Biogas Production for Energy Biogas Production for Energy in Germanyin Germany

-Residues from Food Industry--Residues from Food Industry-

Prof. Dr. Bernd StephanProf. Dr. Bernd Stephan

University of Applied ScienceUniversity of Applied Science

Bremerhaven, GermanyBremerhaven, Germany

Anaerobic Digestion: Biogas HistoryAnaerobic Digestion: Biogas History

• History in Germany starting with utilization of „marsh gas“ in the 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 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 were placed upside down into the wet lands for gas collection and gas utilization for cooking – similar to the Indian Gabor Gas Plantgas utilization for cooking – similar to the Indian Gabor Gas Plant

• Beginning around 1920 trucks of public services were operated with Beginning around 1920 trucks of public services were operated with compressed biogas from digestion of sewage sludge – in the fifties ot compressed biogas from digestion of sewage sludge – in the fifties ot the 20th century this was given up due to low cost mineral oilthe 20th century this was given up due to low cost mineral oil

• In the fifties last century some farmers build biogas plants for the In the fifties last century some farmers build biogas plants for the treatment of aninmal wastes – the technology was based on different treatment of aninmal wastes – the technology was based on different principlesprinciples

• The oil price crisis in the seventies stimulated broad activities on the The oil price crisis in the seventies stimulated broad activities on the research and implementation side of agricultural biogas plants and research and implementation side of agricultural biogas plants and resulted in optimized plant design and process performance. About resulted in optimized plant design and process performance. About 200 plants were bulit and operated at that time, but could not 200 plants were bulit and operated at that time, but could not compete with the market prices for gas or liquid hydrocarbons.compete with the market prices for gas or liquid hydrocarbons.

• The energy policy of German Federal Government now subsidies the The energy policy of German Federal Government now subsidies the utilization of renewables – a result the market for big biogas plant utilization of renewables – a result the market for big biogas plant goes up (most of them are connected to cogeneration plants)goes up (most of them are connected to cogeneration plants)

BasicsBasics

Substrates must be degradableSubstrates must be degradableSubstrates must/should be available at a Substrates must/should be available at a

constant mass/volume flow constant mass/volume flow Substrates should have a nearly constant Substrates should have a nearly constant

compositioncompositionConcentration of organic dry matter should be Concentration of organic dry matter should be

higher than 2 %higher than 2 %Substrates should be a liquid slurrySubstrates should be a liquid slurryDigester volume should be more than about Digester volume should be more than about

100m100m33

Biogas Production process: the main Biogas Production process: the main stepssteps

• Collection and (pre)treatmentCollection and (pre)treatment• Producing a slurry with balanced composition Producing a slurry with balanced composition

(e.g. water-content, total organic solids. C/N ratio)(e.g. water-content, total organic solids. C/N ratio)• Feeding of reactor with constant rateFeeding of reactor with constant rate• Keeping fermenter at nearly constant Keeping fermenter at nearly constant

temperature of about 33temperature of about 33oo Centigrade Centigrade• Mixing of substrate during fermentationMixing of substrate during fermentation• Gas collection, purification, utilization (heat and Gas collection, purification, utilization (heat and

electricity)electricity)• Collection and utilization of fermented slurry e.g Collection and utilization of fermented slurry e.g

as high value organic fertilizereras high value organic fertilizerer

Potential of Biogas Potential of Biogas (Wilfert, R. et al., Institut für Energetik und Umwelt Leipzig, 2002)(Wilfert, R. et al., Institut für Energetik und Umwelt Leipzig, 2002)

• Animal excretaAnimal excreta 4.5 4.5• Vegetable residues from Vegetable residues from

agricultureagriculture 3.0- 3.0-5.35.3

• Wastes from Industry 0.3-Wastes from Industry 0.3-0.60.6

• Waste from parks and gardens Waste from parks and gardens

0.3-0.6 0.3-0.6• Organic municipal waste 0.6Organic municipal waste 0.6• Energy crops Energy crops 3.7 3.7• TOTAL 12.7-TOTAL 12.7-

15.315.3

(billion m(billion m33/a) /a)

total (PJ/year)total (PJ/year) electric. electric.

