Prospective techno-economic assessment of a CO2 purification process for CO2 electrolysis

Reaching net-zero CO2 emissions in Europe by 2050 requires the strategic deployment of carbon capture, utilization, and storage (CCUS) technologies. Among these, CO2 electrolysis (CO2E) stands out as a promising pre-commercial technology. Using captured CO2, for which compositions vary significantly depending on the CO2 source and capture method, poses a practical challenge for CO2E as feedstock impurity tolerances remain poorly understood. To bridge this gap, here we conducted a prospective techno-economic assessment of a CO2 purification process, removing major and trace impurities in raw CO2 from a bioethanol plant. This serves as a first step toward understanding the design and cost implications for future industrial-scale CO2E plants. Three main takeaways were found. Firstly, achieving the stringent CO2 purity requirements anticipated for CO2E (<ppb-level impurities) can result in total CO2 costs exceeding 200 EUR/tonne of purified CO2, an order of magnitude higher CO2 prices assumed in existing CO2E techno-economic studies. Secondly, due to economies of scale, at 1 Mtonne/year, the levelized cost of purified CO2 falls below the projected direct air capture (DAC) costs for 2050, but it approaches the limits related to CO2 electrolyzer scale-up and biogenic CO2 availability in Europe. Thirdly, cryogenic distillation for the removal of non-condensable gases dominates the variable operating expenditures. Future research is needed for improved understanding of impurity tolerance in CO2 electrolyzers to enable potentially simplified CO2 purification trains and reduce costs.