ElectroGas is about storing electricity. The approach is biogenic production of CH4 from CO2 in anaerobic digesters (AD), by either ex situ or in situ supply of reducing equivalents which may be added indirectly via addition of H2 gas produced by electrolysis, or directly via cathodic supply of electrons to the microbes. ElectroGas use recent advances in fundamental microbial ecology, bioelectric synthesis, ion permeable membranes, gas-liquid mixing and AD engineering to overcome the microbial limitations and engineering constraints for biogenic energy conversion (CO2 methanisation) in operating ADs. Two approaches on different Technology Readiness Levels (TRL’s EU H2020 definition) will be used: I) Electrolysis of H2O to H2, subsequently added to the AD (TRL3 to TRL6). Engineering research will be on solutions to efficiently mass transfer very large volumes (>4 times reactor volume per day) of H2 gas directly to the homoacetogenic bacteria or hydrogenothrophic methanogens to 1000-5000 m3 scale AD reactors. Main scientific work will be on microbial community dynamics upon pulse H2 additions and microbial kinetics when CO2 is limited. II) Microbial electrosynthesis (ME) using direct electron transfer (DIET) to a biofilm on a biocathode, ideally inside the AD (TRL 2 to TRL4). Scientific work includes investigation of biofilms and their mechanisms capable of DIET and the potential surface specific current densities. Engineering research includes development of scalable anode and cathode designs with new membranes, materials and structures for efficient charge (e- and H+) transfer. ME on large cathodes
have the clear advantage of omitting stand alone H2 production and gas mass transfer of H2 to the liquid, and possible lower conversion loss.