Generating biogas from various substrates
Biomethane can make a significant contribution to reducing climate-damaging greenhouse gas emissions: It can replace natural gas in numerous applications. Because it is chemically the same molecule, it is the climate-friendly and energy equivalent alternative.
Today‘s enormous potential for harvesting bioenergy from forestry and timber, agricultural raw and residual materials, and organic waste streams is making major contributions to reducing greenhouse gas emissions. Specifically, biogas and biomethane upgraded from these readily-available sources is delivering sustainably produced renewable natural gas made simply from organic (residual) recyclables – yet they provide a substantial alternative energy supply.
Biogas is a gas mixture composed mainly of methane and carbon dioxide. It is produced through the microbial decomposition of organic (i.e. carbon-containing) substances in the absence of oxygen. This is referred to as anaerobic fermentation.
Feedstocks for biogas production (i.e. substrates) can come from all types of biomass. These generally include manure, residual and waste materials, sewage sludge from wastewater treatment plants, plant residues and crops that are not used for food production.
The variety of energy crops allows crop rotation to change annually, and inclusion of flower-forming plants provides a natural habitat for insects. Energy crops offer the advantage of high gas yields.
Previously viewed as useless and harmful, residual and waste materials such as liquid manure or sewage sludge from wastewater treatment enables an ideal circular economy in which the resulting biogas can be used regionally in the form of heat, electricity and fuel. Biomethane can also be obtained from the processing of landfill gas.
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The variety of energy crops provides a great source for biogas by offering the advantage of high gas yields. |
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Agricultural waste like livestock manure from cows, chickens or swine is a valuable source of biogas. |
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Landfills for municipal solid waste are a source of biogas. Biogas is produced naturally by anaerobic bacteria in municipal solid waste landfills and is called landfill gas. |
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Grown only in the tropics, the oil palm tree produces high-quality oil used primarily for cooking in developing countries. It is used in food products, detergents, cosmetics and also as biofuel. |
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Anaerobic digestion is a proven technology for sewage sludge treatment, allowing generation of renewable energy from the same process. |
Biomethane - Renewable and climate neutral energy source
Biogas and biomethane production technologies are well developed and economically viable. In the last five to ten years, the efficiency of biomethane upgrading plants has improved significantly, which benefits plant economics.
The gas produced offers a climate-neutral alternative to natural gas and is available with equivalent power potential. Electricity for the operation of biogas (upgrading) plants should be provided as CO2-neutral and sustainably as possible. The CO2 captured during biomethane production can be reused industrially or in agricultural production. Unused CO2 does not have a negative impact on the greenhouse effect, as it is not of fossil origin and therefore does not affect the carbon balance in the way that fossil CO2 does.
Evonik Industries has developed a technology for the cost- and energy-efficient separation of CO2 highly selective membranes made of several cylindrical hollow polymer fibres. They form the new hollow fibre membrane modules under the brand name SEPURAN® Green.
