Integration of oxycombustion and microbial electrosynthesis for sustainable energy storage

Abstract

Power-to-gas technology makes use of surplus electricity by its conversion and storage in the form of a gas. Currently power-to-gas schemes based on biological processes are of great interest. Microbial electrosynthesis (MES) cells are biological systems that produce biogas via microbial action and a supply of electrical energy. The OxyMES scheme proposed is a power-to-gas system that seeks to neutralize the CO2 emissions of a standard industrial process through the hybridization of oxy-fuel combustion and bioelectrochemical processes that produce CH4 (in cathode) and O2 (in anode). This oxygen is used for oxycombustion in an industrial C-fuel boiler. The energy balance analysis yielded a power-to-gas efficiency in the MES cell close to 51%, and the overall performance of the OxyMES integrated system was close to 60% for a cell with a Faradaic efficiency of 80%, CO2-to-CH4 conversion rate of 95%, and ΔVcell = 1.63 V. With the proper sizing of the CO2, O2, and biogas process tank system, it is possible to achieve 100% autonomy, free from external feedstock supplies.