Cutting emissions with biomethane
Biomethane derived from biogas, which is upgraded to "natural gas quality" in special plants, is of particular importance: Naturally obtained by fermenting biowaste, liquid manure or plant residues, it can contribute to reducing greenhouse gas emissions in the mobility sector.
Biomethane is a renewable gas produced from biogas by upgrading it to "natural gas quality". While pure biogas has a methane content of 40 to 75 percent, biomethane contains at least 96 percent methane. As a result, it can be mixed with conventional natural gas in any quantity. The prefix "bio" stands for the natural biological production method. Biogas is obtained in biogas plants through the natural fermentation of biomass. Today, mainly waste and residual materials such as sewage sludge, biowaste, liquid manure, dung and plant residues are used for this purpose. The emission factor for biogas or biomethane is determined by a multitude of influencing factors. Depending on the selected substrate (energy crops, liquid manure, waste and residual materials) it varies between 36 and 158 g CO2/kWh for biomethane. There are currently around 8,900 biogas plants in Germany with an electrical output of 5 GW. This also includes 200 biogas treatment plants for biomethane, which currently feed about 10 TWh into the German gas grid, i.e. about 1 percent of total gas sendout in Germany.
Since 2007, Germany's gas suppliers have been offering end users across the country supplies of pure biogas or natural gas to which biogas has been added. Biomethane is also of particular interest to the mobility sector. Biomethane, pure or mixed with natural gas and compressed to CNG (compressed natural gas), can be used as fuel for cars, trucks and buses and thus make an important contribution to reducing greenhouse gas emissions.