Techno‐Economic Analysis of a Three‐Compartment CO 2 Electrolyzer for Formic Acid Production

The electrochemical reduction of CO 2 to liquid fuels or chemicals offers a sustainable route to store renewable electricity in chemical form. Among potential products, formic acid stands out for its high energy density, ease of storage, and potential as a hydrogen carrier. However, maintaining selectivity at high product concentrations remains a key challenge for economic viability. Here, we present a techno‐economic analysis of formic acid and formate production in two‐compartment and three‐compartment electrolyzers, using either water oxidation reaction or the hydrogen oxidation reaction at the anode. In two‐compartment cells, operating in acidic media to directly produce formic acid is economically favorable compared to alkaline media, as it avoids post‐protonation and improves CO 2 conversion efficiency by preventing carbonate formation. Three‐compartment configurations achieve the best performance when high product concentrations are reached without compromising selectivity. Concentrations above 15 M require Faradaic efficiencies exceeding 70% for economic feasibility. Employing low‐cost renewable hydrogen for HOR in a three‐compartment cell can further reduce production costs, reaching values below $0.42 kg −1 HCOOH at 70% Faradaic efficiency and 15 M product concentration. This approach holds strong potential for deployment in hard‐to‐abate sectors such as cement, steel, and ammonia synthesis, thereby supporting industrial decarbonization.