Turning Wastes into Watts There is no alternate to energy but certainly there is an alternate energy.
What is biogas? Gas produced by the anaerobic digestion or fermentation of organic matter under anaerobic conditions. Biogas = CH4 + CO2 + H2S + N2 + H2 etc Typical biogas composition: ph-value : 6.5 to 7.5 Due Point : < - 80 C Methane, CH 4 : 55-70% Carbon dioxide, CO 2 : 25-40% Nitrogen, N 2 : 0-2 % Hydrogen Sulphide, H 2 S : 0-3 % Hydrogen, H 2 : 0-2 % Oxygen, O 2 : 0-2 %
Anaerobic Digestion Complex Organic Carbon Hydrolysis Monomers & Oligomers Acidogenesis Organic Acids Acetogenesis Acetate H 2 / CO 2 Methanogenesis CH 4 + CO 2
LIQUEFACTION PHASE GASIFICATION PHASE COMPLEX ORGANIC MATTER SIMPLE ORGANICS ACETATE H 2 / CO 2 ACIDOGENS METHANOGENS METHANE and CARBON DIOXIDE LOW ODOR EFFLUENT
WHERE DOES BIOGAS COME FROM? Vegetation - When vegetation decomposes, it gives off methane gas Farm and ranch animals - cattle, chickens, pigs Sewage The treatment of human waste in anaerobic digesters produces methane Landfills Garbage produces methane as it decomposes
Biogas Cycle Solar energy Biomethane production Photosynthesis Animal husbandry Crop harvesting Industrial processing Human consumption Energy crops Biofertilizer H 2 O CO 2 Electrical and/or thermal energy Organic wastes Anaerobic digestion Biogas Natural gas pipeline Energy crops CO 2 Cleaning & Upgrading
Potential wastes that can be used for biogas power generation Leather Industry Wastes Abattoir Industry Wastes Fruit/Food Processing Wastes Pulp & Paper Industry Wastewater Municipal Wastewater/Sewage Vegetable Market Yard Wastes Animal/Agro Residue
Major types of biogas plants in India 1. Fixed dome type 2. Floating drum type 3. Bag type
Flexible balloon biogas plant
BIOGAS TO POWER.WHY? Power is in short supply. 78,000MW planned in 11 th Plan. 1.25 lac villages and 56 % of household are non electrified- Power is in big deficit. Rural, decentralized and renewable power -A Priority. Enactment of Electricity Act 2003 and Renewable policy 2005 in place. Process industries need high quality and uninterrupted power. Any expansion /New downstream projects will require additional, quality power. Power generation/cogeneration is becoming an important revenue stream.
BIOGAS TO POWER.WHY? Successful reference plants available reduced risk. Elemental Sulphur as a high value biproduct from Bioskrubber process, an added advantage. CDM benefits Generate more power, get more benefit Therefore generating additional power from biogas now makes good business sense.
Biogas application from Heat to Power A High Value Shift Current utilization of biogas - mostly as heat value. Biogas fired Gas Engines - for high value shift. 1 m 3 of gas fired in engine can give 2 units of power. High efficiency - Electrical 40.8%+17.5%+22.9% =81.2% System configuration -Biogas+Scrubber+Gas engines H 2 S in the biogas must be removed for gas engine application. Typical H 2 S in biogas is 3% to 5%.Should be brought down to 250 ppm.
Electricity status in India Break-up of Power Thermal Power Plants 75% Hydro Electric Power Plants - 21% Nuclear Power Plants - 4% Installed wind power Generation 9655 MW 30% to 40% of electrical power is lost in transmission and distribution *(2008)
Contd Per capita electricity consumption: 600 kwhr per year. 84% villages electrified, 44% of rural households electrified. i.e. still a long way to go to achieve a dark free India. Per capita power consumption 612 KWH Annual power production 680 billion KWH
Energy in India Electricity Generation : 557.97 TWh
INSTALLED CAPACITY FROM RENEWABLE ENERGY Source: Ministry of New and Renewable Energy
Power demand India s economy - high growth rate and growing energy demand. Currently a shortage 18% and power cuts are very frequent affecting the industry and continuous production. The Government of India gives special incentives to encourage the use of renewable sources of energy. MNRE has set a goal of installing 10 percent of the additional power generation capacity in the country through grid connected renewable power by 2012. Power generation from biogas has been the least utilised opportunity in India so far.
