Evaluation of a Direct Air Capture Process Combining Wet Scrubbing and Bipolar Membrane Electrodialysis

Abstract

A detailed techno-economic analysis of a novel direct air capture (DAC) process has been carried out. In this process, carbon dioxide is separated from ambient air through wet scrubbing with an aqueous potassium hydroxide solution, while the solvent regeneration and CO2 recovery is carried out through bipolar membrane electrodialysis (BPMED), a novel process exclusively based on electrical-driven regeneration. The results of the techno-economic analysis showed that the regeneration process could be less energy intensive than other solutions, requiring as low as 236 kJ/mol-CO2. However, the high costs of bipolar and ion exchange membranes make the BPMED expensive. In the base-case scenario, the total capture cost has been found to be 773 $/ton-CO2, in line with previous cost estimates for DAC but large for a second generation process. As for other DAC processes, this solution could become particularly interesting in the future, whenever cheaper renewable energy and more affordable and improved membranes become available.