests there will be decreased need for UAF staff to provide daily support and monitoring of the project. Solution: The project full-time technician (Casey Pape) will be relocating to Fairbanks, AK at the end of March in order to pursue further analysis of samples and data catalogued over the previous year as well as begin efforts to research options for upscaling biogas technology in Alaska. Adam Low and CHS students have done a wonderful job filling in for Pape while away on previous work commitments in the past and will no doubt maintain the project with a high level of professionalism once Pape relocates. The CHS students are eager to learn more from the project and begin investigating Phase II problems as well as conduct experiments using biogas. It will be an educator s challenge to come up with more challenging and constructive projects for students to include themselves in during the next phase of the project and researcher s challenge in order to maintain strong ties and communications with the research effort while in Fairbanks. Please see the Implementation Plan in the Phase II scoping report. Pape will travel back to the project site in Cordova occasionally in order to help facilitate project completion and deconstruction later this year. 19

107 References: Gerardi, Michael. The Microbiology of Anaerobic Digestors. (New Jersey: John Wiley & Sons, Inc., 2003), House, David. (1978) The Complete Biogas Handbook. (Alternative House Information, United States), 52. Walter Anthony, K. Vas, D., Brosius, L., Chapin, F. S. III, Zimov, S.A., and Zhuang, Q Estimating methane emissions from northern lakes using ice bubble surveys. Limnol. Oceanogr.: Methods 8, 2010,

108 Appendix I. (Chemical Data Supplement) Figure 4. DO measurements were taken with an Xplorer GLX Pasco PS-2002 Multi-Datalogger until March 24, following which they have been taken by a Hanna HI9142 DO meter. As of October 1, 2010, the Hanna instrument could no longer be calibrated properly. Proper function was restored after servicing the instrument in December

109 Figure 5. Oxidation-reduction potential (ORP) indicates the availability of oxidative molecules and ions in the system. ORP is a valuable measure as it determines the likelihood that bacteria will follow the methane fermentation pathway. For healthy methane production, samples should have an ORP of From January 21-April 9, ORP was measured with an Xplorer GLX Pasco PS-2002 Multi-Datalogger. From May 10 forward, it was measured with an Oakton PC510 ORP meter. 22

110 Figure 6. Results indicate that the ph in Tank 1 fell slightly since Y1Q3 report (currently ph 6.1). We halted daily feeding to allow the opportunity for ph to recover on its own, without reverting to chemical remediation treatments. ph was measured with Macherey-Nagel litmus paper January 21-April , and with more precision using an Oakton PC510 ph meter since April 17, 2010 until the present. 23

111 Appendix II. (Joint and Electrical Retrofit) Newly installed gas outlet system. Work was completed retrofitting all tanks on February 25, The new system only uses standard pipe and gas fittings and the sealant used is Teflon tape. This system is easy to maintain and service in case of future leaks. Picture of the old gas outlet system installed on Tank 5. The system was known to have several weaknesses and exhibited leaks on multiple occasions. Tank 5 (left) was allowed to pressurize and fill Tank 6 (right). This was a test designed to uncover leaks that may have been present in Tank 6. Once Tank 6 was pressurized, soupy water was used to discover several leaks near the valve stem. 24

112 Flowing the install of new gas outlets among all of the tanks in the 25 C room each tank began demonstrating the ability to hold pressure. Here each tank is pictured accumulating biogas prior to a venting. The old connections pictured above used cloth reinforced rubber tubing to connect the gas flow meters though the transducer (bottom) is intended for pipe fittings to be installed. The length installed upstream of the device is intended to allow for uniform flow that is not turbulent, causing a misread by the device. 25

113 The old valve stem is picture here to illustrate the redundant number of fittings used to contain gas within the tank. The separation at the bottom illustrates there were significant weaknesses and failures cause by this apparatus. Several sealants and compounds used to connect the above valve stem have resulted in the wearing the threads of the thru hole on each of the tanks. Here you can see worn or rounded threads caused by using excessive amounts of sealant initially. Picture depicting new unworn threads. Notice the sharpness of the edges which allow for an air-tight fit once installed. Cordova Electric Cooperative CEO is pictured here using a thermal camera to uncover weaknesses in the Connex insulation. The team walked around the interior and perimeter of the project site highlighting the inefficiencies of 26 the heating system.

114 CEC linemen seen here next to the Connex and the current electrical system used for heating and powering the project. New power cable installed to route additional power to the project site. March 8, Once installed, this Rhino TM Spider circuit will be used to power the Connex. This system will be a significant improvement on what is currently in place and will conform to any state or local utility regulations as well as improve the overall electric consumption of the project. 27

115 Appendix III. (Pictures) CHS student and teacher Adam Low pictured with Alaska State Senator Lesil McGuire. McGuire met with students following their presentation on Biogas to the Denali Commission, emphasizing the need for projects that include participation among Alaskan youth. The presentation was held in Juneau on February 14, CHS students and teacher Adam Low pictured at the Alaska Forum on the Environment in Anchorage, AK. The conference was held between February 7-11, 2011 and the students participated in a variety of events show casing the project. The students presented posters on work with biogas as well as presented among other youth oriented projects. 28

116 CHS students presenting on the biogas project at AFE in Anchorage, AK. February 8, Students Craig Bailer, and others working with CHS teacher Adam Low demonstrating the heating potential of biogas. Students later recorded a video showing the ability to boil water with biogas collected from the experiment. Student Brian seen here fills an inner tube in order to use it in the student s classroom for science experiments. The inner tube demonstrates the idea that a simple and elegant containments system provided by using bags or other collapsible structure ultimately has several advantages over other previously explored collections systems. 29

117 Updated photos of the student greenhouse experiment. The interest here is in order to test if the effluent from each tank has potential liquid fertilizer benefits in addition to producing biogas. Several different crops are being test for and more information will be available later. 30

118 The current project profile when viewed from outside. At this point the project has a very minimal footprint though more display may serve to better present the project to the public. Previous gas pressure systems have been dismantled and the project team has taken a minimalistic approach. As Phase II effort commence into full swing the outside appearance is likely to change somewhat in the coming months. 31

119 Denali Emerging Energy Technology Grant: Improving Cold Region Biogas Digestor Efficiency Year 2 Quarterly Report, Y2Q2 June 29, 2011 Table of Contents i. Y2Q2 Summary.1 ii. Schedule and milestone information.2 ii.a) Personnel.2-4 iii. Narrative summary of the project.4 iii.a) Accomplishments..4-7 iii.b) Project Status.7-16 iii.b iii.b iii.b iii.b.4.12 iii.b.5.12 iii.b iii.b iii.b.8.16 iii.c) Health and Safety iii.d) Schedule of project.17 iii.e) Project budget.17 iii.f) Hurdles and solutions References.20 Appendix I. (Chemical Data Supplement) Appendix II. (Gas Collection System) Appendix III. (Student Projects and Pictures) Appendix IV. (Student Reports).32

120 i. Y2Q2 Summary The project is in the final stages of Phase II research and researchers have begun disassembly at the Cordova site. To date, efforts to test and demonstrate applications of biogas technology have been largely successful and recommendations for future use of the anaerobic digestion technology in Alaska have been recently submitted for publication. At this time breakdown of project materials is advised due to decreased daily monitoring and student participation at the Cordova site. Efforts in the final quarter will focus namely on sample analysis and the dissemination of information on biogas technology to communities throughout Alaska. During the second quarter of this year, research efforts focused specifically on demonstrating biogas collection, usage and testing the physical/chemical properties of the gas. Much of this research was carried out by Cordova High School students, who presented their research at this years Alaska State Science Fair. In addition, research scientists at the University of Alaska, Fairbanks concentrated efforts to develop a gas collection system, demonstrate its use in powering cooks stoves and an electrical generator, data analysis, and final collection of gas samples from the Cordova field site. A gas collection system was developed in Fairbanks and installed in Cordova on June 1, The 500 gallon capacity tank collected biogas from all active reactor vessels inside the Conex and was connected to a variety of gas-powered devices. The collection system remained at the site until June 16, 2011 when the project was disassembled and tanks were returned to Fairbanks, AK. Following the relocation of research technician Casey Pape to Fairbanks on March 25, 2011, feeding and daily maintenance of the reactors was halted as of April 18, 2011 due to decreased supervision and hazard awareness. The Conex doors were locked, temperatures in both rooms were increase to 35 C and reactor valves were left open. Excess liable organic material was allowed to continue to react and vent to the atmosphere. As of June 1, 2011, the collective biogas output of all six reactors was recorded at around 155 L indicating significant reduction in the amount of liable carbon located within each of the tanks (previous daily production rates approx Lday -1 ΣAll tanks). During this quarter, two additional reports were prepared. The first report, on the scaling of biogas projects as well as recommendations for the future of anaerobic digestion technology in Alaska, is still in internal review among the UAF researchers. Second, researchers at UAF worked together with ACEP and Cooperative Extension Services (CES) on a flyer publication intending to inform Alaskans interested in biogas technology. The flyer in now available in print as of June 18, 2011 and can be obtained through either ACEP or CES ( Researcher Casey Pape gave a lecture presentation to the Fairbanks public on the project on June 21, 2011 for ACEP s June talk as part of their Community Energy Lecture Series. Information regarding the talk can be found on ACEP s website and INE website:

121 ii. Schedule and milestone information The project continues to closely follow the original outlined plan: - Construct Digestors for Phase 1 by December 15, 2009 Completed January 21, Commence Data Collection by February 1, 2010 Achieved January 18, June 25-27, 2010, project meeting onsite in Cordova (all team members present); High school student presentations - Perform mid-term Analysis of Data by July 30, 2010 Completed informally internally as a project team, and formally in Quarterly reports 2 and 3. - Year 1 Q4 Report, December 15, Phase II Scoping, deadline for revised report: Completed March 15, Phase I Report, including analysis of all Phase I data: Completed March 15, Year 2, Q1 Report: Submitted on March 15, Scaling Report: Submitted [internally] April 15, Year 2, Q2 Report: Extended to June 29, 2011 (this report) - Year 2, Q3 Report due September 15, Scaling Report: Final draft to Denali Commission September 30, Final project report due September 30, 2011 ii.a) Personnel: Cordova Electric Cooperative Clay Koplin Grant Administrator. Koplin has managed most of the financial aspects of the project thus far on behalf of the Cordova Electric Cooperative, serving as the project manager. Koplin also serves as a technical advisor to the project. University of Alaska, Fairbanks Katey Walter Anthony Research Director. Walter-Anthony acts as the primary investigator, and has spearheaded the scientific goals and directions of the project. She provides continual scientific expertise and project management. She contributed to the data analysis, interpretation and writing of this and all reports. Casey Pape Research Technician. Pape joined the project in early September, 2010, to assume the role of primary project technician. Pape worked on-site in Cordova until March 2011, maintaining the digestor experiment, including data collection, analysis, and troubleshooting. Pape led the preparation of the current quarterly report with assistance from other team members. Pape relocated to Fairbanks on March 25, 2011 and will continue working on the project with closer access to lab instruments, consultation with Walter Anthony and ACEP. Pape travels intermittently to Cordova. Pape plans to remain with the project until its completion in September Dane McFadden Project Intern. Currently an undergraduate at Stanford University, Dane McFadden helped maintain digestor performance during August Job responsibilities included: maintaining daily gas data collection, feeding, chemistry measurements and gas sampling. McFadden will be using his experience here in Cordova as his required internship at Stanford University. Laurel McFadden previous Research Technician. McFadden, served the project as Research Technician from the start of the project until August 2010, when she left to begin graduate school at UAA. McFadden was a key contributor to the project development and took 2