Ways to produce power from biogas 1. Biogas used in duel fuel engine with 75% - 80 % replacement of diesel 2. Through 100% biogas engines 3. Through fuel cells direct conversion of biogas into electricity. 4. Through burning biogas in boiler steam electricity turbine
Facts need to keep in mind. Biogas can be burned and used as a heat source (produce hot air, hot water or steam). Biogas can be used to operate an engine generator set that produces electricity and if the waste heat is captured and used, (Combined Heat & Power-CHP), plant efficiency improves. The monetary benefit occurs when the electricity generated is used to replace electricity that s normally bought at retail. A Combined Heat & Power (CHP) unit increases the cost of an anaerobic digester system. You can store gas but can t store electricity.
Biogas into Electricity conversion through Engines
Power generation from biogas..
Contd.
General Process flow diagram.
In Internal Combustion engines 1. Adequate removal of hydrogen sulfide to below 10 ppm is important to reduce engine maintain requirement. 2. Often more frequent changing of engine oil and testing for oil sulfur content can increase engine component life. 3. Dual-fuel carburetor can be employed to start-up and shut down the engine system effectively - removing trace sulfide from the internal parts. 4. Waste heat may be used for digester heating, space heating, hot water and or refrigeration.
Treatment of biogas Treatment includes removal of hydrogen sulfide, water, mercaptans, carbon dioxide, trace organics, and particulates. Treatment of biogas is necessary to maintain the engine in good condition It reduces greenhouse gas emissions Will enhance calorific value of biogas Biogas can be injected into a natural gas pipeline. i.e. can be used as a replacement for natural gas
How comes H 2 S? Concentration of hydrogen sulfide in the gas is a function of feed substrate and inorganic sulfate content. Wastes high in proteins containing sulfur based amino acids (methionine and cysteine) - significantly influence biogas hydrogen sulfide levels. (For instance, layer poultry waste containing feathers made of keratin may produce biogas sulfide levels up to 20,000 ppm). Sulfate present in the waste, either from an industrial source (eg. pulping of wood) or from seawater (marine aquiculture) will be reduced to sulfide by sulfate reducing bacteria. SO -- 4 S -- H 2 S High toxic and corrosive in nature The burning of the gas releases sulfur dioxide which is also a corrosive and toxic gas.
Can H 2 S be removed from Biogas? Removal of H 2 S from Biogas is possible Physical Methods: Absorption in water, adsorption in activated charcoal/peat - Large quantity of scrubber, high cost, useful for low conc. Chemical Methods: Alkali, Alkaloamine, ferric oxides, Zinc salts - High cost, chemical waste generation Biotechnological Methods : Biofilter,Bioscrubber Biotrickling filter - High efficiency, Lower investment costs, Lead to savings on energy, Avoid catalysts, Avoid formation of secondary contaminants.
Biomethane Biomethane the gas obtained after removing the impurities in the biogas, such as carbon dioxide and hydrogen sulfide (H2S). Sr.No Biomethane Methane 1. Limited supply Unlimited supply 2. Renewable Not renewable 3. Good for environment Not good for environment 4. Biomethane recovery, use and production generates "Greentags" or a "Renewable Energy Credit" for the owners. Natural gas sold by the gas company does NOT generate these incentives and new revenue streams.
Basic Concept: How biogas is converted into electricity in engines
Biogas as fuel - Electromechanical device - Convert mechanical energy into AC electric energy - also known as AC generators - based on Faraday's law of electromagnetic induction To alternator
Alternator
Biogas Power generation through dual-fuel Engine Also called as Flexible-fuel engine. Two different fuels (Biogas 70-80 % and other fuel (generally diesel)) mixed together the resulting blend is combusted. Operation produces less complex-hydrocarbon pollution, and the engines have fewer internal problems. Compression ignition is used.
