Biogas is a mixture of methane, CO₂ and small quantities of other gases produced by anaerobic digestion of organic matter in an oxygen-free environment. The precise composition of biogas depends on the type of feedstock and the production pathway; these include the following main technologies:

• Biodigesters: These are airtight systems (e.g. containers or tanks) in which organic material, diluted in water, is broken down by naturally occurring micro‑organisms. Contaminants and moisture are usually removed prior to use of the biogas.
• Landfill gas recovery systems: The decomposition of municipal solid waste (MSW) under anaerobic conditions at landfill sites produces biogas. This can be captured using pipes and extraction wells along with compressors to induce flow to a central collection point.
• Wastewater treatment plants: These plants can be equipped to recover organic matter, solids, and nutrients such as nitrogen and phosphorus from sewage sludge. With further treatment, the sewage sludge can be used as an input to produce biogas in an anaerobic digester.

The methane content of biogas typically ranges from 45% to 75% by volume, with most of the remainder being CO₂. This variation means that the energy content of biogas can vary; the lower heating value (LHV) is between 16 megajoules per cubic metre (MJ/m³) and 28 MJ/m³. Biogas can be used directly to produce electricity and heat or as an energy source for cooking.

IEA (2020), Outlook for biogas and biomethane: Prospects for organic growth, IEA, Paris

Source category: International Organisations

Gas, rich in methane, which is produced by the fermentation of animal dung, human sewage or crop residues in an air-tight container. It is used as a fuel to heat stoves, lamps, run small machines and to generate electricity.

EEA, European Environment Agency, Glossary, accessed 22 November 2023.

Source category: Agency Documents