The result of fermenting biomass is an energy-rich biogas consisting of methane and CO2. Up to now, this gas mostly has been converted into electricity in a combined heat and power plant on site. Since a consumer of the generated heat for a more efficient energy use is missing in virtually all applications, biogas is not only to be converted into electricity on site in future, alternatively, it is cleaned up and processed so that it reaches the quality of natural gas. Then this cleansed biogas, called biomethane, has only to be compressed before it can be fed into the required pressures in the natural gas network - 4/8/16 bar for regional networks or 70/90 bar for long-distance energy supply networks. The infrastructure for further distribution is already existing due to the widely established natural gas supply network.
Presently there are 70 so-called feed-in plants for biogas in operation, another 40 are in the construction phase. The largest plant is run by the German network operator EWE and the biofuel producer VERBIO in Schwedt near the Oder river, was supplied with two modified VMX 250 screw type compressor packages with oil injection by Aerzener Maschinenfabrik in August 2010. “Here, four times 1,750 m³/h of biomethane are compressed to 9 bar in the final extension stage. The final pressure of 70 bar is produced by means of a reciprocating compressor in a redensification, “ said Dr. Uwe Minkus of AERZEN SYSTEMS. The German network operator EWE is pleased with the results. In April, Aerzener Maschinenfabrik will deliver another four compressors for other biogas projects.
Energy sources from renewable raw materials were widely funded during the last decade for environmental reasons and in order to enable us to be more independent from natural gas importation, the German Federal Government wants, in the long run, to replace up to 20 per cent of the imported natural gas by biomethane produced in Germany.
