Electrochemical reduction of CO2 to hydrocarbons to store renewable electrical energy and upgrade biogas

An approach for synthesis of a hydrocarbon fuel from CO2 has been evaluated. The use of electrochemical reduction of CO2 at a copper electrode to a hydrocarbon mixture looks like a promising technology, especially when applied to upgrading biogases. The resulting gas mixture, containing methane and hydrogen with small amounts of ethylene and carbon monoxide, has a similar energy density and composition to Hythane. Therefore, it is hoped that the gas mixture could be directly used in existing gasoline engines with minimal modifications. Estimating from existing literature data, the energy storage efficiency is poor (around 38% based on the fuel product HHV). However, the process equipment requirements are not complex, and the fuel product is also relatively readily used within standard engines. Finally, the paper discusses some of the key areas for research to verify and improve this technology.