122 the lead on organization and preparation for the initial construction and setup. McFadden completed the first draft of a Biogas Handbook for Alaskans, which will be submitted as a deliverable in final form to the Denali Commission by the end of the project. Peter Anthony Research Technician. Anthony consults on the project and continues to provide technical expertise to the maintenance and application of digestors. He participated in all on-site project meetings in Cordova and provided recommendations for simplification and winterization of the gas collection system in preparation for Phase II. Anthony continues to conduct the gas chromatography analyses of biogas composition for the project. Jeffrey Werner State FFA Director. Werner is interested in using the effluent from anaerobic digestors as a liquid fertilizer for agricultural crops. Located at the horticultural center at UAF, Werner remains enthusiastic about the possibilities of the potential uses of the once thought of waste product. Cordova High School Adam Low Science Teacher. Low was integral in bringing in student involvement via classroom curriculum and extracurricular projects. Low was in charge of maintaining a consistent feeding regime and guiding student involvement with the project. While Pape was away from Cordova, Low had the added responsibility of maintaining gas flow and chemistry measurements as well as general troubleshooting. Additionally, Low worked with science club students to set up a greenhouse experiment in which to test effluent samples for their potential use as a liquid fertilizer. Low also assisted in collecting and shipping effluent samples to other project colleagues in Germany in efforts to greater proliferate psychrophilic digestor technology. As of June 5, 2011, Low moved from his home in Cordova to Hawaii with his family and is no longer involved with the biogas project. He has been an integral part of the research project to date, the loss of his help and assistance is most regrettable. Cordova High School Students Volunteers. The students of Cordova High School have been highly involved with construction, feeding, maintenance, demonstration of the use of biogas in science fair projects for Phase II, and public presentations for the project. They include the seventeen Chemistry class students and Science Club students (Craig Bailer, Ben Americus, Adam Zamudio, Sophia Myers, James Allen, Eli Beedle, Josh Hamberger, Keegan Crowley, Kris Ranney, and Carl Ranney). SOLAR Cities TH Culhane Biogas Expert. With an extensive history in biogas technologies, Culhane developed the water-pressure tank design and provided extensive technical knowledge to the engineering of the project at its outset. He worked with and advised the on-site construction in January 2010 and provides expert advice from his home base in Germany. Recently, Culhane requested a 1-L sample of psychrophilic effluent in efforts to test the success of psychrophilic digestors in different locations in Europe, Asia and Africa with different weather patterns and climate regimes as part of a tangential outreach project that Culhane and Walter Anthony have, funded by the National Geographic Society and Blackstone Ranch. Sybille Culhane Co-founder of SOLAR Cities. S. Culhane assisted in initial construction efforts and managing financial aspects of SOLAR Cities involvement. 3

123 Chena Hot Springs Bernie Carl Owner of Chena Hot Springs. Carl has expressed interest in deploying a digestor at Chena Hot Springs, and has offered space for testing a digestor in his greenhouse. Others Brandon Shaw Website Development. Shaw designed the CordovaEnergyCenter.org website, where the project is hosted. He also assisted at the initial construction site, and was integral in the assembly of the flow meter system. Keywords: Biogas, anaerobic digestor, reactor, psychrophiles, mesophiles, methane, methanogens, Alaska, cold-climate, thermokarst lakes. iii. Narrative summary of the project status and accomplishments to date, and addressing the following questions: is the project on schedule, is the project on budget, and what actions are planned to address any project problems. iii.a) Notable Accomplishments: Collection, passive compression, and usages of biogas Phase II experiments to collect, store and utilize biogas have been successful, demonstrating that biogas technology is directly transferable for collectors utilizing psychrophilic cultures. Demonstration projects have largely surpassed researcher expectation and Phase II demonstrations have been mostly concluded at this time. To date, a modified propane burner stove, 4-cycle combustion engine and gas-powered 1850 Watt generator have been demonstrated to work well on biogas produced from the experiment in Cordova. Optimal burn and device efficiencies are not known, but visual accounts confirm high [device] performance. Biogas production Thorough understanding of variables that limit biogas An extensive dataset of daily biogas production from each of the tanks in the experiment has been collected. At peak productivity under experiment set conditions, production levels of flammable gas reached high quantities (between L/day per 1000L tank). The gas has been shown to be safely and easily collectable using passive techniques and retains high flammability when exposed to spark or flame. Even at almost nominal pressures, the gas holds continuous flame and burns clean with no visible soot or residue left after combustion. Proven flammability One of the primary goals of this project was to determine if the psychrophiles that produce methane in thermokarst lakes could be harnessed in an artificial environment to produce biogas. With the initial production of biogas from both psychrophilic and mesophilic microbes we proved flammability possible (refer to Y1Q2 report). Biogas from conventional anaerobic digestors possesses methane content typically between 40-60%. Recently it has been discovered that our biogas contains increasingly high concentrations of methane (50-82%). It is possible that the increased methane concentration(s) observed in our tanks are the result of using psychrophilic methanogens whereas typical anaerobic digestors commonly use mesophilic bacteria 4

124 and archea found in bovine and animal manure. Additional measurements of gas content will be obtained during the final project quarter to confirm consistency in this trend. Stable isotope analysis could also help distinguish pathways of methanogenesis in the manure-vs.-psychrophile tanks. If this high CH 4 -content of psychrophilic biogags holds constant, then this is an important finding as it implicates the use of psychrophilic methanogens for improving the energy content of biogas as opposed to more common mesophilic anaerobic digestor systems. Successful Chemical Remediation of Digestor Tanks As mentioned before in section iii.a) early in the experiment, observed declining ph was foreseen as a potential threat to the digestors microbial health and action was taken to restore ph to previous levels. Ideally, digestor psychrophilic and mesophilic-communities perform under optimal conditions at a ph of around , observing tank ph(s) much lower than this (ph 3.5 6) was an indication that the tanks were acidifying and VFA s were likely being produced in large quantities. Using chemical remediation we successfully prevented all digestors, except #3 and #2 (possibly), from crashing or souring from prolonged exposure to low ph. Remediation was performed in two steps. The first step involved ceasing to feed the digesters until alkalinity was restored. The second step entailed adding calculated quantities of Calcium Carbonate (Lime), and Sodium Hydroxide in order to bring the ph back to the initial conditions. Care was taken to restore the ph in a gradual manner as to not shock the microbial communities. Slow remediation was also essential as over treating the tanks could cause them to become too basic, as anaerobic digestor bacteria are particularly sensitive to increased ammonium concentration and this is to be avoided as even slightly basic tanks can cause total failure of mesophilic communities (pers. com. TH Culhane). All digestors are now at relatively stable ph values with the exception of Tank 3. We note that biogas production is highly sensitive to environmental variables and political regulations, and many efforts to produce biogas often experience considerable setbacks. A recent multi-million dollar project reported that their first kilowatt hour of energy from biogas was finally achieved after two and a half years of effort ( With flammable biogas production observed within the first several weeks of this project, and again with hundreds of kilowatt hours produced in the first four months following acidification/remediation, we claim that highly successful biogas management and production was achieved in this project thanks to the diligence of researchers, teachers, students, the CEC and support from the Denali Commission. Proven High Methane Content of Biogas GC analysis during Phase I of gas samples collected from tanks 1, 4, 5, and 6 showed high levels of detected methane in most cases. Preliminary analysis shows that methane concentrations have increased since the onset of Phase I research. To some extent this is an indication that observed healthy proportions of microbes in several tanks enough to support active methanogenesis. More work will have to be performed on the GC in the final quarter to understand long term trends and behavior of our tanks. 5

125 Student education This project has the fortunate opportunity of involving High School students in rural Alaska in a primary scientific study. Cordova High School students have the unique ability to see some of the technical aspects and complications that go along with scientific research. The science club and chemistry class provide an excellent platform to organize student involvement. Previously, students have had the opportunity to troubleshoot and take the lead on feeding procedures for the project resulting in several very clever and innovative ideas being implemented. The students of Cordova High School presented on the project several times now and were received well with each new appearance. The students demonstrate a thorough understanding of the issues involved with conducting new technology research as well as the factors that contributed to lessons learned during this project. CHS students and teacher Low presented biogas projects for the Alaska State science fair. Student results, reports and photographs from the biogas demonstrations are provided in section iii.b.1 and Appendices III and IV. Community outreach High school students and UAF researchers were given the opportunity to present on project ideas and preliminary results at meetings with the Alaska Power Association and Alaska state legislators in Juneau, and at a variety of conferences, including the Alaska Rural Energy Conference (April th, 2011) and the Alaska Forum on the Environment (February 7-11 th, 2011). Most recently, the project research was featured during ACEP s lecture series for the month of June The talk, given by Casey Pape, was hosted at the Blue Loon in Fairbanks. Slides as well of video of the speech can be found online (web link in section i). Titles of our project presentations and other public dissemination documents are: Walter Anthony, K., Culhane, TH., Koplin, C., McFadden, L., Low, A. Improving Cold Region Biogas Digestor Efficiency. McFadden, L. Alaska Forum on the Environment. Anchorage, Alaska. February 8-12, Walter Anthony, K., Culhane, TH., Koplin, C., McFadden, L., Low, A. Improving Cold Region Biogas Digestor Efficiency. Low, A., Hess, E., Allen, J., Americus, I., Americus, B., Zamudio, A. Alaska Rural Energy Conference. Fairbanks, Alaska. April 27-29, Pape, C. and the Project Team, Energy from Psychrophilic Bacteria: A Cold-Region Alternative for Biogas, ACEP Community Energy Lecture Series, Fairbanks, Alaska, June 21, New Scientist article featuring this project: Cold climates no bar to biogas production. November 4, The project was recently featured by Alaskan Dispatch Magazine in an article on rural Alaska entitled, Biogas could bring new energy to rural Alaska. January 17, 6

