MethaSyn

In the X-Energy sub-project MethaSyn, fundamental relationships and efficiency influences of syntrophic, i.e. mutually beneficial, mixed microorganism cultures for biological methane production are to be researched. This new and innovative approach should contribute to increasing gas production and the stability of biological methanation. The extent to which the syntrophic mixed cultures are also suitable applications for electromethanogenesis (X-Energy sub-project DUEME) will also be investigated.

Effective and stable methane production

Biological methanation (BM), i.e. the biological conversion of hydrogen (H₂) and carbon dioxide (CO₂) to methane, is a way of making green electricity storable. A major advantage of methane gas over the direct use of hydrogen produced by electrolysis is the wide range of technical applications and storage options designed for natural gas. Since the availability of electricity from renewable energy sources to generate the hydrogen required for the BM varies greatly due to fluctuating wind and solar conditions, a BM should ideally be able to withstand these fluctuations without a reduction in performance.

MethaSyn's novel approach aims to use a further group of organisms in addition to the methanogenic archaea traditionally used to ensure almost uninterrupted methane production despite pauses in hydrogen production, thus achieving greater overall efficiency.

When H₂ and CO₂ are fed in, acetogenic bacteria and methanogenic archaea convert these reactant gases equally: to acetic acid by the bacteria and to methane by the archaea. During pauses in the feed, the residual dissolved hydrogen is still converted, then the archaea switch to utilizing the resulting acetic acid and form methane from it. If H₂ and CO₂ are fed in again, hydrogen is again preferred due to the better energy production through hydrogenotrophic methanogenesis. The advantage of acetogenic bacteria is that the pH value is stabilized by capturing the acetic acid formed. The methanogenic archaea benefit from the intermediate substrate acetic acid as an energy source and thus the maintenance of their metabolism.

By using pure green, electrolytically produced hydrogen and CO₂ from industrial processes or CO₂ extraction from the air, the MethaSyn project aims to investigate a new solution for the effective and stable production of biomethane.