Switzerland has committed itself to becoming climate-neutral by 2050. In order to achieve this goal in the corresponding time frame, major efforts are required, such as moving away from fossil fuels (coal, oil, natural gas). A transformation to green hydrogen as a chemical energy source is planned. To favor a balanced integration between the highly fluctuating renewable electricity system and the gas grid, suitable transformation systems must be provided.

There are several options for converting electrical energy into chemical and therefore storable energy sources, and intensive research is currently being promoted. One approach is the biological methanation of CO2 gas, which is in principle 100 % climate-neutral if green hydrogen and renewable CO2 is used, for example from biomass. The research levels of biological in-situ and ex-situ methanation are at different stages; ex-situ methanation has almost reached production readiness, whereas in-situ methanation is still in its early stages. Due to the comparatively simple upgrade of existing fermenters cost advantages can be expected compared to the ex-situ variant.

In this research project, we propose to study the in-situ biological methanation by designing and monitoring the process in two different configurations focusing on the most important and impacting process variables. First, basic research questions that can be investigated in the laboratory are examined in small continuous anaerobic bioreactors, which include the investigation of hydrogen mass transfer, the reaction kinetics, the product gas quality, process inhibitors and the adaptation of the biocenosis. The final goal is the definition of a process upscaling design that will be tested in 60 L continuous anaerobic bioreactors and analyzed in a cost/benefit scenario specifically built for the Swiss economy and energy strategy.