Life cycle and experimental assessment of solar-driven photothermal desorption for CO2 capture and storage

• Experiments show carbon capture adsorbents can be regenerated with solar radiation. • LCA shows regenerating adsorbents using solar increases carbon capture efficiency. • LCA shows highest carbon efficiencies occur when capture system is powered by hydro. This study presents an integrated assessment of photothermal desorption for low-temperature direct air capture (LT-DAC) systems through complementary methodological approaches. ISO 14040/44-compliant life cycle assessment using the ReCiPe Midpoint methodology was performed to evaluate environmental impacts across three regeneration configurations (natural gas, solar-thermal, and hybrid solar-electric) in seven geographical regions. Experimentally, silica-supported polyethyleneimine (SI-PEI) adsorbents were synthesized and their CO 2 capture performance quantified using breakthrough experiments under controlled laboratory conditions (10% CO 2 concentration), comparing conventional thermal and photothermal regeneration methods at 110°C. The experimental results demonstrate photothermal regeneration energy requirements of 0.64 GJ/kg CO 2 versus 2.5 GJ/kg CO 2 for thermal approaches. LCA findings show solar-driven configurations consistently outperform natural gas-based systems, achieving emissions as low as 79 kg CO 2 -eq/tCO 2 in regions with low-carbon electricity grids. Regional analysis reveals carbon removal efficiencies of 92–97% for solar systems in hydropower-dominated regions compared to 42–87% for fossil-based alternatives. Sensitivity analysis indicates that reducing regeneration energy by 1 GJ/tCO 2 yields significantly greater climate benefits in fossil-based systems (168 kg CO 2 -eq/tCO 2 ) than in solar configurations (8 kg CO 2 -eq/tCO 2 ). These findings demonstrate that solar-driven photothermal regeneration, when deployed in regions with favorable renewable resources, can substantially enhance both the energy efficiency and environmental performance of DAC systems.