Title: Biogas Production for Energy in Germany -Residues from Food Industry-
1Biogas Production for Energy in Germany-Residues
from Food Industry-
- Prof. Dr. Bernd Stephan
- University of Applied Science
- Bremerhaven, Germany
2Anaerobic 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 - 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 - 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)
3Basics
- 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 100m3
4Biogas Production process the main steps
- Collection and (pre)treatment
- Producing a slurry with balanced composition
(e.g. water-content, total organic solids. C/N
ratio) - Feeding of reactor with constant rate
- Keeping fermenter at nearly constant temperature
of about 33o Centigrade - Mixing of substrate during fermentation
- Gas collection, purification, utilization (heat
and electricity) - Collection and utilization of fermented slurry
e.g as high value organic fertilizerer
5Potential of Biogas (Wilfert, R. et al.,
Institut für Energetik und Umwelt Leipzig, 2002)
-
- total (PJ/year) electric. (TWh/a)
- 96.5 7.2
-
- 65-113 4.9-8.5
- 6.4-12.2 0.5-0.9
-
- 6.4-12.2 0.4-0.8
- 12.5 0.9
- 78.7 5.9
- 265.1-324.9 19.8-24.2
- Animal excreta 4.5
- Vegetable residues from agriculture 3.0-5.3
- Wastes from Industry 0.3-0.6
- Waste from parks and gardens 0.3-0.6
- Organic municipal waste 0.6
- Energy crops 3.7
- TOTAL 12.7-15.3
- (billion m3/a)
6Food industry with suitable substrates some
examples
- Slaughterhouses
- Canneries
- Diaries
- Distilleries
- Breweries
- Starch production
- Sugar industry
- Big restaurants/kitchens
7Biogas 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 - 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 - Nearly all plants produce electricity and use the
excess thermal energy for specific purposes
8Biogas plant implemention in Germany (2)
- 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 - In North-East Germany 70 of the plants treat
more than 7500 m3 of slurry per year, the average
treatment capacity in Germany is in the range of
1000 to 2000 m3 per year
9Biogas plant implemention in Germany (3)
- 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 - 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 - Retention time for fermentation is in the range
of 20 to 30 days - Power station to produce electricity (gas engine
coupled with generator)
10Biogas plant implemention in Germany (4)
- Low pressure gas storage, integrated into the
fermenter (gas cap) or separated - Gas consumption directly after production
- 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 - 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
11Planning Data 1 (general)
- Biogas potential total organic solids () m3
CH4/m3 substrate - Waste water, municipal 0.05 0.15
- Waste water, food industry 0.15 0.5
- Sewage sludge 2 5 to 10
- Cow manure 8 20 to 30
- Pig manure 6 to 8 30 to 50
12Planning Data 2 effluent of slaughterhousesSubs
trate mixture of cow manure and slaughterhouse
waste waterQuantity 50 m3 per daycontent of
organic matter 4gas producion per day 1000
to 1500 m3Energy production 6000 to 9000 kWh
per day,1/3 electrical, 2/3 thermal
energyRetention time 20 daysDigester volume
1000 m3
13Contributions 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 contributions today comes to 0,002 of the
potential only great potential
14Reasons
- Regional pattern of substrate availability and of
(local) energy demand - Distribution cost
- Biogas technology had its great start up since
2000 - Internal utilization of electricity
15Installed electrical capacity (MW)1999 502000
752001 1102002 1602003 2202004 2702005
350 (estimated)
16Example of Implementation- a typical cluster -
- Biogas plant using agricultural waste,
slaughterhouse waste and sewage sludge - Thermal energy used for slaughterhouse
- Electrical energy sold to the public grid at
subsidies prices
17Biogas plant Brensbach
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21Basic Data(plant under construction, some
figures estimated)
- Digester volume 4 800 m3
- Mesophilc process 33-35 oC
- Retention time 20 days
- Input (organic dry matter) 9 600 to 14 400
kg/day - Treated slurry 80 000 m3/year
- Sludge utilization liquid fertilizer
- Energy output 3000 to 4500 m3/day
6 to 9 million kWh/year - electrical 2 to 3 million kWh/year thermal
4 to 6 million kWh/year -
22Some aspects
- Great market potential
- Cost reduction for plant components with
increasing implementation - Positive effects by standardization, increasing
skillness/experience and competition of
biogas-companies - Cost of substrates/cosubstrates will go up
- Energy crops from East Europe?
- Phosphate recovery from fermented sludges?
23Some Aspects for Future Biogas Development in
Thailand
- Analysis of Potential for implementation
- Cofermentation (are there biogas clusters?)
- Energy demand electrical and thermal in agro
industry - Gas Separation CH4/CO2 e.g. compressed methan as
fuel for automotives CO2 for industriy
(e.g.beverages) - Improvement of fertility of soil
- 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