Techno-economic assessment of enzymatic CO2 capture in hollow fiber membrane contactors with immobilized carbonic anhydrase

CO2 capture technologies to reduce greenhouse gas emissions are widely studied and techno-economic assess-ments (TEA) are needed to assess their feasibility in industrial applications. The current benchmark technology is using amine-based solvents, such as monoethanolamine (MEA), in packed-bed columns because of their high CO2 selectivity and fast absorption rate. However, the capture process is energy extensive and costly, so an alternative must be found. In the present study, a TEA is performed to analyze a novel enzymatic capture process in a 685 MWe coal-fired power plant. Hollow fiber membrane contactors are used as an alternative to packed-bed columns due to their compactness, and ease of operation and to scale up. The carbonic anhydrase enzyme promotes the hydration of CO2 in water in the presence of a buffer and is immobilized on the membranes to increase its stability under harsh industrial conditions. The use of this benign solvent reduces the energy consumed for its regeneration and is non-corrosive. It was found that the energy consumption of the capture and compression unit was reduced by 43%, its capital cost by 31% and OPEX by 28% compared to a benchmark MEA process for a 90% capture rate. A capture cost of 38.5 $/t CO2 was estimated, representing a 44% reduction over the MEA process. To optimize the process, this study also focuses on sensitive parameters that have a significant impact on the capture cost. Particular attention was made toward the cost, lifetime and dimensions of the membranes, gas and liquid velocity, and the enzyme lifetime to be competitive with existing technologies. Overall, enzymatic CO2 capture in membrane contactors is a green, energy-efficient, non-toxic, and low-cost technology that holds promise for industrial applications.