Integrated techno-economic and life cycle assessment of a novel algae-based coating for direct air carbon capture and sequestration

Direct air carbon capture and storage (DACCS) systems are expected to play an important role in fighting global warming. While existing DACCS technologies have demonstrated CO2 removal rates at or below the kiloton scale, high capital costs and significant energy demands represent hurdles in achieving large scale deployment. This study evaluates a novel biomimetic coating primarily consisting of a hydrogel seeded with microalgae biomass printed on a polyethylene substrate. The coating has been developed to exploit the high photosynthetic rates of microalgae to fix atmospheric CO2 into cellulose using incident solar energy. The carbon embodied in the cel-lulose material is converted to biochar through pyrolysis to ensure durable carbon sequestration without the need for underground storage. The proposed system offers many advantages including modularity and scal-ability, the potential for high water retention rates, and long periods of operation with minimal maintenance and management. Three scenarios were evaluated using conservative, baseline, and optimistic assumptions to cap-ture the true range in performance of the system. Results from the modeling work show a carbon removal ef-ficiency ranging from 51% to 73% and carbon capture and sequestration costs of $702-$1585 per tonne CO2 sequestered. Furthermore, the modular design of the coated substrate system and utilization of solar energy supports the rapid upscaling necessary to meet mid-century carbon removal goals. Discussion focuses on the key performance drivers of the system and the challenges and feasibility of meeting target metrics to support eco-nomic and environmental sustainability.