Biogas Production for Energy in Germany -Residues from Food Industry- Prof. Dr. Bernd Stephan University of Applied Science Bremerhaven, Germany

Anaerobic Digestion: Biogas History History in Germany starting with utilization of „marsh gas“ in the 19th century: gas tight drums with an diameter of about 2 to 3 meter were placed upside down into the wet lands for gas collection and gas utilization for cooking – similar to the Indian Gabor Gas Plant History in Germany starting with utilization of „marsh gas“ in the 19th century: gas tight drums with an diameter of about 2 to 3 meter were placed upside down into the wet lands for gas collection and gas utilization for cooking – similar to the Indian Gabor Gas Plant Beginning around 1920 trucks of public services were operated with compressed biogas from digestion of sewage sludge – in the fifties ot the 20th century this was given up due to low cost mineral oil Beginning around 1920 trucks of public services were operated with compressed biogas from digestion of sewage sludge – in the fifties ot the 20th century this was given up due to low cost mineral oil In the fifties last century some farmers build biogas plants for the treatment of aninmal wastes – the technology was based on different principles In the fifties last century some farmers build biogas plants for the treatment of aninmal wastes – the technology was based on different principles The oil price crisis in the seventies stimulated broad activities on the research and implementation side of agricultural biogas plants and resulted in optimized plant design and process performance. About 200 plants were bulit and operated at that time, but could not compete with the market prices for gas or liquid hydrocarbons. The oil price crisis in the seventies stimulated broad activities on the research and implementation side of agricultural biogas plants and resulted in optimized plant design and process performance. About 200 plants were bulit and operated at that time, but could not compete with the market prices for gas or liquid hydrocarbons. The energy policy of German Federal Government now subsidies the utilization of renewables – a result the market for big biogas plant goes up (most of them are connected to cogeneration plants) The energy policy of German Federal Government now subsidies the utilization of renewables – a result the market for big biogas plant goes up (most of them are connected to cogeneration plants)

Basics Substrates must be degradable Substrates must/should be available at a constant mass/volume flow Substrates should have a nearly constant composition Concentration of organic dry matter should be higher than 2 % Substrates should be a liquid slurry Digester volume should be more than about 100m 3

Biogas Production process: the main steps Collection and (pre)treatment Collection and (pre)treatment Producing a slurry with balanced composition (e.g. water-content, total organic solids. C/N ratio) Producing a slurry with balanced composition (e.g. water-content, total organic solids. C/N ratio) Feeding of reactor with constant rate Feeding of reactor with constant rate Keeping fermenter at nearly constant temperature of about 33 o Centigrade Keeping fermenter at nearly constant temperature of about 33 o Centigrade Mixing of substrate during fermentation Mixing of substrate during fermentation Gas collection, purification, utilization (heat and electricity) Gas collection, purification, utilization (heat and electricity) Collection and utilization of fermented slurry e.g as high value organic fertilizerer Collection and utilization of fermented slurry e.g as high value organic fertilizerer

Potential of Biogas (Wilfert, R. et al., Institut für Energetik und Umwelt Leipzig, 2002) Animal excreta 4.5 Animal excreta 4.5 Vegetable residues from agriculture Vegetable residues from agriculture Wastes from Industry Wastes from Industry Waste from parks and gardens Waste from parks and gardens Organic municipal waste 0.6 Organic municipal waste 0.6 Energy crops 3.7 Energy crops 3.7 TOTAL TOTAL (billion m 3 /a) (billion m 3 /a) total (PJ/year)electric. (TWh/a) total (PJ/year)electric. (TWh/a)

Food industry with suitable substrates – some examples Slaughterhouses Slaughterhouses Canneries Canneries Diaries Diaries Distilleries Distilleries Breweries Breweries Starch production Starch production Sugar industry Sugar industry Big restaurants/kitchens Big restaurants/kitchens

Biogas plant implemention in Germany (1) Today nearly all biogas plants in Germany designed and operated for residues of food industry use mixed substrates as feeding material Today nearly all biogas plants in Germany designed and operated for residues of food industry use mixed substrates as feeding material cofermentatation of agricultural waste, effluents with organic load from food industry and similar facilities, energy crops, organic residues from the households cofermentatation of agricultural waste, effluents with organic load from food industry and similar facilities, energy crops, organic residues from the households Plant size and technology depend on the specific substrate mixture and pattern of energy utilization and waste management Plant size and technology depend on the specific substrate mixture and pattern of energy utilization and waste management Nearly all plants produce electricity and use the excess thermal energy for specific purposes Nearly all plants produce electricity and use the excess thermal energy for specific purposes

Biogas plant implemention in Germany (2) The number of plants increased during the last years from about 190 in 1992 to about 2000 in 2004 The number of plants increased during the last years from about 190 in 1992 to about 2000 in 2004 Installed electrical capacity increased from 50 MW per year in 1999 to about 270 MW per year Installed electrical capacity increased from 50 MW per year in 1999 to about 270 MW per year In North-East Germany 70 % of the plants treat more than 7500 m 3 of slurry per year, the average treatment capacity in Germany is in the range of 1000 to 2000 m 3 per year In North-East Germany 70 % of the plants treat more than 7500 m 3 of slurry per year, the average treatment capacity in Germany is in the range of 1000 to 2000 m 3 per year

