Technoeconomic Assessment of Large-Scale Ethylene Production via the Electrochemical Reduction of CO2

Abstract

In the last five years, several works have shown that CO2 may be electrochemically reduced to C2 products such as ethylene at current densities over 1 A cm-2 and Faradaic efficiencies over 70%. For the first time, these current densities and Faradaic efficiencies are comparable with commercial electrolytic processes. For reference, over 100 million metric tons per year of chlorine per is manufactured via the Chlor-alkali process at current densities near 0..4 A cm-2 and Faradaic efficiencies to Cl2 over 80%. While the current densities and Faradaic efficiencies for CO2 reduction are compelling; other metrics such as energy efficiency, selectivity, carbon efficiency, electrolyzer scaling, electrolyzer costs and post-electrolysis separation are not yet at the levels needed for commercialization.In this presentation, we consider the technoeconomics of ethylene production at large scales (25,000 to 150,000 metric tons per year). We investigate the impact of cell potential, Faradaic efficiencies, conversion level, process scaling and post-electrolysis separations on the cost of electrolytic ethylene production. Our results indicate that the “green” ethylene made using CO2 as a feedstock requires anywhere from approximately 1 to 10 times greater manufacturing costs than conventional cracking of ethane depending on factors such as electrical energy cost, electrolyzer costs and other parameters. In this case, we consider key technical and economic needs including: price premiums, tax incentives, CO2 emission taxes, and other factors that could enable electrolytic ethylene manufacturing at large scales within the next decade.