In biogas-fermenting energy plants, farm fertilizer or organic residues are converted with the help of microorganisms, and under anaerobic conditions, to a methane-containing gas. The heating value of biogas is around 5.5 kWh per cubic meter and the options to use it are diverse. The digestate can be used as high value fertilizer in agriculture.

Presently biogas is used mainly in block heat and power stations where it is converted into power and heat. The power is fed in to the public power grid and granted through the renewable energy law (EEG). A portion of the resulting heat is used in the fermenter and in the heating of houses. The heat can also be used for drying processes, cooling and producing electrical power.
The quality of biogas can be improved to allow for its use in the public gas distribution system or as fuel in automobiles.