Biogas plant implemention in Germany (3) Plant design depends on substrate properties Plant design depends on substrate properties Typical patterns are: mesophilic fermentation of a slurry, normally with a pretreatment facitity (collection unit with mechanical components for mixing) and a storage tank for the fermented material Typical patterns are: mesophilic fermentation of a slurry, normally with a pretreatment facitity (collection unit with mechanical components for mixing) and a storage tank for the fermented material Fermenters are totally mixed air-tight reactors with integrated heating systems and thermal insulation, in some cases (e.g. low content of organic matter) up-flow reactors are used or flotation as pretreatment (concentration of organic matter) Fermenters are totally mixed air-tight reactors with integrated heating systems and thermal insulation, in some cases (e.g. low content of organic matter) up-flow reactors are used or flotation as pretreatment (concentration of organic matter) The collection tank usually has a storage capacity for some days of operation The collection tank usually has a storage capacity for some days of operation Retention time for fermentation is in the range of 20 to 30 days Retention time for fermentation is in the range of 20 to 30 days Power station to produce electricity (gas engine coupled with generator) Power station to produce electricity (gas engine coupled with generator)

Biogas plant implemention in Germany (4) Low pressure gas storage, integrated into the fermenter (gas cap) or separated Low pressure gas storage, integrated into the fermenter (gas cap) or separated Gas consumption directly after production Gas consumption directly after production Biogas is dewatered and desulfurized before combustion Biogas is dewatered and desulfurized before combustion Most of the engines (70 %) are modified diesel engines, which use a jet of gas oil for ignition of biogas Most of the engines (70 %) are modified diesel engines, which use a jet of gas oil for ignition of biogas Excess heat is used to warm up water for specific purposes e.g. heating of the fermenter, buildings, process water for cleaning or for food processing Excess heat is used to warm up water for specific purposes e.g. heating of the fermenter, buildings, process water for cleaning or for food processing

Planning Data 1 (general) Biogas potential:total organic solids (%)m 3 CH 4 /m 3 substrate Waste water, municipal Waste water, food industry Sewage sludge25 to 10 Cow manure820 to 30 Pig manure6 to 830 to 50

Planning Data 2: effluent of slaughterhouses Substrate: mixture of cow manure and slaughterhouse waste water Quantity: 50 m 3 per day content of organic matter: 4% gas producion per day : 1000 to 1500 m 3 Energy production: 6000 to 9000 kWh per day, 1/3 electrical, 2/3 thermal energy Retention time: 20 days Digester volume: 1000 m 3

Contributions of Biogas for Energy Supply 2004 The potential of biogas for producing electricity comes to 4% of the annual consumption of electric energy (public grid) The potential of biogas for producing electricity comes to 4% of the annual consumption of electric energy (public grid) The contributions today comes to 0,002 % of the potential only – great potential The contributions today comes to 0,002 % of the potential only – great potential

Reasons Regional pattern of substrate availability and of (local) energy demand Regional pattern of substrate availability and of (local) energy demand Distribution cost Distribution cost Biogas technology had its great start up since 2000 Biogas technology had its great start up since 2000 Internal utilization of electricity Internal utilization of electricity

Installed electrical capacity (MW) (estimated)

Example of Implementation - a typical cluster - Biogas plant using agricultural waste, slaughterhouse waste and sewage sludge Biogas plant using agricultural waste, slaughterhouse waste and sewage sludge Thermal energy used for slaughterhouse Thermal energy used for slaughterhouse Electrical energy sold to the public grid at subsidies prices Electrical energy sold to the public grid at subsidies prices

Biogas plant „Brensbach“

Basic Data (plant under construction, some figures estimated) Digester volume4 800 m 3 Digester volume4 800 m 3 Mesophilc process33-35 o C Mesophilc process33-35 o C Retention time 20 days Retention time 20 days Input (organic dry matter)9 600 to kg/day Input (organic dry matter)9 600 to kg/day Treated slurry m 3 /year Treated slurry m 3 /year Sludge utilizationliquid fertilizer Sludge utilizationliquid fertilizer Energy output 3000 to 4500 m 3 /day 6 to 9 million kWh/year Energy output 3000 to 4500 m 3 /day 6 to 9 million kWh/year electrical2 to 3 million kWh/year thermal4 to 6 million kWh/year

Some aspects Great market potential Great market potential Cost reduction for plant components with increasing implementation Cost reduction for plant components with increasing implementation Positive effects by standardization, increasing skillness/experience and competition of biogas- companies Positive effects by standardization, increasing skillness/experience and competition of biogas- companies Cost of substrates/cosubstrates will go up Cost of substrates/cosubstrates will go up Energy crops from East Europe? Energy crops from East Europe? Phosphate recovery from fermented sludges? Phosphate recovery from fermented sludges?

Some Aspects for Future Biogas Development in Thailand Analysis of Potential for implementation Analysis of Potential for implementation Cofermentation (are there „biogas clusters“?) Cofermentation (are there „biogas clusters“?) Energy demand electrical and thermal in agro industry Energy demand electrical and thermal in agro industry Gas Separation CH 4 /CO 2 : e.g. compressed methan as fuel for automotives; CO 2 for industriy (e.g.beverages) Gas Separation CH 4 /CO 2 : e.g. compressed methan as fuel for automotives; CO 2 for industriy (e.g.beverages) Improvement of fertility of soil Improvement of fertility of soil Used oils from kitchen and residues of restaurants Used oils from kitchen and residues of restaurants Future environmental policy for cities should focus on biogas too as a decentralized system for waste treatment Future environmental policy for cities should focus on biogas too as a decentralized system for waste treatment