Techno-economic and environmental life cycle assessment of next-generation fiber-encapsulated nanoscale hybrid materials for direct air carbon capture

A techno-economic and environmental life cycle assessment was conducted for manufacturing two novel types of solid sorbents used for direct air CO2 capture (DAC). One type of solid sorbent comprised Polyacrylonitrile (PAN)/Organopolysilizane (OPSZ)/nanoscale organic hybrid materials (NOHM), and the other comprised polymers of intrinsic microporosity (PIM)/NOHM. These solid sorbents were assumed to be manufactured via an unconventional route: electrospinning as fibers. Economic analyses revealed that manufacturing costs for a 0.73 MT/year capacity plant were $831 and $1398/kg of electrospun fiber in the case of PAN/OPSZ/NOHM and PIM/ NOHM, respectively. The costs were higher for PIM/NOHM owing to high raw material prices (Spirobisindane and tetrafluoroterephthalonitrile), which are used only in manufacturing PIM. Scaling up the plant capacity from 0.73 to 30 MT/year decreased the manufacturing cost by nearly half from $831 to $379 in the case of PAN/ OPSZ/NOHM, depicting the economies of scale effect. A life cycle assessment (LCA) of both types of solid sorbent was performed using OpenLCA software, the Ecoinvent v 3.5 database, and the TRACI LCI assessment method. The Global Warming Potential (GWP) of PAN/OPSZ/NOHM and PIM/NOHM was observed to be 151 x 10-3 and 166 x 10-3 kg CO2 eq. per kg CO2 captured in the DAC plant, respectively. These GWP values were nearly five times as high as those observed for other solid sorbents existing in the literature, such as PEI on silica gel, carbonate on silica, and carbonate on activated carbon, owing to the large amounts of electricity used in the electrospinning unit operation.