Anode Concepts for SO2 Crossover Reduction in the HyS Electrolyzer

Energy security and global warming are looming issues for the future of our nation¿s vitality, productivity, and environmental health. The notion of a hydrogen-fueled future is positive on many levels, including air quality and efficiency, but its realization depends critically on the identification of a carbon-free, or at least renewable, energy source. Thermochemical cycles, such as the Hybrid Sulfur (HyS) process, have the potential of providing hydrogen from nuclear energy at high efficiency and with minimal environmental impact. This project will develop an innovative electrolyzer design for the HyS proton-exchange membrane (PEM) to correct the SO2 crossover problem inherent in current state-of-the-art HyS electrolyzers. In Phase I, anode technologies were developed to minimize SO2 crossover, which was reduced by 70% (exceeding the 50% reduction target) while maintaining high electro-chemical performance. Phase II will (1) refine the novel anode technology and develop PEM improvements; (2) conduct an analysis and modeling of the sulfur generation chemistry of the cathode; and (3) design, fabricate, and demonstrate a scaled-up (1.6 lbs H2/day) HyS electrolyzer stack incorporating the Phase I anode. Commercial Applications and other Benefits as described by the awardee: The technology should enable the use of thinner PEMs in future HyS electrolyzers and extend operating lifetimes due to reduced sulfur layer buildup, which should significantly increase the total efficiency and operating costs of the HyS thermochemical cycle