Liquid absorbent direct air capture with pH-swing regeneration can be competitive but challenges remain

Carbon dioxide removal (CDR) is required to address residual CO 2 emissions and deliver net-zero climate targets. Direct air capture (DAC) is a scalable CDR pathway, but deployment is constrained by high energy demand and cost. Here, we combine detailed process modeling with prospective techno-economic analysis to evaluate potassium hydroxide solvent-based DAC with bipolar membrane electrodialysis (BPMED) regeneration. Our analysis shows that reductions in BPMED capital costs and optimization of absorbent loading via double contactors enable substantially lower regeneration energy. Carbonic anhydrase (CA) further improves performance by accelerating CO 2 absorption and alleviating the trade-off between capture rate and regeneration cost. Specific electrical energy consumption decreases to 10.9 MJ kgCO 2 -1 for a single contactor and to 8.0 MJ kgCO 2 -1 using air contactors in series with targeted CA integration. At gigaton-scale deployment, projected capture costs are $150–$500 t-CO 2 -1 , bringing solvent-based DAC with BPMED regeneration on par with other DAC technologies.