7 Power generation through 100% biogas engine Also called as gas engines Both compression and spark ignition can be employed Carburetor is replaced by venturi system to introduce gas into the air flow Maximum power output is lower than dual fuel engine Electrically efficiency is lower than duel fuel engine Will cause corrosion in mechanical parts Overall, the dual-fuel engine perform well and have great potential for use on-farm energy utilization.
Genset?? Known as Engine-generator set Combination of an electrical generator and an engine (prime mover) mounted together - a single piece of selfcontained equipment. Located in proximity to the end-user rather than in a central location Economic, easy, and safe to install even on the domestic level Ranging from small to very large size
GE Jenbacher engine models Type 2 250 330 kwe Introduced 1976 30 years continuous development 8 cylinder
GE Jenbacher engine models Type 3 500 1,100 kw e
Engine Generator set: Internal combustion engine with 135 kw 240 VAC electrical generator. Caterpiller 3406
Advanced Reciprocating Engine System ARES: High efficiency, low emissions gas engine US DOE, Caterpillar, Cummins, Waukesha Engine Biogas to electricity efficiency: 42% now, target 50% (Conventional efficiency 30%) Reduces NO X by 90%
Example of 1030kW & 300kW Generators Biogas Technology Group is able to provide modular power generation units ranging from 300KW 1MW, using mostly Caterpillar or Perkins engines
What is CHP? Combined Heat and Power (CHP) is a highly efficient and environmentally friendly technology for generating heat and power (usually electricity) on site from a single fuel source usually gas. Power generation systems create large amounts of heat when converting fuel into electricity. Avg. central utility power plant turns 60% of the energy content of the input fuel into heat and wasted. Typical Co-generation Efficiency - 30% conversion of biogas to electricity - 50% recovery of waste heat Capturing these waste heat - increase energy efficiency, operating cost savings, and reduced air pollution and global warming.
How does CHP work? The basic elements of a CHP plant: 1.A prime mover (gas engine) 2. Electrical generator driven by the engine 3. Heat exchangers recovering heat from the engine Jacket cooling water Lubricating oil Turbocharger intercooler Exhaust gases 4. System control panel
GE Jenbacher gas module Heat recovery - heat exchanger Engine Engine control panel Generator
Process flow diagram of CPH in Genset
Secondary heat exchanger Typical CHP flow diagram Gas input Electrical output Engine hot water circuit Exhaust Exhaust heat exchanger Building hot water return Engine hot water circuit Building hot water feed
Biogas plants in India Potential -12 million family type biogas plants Achieved - 4.12 million family type biogas plants - 34% of the potential. Functionality of the biogas plants is about 95.80% Domestic biogas plants can supply few hours of electricity for domestic needs.i.e. More beneficial in rural areas. Electricity can simply be produced by using Biogas generators of few kw capacity. *APITCO Survey
Power generation Potential in Distillery Units 1 litre alcohol distilled 15 litre wastewater Anaerobic Digestion 1 litre wastewater 15 litre of biogas Per litre of alcohol distilled 225 litre biogas No. of distilleries: Nearly 300 Total alcohol production : 3.20 billion litres/year Wastewater : 45 billion litres/year Biogas production: 1200 million m 3 biogas Electricity Generation: 1 M 3 Biogas 2KWh Total electricity: 2.4 million MWh/year. Directory of Indian Distilleries, All India Distillers' Association.
TARGET DISTILLERIES Biogas to Power project will benefit all Distilleries such as: Those having high power consumption from the grid. Those having other plants/offices in Group companies buying high and expensive power from the grid. Those attached to sugar factory having cogen unit and selling power to the grid. Those wanting to sell power to a Third party
Alternative: Biogas Engine Very few distilleries have gone for power generation using biogas engines although it can be an attractive alternative: Significant savings can be achieved by supplying the entire electricity demand of the facility from own source Additional revenue can be achieved by exporting the surplus power to the National Grid. Distilleries can earn additional revenue through the CDM mechanism
CDM in distilleries The Clean Development Mechanism (CDM), under the Kyoto Protocol, has introduced the possibility of earning CERs - Certified Emissions Reductions, Carbon Credits through utilisation of the biogas for power (electricity) generation.
