FEASIBILITY OF HIGH TEMPERATURE CONCENTRATED SOLAR POWER FOR COGENERATION OF ELECTRICITY AND HYDROGEN USING SUPERCRITICAL CARBON DIOXIDE RECEIVER TECHNOLOGY

The objective of this study is to evaluate the feasibility of cogeneration of electricity and hydrogen using a high temperature, concentrated solar power central receiver with supercritical carbon dioxide as the working fluid. Carbon dioxide is heated directly in a high efficiency receiver to a temperature of 720°C, which then provides thermal input in series to a supercritical carbon dioxide (sCO2) Brayton cycle for producing electricity and then to a thermochemical hydrogen production cycle. Three different methods of producing hydrogen are examined: the 4-step copper-chlorine (Cu-Cl) thermochemical cycle, the hybrid sulfur (HyS) thermochemical cycle, and two different electrolyzers: the alkaline electrolyzer and the polymer exchange membrane electrolyzer. Simulations developed in Aspen Plus were used to estimate the thermochemical hydrogen production efficiency, while the solar receiver and sCO2 Brayton cycle performance were based on results of prior work. The initial results show that the overall solar-to-electricity and H2 efficiencies for the Cu-Cl cycle, hybrid sulfur cycle, alkaline electrolyzer, and polymer exchange membrane electrolyzer are 39.6%, 26.1%, 29.6%, and 22.8%, respectively. These systems' hydrogen capacities are 864, 715, 524, and 403 kg/h, respectively, for an equivalent sCO2 Brayton cycle.