(TWh/a)(TWh/a)96.596.5 7.27.2

65-11365-113 4.9-8.54.9-8.56.4-12.26.4-12.2 0.5-0.5-0.90.9

6.4-12.26.4-12.2 0.4-0.4-0.80.812.512.5 0.90.978.778.7 5.95.9265.1-324.9265.1-324.9 19.8-19.8-24.2 24.2

Food industry with suitable substrates Food industry with suitable substrates – some examples– some examples

• SlaughterhousesSlaughterhouses

• CanneriesCanneries

• DiariesDiaries

• DistilleriesDistilleries

• BreweriesBreweries

• Starch productionStarch production

• Sugar industrySugar industry

• Big restaurants/kitchensBig restaurants/kitchens

Biogas plant implemention in Germany Biogas plant implemention in Germany (1)(1)

• Today nearly all biogas plants in Germany Today nearly all biogas plants in Germany designed and operated for residues of food designed and operated for residues of food industry use mixed substrates as feeding materialindustry use mixed substrates as feeding material

cofermentatationcofermentatation of agricultural waste, of agricultural waste, effluents with organic load from food industry and effluents with organic load from food industry and similar facilities, energy crops, organic residues similar facilities, energy crops, organic residues from the householdsfrom the households

• Plant size and technology depend on the specific Plant size and technology depend on the specific substrate mixture and pattern of energy substrate mixture and pattern of energy utilization and waste managementutilization and waste management

• Nearly all plants produce electricity and use the Nearly all plants produce electricity and use the excess thermal energy for specific purposesexcess thermal energy for specific purposes

Biogas plantBiogas plant implemention in Germany implemention in Germany (2)(2)

• The number of plants increased during the last The number of plants increased during the last years from about 190 in 1992 to about 2000 in years from about 190 in 1992 to about 2000 in 20042004

• Installed electrical capacity increased from 50 Installed electrical capacity increased from 50 MW per year in 1999 to about 270 MW per yearMW per year in 1999 to about 270 MW per year

• In North-East Germany 70 % of the plants treat In North-East Germany 70 % of the plants treat more than 7500 mmore than 7500 m33 of slurry per year, the of slurry per year, the average treatment capacity in Germany is in the average treatment capacity in Germany is in the range of 1000 to 2000 mrange of 1000 to 2000 m33 per year per year

Biogas plantBiogas plant implemention in Germany implemention in Germany (3)(3)

• Plant design depends on substrate propertiesPlant design depends on substrate properties• Typical patterns are: mesophilic fermentation of a slurry, Typical patterns are: mesophilic fermentation of a slurry,

normally with a pretreatment facitity (collection unit with normally with a pretreatment facitity (collection unit with mechanical components for mixing) and a storage tank for mechanical components for mixing) and a storage tank for the fermented materialthe fermented material

• Fermenters are totally mixed air-tight reactors with Fermenters are totally mixed air-tight reactors with integrated heating systems and thermal insulation, in some integrated heating systems and thermal insulation, in some cases (e.g. low content of organic matter) up-flow reactors cases (e.g. low content of organic matter) up-flow reactors are used or flotation as pretreatment (concentration of are used or flotation as pretreatment (concentration of organic matter)organic matter)

• The collection tank usually has a storage capacity for some The collection tank usually has a storage capacity for some days of operationdays of operation

• Retention time for fermentation is in the range of 20 to 30 Retention time for fermentation is in the range of 20 to 30 daysdays

• Power station to produce electricity (gas engine coupled Power station to produce electricity (gas engine coupled with generator)with generator)

Biogas plantBiogas plant implemention in Germany implemention in Germany (4)(4)

• Low pressure gas storage, integrated into the Low pressure gas storage, integrated into the fermenter (gas cap) or separatedfermenter (gas cap) or separated

• Gas consumption directly after productionGas consumption directly after production• Biogas is dewatered and desulfurized before Biogas is dewatered and desulfurized before

combustioncombustion• Most of the engines (70 %) are modified diesel Most of the engines (70 %) are modified diesel

engines, which use a jet of gas oil for ignition of engines, which use a jet of gas oil for ignition of biogasbiogas

• Excess heat is used to warm up water for specific Excess heat is used to warm up water for specific purposes e.g. heating of the fermenter, buildings, purposes e.g. heating of the fermenter, buildings, process water for cleaning or for food processing process water for cleaning or for food processing

Planning Data 1 (general)Planning Data 1 (general)

Biogas potential:Biogas potential: total organic solids (%)total organic solids (%) mm33 CH CH44/m/m33 substratesubstrate