Hypothetical case in distillery Theoretical case study of electricity generation using biogas engine in a typical distillery: 1. CDM project development CER revenue options 2. Power generation example, considering two scenarios: Case 1 Selling the electricity to the grid and royalty to the client Case 1 Selling the electricity to the Client; Savings for the Client
Process flow diagram with CDM and power generation Raw materials Power Steam Distillery 35 KLPD Raw Spent Wash A.D. Facility Treated Spent Wash Press mud Bio composting Alcohol 35 KL Boiler Furnace Oil Bagasse Biogas 1 MW Power generation package Compost for sale Option 2 power 966 KW Option 1 (to Grid)
Hypothetical Process Flow diagram before CDM Raw materials Power Steam Distillery 35 KLPD Raw Spent Wash Open lagoon Alcohol Boiler Furnace Oil
. Puente Hills 50 Megawatt Boiler run by Biogas, Los Angeles in U.S
A waste-to-energy power plant located in Westchester County, U.S.A
58 megawatt Waste-to-Energy power plant biogas obtained from wastes, expanded in 2007, Florida, US
Sandon Dock waste water treatment works, Liverpool *CHP for digester heating water
Shakarganj Mills Ltd, Pakistan 5 fully mixed digesters (CSTR) tanks (each above 12,000 m3), gas holder and control room
Jack s Gulley MBT plant, New South Wales, Australia
A Major Boost for Promotion of the Renewable Energy Sector in India Electricity Act 2003'' notified on 10th June, 2003 - The most important legislative development - encouraged the recent growth in renewable power Important features of this Act w.r.t. renewable energy: It identifies the role of renewable energy technologies for supplying power to the utility grid as well as in stand-alone systems. The Act provides for the Independent Power Producers (IPP) to set up renewable power plants for captive use, third party sale, power trading and distribution. It empowers the State Electricity Regulatory Commissions (SERCs) to promote renewable energy and specify, for purchase of electricity from renewable energy sources, a percentage of the total consumption of electricity in the area of a distribution licensee.
Sample of Basic data for power generation Parameter Unit Data Distillery Operational Data Distillery capacity KL/day 35 Spent wash generation m3/day 438 Inlet COD mg/l 110000 Biogas generation m3/hr 587 Methane content % 60 H2S content after H2S scrubber ppm < 300 Methane quantity fed to biogas engine m3/hr 352 Methane quantity fed to biogas engine m3/day 8446
Basic evaluation data Power consumption Present in house power consumption KWH/d 500 Present power consumption pattern through out the day uniform hours/year for power consumption (270 days/year) hrs/year 6480 Present in house power consumption/yr KWH/yr 3240000 Power generation through biogas engine Biogas engine rated power generation KW 1136 Biogas specific power generation for the biogas engine @ 65% methane KWH/m3 1.94 Auxiliary power for the biogas engine (85% efficiency) KWH 170 Net power generation KWH 966 Yearly power generation for say 6000 hrs KWH/yr 5,793,600
Engine sizing for biogas Engine has fixed energy input Rated electrical & thermal output Electrical efficiency Points to ponder before engine selection: 1. Assess feedstock to digesters Food waste, energy crops? 2. Estimate biogas CH 4 content 3. Estimate biogas volume 4. Determine biogas energy content (kw) 5. Select appropriate engine
the time is running out soon, there will be nothing left to burn on earth but earth itself
BENEFITS OF RENEWABLE ENERGY Avoid the high costs involved in transmission capex. Avoid distribution losses Technical & otherwise Avoid recurring fuel cost Boost the rural economy Encourage self help groups & self dependence Enable village co-operatives to supply and / or monitor distribution Make available much needed energy for basic needs at the doorstep at affordable prices.
Potential of urban wastes in India 1. About 50 million tonnes of solid waste (1.48 lakh tonnes per day) and 6000 million m 3 of liquid waste are generated every year by our urban population. 2. This translates into a potential for generation of over 2600 MW of power from urban wastes. 3. Generating substantial decentralized energy besides reducing the quantity of waste for its safe disposal. 4. Requires 1750 acres of land for land filling/year. *MNRE 2008-2009 Annual report
The major benefits of recovery of energy from urban wastes are: Reduction in the quantity of waste by 60 % to 90%. Reduction in demand for land as well as cost for transportation of wastes to far-away landfill sites. Net reduction in environmental pollution, and generation of substantial quantity of energy.
