Raw biogas is  generated through the fermentation of feedstocks. These occurs in so-called “fermenters.” In these “fermenters,” microorganisms assist the process of material conversion that produces the biogas. The processes involved in fermentation are exceedingly complex, and are currently understood only poorly. Various current research projects seek to improve this understanding. The optimization of the fermentation processes hinges on the measurement and control systems and procedures used.

Raw biogas consists of 45-70% methane (CH4). The second largest component of the gas is carbon dioxide (CO2), making up 25-50% of the total. The rest contains minimal portions of hydrogen sulfide (H2S), ammonia (NH3),and water vapor (H20). Fossil-based natural gas contains 85-98% methane. To guarantee the consistent quality of the natural gas in the grid, the methane content of the raw biogas must increased before being fed in. This methane content “upgrade” occurs through a purification of the raw biogas.

The flammable and thus relevant component of biogas is methane. Hence, the amount of methane contained in the biogas should be increased to as large a percentage of the whole as possible. The initial methane content of raw biogas varies chiefly with the feedstock used.

The upgrading of biogas’s methane content is achieved through the optimisation of facility systems for particular feedstocks, and through the implementation of measurement and regulation systems.