Co-electrolysis of CO2 and glycerol as a pathway to carbon chemicals with improved technoeconomics due to low electricity consumption

Abstract

The renewable electricity-driven electroreduction of carbon dioxide (CO2) offers an alternative pathway to producing carbon chemicals that are traditionally manufactured using fossil fuels. Typical CO2 electroreduction approaches couple cathodic CO2 reduction with the anodic oxygen evolution reaction (OER), resulting in approximately 90% of the electricity input being consumed by the OER. Here, we explore alternatives to the OER and show that the anodic electro-oxidation of glycerol (a byproduct of industrial biodiesel and soap production) can lower electricity consumption by up to 53%. This reduces the process’s operating costs and carbon footprint, thus opening avenues for a carbon-neutral cradle-to-gate process even when driven by grid electricity (~13% renewables today), as well as economical production of the 12-electron products ethylene and ethanol. This study may thus serve as a framework for the design of CO2 electroreduction processes with low electricity requirements, enhancing their CO2 utilization potential and economic viability. Electrochemical CO2 reduction to fuels and chemicals is typically accompanied by oxygen evolution as the anodic half reaction. Here, Verma et al. identify glycerol oxidation as a viable alternative half reaction, reducing cradle-to-gate CO2 emissions and improving the economics of CO2 conversion.