MIKE – Methanation of CO₂ from biogas by microbial electrosynthesis

Commercial produced biogas contains app. 60% of methane, 35% of CO₂ and 5% of steam, nitrogen and further impurities. To feed in the biogas into the existing natural gas grid it has to be cleaned from all impurities at the moment in a cost-intensive way.

In line with the funding initiative “CO₂Plus – Stoffliche Nutzung von CO₂ zur Verbreiterung der Rohstoffbasis“ from the Federal Ministry of Education and Research the project “MIKE” is going to use microbial electrosynthesis to increase the methane output of an industrial biogas plant and therefore to reduce the cleaning effort.

In microbial electrosynthesis electroactive microorganisms take up electrons from a cathode for the reduction of CO₂ to different chemical products, e.g. methane. In contrast to other processes, the microbial electrosynthesis has very high cathodic electron efficiency (> 80%). As electron source current can be used from renewable energies or from excess current.

The main goals of the project are as follows:

1. Development of a robust biocatalyst for the microbial electrosynthesis of CH₄ from impure CO₂ of an industrial biogas plant.
2. Engineering and construction of a MES-prototype and testing on the lab scale.
3. Integration of the MES pilot plant into one of the biggest industrial biogas plants at the industrial park Höchst (Frankfurt, Germany).
4. Operation of the MES-prototype under real industrial conditions over several months.
5. Evaluation of the developed processes by economic calculations and CO₂ footprint.

Due to the project “MIKE”, not only the methane yield of an industrial biogas plant can be increased, but also excess current can be stored as methane.