ENERGY SELF-SUSTAINING AND ENVIRONMENTAL FOOTPRINT REDUCTION ON WASTEWATER TREATMENT PLANTS VIA FUEL CELLS

Transcription

1 ENERGY SELF-SUSTAINING AND ENVIRONMENTAL FOOTPRINT REDUCTION ON WASTEWATER TREATMENT PLANTS VIA FUEL CELLS LAYMAN S REPORT 2012 LIFE07 / ENV / E /

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3 OUTLINE CONTEXT AND BACKGROUND 2 THE BIOCELL PROJECT Introduction Fuel cell technology: the clean and efficient path Methodology: pilot plants description RESULTS PEMFC results SOFC results Environmental assessment Fuel cell application field DISSEMINATION 24 CONCLUSIONS 28

4 CONTEXT AND BACKGROUND

5 LAYMAN S REPORT BIOCELL CONTEXT AND BACKGROUND Every time we turn on the tap and wash our hands, the water passes down the sink, towards the sewage network, where a series of pipes and tubes interconnected to every street of our villages, towns and cities, are responsible for carrying it to the wastewater treatment plant (WWTP). Then it runs through a series of complex systems where modern technologies purify it. Energy consumption in Wastewater treatment plants accounts for around 25 35% of the total operational expenditures of sewage treatment. WASTEWATER TREATMENT COSTS REAGENTS 5% OTHERS 5% MAINTENANCE 13% MANPOWER 30% SLUDGE AND WASTE 17% ENERGY 30% MURCIA ESTE WWTP 3

6 BIOCELL LAYMAN S REPORT CONTEXT AND BACKGROUND Taking into account the expected increase on the worldwide energy demand (up to 45% in 2030, International Energy Agency), the energy cost and its corresponding environmental impact will surely rise, affecting the water sector since it is highly energy-intensive. Therefore, energy in WWTP must be considered not only in terms of consumption reduction, but also in terms of production and use of green energy. In addition, the emissions of greenhouse gases from water utilities have to be reduced and synergies for the reduction of these emissions have to be identified. Anaerobic digestion is widely used in WWTP to treat sludge and organic wastes because it provides volume and mass reduction of the input material and is also a renewable source of energy as the process produces a methane rich biogas suitable for energy generation. For long time, chemical energy contained in the biogas was transformed into electricity in Internal Combustion Engines (ICE) and more recently in micro-turbines. RAW SEWAGE BIOGAS CLEANING (REMOVAL OF WATER, H 2 S, SILOXANES,...) CLEAN SEWAGE BIOGAS (CH 4 +CO 2 ) 4

7 Nowadays, new promising technologies have been developed which offer both a higher efficiency and a further reduced environmental impact: fuel cells. CLEAN SEWAGE BIOGAS (CH 4 +CO 2 ) REFORMING LOW TEMPERATURE FUEL CELLS HIGH TEMPERATURE FUEL CELLS CLASSIC COGENERATION COMBINED HEAT AND POWER 5

8 THE BIOCELL PROJECT

9 LAYMAN S REPORT BIOCELL THE BIOCELL PROJECT INTRODUCTION The BIOCELL project, with a 2.4 M budget funded by the LIFE+ Programme of the European Commission (LIFE07 ENV/E/000847), has the main goal of demonstrating the technical feasibility of energy production from biogas both with low - and high - temperature fuel cells. Secondary objectives include: - Technical assessment: guidelines on selection, implementation, operation and optimization of energy production from biogas, via fuel cells adapted to WWTP - Feasibility and impact assessment: energy self-sustainability, economic feasibility and reduction of environmental impact of WWTP using biogas energy recovery via fuel cells. - Application field: biogas as a fuel, requirements and limits. CETaqua is the coordinating beneficiary of the project and the ultimate responsible of its success. Apart from CETaqua, three other partners are strongly contributing to the project: EMUASA, CIRSEE and Degrémont. In addition, the project stakeholders are actively involved, as well as several biogas treatment suppliers and fuel cell manufacturers. PROJECT STAKEHOLDERS 7

10 BIOCELL LAYMAN S REPORT THE BIOCELL PROJECT FUEL CELL TECHNOLOGY: THE CLEAN AND EFFICIENT PATH A fuel cell is an electrochemical device that directly turns the chemical energy of a fuel into electricity. This conversion avoids the Carnot efficiency limitation present in combustion engines, what implies a higher efficiency by design. FUEL CELL WORKING PRINCIPLE ELECTRIC CURRENT FUEL IN e- e- AIR IN e- H+ e- O 2 H 2 H+ H 2 O EXCESS FUEL ANODE CATHODE ELECTROLYTE UNUSED GASES OUT The basic working principle for all the fuel cells consists in an oxidation/reduction reaction in which fuel (e.g. biogas) is oxidized, and oxygen is reduced, thus exchanging electrons and producing an electrochemical induced current. 8