126 Low, A. Youth Participation: Improving Cold Region Biogas Digestor Efficiency. Low, A., Bailer, C., Allen, J., Americus, B., Zamudio, A. Alaska Forum on the Environment. Anchorage, Alaska. February 8, Walter Anthony, K., Culhane, TH., Koplin, C., Low, A., Pape, C. Improving Cold Region Biogas Digestor Efficiency. Low, A., Bailer, C., Allen, J., Americus, B., Zamudio, A. Denali Commission Public Forum on the Emerging Energy Technology Grant. Juneau, Alaska. February 14-15, The project was also mentioned in Senator Lesil McGuire s recent press release on the Deadline for Emerging Energy Technology Fund Grant Applications Approaching. Released March 3, Last year, the chemistry students took a class trip to the Alaska Power Association in Feb Students C. Bailer, D. Hess, C. Morrissett, J. Smyke, S. Lindow, and T. Kelley presented on the project and it was received well among those who attended the meeting. The project team intends to present at next years Alaska Rural Energy Conference in Juneau, Sept , Website development- Website developer Brandon Shaw designed a site ( for the Cordova Energy Center, the venue at which the biogas experiment has been conducted. The website provides a venue for students and community members to obtain information about the project and how to get involved. It is important to update the website often as a means to show visitors that the project is still underway, that is still producing results and that people are still encouraged to get involved. iii.b) Project Status Phase II Research The project is currently in Phase II: the testing and demonstration of biogas technology in Alaska. Research interests during this quarter were to develop a gas collection system for storage of produced biogas, demonstrate the utility of biogas in a variety of gas powered devices and to encourage student experimentation and self-driven research by making the gas accessible in a safe learning environment. iii.b.1) Overview of student-led Phase II biogas projects Science club students at Cordova High School were encouraged to submit individual research proposals which, upon receiving funding through the grant and Cordova School 7

127 District, many students used as part of their state science fair project (Appendix III). Many student projects exceeded expectation and their work has greatly improved the overall grant project portfolio. Student projects ranged in varying degree of scale and complexity and are a testament to the creativity and innovation that can result from projects that include some facet of academic student learning/involvement. There were four student [managed] projects that were supported through the grant this year. Students were first asked to present project proposals in order to get researcher and teacher approval then submit a final project report along with photo documentation before April 15, Photos and original project reports are provided in Appendices III and IV, and summarized here: Student run greenhouse to test effluent nutrient levels (Elaina Allen, Shannon Lindow, Jessica Smyke, and Carl Ranney) On November 24, 2010, CHS science club students began a five month experiment to test the nutrient availability of psychrophilic effluent taken from Tank 4. The students planted lilies, radishes, carrots, lettuce and parsley in a heated greenhouse setting up both experimental and control populations to test the effects of effluent fertilizer on plant growth. Effluent treatments were delivered in mixture ratio 1:16 effluent to water so as not damage the plants. The control group was just given sterilized sandy soil and water treatments. Students contend that there was a noticeable difference in height, fullness and health of many plants treated with effluent over those which only received water. This was more so observed among the flowering plants, Lilium Pumilum and Asiatic Pink Pixies, which responded very well to effluent treatments; however, others like Lilium Regales and Asiatic Orange Pixies hardy grew at all when given effluent treatment. Less of a difference in size was noted among the food crop plants, but it was observed that plants fertilized with effluent tasted better on many occasions. One exception was the root and carrot plants, which were said to not be very appetizing when given effluent fertilizer (Appendix III). No other mass comparison or root-shoot ratio analysis was performed at this time. Calorimetry Experiments (Craig Bailer) A standard calorimetry experiment was set up in order to test the comparable heat content of project biogas with that of another common heating fuel propane. In this experiment, two soda cans were assembled with thermometers, ring stands and modified Bunsen burners set 1.5 inches from the bottom of the can. Each can was filled with 100 ml of water and individual balloons were filled with biogas and propane respectively. Flow rate and burn time were measured, and steps were repeated for both gases. The student used the gas to heat the water in each of the cans and then calculate the resulting heat content of the gas (Equation 1). The test revealed that the measured heat content of biogas was much less than propane. By comparison, the propane used in this experiment was observed to contain an energy density of approximately 570 Btu/ft 3 whereas biogas was shown to be approximately 180 Btu/ft 3. Using propane as a control 8

128 illustrates that this high-school lab technique underestimated the energy density of the gas as propane and biogas energy values are both well known throughout the scientific literature (2,500 Btu/ft 3 and 600 Btu/ft 3 respectively). Still this is a great initial test to understand the relative energy content of gas produced at the Cordova site. Q = Mc T Q = Heat Energy(J) M = Mass (g) c = Specific Heat T = Change in temperature (T f T i ) Equation 1. Heat Capacity Equation for a closed system. Solving for heat energy (Q) the students at CHS were able to obtain initial estimates on the heat content of biogas. Running an Engine on Biogas (Ben Americus and Adam Zamudio) Prior to having a gas collection and storage system in place at the Cordova site, students attempted to run a gas powered engine on biogas. Over a two month period, CHS students obtained an 1850 Watt 4-cycle Husky generator with Subaru engine and began converting the engine to run on biogas. A regulator and conversion kit was installed in order to feed biogas or propane fuel equivalent into the engine carburetor, therefore powering the device as the fuel line to the gasoline tank was disconnected. The engine was demonstrated to run effectively and continuously on propane, but was unsuccessful when attempted with biogas. The student s reasoning was that they had inadequate supply of biogas. At that time, students were using tire inner tubes and bypassing the shraeder valve. At low pressure and heavy restriction the generator was not able to be powered by biogas, but the students effectively converted the generator to run on gaseous fuels. Biogas was demonstrated to power a lawnmower engine using the same conversion techniques and the students were very excited to attempt the experiment again once a collection and delivery system could be provided. Later, on June 14, 2011, the generator was demonstrated to run properly on biogas once a storage and pressure system was installed and the gas pressure was increased to around 0.5psi (Appendix II). Cleaning Biogas (Keegan Crowley) Efforts to purify biogas were taken in order to see how easily impurities could be removed from the synthesized gas. In this experiment, students bubbled measured amounts of biogas through a 4 ft column containing saturated lime water (CaCO 3 ), recovering and measuring the gas once it reached the top of the column. The gas was pumped manually using a one-way hand pump and samples of gas, upstream and downstream, were analyzed for CO 2 and heat content. Their results indicated that bubbling biogas through a lime water column measurably altered the composition of the gas. Carbon dioxide levels in the 9

129 biogas were reduced by 21.7% and the measured heat content was reported to have increased by 21.8%; illustrating that biogas can be easily purified to become more competitive with other fuel types (for more on heat content, refer to Equation 1). The scholastic year ended on June 3, 2011, and student involvement with the project is likely to be nominal until the start of the next school year. The project team would like to thank all Cordova High School students who participated in the project for their efforts and wish them a safe and happy summer break. Students involved with the project will be contacted again in September 2011 in order to participate and present on the project at the Alaska Rural Energy Conference 2011 (Sept th ) in Juneau, AK. Of those involved with the project, a special recognition and thanks should be given to CHS teacher Adam Low and all of his efforts to encourage student learning and enhancement through use of the Biogas project. As of June 5, 2011, Low relocated with his family to Hawaii and will no longer be able to assist with the project. Low s efforts were pivotal in many of the project successes to date. His enthusiasm and assistance will be missed. Low still remains as a valued advisor and consultant to the project. iii.b.2) Gas Collection System Development of a gas collection system for storage and pressurization of biogas is one of the most important design elements to consider when implementing a biogas reactor for personal or small-scale use. To this end, construction and installation of a gas collector was a pivotal part of Phase II research. Over the course of the project, several gas storage designs were tested for their utility. On April 6, 2011 a meeting was held at ACEP in order to discuss options for gas collection systems to test and install in Cordova. ACEP engineers and UAF researchers concluded that a telescoping-style collector had the greatest amount of utility and should be pursued for the project (Appendix II). Apart from the small-scale inner tube collector used by students, other designs involving larger bladder-type collectors and standard high compression were largely dismissed given the time and logistical needs of those who would likely implement a biogas reactor in rural Alaska. On May 23, 2011, two HDPE water tanks were purchased from Greer Tank and Welding, Inc. and delivered to ACEP building on the UAF campus. The larger, 1000 gallon receiver tank was used to hold and stabilize an internal 500 gallon tank which would be used to store biogas. Cutting the bottom section out the 500 gallon tank, the exterior tank could be filled half-full with water and still allow the internal tank to move freely inside (Appendix II). Tubing and securing brackets were installed in order to transport the tank to Cordova on May 28, 2011 and the collection system was fully installed at the Cordova biogas site on June 1, The tank consolidated gas produced from tanks 1, 4, 5 and 6 from June 1-June 15, 2011 when the project was dissembled and shipped back to Fairbanks. The tank is currently located outside the ACEP building and will likely be used in the future for other biogas-related projects. The gas collection tank is specified to store up to 500 gallons of gas at a time. The telescoping tank weighs approx. 120lbs and provides enough continuous pressure to sustain a flame when burned. The inlet and outlet tubing is ¼ in gas hose and connects to standard ¼ in gas flare compression fittings. In order to run devices that demand high rates of gas flow, 10

130 additional water weight was used to increase the gas pressure inside the tank. With about 1500 lbs of weight, the gas pressure increased to about 0.5 psi. This was enough pressure to run the 1850 Watt generator (see Phase II Research). Additional weight could be added if needed, but was not required to run devices used in this experiment. iii.b.3) Powering Devices on Biogas In addition to the student driven research (section iii.b.1), UAF researcher, Casey Pape, demonstrated several applications of biogas this quarter to illustrate its potential function and utility to Alaskans interested in the technology. Most notably, this was accomplished through demonstration of biogas usage as a cooking fuel and as a combustion fuel which could be used to power engines and common appliances. In addition, measures were taken to minimize fuel consumption as well as quantify hourly demand and pressure requirements for each application. The vast majority of small-scale biogas projects are used in order to supply single family dwellings with daily cooking fuel in order to prepare meals and sterilize water. As a result, replication of the ability to cook a meal and/or boil water using biogas was of a high priority during Phase II. Previously, the project had acquired a large, natural gas, single-burner stove which was intended to be powered off of biogas. When initially connected to a supply of biogas, the burner failed to light, though the biogas would exhibit strong flame when burned directly. Later, it became apparent that the burner was specified for high rates of flow and fuel consumption (i.e. designed to boil large quantities of water quickly) and would not work under low pressure conditions at which the gas was being supplied. Modifying the stove so that proper function could be utilized with less fuel demand was required in order to sustain a flame and demonstrate the ability to cook a meal. The result was a simplified burner that, though less powerful than the original stove, was perfectly sufficient at boiling water once lit (Appendix II). Using biogas to fuel this stove, 4 Liters of water were boiled (T i = 15 C), placed in a covered pot, in 20 min and sustained a continuous flame throughout the demonstration despite being in an open, outdoor environment. The stove was used to cook a meal consisting of hot dogs and carrots and consumed roughly 300 L of biogas per hour (~80 Gal/hr). The next demonstration was designed to illustrate transduction of the energy stored in biogas and convert it into some other usable form electricity. As mentioned in the previous section, CHS students involved with the project had once already attempted to power a generator off of biogas, but were unsuccessful in that attempt. The reason for this was simply because of inadequate biogas supply, as students did not yet have access to a large store of biogas which they could easily pressurize. Once connected to an ample supply of biogas in our new gas collection system, the converted 1850 Watt Husky generator ran normally. When first connected to the biogas collection tank, the generator failed to turn over, indicating that it had insufficient supply or access to fuel. This was due to the extreme low pressure at which the biogas (at that time) was being stored. We increased pressure in order to sustain combustion. Since the tank used to store the biogas was large (Diameter: 60in), the amount of weight needed to increase the pressure would need to be substantial (e.g. it would take the weight of a mid-sized SUV in order to generate 1 psi). Increasing the pressure was accomplished by adding a second tank on top of the collection vessel and filling it with approx. 175 Gal of water (D 15 C = 1000kg/m 3 or

