Technoeconomic Analysis and Process Design for CO2 Electroreduction to CO in Ionic Liquid Electrolyte

Abstract

Electrochemical reduction of CO2 to chemical feedstocks offers a sustainable way to reduce carbon emissions by shifting the industry away from fossil fuel dependence. However, the lack of understanding of economic feasibility is hindering this technology from large-scale application. We proposed a systematic methodology to evaluate and design the novel route of CO2-to-CO conversion taking ionic liquid as the electrolyte. Not only a comprehensively economic model was developed to offer targets for achieving economically competitive industrialization, but also the Route Selection Index was established to quickly identify the minimum feed concentration for making use of diluted CO2 feed more profitable than using pure CO2 streams. We found that although this route is currently expensive owing to high electrolyzer capitals, it can be economically acceptable if advanced electrocatalytic performance and electrolyzer system could be obtained. The results showed that current densities need to reach at least 200 mA cm–2 at 99% faradaic efficiency to make this route become competitive with fossil fuel-derived feedstocks. Furthermore, a minimum concentration of 28 mol % is required to make the route of using diluted CO2 feed more economically attractive, providing insights into the feasibility of directly utilizing CO2 from different industry sources.