In airtight fermentation vessels - the so-called digesters - a fermentation process is stimulated and produces biogas using bacteria. The bacteria are similar to those which can also be found in the digestive tract of a cow. Main products of anaerobic degradation are energy-rich methane and carbon dioxide. Since both are gaseous, they separate from the fermentation substrate and form the main components of biogas. Carbon dioxide is not oxidized, but then can be supplied together with the energy-rich methane cogeneration power stations of combustion and fed into each locally existing heat network.
In our animated film, you can see the whole process of biogas production.