131 lb/us gallon). The resulting water weight (approx lbs) was enough to increase the pressure in the gas line to about 0.5psi, which was sufficient to power the generator. The generator performed optimally (i.e. 120 V 60 Hz AC, enough to sustain a CFL bulb) for over an hour before exhausting the biogas storage tank. To this end, the 1850 Watt generator was rated at a consumption rate of approx. 300 gal/hr or ~1,100 L/hr (Appendix II). iii.b.4) Scaling Report In addition to Phase II efforts, this quarter, UAF researchers drafted a report on biogas technology entitled: Scaling and Feasibility Recommendations for Alaska. The report details the current U.S. and global trends in Anaerobic Digestion (AD) technology as well as recommendations for future Alaskan biogas projects. The report contains assessments of Alaskan energy consumption and initial evaluation of basic waste streams, those which would be necessary feedstock for biogas production. Various cases studies are discussed along with additional resources and links to other projects which may be useful for future work performed in Alaska. The report was submitted April 15, 2011 internally to the project PIs, and will be submitted in final form to the Denali Commission for public dissemination in September iii.b.5) ACEP Flyer In addition to the scaling and feasibility report, UAF researchers and ACEP staff collaborated with Cooperative Extension Services (CES) to produce a flyer publication on Biogas for Alaskans interested in the technology. The flyer is intended to be a general introduction to AD technology and inform readers what is happening around the state as well as where to go to find additional information. The Cordova Biogas project is well represented on the back page of the flyer with references made to the project website, project contributors and funding provided by the Denali Commission as part of the emerging energy technology grant program. The flyer was finalized for publication in mid-june and was available in print for the June 21 st lecture at the Blue Loon in Fairbanks. The flyer is now available in print through ACEP and Cooperative Extension Services and can be located online at: The ACEP and CES flyer on Biogas in Alaska. The flyer became available as of June 21, 2011 and is available electronically and in print through CES. 12

132 iii.b.6) Gas flow measurements Due to the lack of an extensive dataset that accurately demonstrated biogas production among all reactor tanks, the research team conducted an intermediate phase in the second year first quarter to obtain a solid data set for hypothesis testing. The study was entitled Phase 1.5 as it contained both elements of Phase I and Phase II (see Phase I Final Report for details regarding Phase 1.5). Recent data obtained in June 2011 at the Cordova field site was in accordance with previously approved measurement techniques and has been added here to the Phase 1.5 data set. On June 1, 2011 the collective total amount of biogas produced from each tank was approx. 155L, indicating that most of the available carbon inside each reactor had been consumed and liberated to the atmosphere during the shut-off period from April 18-June 11, 2011 (see section i. Y2Q2 Summary). Feeding was resumed on June 11, 2011 and flow meter data were analyzed to see if any feeding-response curves resulted (Figure 1). Tank 1 was the only tank fed for multiple days (from June th, 2011) and individual gas flows are known, though not shown here. Tank 1 exhibited the highest amount of gas production for the period (roughly half of the synthesized gas). The flow data recorded for this period suggests that gas production increased substantially with increased feeding, however, the increase was not linear and suggests that microbial activity may have been limiting in this case. On June 13, 2011 the bleeding and recording procedures changed slightly as gas was collected inside of the gas collector further downstream of the Sierra flowmeter. The resistance of the tank may explain the decrease in observed gas production on June 13 th (Table 1). Ultimately, a longer retention time is needed in order to fully understand feeding-response curves and elucidate optimum culture incubation times. Table 1. Biogas summary data for Phase 1.5. The numbers present average gas production within a 24hr period for each tank. Data are not normalized by the volume of slurry inside each tank. Normalized data are presented in the Phase I Final Report. On several occasions, gas pressure contained in the headspace of the reactors caused tanks to expel some of their liquid contents from the tanks. Dates of occurrences of tanks spills are both documented and undocumented as students may not have reported a spill during several instances when researcher and teacher support was not available. Gas Production Summary Data (Raw Data) Date Tank 1 15 C Room 25 C Room Tank 2 Tank 3 Tank 4 Tank 5 Tank 6 12/11/ /17/ /18/ /19/ /20/ /21/ /22/ /23/ /24/ /26/ /29/ * /30/ All Tanks

133 1/31/ * 136 2/1/ /2/ /3/ * * 2/4/ /25/ * /26/ * 157 2/27/ /28/ /1/ /2/ /3/ /4/ * 163* 163 3/5/ /6/ /7/ /8/ * 3/9/ /10/ /1/ /11/ /12/ /13/ Average Standard Dev Total * Days in which a documented leaks occurred (exact volume released is not known) Biogas Production (Dec. 11, Jun. 13, 2011) Biogas Production (L/day) Tank 1 Tank 4 Tank 5 Tank 6 All Tanks 11/18/10 1/7/11 2/26/11 Figure 1. Current flow measurements from Phase 1.5 and graphical representation of unnormalized data presented in Table 1. Biogas production shows marked increase from the beginning of the week (01/17/11) and the end (01/23/11). Tank(s) # 2 and 3 valves were closed and were not observed to have produced gas above nominal levels for the 14 4/17/11 6/6/11 7/26/11

134 entire period. Any noise recorded by the Serria Top-Track 820 mass flow meters was given a value of zero. Data gaps may exist during times where either no flow data was being recorded or data collected did not align with the above mentioned protocol(s). For more information regarding data collected during Phase I please refer to the Phase I Data Report submitted March 15, Supplemental chemistry data is provided at the end of this report (See Appendix I) iii.b.7) Temperature control in the Conex Temperature is one of the most imporant factors that influences methanogenic metabolic rate (House 1978). The Conex used to house the digestors was designed by the project team to maintain two rooms at separate cold (15 C) and tepid (25 C) temperatures (as opposed to conventional biogas deg C, warm temperatures). The temperature is visually monitored by digital thermometers (less accurate) and recorded by (more accurate +/-0.47 C, Drift +/-0.1 C/yr) dataloggers suspended in both rooms as well as inside the slurry of each digestor. Several dataloggers, suspended at different depths within some of the tanks, were recovered during project breakdown on June 15, Summary data from all tempertature loggers over the course of the experiment are illustrated in Figure 2. On April 18, 2011 the Conex doors were locked and all feeding was ceased due to lack of researcher supervision and concerns raised over proper safety. The tanks were no longer fed and all valves were turned to the OPEN position so that residual gas would be vented to the outside atmosphere. The tempurature inside the Conex was increased to 35 C in order to allow increase microbial activity and further decomposisiton of organic material inside each reactor. The temperature loggers were uninstalled on June 15, 2011 in accordance with project breakdown proceedures. Data from the temperature loggers are shown in Figure All Temperatures Cordova Temp Cold Room Temp Tank 1 Temperature (C) Tank 2 Tank 3 Warm Room Temp /12/10 2/11/10 3/13/10 4/12/10 5/12/10 6/11/10 7/11/10 8/10/10 9/9/10 10/9/10 11/8/10 12/8/10 1/7/11 2/6/11 3/8/11 4/7/11 5/7/11 6/6/11 7/6/11 8/5/11 Tank 4 Tank 5 Tank 6-30 Date (mm/dd/yy) 15

135 Figure 2. Mean hourly temperature of the data loggers in the Conex cold and tepid room, and mean daily temperature recorded in Cordova. As the temperatures in Cordova began to drop from temperate summer conditions, the Conex experienced a noticeable and unfavorable drop in temperature during the winter, but returned to warmer temperatures the next summer. Digester temperatures tended to track room temperatures, which followed the trend of outdoor air temperatures. Biogas project temperatures are measured with Hoboware U Water Temp Pro V2 loggers recording hourly. Cordova air temperature data was obtained from online sources (source: wunderground.com) iii.b.8) Project Site Breakdown Research technician Casey Pape traveled to the Cordova site from May 28, 2011 to June 16, 2011 in order to finalize Phase II demonstration of gas collection and utilization as well as lead the breakdown of the digesters. Pape and other project team members from CEC began disassembly on June 14, Each of the reactor vessel s contents was evacuated using an industrial garbage pump into a secondary storage container which was used to screen out most of the sediment and heavy solids that were located within each of the tanks. The remaining liquid was discharged into the local storm water runoff drain as it contained no harmful material. In order to finish evacuating all of the tank contents, each tank had to be cut and the bottom sludge layer agitated in order to loosen the remaining material of each tank, allowing them to drain more easily. The remaining tank components were disposed of at the local bailer waste compactor site and all instrumentation was returned either to CHS or UAF labs when Pape returned to Fairbanks. The project Conex is now vacant as of June 27 th 2011, and aside from the R-10 foam insulation and updated electrical system provided by the project, the Conex was returned to the school in its original condition prior to the onset of this project. Spare materials (e.g. construction materials, garbage cans, water pumps, pipe fittings, ball valves, and spare tubing), along with the converted Husky generator and stove instruments were left at the Cordova High School Energy Center for future use by students and teachers. iii.c) Health and Safety Conventional small-scale anaerobic digestors are generally considered to be nonhazardous when given proper ventilation and maintenance. Still anaerobic digestors are used for the synthesis of combustible gases and have some safety concerns associated with them. As of April 18, 2011 the project Conex was locked and given a standby status upon discussing the project with UAF Environmental Health and Safety workers. EH&S had expressed some concern over proper project ventilation and the intrinsic safety of some of the equipment used on-site. With decrease supervision, coinciding with Pape s relocation to Fairbanks, it was determined that the best plan was to minimize access to the inside of the Conex, cease feeding experiments, increase the temperature and open all valves in order to react all remaining organics within the reactors. Upon revisiting the project in June 2011, researchers consulted with EH&S in order to follow the best procedures for finalizing the gas collection, demonstration of gas utilization, and site breakdown. No health problems or accidents were ever reported during the course of this project. 16

