Bio-gas is primarily methane (CH4) and carbon dioxide(CO2) and may have small amounts of hydrogen sulphide(H2S), moisture and siloxanes. The gases methane, hydrogen, and carbon monoxide (CO) can be combusted or oxidized with oxygen. This energy release allows bio-gas to be used as a fuel; it can be used for any heating purpose, such as cooking. It can also be used in a gas engine to convert the energy in the gas into electricity and heat.