Biogas is produced by the anaerobic decomposition of organic materials, whereby microorganisms decompose the organic waste and produce biogas in the process. The process takes place in special containers or biogas plants.
There are basically two types of biogas plants: so-called "pressurised fermentation" and "vacuum fermentation".
Biogas plants can process a variety of source materials, such as slurry, manure, maize silage, green waste, fruit and vegetable waste, fermentation residues from the food industry, paper and cardboard waste, sewage sludge, etc.
After the fermentation process, impurities such as water, hydrogen sulphide and carbon dioxide are removed from the biogas in a gas treatment plant. The resulting biomethane can then be used to generate electricity and heat or liquefied to produce biomethane for use as a fuel.
Biogas production through dry fermentation works by fermenting organic waste, such as garden waste, green waste or manure, in an anaerobic environment without the addition of water. The process takes place under oxygen-free conditions in which microorganisms break down the organic waste and produce biogas in the process.
Dry fermentation takes place in special tunnels or silos that are sealed airtight to maintain the anaerobic environment. These containers are filled with the organic waste and the microorganisms begin the fermentation process.
During the fermentation process, biogas is produced, which consists mainly of methane and carbon dioxide. The biogas can then be collected and sent to a gas treatment plant to be upgraded to the quality of natural gas and then used to generate electricity and heat.
It is important to note that dry fermentation is not the only method of biogas production. There are also wet fermentation and hybrid processes.