136 Electrical and Power: The project site is maintained by electrical heat and power supply. At present, that electricity has been provided by extension cords that run from inside the school and out to Conex. The CEC recently renovated the electrical system and increased the power capacity of the site. The project Conex electrical system now complies with all state and federal building and transmission codes and is wired for both 120V and 240V AC power. Flammability: Biogas is very flammable and it is important that measures be taken to prevent any undesirable fires that may cause explosion. No open flame was allowed within the Conex and students handling biogas were instructed to wear appropriate eye protection at all times. Students conducting experiments with biogas were required to wear eye safety glasses and proceed under adult or teacher supervision. No injuries due to fire or explosions occurred during this project though several fire alarms were been triggered when demonstrating biogas flammability was conducted without proper ventilation. Ventilation: The build-up of certain gases in an enclosed space can be toxic. Biogas digestors produce methane, carbon dioxide, hydrogen sulfide, and other gases which can be deadly at high concentrations. It is apparent to anyone entering the Conex which houses the experiment that a noticeable barn-like smell can be detected. The smell is due to volatile organics. Methane is odorless. This smell was significantly reduced once the new tank gas outlets were installed. Tanks were monitored daily and were not thought to pose any threat to human health. The air was cycled daily to a certain extent when the Conex container was opened for daily download of the gas flow data. Tubes are connected to the tanks to allow lighter than air constituents escape the container. H 2 S tags were located in the Conex throughout the duration of the experiment to visually monitor H2S levels in the Conex. They never reached any level of concern. The Cordova fire department had visited the site and tested it for noxious gases. The results of the fire departments testing came up negative for any toxic gases. iii.d) Schedule of project The project is still on schedule as defined by the original project outline. Phase I is complete and Phase II is in its final stages. Throughout the rest of the project research efforts will focus on sample and data analysis, writing of reports and information for public dissemination. The last quarterly (Y2Q3) report will be prepared for September 15, The final project report will be completed and submitted on September 30, 2011 including all the findings of Phase II research. iii.e) Project budget We anticipate that the budget is on target. At this time, the budget is not expected to exceed the grant, and the matching contribution is expected to significantly exceed the grant requirement. Clay Koplin will provide more details on the budget when he returns from vacation. iii.f) Hurdles and solutions Project problems and solutions were mentioned in iii.a, and are outlined in more detail here. 17

137 Confidence in biogas measurements: Due to offsets between the flow meter calibration levels and our gas production rates, we were not able, until Phase I.5, to provide the true values of biogas produced. Previous values represented averaged daily flow rates as opposed to cumulative daily gas production. Though this is generally an acceptable method for smoothing out noise in any data set, the true biogas production rates was underestimated. Solution: Casey Pape determined a new method to achieve our goal of daily gas production determinations by closing tanks, allowing them to swell with produced gas, opening the valves over a short period of time to allow high rates of gas flow within the level of the flow meter calibration. We now have an extensive dataset on the biogas production among tanks in the experiment and can make clear predictions about the future of biogas small-scale technology in Alaska. Data collection was updated on June 13, 2011 and the project report was submitted in the Phase I Data report. Date submitted March 15, Other potential considerations: The following factors are important considerations that generally can lead to problems in biogas technology. While we have no reason to think that any of these factors caused a problem in our systems, for the sake of thoroughness, here we evaluate each as a potential problem in the context of our study. Temperature fluctuation. Problem: It is a major goal of this study to preserve the cold (15 C) and tepid (25 C) conditions as was defined in the original project proposal for the purpose of incubation of microbes. The Conex constructed for the project is insulated with R-10 pink foam insulation, but has poor seals and air spaces that cause it to have a heat/cooling regime that mimics that of the local environment of Cordova. Over the course of this quarter, average temperatures for both cold and tepid rooms was 4.2 C and 1.9 C below target values respectively. This is not ideal and will need to be better monitored in the future as our impression of the day to day gas production is that it should be consistent if temperature and food inputs are maintained at a constant level. Solution: Following the meeting with EH&S, the project Conex heating systems was increased in order to increase methanogenic activity and deplete each of the tanks of any liable organic material which they might contain. After April 28, 2011, the average temperature within each of the tanks was recorded on average around 35 C. Logistical and management concerns: Digestor/tank and fittings integrity. Problem: Generally speaking, the more holes and fittings installed on a digestor or any gas-holding container increases the chance for a leak to develop. At the beginning of the scholastic year, the project gas outlet system installed on each of the tanks were known to have as many as separate joints and fittings. This many fittings can make it very difficult to ensure the vessels remain leak-proof and anaerobic. When Pape arrived to the project, leaks were uncovered among the secondary gas containment systems outdoors and resulted in biogas collected in the outside tanks no longer being flammable. Simple tests of pressurizing the tanks revealed that many contained significant leaks that compromised 18

138 researcher efforts to record gas flow. Much of the data may have been skewed during the Phase I study as tanks showing no signs of biogas production have been demonstrated to be active after leaks were repaired. Recurring issues continually compromised research efforts to understand gas production as multiple leaks were continually discovered among several tanks and within different joints throughout the gas outlet system. Solution: As of February 25, 2011 the last of the tank retrofits were completed by Pape and no leaks have been detected since. All tanks expected to be producing biogas exhibited the ability to maintain a positive pressure throughout the remainder of the project. Soapy water test on June 1, 2011 did not reveal any additional leaks and the problem is thought to have been resolved. Balance of responsibilities. Problem: The project is designed to be conducted in joint partnership between Cordova High School, a public utility (CEC) and the University of Alaska, Fairbanks. Collective effort between these parties is necessary in order to maintain the project and pursue additional research development during the Phase II study. Students were very capable of feeding and maintain digestors from day to day, but both students and high school staff were ill-equipped to combat many of the more technical problems that arose due to the nature of high quality data collection required in Phase I. Phase I data collection required full time on-site technical support from UAF. When the project switched focus in Phase II, there was a decreased need for UAF staff to provide daily support during all parts of Phase II. Solution: The project full-time technician (Casey Pape) relocated to Fairbanks, AK on March 18, 2011 in order to pursue further analysis of samples catalogued over the previous year as well as begin efforts to research options for upscaling biogas technology in Alaska. Adam Low and CHS students did a wonderful job filling in for Pape while away on previous work commitments in the past maintained the project with a high level of professionalism after Pape relocated. The CHS students learned a lot from the project in Phase II by conducting experiments using biogas. 19

139 References: House, David. (1978) The Complete Biogas Handbook. (Alternative House Information, United States),

140 Appendix I. (Chemical Data Supplement) Figure 3. Results indicate that the ph in Tank 1 fell slightly since Y1Q3 report, but has recovered to almost neutral ph following the cessation of feeding on April 18, 2011 (currently ph 7.71). We halted daily feeding to allow the opportunity for ph to recover on its own, without reverting to chemical remediation treatments. ph was measured with Macherey-Nagel litmus paper January 21-April , and with more precision using an Oakton PC510 ph meter since April 17, 2010 until the present. 21

141 Figure 4. Oxidation-reduction potential (ORP) indicates the availability of oxidative molecules and ions in the system. ORP is a valuable measure as it determines the likelihood that bacteria will follow the methane fermentation pathway. For healthy methane production, samples should have an ORP of From January 21-April 9, ORP was measured with an Xplorer GLX Pasco PS-2002 Multi-Datalogger. From May 10 forward, it was measured with an Oakton PC510 ORP meter. 22

142 Figure 5. DO measurements were taken with an Xplorer GLX Pasco PS-2002 Multi-Datalogger until March 24, following which they have been taken by a Hanna HI9142 DO meter. As of October 1, 2010, the Hanna instrument could no longer be calibrated properly. Proper function was restored after servicing the instrument in December

143 Appendix II. (Gas Collection System) Newly installed gas collection system. The 500 gallon capacity tank was installed on June 1, 2011 and was removed when the project was disassembled on June 15 of the same year. While in operation the tank consolidated and stored gas synthesized from all reactors vessels inside the Conex. The orginal tanks were purchased from Greer Tanks and Welding, Inc. in Fairbanks, AK on May 23, These tanks will be available for future biogas projects at UAF or donated to an Alaska resident for implementation of home-scale biogas production in Fairbanks. Picture of the tank during assembly. When completed, internal tank (right) will have the bottom sections removed in order to allow the tank to move freely up and down in within the tank media. Picture of both tanks together. The gas storage tank (Black) sleeves conveniently inside of the larger 1000 gallon (White) containment vessel. The tight design parameters of these tanks means that the gas storage tanks can fill and discharge freely within the tanks without fear of tipping or air contamination. 24

144 The completed storage tank, prior to being assembled inside of the larger containment vessel. CHS Janitor Romey assists in the assembly within the Cordova Energy Center, located at CHS. The gas storage vessel was calibrated and given indication markings for how much gas is stored inside. The aluminum bar attached to the tank is used as a level indication that can be viewed once the tank is fully assembled. This looks great, Casey! 25

145 One gallon of boiling water is used to illustrate biogas usage as a cooking fuel. The modified stove pictured sustained a constant flame with a burn rate of about 300 L/hr. Biogas being used to power a generator. Note the additional water weight used to increase the pressure of the gas supply for running an electrical generator. The water weight was not required for cook stove operation on biogas. This 1850 Watt Husky generator ran completely on biogas for over an hour before exhausting the biogas storage tank and powering down. Starter fluid was used in order to start the device, but then was sustained entirely on gas collected from inside the Conex (behind). The estimated burn rate for this device is around 1,100 L/hr or psi. 26

146 Appendix III. (Student Projects and Pictures) CHS student present their biogas and other science projects at the Alaska State Science Fair in Anchorage, AK, April 15-17, Students received honorable mention and many won their category for their work with biogas. First place was awarded to CHS student Sophie Myers, whose project centered on the study of fluid dynamics of shark skin. Student Craig Bailer prepares his calorimetry experiment for testing the heat content of biogas vs. propane. 27

147 Student Keegan Crowley performs a calorimetry experiment to test the heat content of biogas prior to purifying the gas through lime water. Keegan reports his findings at the state science fair, Anchorage, Here, students Keegan Crowley and Ben Americas attempt to purify biogas along with teacher Adam Low. 28

148 CHS students Elaina Allen and Shannon Lindow touting their awards for their project on AD effluent as liquid fertilizer. Students used the liquid effluent from tank 4 to test an experimental greenhouse over the course of the school year. Here, student Sophie Myers uses a diluted solution of effluent to water and treat plants in the Cordova Energy Center. Student Brian seen here along with Josh Hamberger burning biogas. Students were acutely aware of biogas properties and potential uses for Alaskans interested in the technology. 29

149 CHS Students Ben Americus and Adam Zamudio present on their work to run a generator off of biogas at the state science fair, Anchorage, AK April 15-17, Students rig a common lawnmower to run off of biogas. A 4-cycle 1850 Watt Husky generator was converted to run on biogas and other available gaseous fuel types. Here students celebrate as the generator successfully starts using propane. 30

150 The current project profile when viewed from outside. At this point the project has a very minimal footprint. Previous gas pressure systems have been dismantled and the project team has taken a minimalistic approach. This is how the project appeared until final breakdown commenced on June 15,

151 Appendix IV (Student Reports) See attached documents. 32

152 Denali Emerging Energy Technology Grant: Improving Cold Region Biogas Digestor Efficiency Year 2 Quarterly Report, Y2Q3 September 15, 2011 Table of Contents i. Y2Q3 Summary.1 ii. Schedule and milestone information.1 ii.a) Personnel.2-3 iii. Narrative summary of the project.4 iii.a) Accomplishments..4-6 iii.b) Project Status.6-13 iii.b iii.b.2.10 iii.b iii.b.4.13 iii.c) Health and Safety iii.d) Schedule of project.14 iii.e) Project budget.14 iii.f) Hurdles and solutions.15 References.15 Appendix I. (Chemical Data Supplement) Appendix II. (Final Project Breakdown) 19-20