Contd.. In case of projects for generation of only biogas for thermal application, the financial assistance is limited to Rs.1.0 crore/mweq (i.e. biogas production of 12000 cu.m/day). The Central Financial Assistance (CFA) in the range of Rs.40,000 to Rs.30,000 per kw is available for implementation of the programme by State Nodal Agencies through village level organizations, institutions and private entrepreneurs in rural areas for sale of electricity to individual/ community/grid etc. Capital subsidy on re-imbursement basis is provided for projects ranging from Rs.50 lakh to Rs.100 lakh per MW, depending upon the systems, configuration and type of project. The Scheme is open to private and public sector enterprises and organizations, as well as NGOs.
Potential from Industrial wastes India s rapid industrialization has resulted in the generation of huge quantity of wastes, both solid and liquid. Industrial sectors such as -sugar, pulp and paper, fruit and food processing, -sago/starch, distilleries, dairies, tanneries, -slaughterhouses, poultries, etc. The potential for recovery of energy from industrial wastes is estimated at about 1300 MW. * MNRE annual report 2008-09.
Installed projects on Biogas power generation in India A total of 48 projects with aggregate capacity of about 69.62 MWeq have been installed in distilleries, pulp and paper mills, slaughter houses, tanneries, starch industries, sea-food processing, poultry and oil extraction industries. * MNRE annual report 2008-09.
Industrial waste-to energy projects Projects under Installation: (i) A 6 MW power project in Andhra Pradesh based on poultry litter; (ii) Two projects of 1 MW capacity each in Andhra Pradesh based on biogas; (iii) A 5MW project in Maharashtra based on biogas from distillery effulents. (iv) A National Working Group for the development of Biogas based power projects in distilleries aimed at installation of 500 MW capacity projects in distilleries by the year 2012
MNRE s Financial assistance for projects of various types : Setting up five pilot projects on energy recovery from Municipal Solid Wastes: Rs.2 crore per MW, subject to ceiling of 20% of project cost and Rs.10.00 crore per project, whichever is less, is provided for five pilot projects. Power from biogas generated at Sewage Treatment Plants: 40% of the project cost subject to a maximum of Rs.2.0 crore/mw for projects Power generation from other Urban Wastes and mix of Urban and Agricultural / Agro industrial Wastes: 50% of project cost subject to a limit of Rs.3 crore per MW for projects. Biomethanation technology for power generation from a mix of cattle dung, vegetable market and slaughterhouse wastes along with agricultural residues and agro-industrial wastes: Financial assistance of 30% of project cost subject to upper limit of Rs.3.0 crore/mw is provided for projects.
Contd In Jan 2006, the Ministry launched a programme on biogas based distributed/grid power generation of unit capacity from 3 kw to 250 kw. The Central Financial Assistance (CFA) in the range of Rs.40,000 to Rs.30,000 per kw is available for implementation of the programme by State Nodal Agencies through village level organizations, institutions and private entrepreneurs in rural areas for sale of electricity to individual/ community/grid etc.
