Scale-Dependent Techno-Economic Analysis of CO₂ Capture and Electroreduction to Ethylene

The decarbonization of the chemical industry is essential to mitigate carbon dioxide (CO2) emissions. Ethylene (C2H4) is the highest production petrochemical globally. When powered by renewable electricity, the electrochemical conversion of CO2 to C2H4 offers a promising route to low carbon C2H4 production. We perform a detailed techno-economic assessment (TEA) of the CO2 reduction reaction (CO2RR) process, converting CO2 from an industrial point source to polymer-grade C2H4. We pair the CO2 electrolyzer with industrially mature upstream and downstream separation technologies in an Aspen Plus model. This comprehensive approach enables us to assess the valorization of both gas and liquid byproduct streams at commercial specification and assess the viability of these processes as a function of scale. We demonstrate that a minimum plant size of similar to 3,000 tonne C2H4/year is needed to achieve economies of scale among the upstream and downstream processes. This minimum plant size is similar to 200-fold smaller than that of conventional C2H4 plants, coincides with that of typical utility-scale solar installations (similar to 25 MW), and could enable a more distributed model of chemical production going forward. We further highlight technical and economic enablers that would increase the profitability of the CO2RR to C2H4 technology.