153 i. Y2Q3 Summary The project is nearing its final completion date on September 30, 2011, and all research obligations have been completed at this point. During the last quarter, research efforts focused primarily on analyzing gas and effluent samples collected over the course of the project and conducting a study on the economic feasibility of the technology in Alaska. In addition, researchers improved techniques for measuring gas flow at low rates of production in order to aid future biogas production research. At the time of the last quarterly report, we were in the process of disassembling the major components of the biogas project at the Cordova High School research site. Reactor contents were not fully disposed of until July 18 th, 2011 and the site has since been returned to it its original condition. The Conex used throughout the project (now vacant), was left at the high school for future use, with additional improvements of insulation, heat and electricity capacity upgrades. Re-usable reactor components remained with the Cordova High School Science Club for future use - no complete reactor assemblies remain at this time. The main 1000-L reactor vessels were disposed of by the Cordova Electric Cooperative. The gas collection system developed during the Y2-Q2 remains intact and is currently stored outside the ACEP building at the University of Alaska, Fairbanks. UAF researcher Casey Pape gave a lecture presentation to the Fairbanks public on the project on June 21, 2011 for ACEP s June talk as part of their Community Energy Lecture Series. Information regarding the talk can be found on ACEP s website and INE website ( Lastly, students as well as members of the research team plan to attend the Alaska Rural Energy Conference hosted in Juneau, from September th, where upon they will give a final presentation regarding their findings and experience(s) with the project. The project s Final Report will be submitted by September 30 th, 2011, marking the completion of the project. ii. Schedule and milestone information The project continues to closely follow the original outlined plan: - Construct Digestors for Phase 1 by December 15, 2009 Completed January 21, Commence Data Collection by February 1, 2010 Achieved January 18, June 25-27, 2010, project meeting onsite in Cordova (all team members present); High school student presentations - Perform mid-term Analysis of Data by July 30, 2010 Completed informally internally as a project team, and formally in Quarterly reports 2 and 3. - Year 1 Q4 Report, December 15, Phase II Scoping, deadline for revised report: Completed March 15, Phase I Report, including analysis of all Phase I data: Completed March 15, Year 2, Q1 Report: Submitted on March 15, Scaling Report: Submitted [internally] April 15, Year 2, Q2 Report: Completed June 29, Year 2, Q3 Report: Due September 15, 2011(this report) - Biogas Handbook: First draft due (August 7, 2011, submitted internally); Final draft due Sept. 30, Scaling Report: Final draft to Denali Commission September 30, Final Report due September 30, 2011 [First draft Sep. 20, 2011] 1

154 ii.a) Personnel: Cordova Electric Cooperative Clay Koplin Grant Administrator. Koplin has managed most of the financial aspects of the project thus far on behalf of the Cordova Electric Cooperative, serving as the project manager. Koplin also serves as a technical advisor to the project. University of Alaska, Fairbanks Katey Walter Anthony Research Director. Walter Anthony acts as the primary investigator, and has spearheaded the scientific goals and directions of the project. She provides continual scientific expertise and project management. She contributed to the data analysis, interpretation and writing of this and all reports. Casey Pape Research Technician. Pape joined the project in early September, 2010, to assume the role of primary project research technician. Pape worked on-site in Cordova until March 2011, maintaining the digestor experiment, including data collection, analysis, and troubleshooting. Pape led the preparation of the current quarterly report with assistance from other team members. Pape relocated to Fairbanks on March 25, 2011 and will continue working on the project with closer access to lab instruments, consultation with Walter Anthony and ACEP. Pape travels intermittently to Cordova. Pape plans to remain with the project until its completion in September Dane McFadden Project Intern. Currently an undergraduate at Stanford University, Dane McFadden helped maintain digestor performance during August Job responsibilities included: maintaining daily gas data collection, feeding, chemistry measurements and gas sampling. McFadden used his experience with the project as his required internship at Stanford University. Laurel McFadden previous Research Technician. McFadden, served the project as Research Technician from the start of the project until August 2010, when she left to begin graduate school at UAA. McFadden was a key contributor to the project development and took the lead on organization and preparation for the initial construction and setup. McFadden completed the first draft of a Biogas Handbook for Alaskans, which will be submitted as a deliverable in final form to the Denali Commission by the end of the project. Peter Anthony Research Technician. Anthony consults on the project and continues to provide technical expertise to the maintenance and application of digestors. He participated in all on-site project meetings in Cordova and provided recommendations for simplification and winterization of the gas collection system in preparation for Phase II. In the UAF laboratory, Anthony conducted the gas chromatography analyses of biogas composition for the project. Jeffrey Werner State FFA Director. Werner is interested in using the effluent from anaerobic digestors as a liquid fertilizer for agricultural crops. Located at the horticultural center at UAF, Werner remains enthusiastic about the possibilities of the potential uses of the once thought of waste product. Cordova High School Adam Low Science Teacher. Low was integral in bringing in student involvement via classroom curriculum and extracurricular projects. Low was in charge of maintaining a 2

155 consistent digestor feeding regime and guiding student involvement with the project. While Pape was away from Cordova, Low had the added responsibility of maintaining gas flow and chemistry measurements as well as general troubleshooting. Additionally, Low worked with science club students to set up a greenhouse experiment in which to test effluent samples for their potential use as a liquid fertilizer. Low also assisted in collecting and shipping effluent samples to other project colleagues in Germany in efforts to greater proliferate psychrophilic digestor technology. On June 5, 2011, Low moved from his home in Cordova to Hawaii with his family and is no longer involved with the biogas project. He was an integral part of the research project, so the loss of participation is most regrettable. Cordova High School Students Volunteers. The students of Cordova High School have been highly involved with construction, feeding, maintenance, demonstration of the use of biogas in science fair projects for Phase II, and public presentations for the project. They include the seventeen Chemistry class students and Science Club students (Craig Bailer, Ben Americus, Adam Zamudio, Sophia Myers, James Allen, Eli Beedle, Josh Hamberger, Keegan Crowley, Kris Ranney, and Carl Ranney). SOLAR Cities Thomas TH Culhane Biogas Expert. With an extensive history in biogas technologies, Culhane developed the water-pressure tank design and provided extensive technical knowledge to the engineering of the project at its outset. He worked with and advised the on-site construction in January 2010 and provided expert advice from his home base in Germany. In Nov. 2010, Culhane requested a 1-L sample of psychrophilic effluent in efforts to test the success of psychrophilic digestors in different locations in Europe, Asia and Africa with different weather patterns and climate regimes as part of a tangential outreach project that Culhane and Walter Anthony have, funded by the National Geographic Society and Blackstone Ranch. Sybille Culhane Co-founder of SOLAR Cities. S. Culhane assisted in initial construction efforts and managing financial aspects of SOLAR Cities involvement. Chena Hot Springs Bernie Carl Owner of Chena Hot Springs. Carl has expressed interest in deploying a large scale biogas digestor at Chena Hot Springs, and has offered space for testing a digestor in his greenhouse. Others Brandon Shaw Website Development. Shaw designed the CordovaEnergyCenter.org website, where the project is hosted. He also assisted at the initial construction site, and was integral in the assembly of the flow meter system. 3

156 Keywords: Biogas, anaerobic digestor, reactor, psychrophiles, mesophiles, methane, methanogens, Alaska, cold-climate, thermokarst lakes. iii. Narrative summary of the project status and accomplishments to date, and addressing the following questions: is the project on schedule, is the project on budget, and what actions are planned to address any project problems. iii.a) Notable Accomplishments: Collection, passive compression, and usages of biogas Phase II experiments to collect, store and utilize biogas successfully demonstrated that biogas technology is directly transferable for collectors utilizing psychrophilic cultures. Demonstration projects largely surpassed researcher expectation, and have all been completed at this time. A modified propane burner stove, 4-cycle combustion engine and gas-powered 1850 Watt generator were all demonstrated to work well on biogas produced from the experiment in Cordova. Optimal burn and device efficiencies are not known, but visual accounts confirmed high device performance. Biogas production Understanding of variables that limit biogas One of the primary goals of this project was to determine if lake-bottom mud containing coldtolerant methanogens could be used in an artificial environment to produce biogas. We observed production of flammable biogas from both psychrophilic and mesophilic microbes in this study, though psychrophiles tended to produce more biogas at cold temperatures. An extensive dataset of daily biogas production from each of the tanks in the experiment was collected. At peak productivity under experimental cold temperature conditions, production levels of flammable gas reached high quantities (between L/day per 1000L tank). The gas, shown to be safely and easily collectable using passive techniques, retained high flammability when exposed to spark or flame. Even at almost nominal pressures, the gas held continuous flame and burned cleanly with no visible soot or residue after combustion. Biogas from conventional anaerobic digestors possess a methane content typically between 40-60%. We observed in this project that biogas produced on-site contained high concentrations of methane (50-82%). Improvement on method for measuring biogas production rates During the past quarter, Casey Pape made substantial progress on improving our capability of measuring biogas production and flow rates. He modified existing tipping cup technology, typically used for gauging rain fall, for use in measurement of a range of gas flow rates in submerged settings. Determination of nutrient concentrations in digestor effluent We analyzed samples of biogas digestor effluent for nutrient concentration. High levels of bioavailable phosphate were found in the effluent. This could explain our observation of enhanced growth of greenhouse plants fed with effluent from the digestors, and suggests that biogas digestors have the added benefit of nutrient-rich organic fertilizers from effluent in addition to producing methane gas. Student education This project has the good fortune to involve High School students in rural Alaska in scientific research. Cordova High School students have had 4

157 the opportunity to see some of the technical aspects and complications that go along with research. The science club and chemistry class provided an excellent platform to organize student involvement. Students had the opportunity to troubleshoot and take the lead on feeding procedures for the project resulting in implementation of several very clever and innovative ideas. The students of Cordova High School made multiple public presentations of the project progress and results. They were received well with each new appearance. The students demonstrate a thorough understanding of the issues involved with conducting new technology research as well as the factors that contributed to lessons learned during this project. In 2010 and 2011, CHS students and teacher Low presented biogas projects for the Alaska State science fair. Student results, reports and photographs from the biogas demonstrations are available (please refer to Y2Q2 report). Community outreach High school students and UAF researchers were given the opportunity to present on project ideas and preliminary results at meetings with the Alaska Power Association and Alaska state legislators in Juneau, and at a variety of conferences, including the Alaska Rural Energy Conference (April th, 2010) and the Alaska Forum on the Environment (February 7-11 th, 2011). Most recently, the project research was featured during ACEP s lecture series for the month of June The talk, given by Casey Pape, was hosted at the Blue Loon in Fairbanks. Slides as well of video of the speech can be found online (web link in section i). Titles of our project presentations and other public dissemination documents are: Walter Anthony, K., Culhane, TH., Koplin, C., McFadden, L., Low, A. Improving Cold Region Biogas Digestor Efficiency. McFadden, L. Alaska Forum on the Environment. Anchorage, Alaska. February 8-12, Walter Anthony, K., Culhane, TH., Koplin, C., McFadden, L., Low, A. Improving Cold Region Biogas Digestor Efficiency. Low, A., Hess, E., Allen, J., Americus, I., Americus, B., Zamudio, A. Alaska Rural Energy Conference. Fairbanks, Alaska. April 27-29, Pape, C. and the Project Team, Energy from Psychrophilic Bacteria: A Cold-Region Alternative for Biogas, ACEP Community Energy Lecture Series, Fairbanks, Alaska, June 21, New Scientist article featuring this project: Cold climates no bar to biogas production. November 4, < The project was featured by Alaskan Dispatch Magazine in an article on rural Alaska entitled, Biogas could bring new energy to rural Alaska. January 17, < 5

