Hydrogen-powered Electrochemically-driven CO 2 Removal from Air Containing 400 to 5000 ppm CO 2
The performance of a hydrogen-powered, electrochemically-driven CO 2 separator (EDCS) was demonstrated at cathode inlet CO 2 concentrations from 400 ppm to 5,000 ppm. The impact of current density and CO 2 concentration were evaluated to predict operating windows for various applications. The single-cell data was used to scale a 100 cm 2 , multi-cell stack using a shorted-membrane design for four applications: direct air capture (DAC), hydroxide exchange membrane fuel cell (HEMFC) air pretreatment, submarine life support, and space habitation. For DAC, a 339-cell EDCS stack (7.7 L, 17 kg) was projected to remove 1 tonne CO 2 per year. The addition of the EDCS in HEMFC systems would result in nearly a 30% increase in volume, and therefore further improvements in performance would be necessary. A module containing five 338-cell EDCS stacks (38 L, 85 kg) in parallel can support a 150 person crew at 2.1% of the volume of the liquid amine system employed in submarines. For space habitation, a 109-cell EDCS stack (3.2 L, 10 kg) is adequate for 6 crewmembers, and is less than 1% the size and 5% the weight of the current CO 2 removal system installed on the International Space Station.