ANOTHER GREEN GAS: Biomethane is a type of biofuel that is produced from the biological breakdown of organic matter in an environment void of oxygen. Various types of biodegradable material can be fermented to produce biogas -- the crude form of biomethane -- including manure, sewage, municipal waste, and plant material. Biogas can be used as a fuel due to the energy release that results from the combustion of methane, hydrogen or carbon dioxide with oxygen. Biogas can then be cleaned and upgraded to natural gas standards as biomethane.