11 Eventually, biogas-powered fuel cells combine a high-efficient technology for electrical generation with the use of a renewable fuel, hence being one of the most environmentally friendly technologies that can contribute to energy self-sufficiency in WWTP. Nevertheless, biogas needs to go through a thorough and extensive process of cleaning upstream the fuel cell in order to remove its pollutants. COUPLING RAW BIOGAS TO FUEL CELLS Biogas contains many compounds that are harmful to fuel cell materials, especially for catalysts. Their tolerance to these compounds varies depending on each pollutant, and type of fuel cell: COMPOUND SOFC* MCFC* PAFC* PEMFC* H 2 S <0,1 ppm <0,1 ppm <20 ppm 0,1 ppm SILOXANES 0,5-1 mgsi/m 3 0,5-1 mgsi/m 3 0,5-1 mgsi/m 3 0,2 mgsi/m 3 HALOGENS (HCI) <1 ppm <0,1 ppm 4 ppm not known CO acts as fuel acts as fuel 1% 10 ppm HIGH TEMPERATURE LOW TEMPERATURE *SOFC: Solid Oxide Fuel Cell *MCFC: Molten Carbonate Fuel Cell *PAFC: Phosphoric Acid Fuel Cell *PEMFC: Proton Exchange Membrane Fuel Cell BIOGAS CLEANING UPSTREAM THE FUEL CELL 9

12 BIOCELL LAYMAN S REPORT THE BIOCELL PROJECT In order to comply with the stringent inlet requirements of both low - and high - temperature fuel cells, a previous biogas cleaning step is necessary. Different technologies are available for this purpose: CHEMICAL SCRUBBERS ACTIVATED CARBON BIO- SCRUBBER MAIN REMOVAL (H 2 S) GAS CLEANING TECHNOLOGIES POLISHING (H 2 S, SILOXANES, VOCs) BIO-TRICKLING FILTER IRON SPONGE BIOGAS CLEANING TECHNOLOGIES 10

13 After the cleaning of the biogas, further processing of the biogas is needed, depending on the operating temperature and type of fuel cell: RAW BIOGAS BIOGAS TREATMENT CLEAN BIOGAS REFORMING CO REMOVAL CO CATALYTIC OXIDATION DRY REFORMING STEAM REFORMING WATER GAS SHIFT COPROX 30-50% H % CO 50-65% H 2 <1% CO 50-65% H 2 <10 ppm CO SOFC MCFC PAFC PEMFC High temperature fuel cells (SOFC and MCFC) internally process the biogas. On the contrary, low temperature fuel cells (especially PEMFC) need an external fuel processing, plus further CO removal. 11

14 BIOCELL LAYMAN S REPORT THE BIOCELL PROJECT METHODOLOGY: THE TWO PILOT PLANTS Two pilot plants in Spain have been built in order to achieve the objectives of the project. The plant in Murcia contains a Proton Exchange Membrane Fuel Cell (PEMFC), which operates at low-temperature (around 65 ºC), and has been designed to produce 3 kw of electric power, using 10 m 3 /h of biogas. PEMFC PILOT PLANT IN MURCIA ESTE WWTP INSTALLATION SITE The biogas cleaning is achieved by using a caustic scrubber, followed by a drying process (removal of water) and, eventually, adsorption on activated carbon and silica gel (for extra drying of the gas) to achieve the stringent fuel requirements of the fuel cell. Since hydrogen is the only fuel that is accepted by PEMFC, a biogas reforming process, from methane to hydrogen, is necessary. The BIOCELL project has developed a specific and innovative biogas dry reforming process, producing a high quality reformed gas suitable for PEMFC. CLOSE VIEW OF PEMFC PILOT PLANT RAW BIOGAS 10 m 3 /h CLEANING NaOH SCRUBBER + DRYING + AC + SILICA CLEAN BIOGAS REFORMING DRY REFORMING + CO PURIFICATION REFORMED GAS FUEL CELL PEMFC ELECTRICITY 3kW e 12