Few installations in industries 1 PROJECT SECTOR Type Of Gas Kanoria Chemicals & Ind. Ltd., Ankleshwar, Gujrat SOM Distilleries, Bhopal, M. P. BMSS Ltd., Shripur, Dist. Solapur,(Maharashtra) Degremont India Ltd. For Delhi Jal Nigam Delhi. At Rithala India Glycols Ltd Kashipur, Uttranchal VA Tech Wabag Ltd.. For Chennai Metro-Perungudi VA Tech Wabag Ltd. For Chennai Metro-Kodungaiyur FLOW M 3 /hr H 2 S In % H 2 S Out ppm POWER Equivalent MW Distillery Biogas 875 2.0 500 2.0 Distillery Biogas 1250 3.0 500 2.7 Distillery Biogas 500 3.0 1000 1.0 Sewage Treatment Plant Distillery & Allied Chemicals Sewage Treatment Plant Sewage Treatment Plant Biogas 840 1.0 1000 2.0 Biogas 800 4.6 0.1 1.8 Biogas 381 1.0 630 0.60 Biogas 521 1.0 630 1.0
Contd.. PROJECT SECTOR Type Of Gas FLOW M 3 /hr H 2 S In % H 2 S Out ppm POWER Equivalent MW MMS Steel & Power Pvt. Ltd Narimanan,T.N. Power Plant Natural Gas 3333 0.08 10 10.0 MMS Steel & Power Pvt. Ltd Kovilkallapal, T.N. Power Plant Natural Gas 1666 0.08 10 5.00 Luna Chemicals Ltd. Asnad, Gujrat Power Plant Biogas 650 3.5 500 1.30 Riddhi Siddhi Gluco Biols Ltd. Gokak, Karnataka Starch Plant Biogas 1200 2.0 500 2.0 Trichy Distilleries & Chem. Ltd. Trichy, T. N. Distillery Biogas 750 5.0 500 1.4
1.89 MW Power Generation Project Based on Biogas Produced from Starch Industry Liquid Waste Through 100% Biogas Engines by Riddhi Siddhi Gluco Biols Ltd., Golak, Belgaum Dist, Karnataka
Kanoria Chemicals Ltd. Ankleshwar, Gujarat
8.25MW biogas based power project in a distillery at Banur, Dist. Patiala, Punjab
Brihan Maharashtra Sugar Syndicate Ltd. Akluj,Maharashtra
A 30 tonnes/day capacity Biomethanation Plant for Power Generation in Koyambedu Vegetable Market, Chennai
A 5500 M 3 biogas plant for power generation using starch industry waste at Phagwara, Punjab
A 1 MW Biogas Plant using distillery effluents installed at a Sugar Mill in West Godavari District, A.P.
2.5 MW poultry litter based power generation project under construction at Namakkal, Tamil Nadu
Biogas based power generation project (1x20kW and 1x40 kw) setup at a Dairy Farm in Dist. Satna, Madhya Pradesh
INDIA LYCOLS Ltd. Kashipur,Uttaranchal
INDIA GLYCOLS Ltd. Kashipur,Uttaranchal
8.25 MW biogas based Cogeneration power plant by M/s Chandigarh Distillers and Bottlers Ltd., Banur, Distt. Patiala, Punjab
3 MW power generation project based on palm oil Industry Waste by Sai Renewable Pvt. Ltd, West Godavari District, A.P
A biomethanation plant of 0.15 MW based on vegetable market and slaughter house wastes for generation of power at Vijayawada, A.P.
5 MW power and 75 tonnes per day biofertiliser from Municipal Solid Waste of Lucknow city, by M/s Asia Bioenergy India Ltd., Chennai
25 KWe Bio-methanation project based on leather solid waste (chrome shavings) at M/s. Tata International Ltd., Dewas, M.P.
0.2 MW power generation project utilizing Sago industry liquid waste at Ms. Varalakshmi Company, Salem, Tamil Nadu
Biogas power generation by steam turbine Utilise the biogas for power generation by burning as supplemental fuel in the boiler. High pressure steam produced is used to generate power using a steam turbine.
Biogas Power Generation through boiler biogas Boiler Turbine Transformer Cooling tower Generator
What does each part do? The boiler is where the biogas is burnt to boil water The steam from the boiler is used to turn a turbine The turbine is connected to the generator, which acts like a dynamo it generates electricity out of movement The steam is cooled down and turned back into water in the cooling tower
Biogas power generation through fuel cells
Basic principles of fuel cell (FC) Related to battery: both convert chemical energy into electricity Battery: the chemical energy has to be stored beforehand FC only operates when it is supplied from external sources Fundamental mechanism: inverse water hydrolysis reaction Anode: 2H 2 4H ++ 4e - Cathode: 4e - + 4H + + O 2 2H 2 O Net reaction: 2H 2 + O 2 2H 2 O
Biogas power generation through fuel cells A fuel cell is an electrochemical conversion device It produces electricity from fuel (on the anode side) and an oxidant (on the cathode side), which react in the presence of an electrolyte. The reactants flow into the cell, and the reaction products flow out of it, while the electrolyte remains within it. Stationary equipment for power generation Generating Fuel cells can operate virtually continuously as long as the necessary flows are maintained
Contd.. They consume reactant from an external source, which must be replenished a thermodynamically open system. By contrast, batteries store electrical energy chemically and hence represent a thermodynamically closed system. Many combinations of fuels and oxidants are possible. A hydrogen fuel cell uses hydrogen as its fuel and oxygen (usually from air) as its oxidant. Other fuels include hydrocarbons and alcohols. Other oxidants include chlorine and chlorine dioxide.