Waste water, municipalWaste water, municipal 0.050.05 0.150.15

Waste water, food industryWaste water, food industry 0.150.15 0.50.5

Sewage sludgeSewage sludge 22 5 to 105 to 10

Cow manureCow manure 88 20 to 3020 to 30

Pig manurePig manure 6 to 86 to 8 30 to 5030 to 50

Planning Data 2: effluent of Planning Data 2: effluent of slaughterhousesslaughterhouses

Substrate: mixture of cow manure and slaughterhouse waste Substrate: mixture of cow manure and slaughterhouse waste waterwaterQuantity: 50 mQuantity: 50 m33 per day per daycontent of organic matter: 4%content of organic matter: 4%gas producion per day : 1000 to 1500 mgas producion per day : 1000 to 1500 m33

Energy production: 6000 to 9000 kWh per day,Energy production: 6000 to 9000 kWh per day,1/3 electrical, 2/3 thermal energy1/3 electrical, 2/3 thermal energyRetention time: 20 daysRetention time: 20 daysDigester volume: 1000 mDigester volume: 1000 m33

Contributions of Biogas for Energy Contributions of Biogas for Energy Supply 2004Supply 2004

• The potential of biogas for producing The potential of biogas for producing electricity comes to 4% of the annual electricity comes to 4% of the annual consumption of electric energy (public consumption of electric energy (public grid)grid)

• The contributions today comes to 0,002 % The contributions today comes to 0,002 % of the potential only – great potentialof the potential only – great potential

ReasonsReasons

• Regional pattern of substrate Regional pattern of substrate availability and of (local) energy availability and of (local) energy demanddemand

• Distribution costDistribution cost

• Biogas technology had its great start Biogas technology had its great start up since 2000up since 2000

• Internal utilization of electricity Internal utilization of electricity

Installed electrical capacity (MW)Installed electrical capacity (MW)

19991999 505020002000 757520012001 11011020022002 16016020032003 22022020042004 27027020052005 350 (estimated)350 (estimated)

Example of ImplementationExample of Implementation- a typical cluster -- a typical cluster -

• Biogas plant using agricultural waste, Biogas plant using agricultural waste, slaughterhouse waste and sewage sludgeslaughterhouse waste and sewage sludge

• Thermal energy used for slaughterhouse Thermal energy used for slaughterhouse

• Electrical energy sold to the public grid at Electrical energy sold to the public grid at subsidies pricessubsidies prices

Biogas plant „Brensbach“Biogas plant „Brensbach“

Basic DataBasic Data(plant under construction, some figures (plant under construction, some figures

estimated)estimated)

• Digester volumeDigester volume 4 800 m4 800 m33

• Mesophilc processMesophilc process 33-35 33-35 ooCC

• Retention time Retention time 20 days20 days

• Input (organic dry matter)Input (organic dry matter) 9 600 to 14 400 kg/day9 600 to 14 400 kg/day

• Treated slurryTreated slurry 80 000 m80 000 m33/year/year

• Sludge utilizationSludge utilization liquid fertilizerliquid fertilizer

• Energy output Energy output 3000 to 4500 m3000 to 4500 m33/day /day 6 to 9 million kWh/year6 to 9 million kWh/year

electricalelectrical 2 to 3 million kWh/year2 to 3 million kWh/yearthermalthermal 4 to 6 million 4 to 6 million

kWh/yearkWh/year

Some aspectsSome aspects

• Great market potential Great market potential • Cost reduction for plant components with Cost reduction for plant components with

increasing implementationincreasing implementation• Positive effects by standardization, Positive effects by standardization,

increasing skillness/experience and increasing skillness/experience and competition of biogas-companiescompetition of biogas-companies

• Cost of substrates/cosubstrates will go upCost of substrates/cosubstrates will go up• Energy crops from East Europe?Energy crops from East Europe?• Phosphate recovery from fermented Phosphate recovery from fermented

sludges?sludges?

Some Aspects for Future Biogas Some Aspects for Future Biogas Development in ThailandDevelopment 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 industryEnergy demand electrical and thermal in agro industry• Gas Separation CHGas Separation CH44/CO/CO22: e.g. compressed methan as : e.g. compressed methan as

fuel for automotives; COfuel for automotives; CO22 for industriy (e.g.beverages) for industriy (e.g.beverages)• Improvement of fertility of soilImprovement of fertility of soil• Used oils from kitchen and residues of restaurantsUsed oils from kitchen and residues of restaurants• Future environmental policy for cities should focus on Future environmental policy for cities should focus on

biogas too as a decentralized system for waste biogas too as a decentralized system for waste treatmenttreatment