15 The plant in Mataró contains a Solid Oxide Fuel Cell (SOFC), which operates at high temperature; around 800 ºC. It has a design power of 2.8 kw, and the plant treats a biogas flow rate of 10 m 3 /h. In this case, a biotrickling filter is used as the main biogas desulphurization technology. Biogas is THE PILOT PLANT IN MATARÓ further purified by the polishing system via adsorption on iron oxides, biogas drying, and further adsorption of other contaminants on activated carbon. Clean biogas directly fuels a completely heat-integrated SOFC unit producing both electricity and heat. BIOGAS CLEANING SYSTEM OF SOFC PILOT PLANT THERMAL ENERGY 0,9 kw t RAW BIOGAS 10 m 3 /h CLEANING BIOTRICKLING FILTRE + IRON SPONGE + DRYING + AC CLEAN BIOGAS FUEL CELL SOFC ELECTRICITY 2,8 kw e 13

16 RESULTS

17 LAYMAN S REPORT BIOCELL RESULTS Technical, economical and environmental indicators have been gathered during the whole project, and especially during the operation of both pilot plants, regarding design, start-up and operation of biogas treatment and fuel cells adapted to WWTP. PEMFC PLANT RESULTS The results on operation and performance can be divided in two separate chapters: the biogas cleaning system (or treatment line), and the fuel cell (including the reforming of methane into hydrogen). Treatment line After some trials to determine the best operating parameters for the treatment line, results from long-term operation, over a period of 6 months, have been gathered: TREATMENT UNIT PARAMETER AVERAGE VALUE CHEMICAL WASHING (NaOH SCRUBBER) POLISHING (DRYING + ACTIVED CARBON) EXTRA DRYING (SILICA) H 2 S in (ppm) H 2 S out (ppm) removal efficiency (%) H 2 S out (ppm) siloxanes in (mgsi/m 3 ) siloxanes out (mgsi/m 3 ) removal efficiency (%) H 2 S out (RH%) removal efficiency (%) <0,1 3 <0,1 >99 <2 92 Even though the content in sulphur is very high, its removal is effectively carried out by a caustic scrubber, a very mature and commercially deployed technology that uses chemicals (soda) to remove the sulphur. The rest of contaminants are removed by adsorption on activated carbon with efficiencies higher than 99%. With this combination of technologies, it is possible to achieve the fuel cell inlet requirements 15

18 BIOCELL LAYMAN S REPORT RESULTS Operational expenditures (OPEX) are between 6 7 c /m 3 of treated biogas, and are fairly split between caustic scrubbing and the polishing system: kwhe year 800 KgNaOH year 3 70 m H 2O year 80 Kg AC year RAW BIOGAS 10 m 3 /h BIOGAS TREATMENT CLEAN BIOGAS 9,15 m 3 /h 70 m 3 bleed year OPEX Caustic scrubbing Polishing TOTAL 3-3,5 3-3,5 6-7 c /m 3 c /m 3 c /m 3 CAUSTIC SCRUBBING AND POLISHING OF PEMFC PILOT PLANT 16

19 The reforming process for the fuel cell has accounted up to a total operation of 385h, demonstrating that it is possible to produce a suitable gas to be used as a fuel for PEM fuel cells: REF WGS COPROX 1 Nm 3 /h PEMFC PEMFC 4,58 Nm 3 /h CH 4 /CO 2 1:1 2 X PEMFC 3kW, 2,4 Nm 3 /h GAS COMPOSITON BURNER FUEL REFOMRING PROCESS These results indicate that a good reforming performance has been achieved, reaching hydrogen contents up to 44%, and CO concentrations lower than 4 ppm. In addition, a case study for a PEMFC unit of 3 kw has been built in order to forecast the technical performance of such systems, leading to the following outputs. PARAMETER INSTALLED POWER PRODUCED POWER ELECTRICAL EFFICIENCY EXHAUST GAS TEMPERATURE THERMAL POWER THERMAL EFFICIENCY UNIT kw kw % ºC kw % AVERAGE VALUE , ,2 4,3 These simulation results indicate that more basic research is still needed to enhance the technical performance and feasibility of these complex and innovative systems. 17

20 BIOCELL LAYMAN S REPORT RESULTS SOFC PLANT RESULTS The results are as well presented considering that the plant has two functional areas: the treatment line (contaminant removal) and the fuel cell (power generation). Treatment line After the execution of many short experiments to determine the best operating conditions, long-term operation over a period of 12 months of the biogas treatment, offered the next average results: TREATMENT UNIT PARAMETER AVERAGE VALUE BIOTRICKLING FILTER POLISHING (IRON OXIDES + DRYING + ACTIVED CARBON) H 2 S in (ppm) H 2 S out (ppm) removal efficiency (%) H 2 S out (ppm) siloxanes in (mgsi/m 3 ) siloxanes out (mgsi/m 3 ) removal efficiency (%) <0,1 100 The main sulphur removal is carried out by the living bacteria, inside the biotrickling filter (around 70%). The remaining sulphur content is adsorbed in the iron oxides with removal efficiencies higher than 99.9%. Other harmful contaminants (such as silicon and halogenated compounds) are as well completely removed by adsorption on activated carbon. 18

