The share of renewable energies in the German electricity mix is steadily increasing. In order to succeed the energy transition, there is a trend to further expand the implementation of renewable energy technologies. The development of conversion and storage technologies is a crucial element to ensure an efficient and sustainable energy supply.
One promising concept for flexible, long-term energy storage is the generation of methane from hydrogen and carbon dioxide (power-to-gas). In this process, hydrogen is produced from excess renewable electricity by electrolysis. Carbon dioxide from wastewater treatment plants, biogas plants, or the industry can be used directly at the point of origin.
Compared to the well-known chemical-catalytic Sabatier process, microbiological methanation uses hydrogenotrophic methanogenic archaea to convert the supplied gases. This has the advantage that the biological process already operates at ambient pressure and temperatures between 5°C and 122°C (typically at 35°C to 60°C) and has a higher tolerance to impurities in the raw gas. While hydrogen sulfide in biogas is a major challenge for chemical catalytic processes due to its corrosive effect, sulfur is an essential nutrient for microorganisms, resulting in a much lower hydrogen sulfide concentration in the product gas.
The product gas from microbiological methanation can then be used directly, e.g., as fuel in the mobility sector or, depending on the gas quality required in each case, fed into the existing natural gas grid.