Status of the Solar Sulfur Ammonia Thermochemical Hydrogen Production System for Splitting Water

AbstractA sulfur ammonia (SA) cycle for splitting water to produce hydrogen with solar energy was evaluated using the Aspen Plus® chemical process modeling tool. The hydrogen production step consists of electrolytic oxidation of ammonium sulfite and the oxygen evolution side is a molten salt sub-cycle. Laboratory testing for the thermochemistry of molten salts and electrolysis has indicated that the cycle is viable. The solar field, reactor configurations and continuous operation with storage have been evaluated. The SA cycle is an all-fluid cycle and the solar receiver operates below 1073K. All of the electricity needed by the process is generated internally from waste heat. Using thermal energy storage, the system will operate continuously with no shut downs required due to the variability of solar energy