Industrial-scale electrochemical CO2 reduction to formate offers a promising low-emission alternative to conventional petrochemical processes for the $700 million global market, where formate serves as a de-icer, animal feed preservative, and drilling fluid additive. While current fossil-based formic acid production generates 2.6 kg CO₂eq/ton, electrochemical alternatives can remove 1.1 ton CO₂eq/ton. Electrochemical production of formate from CO₂ has been widely demonstrated on the lab scale with high faradaic efficiency. However, commercial viability faces significant obstacles in scaling, including catalyst durability issues (dissolution, agglomeration, membrane poisoning) and salt formation blocking gas diffusion electrode porosity. Therefore, industrial-scale demonstration of stable CO₂ electrolyzers is critical to establish this technology's commercial viability.
RenewCO₂ has constructed and tested a pilot scale CO₂ to formate electrolyzer stack. This electrolyzer stack is comprised of five cells each of 500 cm² active area for a total of 2500 cm² of active area. The stack incorporates cells with an inexpensive anode material and careful catalyst ink formulation and preparation on the cathode. This stack achieved a significant 1000+ hours of operation producing formate. Over this extended course of operation, the electrolyzer fixed 16.8 kg of CO₂ as 32 kg of formate in 600 liters of aqueous solution. This represents a product concentration of over 5% by weight and a single-pass CO₂ utilization of over 12%. Key factors in achieving stability in the stack include careful water management at the cathode and maintenance of anolyte purity and concentration. Operational stability on this scale is a major milestone in demonstrating the viability of electrochemical CO₂ reduction on an industrial scale. This presentation will share key results from the stability test as well as lessons learned in the scale-up process.

Anders Laursen

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