The term 'biogas' is commonly used to refer to a gas which has been produced by the biological breakdown of organic matter in the absence of oxygen. The gases methane, hydrogen and carbon monoxide can be combusted or oxidized with oxygen and the resultant energy release allows biogas to be used as a fuel.

Biogas is made in a biogas digester. We call it a digester because it is a large tank filled with bacteria that eats (or digests) organic waste and gives a flammable gas, called biogas