21 The operational expenditures account up to a total of 5-6 c /m 3 of treated biogas, being the polishing step the responsible of 90% of these costs due to ferric oxide and activated carbon consumption: kwhe year 1500 kwhe year 90 KgNaOH year 450 KgBiOnFe year 300 Kg AC year RAW BIOGAS 10 m 3 /h BIOGAS TREATMENT (AVAILABILITY 79%) CLEAN BIOGAS 11,1 m 3 /h 130 m 3 bleed year Biotrackling filter Polishing TOTAL 0,5-0, c /m 3 c /m 3 c /m 3 Soda consumption is considerably lower than for a caustic scrubber (PEMFC plant), since it is not needed for regular operation, but necessary to periodically clean up the biotrickling filter. Considering all short and long-term operational results, it has been demonstrated that this treatment line is prepared to meet the stringent requirements of the fuel cell. 19

22 BIOCELL LAYMAN S REPORT RESULTS Fuel cell Experimentation of the SOFC was carried out for a total of 220 hours, giving the next average results: PARAMETER INSTALLED POWER PRODUCED POWER ELECTRICAL EFFICIENCY EXHAUST GAS TEMPERATURE THERMAL POWER THERMAL EFFICIENCY UNIT kw kw % ºC kw % AVERAGE VALUE 2,8 1,3 24, ,1 39,4 These experimental results indicate that electrical and thermal efficiencies are high. In particular, the electrical efficiency of stack, which has been of 48.5%, is comparable to large power generation facilities (> 500 kw). However, the achieved electrical power only reached 45% of its design power (which is 2.8 kw), because at high fuel loads, operation was unstable due to insufficient heat evacuation capacity. SOFC UNIT INSTALLED IN MATARÓ WWTP 20

23 ENVIRONMENTAL ASSESSMENT The environmental impact of the two units was assessed, including the manufacturing and operation of both facilities. The Life Cycle Assessment is based on inventory data, and has been carried out according to the following steps: At this stage each impact is charcterized, the study may be limited at this stage if it meets the initial objectives DEFINITON OF THE OBJECTIVES & SCOPE OF THE STUDY INVENTORY CLASSIFICATION The analysis can be limited to the Inventory if the objectives are met Evaluation allows, at the end of the study, to score every studied hypothesis CHARACTERITZATION NORMALITZATION EVALUATION Sensitivity analysis & weighing of different environmental imapcts The environmental assessment has been carried out both for the construction and the operation phases. The results for the construction phase show that energy conversion systems (the fuel cells) are the main contributors to the environmental impact, both in PEMFC and SOFC pilot plants, having a much higher impact than their corresponding biogas cleaning and conditioning steps. ENVIRONMENTAL IMPACT As for the operation CONSTRUCTION CONSTRUCTION OF TREATMENT OF FUEL CELL phase, fuel cells show LINE a positive environmental impact because of green electricity and green thermal energy PEMFC PILOT PLANT ENVIRONMENTAL SOFC PILOT PLANT generation, comparable BENEFITS to mature and already deployed technologies such as Internal Combustion Engines (ICE). Results are influenced by the location where they are calculated; hence the environmental impact will be more positive in countries with a high-carbon electricity mix, such as Spain, but smaller in low-carbon countries, such as France. OPERATION OF THE WHOLE PILOT PLANT 21

24 BIOCELL LAYMAN S REPORT RESULTS FUEL CELL APPLICATION FIELD IN WWTP The application field of fuel cells adapted to WWTP was studied, and compared with other technologies. A technical and economic study of different case studies has been issued with the objective of giving recommendations for the choice of different CHP (Combined Heat and Power) technologies and their required biogas treatment. MATARÓ WWTP The model used for this case study assessment is comprised of the information gathered by the two pilot plants, and other literature and manufacturer information. MATARÓ SOFC PILIOT MURCIA PEMFC PILIOT BIOGAS FLOW, COMPOSTION ENERGY COSTS MODEL REVENUE OPERATION COSTS LITERATURE INTERNAL EXPERIENCE DATA FROM MANUFACTURERS PROCESSES MATHEMATICAL MODELS INPUTS OUTPUTS INTERNAL DATABASE BIOCELL PILOT DATA 22

