Power-to-methane by a bioelectrochemical system (BES) is a novel electricity storage concept which utilizes electrical energy to convert CO2 from waste-streams into methane (CH4) using mixed culture microorganisms. CH4 can then be stored into or transported through existing natural gas pipeline infrastructure. In this context, energy efficiency is crucial to quantify the recovery of methane from electrical energy. So far, the energy efficiency of methane-producing BESs is low (below 25%) in comparison to developing or currently implemented electricity storage technologies. Additionally, biocathodes in methane-producing BES have only ran at constant supply of electricity and pure CO2 streams. However, in the case of designing a technology for electricity storage this is not translatable, once excess electricity supply for storage will be intermittent and gas waste streams will have other compounds besides CO2.
With this said, the overall goal of this research is to develop a state-of-the-art methane-producing BES for renewable electricity storage, by (I) identifying energy losses in current methane-producing BESs and optimizing reactor configuration and electrode materials to contradict these; and (II) studying the influence of the supply of intermittent electricity and the composition of gas waste streams on the performance of the state-of-the-art system.