Integration of direct air capture with the chlor–alkali process for CO₂ mineralization: Techno-economic and life cycle assessment

Although direct air capture (DAC) is a promising negative-emission technology, its widespread deployment remains hindered by high energy requirements and unfavorable economics. This paper presents a novel configuration integrating DAC with a chlor–alkali (CA) process referred to as the CADAC system. Key innovation involves directly supplying Ca(OH)₂ from the CA process to the DAC unit, eliminating the energy-intensive calciner–slaker loop required in conventional DAC configurations. Comprehensive technoeconomic and life cycle assessment are conducted to evaluate system performance. Economic analysis results confirm that the CADAC system achieves net profit margins of 18.0–35.1 M USD yr−1, a 62–216% improvement over the standalone CA process with heat exchanger network integration. The levelized cost of DAC (LCOD) remains negative across most evaluated scenarios, indicating net revenue generation during CO₂ capture. Environmental assessment reveals a 72.7% reduction in global warming potential (GWP) compared to that of the standalone CA process based on brine treatment. Integrating renewable electricity enables carbon-negative operation when the renewable fraction exceeds 44.3% of the total supply, with GWP values ranging from −3.15 to −3.68 kg CO₂-eq kg−1 CO₂ captured. The sensitivity analysis confirms electricity price as a dominant factor governing system performance, with LCOD being ∼13.6 times more sensitive to electricity prices than that to carbon credit prices. The CADAC system demonstrates sufficient economic and environmental performances for near-term industrial-scale negative-emission deployment in regions with partially decarbonized grids.