The German biogas industry
The combustion of biogas, produced by fermenting biomass, to generate electricity in co-generative heat/power stations has greatly expanded in Germany in recent years to become an independent sector within the fast-growing bioenergy industry. Biogas can be produced from various sources: organic waste from refuse tips (landfill gas), communal waste water (sewage gas), industrial/commercial organic waste as well as from agricultural waste and specific energy crops. Only the last two are considered to be renewable energy sources in Germany. In 2007, 22.4 billion kWh of biogas were produced, 49 % of which was produced from landfill and sewage gas and 51 % from commercial and agricultural biogas plants.
Applications and technologies
Biogas is produced during the fermentation of organic substances in an air/oxygen free environment. This process uses various anaerobic bacteria, the composition of which depends on their organic source materials and specific process conditions (temperature and pH level). Agricultural biogas plants use liquid and solid manure as base materials. Renewable sources such as corn, cereal crops and other energy plants such as sunflowers, Sudan grass, radish, Sorghum bicolor etc., are being used more and more often to increase gas yields.
Commercial plants process waste water (from purification plants) as well as waste from food production, waste food, grease traps and slaughterhouse waste. The most useful component of biogas is methane, but the gas also includes carbon dioxide as well as minimal amounts of hydrogen sulphide, ammonia and hydrogen. Aside from the biogas itself, a mix of water, minerals and organic substances which are not broken down is produced as a by-product. This by-product is valued as a high grade fertiliser by the agriculture industry.
Because the productivity of biogas plants depends on microbiological processes during fermentation, both biotechnology and process-specific know-how are required to ensure the procedure returns the best results. German companies are literally leading the way in the development and shaping of biogas systems and plants.
Currently, biogas is mainly used in co-generation heat and power plants with very high levels of efficiency. The electricity which is produced can be fed into public grids or used in self-sufficient industrial and commercial applications as well as by remote off-grid settlements.
The warmth that is generated can be used by downstream units to create more electricity or used directly for heating, drying or to operate refrigerators. If the location of the biogas plant does not possess a heat sink, the biogas can be fed directly into existing gas networks. Linking production with utilisation presents new fundamental options for efficient electricity production in co-generative generation as well as for the use of biogas as a bio-fuel.
German companies are world leaders in the area of biogas technology. Their many years of experience concerning plant operations, the biology of biogas processes and associated laboratory services ensure successful plant operations. German companies offer a full range of services that covers the entire value chain and supports projects throughout all phases, from planning and funding right through to operations and maintenance. A full range of products also exist to cover co-generative heat/power plants, storage and tank systems and biogas analysis.
Market trend
Biogas production in the EU 27 continued to rise over the last few years and totalled 62 TWh in 2006. The largest area of growth was experienced in agricultural biogas plants and fermentation systems for household waste. Within Europe, Germany is the largest biogas producer. By the end of 2007, over 3,700 agricultural biogas plants were in operation, producing a total capacity of 1,270 MW of electricity.
Currently, biogas plants constructed by farmers themselves and in which they ferment waste from harvests and industrial fertiliser, still dominate the biogas production industry, even in Germany. As the trend for ever larger and more powerful biogas plants continues, interest in biogas projects is growing amongst large national energy producers and suppliers. At any rate, positive structural developments in rural areas and the creation of workplaces are associated with the construction and operation of biogas plants.
Regulatory framework
In Germany, the Renewable Energy Act (EEG) has produced a commercial environment in which this young industry sector has been able to flourish. The EEG gives priority to electricity produced from renewable sources concerning the supply of public grid systems and secures proper payment with a 20 year price fix.
Other countries obligate their conventional energy producers to fulfil a renewable energy quota regarding the purchase of certified green energy from renewable energy producers on specially set-up national exchanges.
Biogas plants can be adapted to process practically all agricultural products. Making organic waste economically viable in terms of energy production doesn’t just provide a waste solution, it also supplies the necessary energy for these processes. Biogas plants could become the starting point of local value creation. Companies which locate near to biogas plants can benefit from a constant and, above all, secure supply of electricity and heat.
Outlook
The ability to convert biogas to a quality level matching that of natural gas opens the door on a whole range of alternative possibilities. For instance, it allows biogas to be fed into the natural gas network and be used in large power stations or for transport purposes. This process involves removing sulphur and CO2 content as well as a process known as gas drying. In Europe, the most common methods of CO2 separation are Pressure Swing Adsorption (PSA) and gas washing.
Biogas plants first began supplying German gas networks back in December 2006. Currently around a dozen plants have begun doing this. Another twelve are currently in planning/construction.
According to a study, an annual biogas potential of 100 billion kWh exists in Germany up to 2030. This quantity equates to roughly 10 % of current energy consumption in Germany.
Depending on location, grid supply plants or small self-sufficient plants may provide the most efficient method of energy production. Estimates suggest that by 2020, capacity in Germany will exceed 3,000 MW. Worldwide, biogas represents an important component of any secure and affordable energy policy, so long as presently unused biomass can be utilised. Currently, large quantities of agricultural waste, which are suitable for use in biogas production, are going unused.