25 Different plant sizes, types of biogas and end-use technologies have been considered, building up to a total of 24 case studies: PE (62,5 m 3 /h) PE (312,5 m 3 /h) H 2 S = 2500 ppm VOSiC = 10 mg/nm 3 H 2 S = 250 ppm VOSiC = 10 mg/nm 3 FLARE ICE ICE + ORC MICRO- TURBINE MCFC SOFC PEMFC In this assessment, it has been observed that MCFC are technically superior. In addition, these electrochemical devices have very clean emissions, what is a potential advantage towards future stringent legislation standards. However, when economic considerations come into play, microturbines and especially internal combustion engines are the unique technologies that offer investment payback. Fuel cell facilities can only be considered if investment subsidies are provided. In any case, results have also shown that most of these technologies can cope with the heating demand of a WWTP, while satisfying up to 60-70% of its electrical needs. 23

26 DISSEMINATION

27 LAYMAN S REPORT BIOCELL DISSEMINATION Communication and dissemination of results and other important information has been carried out from the very beginning of the project, including: Website and video A project website ( has been developed to open the door to the internet. The web contains general information about the project and its participants, receiving up to 760 visits per month. A short 15 minutes documentary with a global overview of the entire BIOCELL project is also available in this website. Conferences and publications Publications on general media and technical/scientific journals and conferences have been a very important part of the communication plan, including: - 8 publications at general and scientific media (local and worldwide newspapers and magazines) 25

28 BIOCELL LAYMAN S REPORT DISSEMINATION - 7 oral presentations and 9 posters at different technical conferences (including International Water Association, European Fuel Cell and International Water Week events, amongst others) - 6 oral presentations at workshops (including Water supply and sanitation Technology Platform, International Energy Agency, and others) Technical visits On-site visits of partners and manufacturers involved in the project, as well as external audience, have also been organized, in order to enhance project dissemination in a more technical point of view. A total of 20 visits, 13 at the SOFC pilot plant and 7 at the PEMFC pilot plant, have been carried out. VISIT OF THE TECHNICAL COMITEE OF SUEZ ENVIRONNEMENT TO THE PEMFC PILOT PLANT VISIT OF THE AGBAR - UPC MASTER (2011/12) IN WATER MANAGEMENT TO THE SOFC PILOT PLANT Workshop A final workshop in Barcelona took place in June 2012, with the participation of more than 50 people, including participants and other audience related to the world of biogas exploitation (Administration, stakeholders, providers, etc.). WORKSHOP SESSION IN BARCELONA 26

29 AwardS The BIOCELL project received the following awards, which acknowledge the quality of the project results and the efforts made by all participants. 1. Honour Awardee at the Europe West Asia Project Innovation Awards 2012 organized by the IWA for the category Applied Research (May 15th of 2012, Brussels, Belgium) 2. Best poster presentation award of the conference ORBIT 2012 Global assessment for organic resources and waste management (June 13th of 2012, Rennes, France) 3. Grand Honour Awardee at the World Project Innovation Awards 2012 organized by the IWA for the category Applied Research (September 19th of 2012, Busan, Korea) EUROPEAN PROJECT INNOVATION AWARD RECEIVED IN BRUSSELS After LIFE+ The After LIFE+ communication plan has the objective of ensuring that results are effectively transferred and communicated, even after the end of the project. This opens the door to the prospection and identification of future opportunities and applications related to the field of biogas powered fuel cells. For this purpose, CETaqua will focus in maintaining and prospecting new relationships with all the related actors, and EMUASA will continue to run the PEMFC pilot plant. In addition, website will be periodically maintained and updated, with the latest relevant information. 27

30 CONCLUSIONS

31 LAYMAN S REPORT BIOCELL CONCLUSIONS The BIOCELL project has achieved the main goal of demonstrating the technical feasibility of energy production on WWTP from biogas via fuel cells. The biogas treatment technologies are prepared to achieve the fuel cell requirements. It is suggested to have a treatment line consisting in a main contaminant removal, followed by a polishing or deep contaminant removal step. It is important to design robust treatment lines to avoid unexpected shutdowns. Comparing the two types of fuel cell tested, it has been observed that SOFC seem to be more adapted for biogas applications. PEMFC need more basic research regarding design issues. The lifetime and long-term performance of such systems needs to be further assessed. It has been demonstrated as well, that today fuel cells are still a very expensive technology for industrial implementation. New projects with direct cooperation between biogas producers, biogas cleaning systems providers and fuel cell manufacturers are necessary, both for scientific and industrial purposes. BIOGAS HOLDERS IN WWTP MURCIA ESTE 29

32 LAYMAN S REPORT 2012 CETAQUA WATER TECHNOLOGY CENTRE Carretera d Esplugues Cornellà de Llobregat, Barcelona (Spain) info@life-biocell.eu