Working of Fuel cell
Technical Feasibility of Biogas Fuelled Fuel Cells Numerous demonstrations have already proven the technical feasibility phosphoric acid fuel cell (PAFC) Low Temperature molten carbonate fuel cell (MCFC) High Temperature solid oxide fuel cell (SOFC) High Temperature Most technical problems have been overcome wide array of contaminants to clean up high degree of variability in fuel quality
PAFC Demonstrations UTC Fuel Cells PC-25 currently in operation 200-kilowatt PC25 that converts anaerobic digester gas generated by the wastewater treatment facility into usable heat and electricity for the facility.
MCFC System on Wastewater Treatment BioGas 1 Megawatt
Fuel Cells Solid Oxide Fuel Cell powered by biogas, Finland
New York City WWTP Fuel Cell Systems
Technical Challenges Gas Clean Up Contaminant removal requirements are highly dependent on type of fuel cell used and the type of biomass. H 2 S, organic acids, siloxanes, alkali metals, halogens. PAFC clean up system has been successfully demonstrated and a performance verification report published. PAFC more sensitive to poisons than SOFC and MCFC Siloxanes are a more serious problem! In high temperature fuel cells siloxanes form glassy deposits Moisture removal Need dry gas
Gas Clean Up Siloxane Removal Siloxane removal is one of the more challenging aspects of using landfill or AD biogas Agricultural waste ADG does not contain siloxanes cows don t use cosmetics and conditioner!!
Economic Feasibility The economics of biogas fuelled fuel-cell systems are still very difficult to assess. Even for PAFC systems that have had a long operating history the predicted cost per kw and the actual cost per kw can differ by a factor of two or three. The cost of the fuel cell is also very vague. Based on material costs SOFC stacks look very competitive near term projected cost = US$400 per kw the potential cost reduction with large-volume manufacturing methods is as low as US$180 per kw.
Biogas Fuel Processing A fuel processor changes - composition of the biogas - can be fed to a fuel cell system to a hydrogen-rich mixture that can be fed to a fuel cell The process adds complexity to the system but usually is necessary in order to obtain acceptable fuel cell performance and lifetime.
Conclusions 1. Biogas-fuelled fuel cell systems are technically feasible and can operate for extended periods with good reliability and performance 2. Economic feasibility is much more difficult to assess but it appears that costs are too high - The impact of carbon credits on the economics of biomass fuelled fuel cell systems may be a significant factor in the near future. 3. Utilising waste biomass for power generation will not solve our energy and GHG problems but it can significantly reduce GHG emissions
Sr.No Fuel cell system Engine Generator System 1. Cost per kilowatt is very high. Cost per kilowatt is low. 2. The biogas must be cleaned up to strict specifications. Adds cost and complexity while consuming energy. 3. The fuel cell is an emerging technology. 4. The greenhouse emissions and particulates are very low 5. The fuel cell technology is continuously improving at a rapid rate. The biogas can be used directly from the digester with no cleanup. It is a mature technology. The greenhouse emissions of carbon dioxide, sulfur dioxide carbon monoxide and particulates are significant. The technology is mature and changing slowly 6. The system is very quiet. The noise level is very high and sound mitigation is necessary 7. There are few moving parts. There are many moving parts, most moving in a hot environment needing oil and cooling
Advantages of biogas based power generation Usable fuel Useful by-products from the biogas process Reduces Greenhouse Gas emissions Sustainable Resource as long as we have wastes Could fulfill the gap in the peak electricity demand and supply Highly possible in community and institutional biogas plants
So, in a word A plethora of renewable energy is all around us, with even more ways to make use of it.
Recycle The Three Rs of Recycling Plus One! Reduce RECOVER Reuse