Insights from techno-economic analysis can guide the design of low-temperature CO₂ electrolyzers towards industrial scaleup

The field of CO₂ reduction has identified several challenges that must be overcome to realize its immense potential to simultaneously close the carbon cycle, replace fossil-based chemical feedstocks, and store renewable electricity. However, frequently cited research targets were set without quantitatively predicting their impact on the economic viability of CO₂ reduction. Using a physics-informed techno-economic assessment, we offer guidance on the most pressing research priorities for CO₂ reduction based on state-of-the-art electrolyzer performance. We find that the levelized product cost is dominated by the cost of electricity used to drive electrolysis, and the capital cost of the process mostly arises from separations, especially of unreacted CO₂ to be recycled. At a cell resistance as low as 1 Ω·cm² and retail electricity prices, operating at a total current density >475 mA/cm² drives up electricity demands and increases the cost of producing CO. High current density operation is therefore undesirable unless low cell voltages can be maintained. Although wholesale wind and solar electricity are cheaper than retail electricity, their capacity factors are too low for economical process operation. Adding energy storage to increase the capacity factor of solar electricity triples the capital cost from $34.4 million to $112.6 million for a plant making 50 tCO/day. Improving single-pass conversion is not a priority because it leads to selectivity loss in contemporary membrane electrode assemblies, giving an optimum conversion at <15%. To overcome this limitation, we identify the opportunity to modify reactor design to improve CO₂ availability to the catalyst. Decoupling selectivity and single-pass conversion by moving away from a plug flow reactor design, without adding cell voltage, would reduce the base case levelized cost of $1.22/kgCO to $0.97/kgCO and save 36% on capital cost. Finally, we conclude that resolving the “carbonate crossover problem” in neutral electrolytes is not a priority for improving the levelized cost of product.