NASA has been evaluating closed-loop atmosphere revitalization architectures that include carbon dioxide (CO 2 ) reduction technologies. The CO 2 and steam (H 2 O) co-electrolysis process is one of the reduction options that NASA has investigated. Utilizing recent advances in the fuel cell technology sector, the Idaho National Laboratory, INL, has developed a CO 2 and H 2 O co-electrolysis process to produce oxygen and syngas (carbon monoxide (CO) and hydrogen (H 2 ) mixture) for terrestrial

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... ergy production) application. The technology is a combined process that involves steam electrolysis, CO 2 electrolysis, and the reverse water gas shift (RWGS) reaction. Two process models were developed to evaluate novel approaches for energy storage and resource recovery in a life support system. In the first model, products from the INL co-electrolysis process are combined to produce methanol fuel. In the second co-electrolysis, products are separated with a pressure swing adsorption (PSA) process. In both models the fuels are burned with added oxygen to produce H 2 O and CO 2 , the original reactants. For both processes, the overall power increases as the syngas ratio, H 2 /CO, increases because more water is needed to produce more hydrogen at a set CO 2 incoming flow rate. The power for the methanol cases is less than pressure swing adsorption, PSA, because heat is available from the methanol reactor to preheat the water and carbon dioxide entering the co-electrolysis process. v vi CONTENTS