Biogas is a combustible gas produced by the fermentation of all types of biomass.

It is produced in biogas plants, for which both waste and renewable raw materials are fermented. The prefix Bio points to the biotic mode of formation as opposed to fossil natural gas, not to an origin from ecological farming.

The gas can be used for manufacturing electronical energy, for the operating of vehicles or for feed in a gas supply network.
The proportion of methane is most important for the utilization of biogas since its combustion.