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. The residues of biogas production are used as a low-grade organic fertilizer. Biogas fuels do not usually cause any pollution to the atmosphere, and because they come from renewable energy resources they have great potential for future use.
Scope note is not available.