Biogas typically refers to a gas produced by the biological
breakdown of organic matter in the absence of oxygen. Biogas
originates from biogenic material and is a type of bio-fuel.
One type of biogas is produced by anaerobic digestion or fermentation
of biodegradable materials such as biomass, manure or sewage,
municipal waste, green waste and energy crops. This type of biogas
comprises primarily methane and carbon dioxide. The other principal
type of biogas is wood gas which is created by gasification of wood or
other biomass. This type of biogas is comprised primarily of nitrogen,
hydrogen, and carbon monoxide, with trace amounts of methane.
The gases methane, hydrogen and carbon monoxide can be combusted or
oxidized with oxygen. Air contains 21% oxygen. This energy release
allows biogas to be used as a fuel. Biogas can be used as a low-cost
fuel in any country for any heating purpose, such as cooking. It can
also be used in modern waste management facilities where it can be
used to run any type of heat engine, to generate either mechanical or
electrical power. Biogas can be compressed, much like natural gas, and
used to power motor vehicles. Biogas is a renewable fuel, so it
attracts renewable energy subsidies in some parts of the world.