158 Low, A. Youth Participation: Improving Cold Region Biogas Digestor Efficiency. Low, A., Bailer, C., Allen, J., Americus, B., Zamudio, A. Alaska Forum on the Environment. Anchorage, Alaska. February 8, Walter Anthony, K., Culhane, TH., Koplin, C., Low, A., Pape, C. Improving Cold Region Biogas Digestor Efficiency. Low, A., Bailer, C., Allen, J., Americus, B., Zamudio, A. Denali Commission Public Forum on the Emerging Energy Technology Grant. Juneau, Alaska. February 14-15, The project was also mentioned in Senator Lesil McGuire s recent press release on the Deadline for Emerging Energy Technology Fund Grant Applications Approaching. Released March 3, < Last year, the chemistry students took a class trip to the Alaska Power Association in Feb Students C. Bailer, D. Hess, C. Morrissett, J. Smyke, S. Lindow, and T. Kelley presented on the project and it was received well among those who attended the meeting. The project team intends to present at this years Alaska Rural Energy Conference in Juneau, Sept , Website development- Website developer Brandon Shaw designed a site ( for the Cordova Energy Center, the venue at which the biogas experiment has been conducted. The website provides a venue for students and community members to obtain information about the project and how to get involved. It is important to update the website often as a means to show visitors that the project is still underway, that is still producing results and that people are still encouraged to get involved. iii.b) Project Status iii.b.1) Gas Sample and Effluent Analysis As specified in the initial project proposal, researchers at the University of Alaska, Fairbanks were charged to analyze samples collected from the Biogas project and report on the relative gas and nutrient composition levels of each reactor used during the experiment. During the last quarter of the project, liquid and gas chromatographs were run on gas and effluent samples collected and cataloged from the Cordova site. These tests were employed to reveal the heat content of biogas produced (BTU rating) as well as the presence of usable nutrients found within detectable quantities from samples of the reactor effluent. The results are as follows: Gas Chromatograph Gas chromatography is a powerful analytical technique used to determine the composition and relative gas concentrations in a sample. Throughout the experiment, several 6

159 samples of biogas, collected from the project site were analyzed by GC and revealed high concentrations of methane, as much as 82% in some cases (Figure 1). At the time, it was suspected that the observed high levels of methane, uncommon in typical anaerobic digestors (AD) (typically 40-60%), was due, likely in part to decreased feeding regime which shifted the balance between fermenting bacteria and methanogenic anaerobes (see Y1Q3 report). Once a feeding schedule by students resumed on a regular basis with the onset of the new school year, methane levels began to decrease slightly, more closely resembling that of other anaerobic digestor systems of similar type and scale (Figure 1). The last set of samples taken in June of this year, revealed a range in methane content between 61-69% among all actively producing tanks in the experiment (Tanks 1, 4, and 5 respectively; Tank 6 s activity was observed, but could not be isolated in order to obtain a sample). At the time the samples were taken, each of the tanks had been incubated at a temperature of approximately 35 C on average. Therefore, it is unknown at this time whether the cause of the change in methane concentration was primarily due to changes in feeding regime or temperature since the tanks had not been given additional food material since April of that year (see Y2Q2 report). However, previous samples obtained from earlier in the year suggest that the methane content of biogas was similar to that of typical anaerobic digestor systems commonly cited throughout the scientific and other related literature. In addition to methane content, other gases were measured as well for their relative abundance within the collected biogas. Most notably worth mentioning here is that all trace gases (i.e. CO 2, N 2, O 2, etc.) decreased since the last set of samples were run in September 2010 (Appendix I). The likely explanation for the decrease in atmospheric molecules (O 2 and N 2 ) was that leaks were since identified and fully repaired. Once repaired, oxygen and nitrogen levels decreased to nominal levels which otherwise would only be expected to be present in any quantity within a reactor where air contamination has occurred (Appendix 1). Figure 1. Methane (CH 4 ) concentration in biogas samples determined on a Shimadzu 2014 gas chromatograph equipped with FID and TCD. Concentration of gases are presented as percent by volume. It should be noted that 70% CH 4 in Tank 4 shown for Aug. 28 and Sep. 5 was calculated as a correction to lower concentrations measured in samples due to a leak in the sampling system. Both the samples from August/September Tank 7

160 4 had the same methane/carbon dioxide ratio - =4.4 Based on a review of the other biogas samples, this should put the methane level of the biogas at ~65-70%, after correcting for presumed dilution from air contamination. The fact that the two samples had the same ratio of these gases, despite a two-fold difference in the methane level, is a good indication that the low reading is due to dilution by atmospheric air in the sample collection stage. Based on the samples gathered, sufficient information now exists in order to rate the quality and BTU equivalent of the biogas produced during the experiment. Referring back to the Phase 1 Data report, the highest observed production rate of any given 1000L tank within a twenty-four hour period was 345L. Combining the observed production rate(s) with the average methane concentration of biogas collected from the site (~69% CH 4 by volume), a good estimate of heat production value can be determined at this time. Based on the information available, gas collected at the end the project, which at the time of the last report was used to run a generator and boil water (see Y2Q2 report), had an equivalent BTU rating of approximately 8.4 btu day -1 L -1 (Equation 1). It is important to note, that this BTU rating is helpful in calculating possible efficiencies of combustion across a range of gas powered devices, but should not be viewed as a static number as the quality of produced biogas has been demonstrated to change over time and should therefore be viewed only as a helpful approximation of gas heat content (Figure 1). Equation 1. Rating BTU content of biogas High Pressure Liquid Chromatography The research team also ran tests on the relative nutrient content of reactor effluent collected throughout the experiment. Similar to GC analysis, high pressure liquid chromatography (HPLC) is another analytical technique which can be used to determine the composition of a material when the material of interest is in the liquid form as opposed to a gas. The same concept applies in both cases were individual components and their concentrations are determine based on the amount of time it takes them to travel through a charged column, know as retention time. Here, the retention times of the sample are compared to a set of standards (i.e. prepared samples of known concentration) which are used in order 8

161 to determine the sensitivity and accuracy of the instrument and therefore quality of the results for samples run (Figure 2). Figure 2. The calibration curve for phosphate. The linear relationship observed in the calibration curve was used to determine concentration of phosphate in digestor effluent samples based on the magnitude of the peak signal that occurred at the retention time of phosphate. All liquid chromatography testing was performed on a Dionex LC 20 HPLC with automatic feeding and sample control. All concentrations are reported in ppm. Upon sampling, effluent samples were stored refrigerated until analysis on a Dionex LC 20 with Chromeleon software package was performed on April 18, The instrument was programmed to determine the relative levels of fluoride, phosphate, nitrate, nitrite, and chloride. Some species of interest (e.g. potassium, ammonium, ammonia, etc.) could not be determined due to unavailability of instrumentation needed to perform these analyses. A cataloged list of frozen samples still exists, in case further analysis is desired in the future. Perhaps, most surprising was the low, mostly undetectable, levels of nutrient and mineral content within the samples run. Indeed, aside from chloride, which had very high levels due to the use of tap water in the experiment, only phosphate was detectable in any measurable quantity among samples run. Nitrate and nitrite were below the detection limit of the instrument; however, we suspect that most nitrogen found within the tanks would likely be in some other usable form (e.g. ammonia, ammonium, etc.) (House, 1978). Phosphate, which is an important nutrient used in agriculture, was found in concentrations as high as 55 parts per million (ppm) (Appendix I). Soils containing phosphate levels below 14 ppm are considered phosphorous deficient so reactor effluent can be considered as good source of liquid fertilizer (Swift, 2009). 9

162 iii.b.2) ACEP Cost Benefit Analysis, Performed by ISER This section of the report briefly outlines the work performed in the last quarter on evaluating the feasibility and cost benefit analysis of this project. This portion of the project was performed in order to make recommendations regarding the future of the technology for Alaskans interested in installing a reactor of similar scale within an individual home. The Institute of Social and Economic Research (ISER) is currently in the process of evaluating the Cordova Biogas project in order to determine the technology s level of marketability to Alaskan communities at large. Working in conjunction with ACEP, research associate Sohrab Pathan at ISER has been reviewing the project throughout the last quarter in order to determine if small, household-scale anaerobic digestor projects, like those assessed in this study, have any future potential to Alaska residents interested in biogas technology. In early July of this year, the UAF research team, along with ACEP and ISER met to discuss what an economic feasibility study would likely look like. It was determined at that time, and reaffirmed in later meetings at ACEP in August, that a Cost Benefit Analysis would be the most appropriate form of analysis as this project did not fall under the same parameters of other studies under the Emerging Energy Technology Grant (EETG) and should therefore not be evaluated along the same baselines of measure. The study is currently underway and should be finalized before the project s termination date on September 30, For more information regarding the details of the report, please contact: Sohrab Pathan Research Associate Institute of Social and Economic Research University of Alaska Anchorage Phone: Fax: ahpathan@uaa.alaska.edu iii.b.3) Wet-cup Flux Trap and Low Biogas Production Monitoring A critical limitation to determining gas production rates during Phase I and Phase II of this study was the lack of a manageable and reliable method of measuring gas flow rates (Y1Q4, Y2Q1-2). Much information was lost during the first year of the project with respect to daily gas production rates of individual reactor vessels due to improper calibration of the Sierra Top- Track 820 mass flow meters installed on site (see Y1Q4 report). The issue arrose because the flow meters could not distinguish significant quanties of gas movement across the flow tranducer (calibrated at ~3 SLPM) and therefore gave faulty readings. Later in the project, this issue was remedied for short-term flow determinations by closing off reactor valves in order to let the tanks accumulate gas pressure over 6-8 hour periods (Y2Q1-2), thereby releasing the gas at high enough rates of flow in order for the meters to detect the mass movement (see Y1Q4 report). This method improved the accuracy and understanding of daily biogas production rates, but was too costly and inefficient to to be employed on the long term. In general, it was 10

