The efficiency of current liquid-amine carbon capture methods is limited by the energetically expensive step whereby CO2 is separated from capture solutions. This step requires large energy inputs to heat a solution to release CO2 and regenerate solvent. Previous work has shown that the photothermal excitation of nanoparticles initiates CO2 release without the typical energy inputs required to heat the bulk solution. This photothermal phenomenon has the potential to lower the overall energy cost of current carbon capture methods by increasing the efficiency of CO2 release using localized photothermal heating and by using solar energy instead of coal, gas, or biomass. We propose to utilize this photothermal phenomenon in an apparatus which can passively pull CO2 out of the atmosphere and continuously regenerate solvent via solar energy. This apparatus has been demonstrated at bench-scale by suspending carbon-black nanoparticles in capture solution and layering this suspension between two CO2-permeable membranes. The efficiency of this system is largely dependent on the composition and thickness of the membranes, and the surface area to volume ratio (A/V) of the solvent-air interface.