163 determined that other, less costly methods must be developed in order to reliably determine flow rate and daily biogas production levels. In effort to improve biogas data collection methods, UAF researchers worked during the last quarter to improve upon the design of existing flux trap technology for better gas flow measurements. Improvements made to the technology now allow for reliable low and highlevel gas flow rate monitoring. In the last quarter, at the sugestion of PI Katey Walter Anthony, a new method of gas production monitoring was developed by researcher Casey Pape, et al. using wet-cup gas meters. The idea has been used before in experiments similar to that of the Cordova biogas project, though never in this exact application, and was therefore not commercially available (Massé, 1997). Figure 3, component 7 illustrates the underlying principle of the wetcup gas flow meter. The mechanism is operated by a double-walled typing cup which is balanced at a single, central pivot point. When the leading cup fills with gas, its moment of inertia changes once it reaches a certain constant volume, causing the cup to tip while at the same time, orienting the cup opposite into the proper position to collect gas until it fills and tips - restarting the cycle. This is very much the way in which a typical rain gauge operates, the only difference being the cup and gauge is inverted in this case, being held in place by the bouyancy of the material, rather Figure 3. Illustration of the wet-cup gas meter used to develop a method to measure gas flux at low rates of production (from Massé, 1997). than gravity (Figure 2). As the cup begins to empty, losing its contents and orienting in the adjacent position, a small magnet placed in the middle ot the mechanism travels past a magnetic proximity switch which triggers a data logging device to record the event. 11

164 Figure 4. The internal working mechanism of the wet-cup flux trap (Left). Set screws can be used to adjust the relative position and tipping volume of each event. The magnetic switch delivered from the manufacture does not have adequate waterproofing and needs additional treatments of epoxy or equivalent in order to be deployed in an aquatic environment (Right). Table 2. Calibration table of a wet-cup flux trap for gas flow measurements. Trap Calibration Trial Trap 2 (5mL) Trap 3 (10mL) Trap 1 (40mL) # (ml) Average STDEV Mode Since both cups are identical, once calibrated, a total volume of gas evolved from the system can be ontained by simply multiplying the number of events recorder by the amount of gas required to cause a tipping event (Table 2). Since each event is given a time stamp, information regarding rates of flow and daily production are still retained and can be calculated based on the slope of the gas production graph (Figure 4). This method is ideal for studies where high resolution flux data is prefered because the individual tipping cup s capacity is on the order of hundreths of a liter per tipping event. Most gauges tip at 20 ml or less. Initial efforts to monitor gas flow in the six Cordova digestors using the wet-cup method were challenged by inadequate (non-standardized) tipping cup apparatus as well as by shorting out of electronics for data logging (Figure 5). The improvements made during the past quarter seem to have resolved these problems. In addition to laboratory testing and calibration, the wet-cup flux traps were deployed and tested in the field to monitor the gas flow rate from methane seeping in a thermokarst lake. Results suggest that the method would work well as a gas flow monitoring technique for anaerobic digesters as initially intended for this project (Figure 5). For the average consumer interested in developing an anaerobic digestor of their own, this tipping cup method presents a cheap and simple way to closely monitor gas production. Gauges of this type can be obtained and adapted for for the wet-cup application for around $100 USD. 12

165 Figure 5. Installation and deployment of the wet-cup flux traps at the Cordova digestor site earlier in the project. Automated bubble traps were installed on 10/15/2010 in an effort to monitor total gas flux from digesters 1, 4, 5, and 6 in a to the Sierra Top-Trak 820 Mass Flow meters iii.b.4) Final Project Site Breakdown Research technician Casey Pape traveled to the Cordova site from May 28, 2011 to June 16, 2011 in order to finalize Phase II demonstration of gas collection and utilization. He also led the breakdown of the digesters at the Cordova field site. Pape and other project team members from CEC began disassembly on June 14, Each of the reactor vessel s contents was evacuated using an industrial garbage pump into a secondary storage container which was used to screen out most of the sediment and heavy solids that were located within each of the tanks. The remaining liquid was discharged into the local storm water runoff drain as it contained no chemically harmful material. In order to finish evacuating all of the tank contents, each tank had to be cut and the bottom sludge layer agitated in order to loosen the remaining material of each tank, allowing them to drain more easily. The remaining tank components were disposed of at the local bailer waste compactor site and all instrumentation was returned either to CHS or UAF labs when Pape returned to Fairbanks. The project Conex is now vacant as of June 27 th 2011, and aside from the R-10 foam insulation and updated electrical system provided by the project, the Conex was returned to the school in its original condition prior to the onset of this project. Spare materials (e.g. construction materials, garbage cans, water pumps, pipe fittings, ball valves, and spare tubing), along with the converted Husky generator and stove instruments were left at the Cordova High School Energy Center for future use by students and teachers. Field-based activity at the Cordova field site ceased as of July 18, Pictures of the final breakdown are available at the end of this report (Appendix II). iii.c) Health and Safety Conventional small-scale anaerobic digestors are generally considered to be nonhazardous when given proper ventilation and maintenance. Still anaerobic digestors are used for the synthesis of combustible gases and have some safety concerns associated with them. As of April 18, 2011 the project Conex was locked and given a standby status upon discussing the project with UAF Environmental Health and Safety workers. EH&S had expressed some concern over proper project ventilation and the intrinsic safety of some of the equipment used on-site. With decrease supervision, coinciding with Pape s relocation to Fairbanks, it was determined 13

166 that the best plan was to minimize access to the inside of the Conex, cease feeding experiments, increase the temperature and open all valves in order to react all remaining organics within the reactors. Upon revisiting the project in June 2011, researchers consulted with EH&S in order to follow the best procedures for finalizing the gas collection, demonstration of gas utilization, and site breakdown. No health problems or accidents were ever reported during the course of this project. Electrical and Power: The project site is maintained by electrical heat and power supply. At present, that electricity has been provided by extension cords that run from inside the school and out to Conex. The CEC recently renovated the electrical system and increased the power capacity of the site. The project Conex electrical system now complies with all state and federal building and transmission codes and is wired for both 120V and 240V AC power. Flammability: Biogas is very flammable and it is important that measures be taken to prevent any undesirable fires that may cause explosion. No open flame was allowed within the Conex and students handling biogas were instructed to wear appropriate eye protection at all times. Students conducting experiments with biogas were required to wear eye safety glasses and proceed under adult or teacher supervision. No injuries due to fire or explosions occurred during this project though several fire alarms were been triggered when demonstrating biogas flammability was conducted without proper ventilation. Ventilation: The build-up of certain gases in an enclosed space can be toxic. Biogas digestors produce methane, carbon dioxide, hydrogen sulfide, and other gases which can be deadly at high concentrations. It is apparent to anyone entering the Conex which houses the experiment that a noticeable barn-like smell can be detected. The smell is due to volatile organics. Methane is odorless. This smell was significantly reduced once the new tank gas outlets were installed. Tanks were monitored daily and were not thought to pose any threat to human health. The air was cycled daily to a certain extent when the Conex container was opened for daily download of the gas flow data. Tubes are connected to the tanks to allow lighter than air constituents escape the container. H 2 S tags were located in the Conex throughout the duration of the experiment to visually monitor H 2 S levels in the Conex. They never reached any level of concern. The Cordova fire department visited the site and tested it for noxious gases. The results of the fire departments testing came up negative for any toxic gases. iii.d) Schedule of project The project is still on schedule as defined by the original project outline. Phase I is complete and Phase II is in its final stages. Throughout the rest of the project research efforts will focus final data synthesis, writing of reports and information for public dissemination, and public presentation at the Alaska Rural Energy Conference. iii.e) Project budget We anticipate that the budget is on target. At this time, the budget is not expected to exceed the grant, and the matching contribution is expected to significantly exceed the grant requirement. Clay Koplin will provide more details on the budget in the Final Report. 14

167 iii.f) Hurdles and solutions Project problems and solutions were outlined in previous progress reports. The remaining hurdles to which we found solutions during the past quarter were finding a reliable method for measuring gas flow rates (see iii.b.3) Wet-cup Flux Trap and Low Biogas Production Monitoring), and building and employing a suitable gas collection system for biogas produced among the digestors (see Y2Q2). References: House, David. (1978) The Complete Biogas Handbook. (Alternative House Information, United States), 52. Massé, D.I., Droste, R.L., Kennedy, K.J., Patni, N.K., and Munroe, J.A.( 1997) Potential for the psychrophilic anaerobic treatment of swine manure using a sequencing batch reactor. Canadian Agricultural Engineering. Vol. 39, No. 1. pp Swift, C.E. (2009) Colorado State University area extension agent, horticulture, Tri River Area, Grand Junction; and J. Self, CSU extension specialist soil testing, soil, water, and plant pesting lab manager, Colorado State University, Fort Collins. Revised 2/09. < 15

168 Appendix I. (Chemical Data Supplement) Figure 5. Concentration of carbon dioxide in digesters, presented as percent by volume. Figure 6. Concentration of oxygen gases are presented as percent by volume. Data label All Tanks is suspected to be above other measured gas samples due only to not being fully evacuated prior to collecting and storing gas produced from the other tanks in the experiment. 16

169 Figure 7. Concentration of nitrogen in digestors presented as percent by volume. Data label All Tanks is suspected to be above other measured gas samples due only to not being fully evacuated prior to collecting and storing gas produced from the other tanks in the experiment. 17

170 Table 1. Liquid chromatography table for phosphate in all effluent samples collected over the course of the experiment. The samples were all run with a 1:5 dilution; therefore actual concentrations are reported in the right-most column. All samples were run on a Dionex LC 20 chromatograph with Chromeleon data processing software package. Run Date: 04/18/2011 Sample Name (Tank #) Sample Date Sample No. Sample Name Ret. Time min Phosphate Area (µs*min) Phosphate Dilution (1:5) standard/sample concentration [ppm] Actual [ppm] Standards 1 lrb n.a. n.a standard standard standard standard standard lrb 7 lrb n.a. n.a. ccv2 8 ccv /13/ n.a. n.a. 2 7/13/ /13/ /13/ n.a. n.a. 5 7/13/ n.a. n.a. 6 7/13/ /28/ n.a. n.a. 2 7/28/ /28/ /28/ n.a. n.a. 5 7/28/ n.a. n.a. 6 7/28/ /4/ n.a. n.a. 2 8/4/ n.a. n.a. blank n.a. n.a. 4 8/4/ n.a. n.a. blank n.a. n.a. 6 8/4/ lrb 27 lrb n.a. n.a. ccv2 28 ccv /27/ n.a. n.a. 2 8/27/ /27/ /27/ n.a. n.a. 5 8/27/ n.a. n.a. 6 8/27/ /23/ /23/ /23/ /23/ /23/ /23/ lrb 41 lrb n.a. n.a. ccv2 42 ccv

171 Appendix II. (Final Project Breakdown) Final project site as of July 18, Insulation and lighting arrays remain to be removed at the school districts discretion. Photo credit: Clay Koplin. Evacuated tanks had to be cut with a sawz-al in order to be removed and their remaining contents disposed of properly. Photo credit: Clay Koplin. Empty tanks. 19

172 The project site, when viewed from the outside. Final project site remains undisturbed since July 18, Photo credit: Clay Koplin. 20