Solar Cadmium Hydrogen Cycle Update

Flowsheet evaluation of the cadmium solar thermochemical hydrogen generating cycles has indicated thermal efficiencies of nearly 70% (58% lhv) and this has the potential of supplying low cost hydrogen made with a renewal energy source. Laboratory demonstration of the thermodynamics and kinetics of the associated chemical reactions has been on going to validate the possible application of using such cycles on a solar tower. Dissociation experiments of cadmium oxide under various gas compositions have been conducted in order to determine the optimal dissociation process setting. The recombination rates of post decomposition cadmium and oxygen vapors at various temperatures have been measured. This provides input to the design of a quenching step to maximize the cadmium yield. Finally, hydrolysis using molten cadmium at different temperatures has been carried out and results from a rotary kiln designed to demonstrate the hydrolysis process for an on sun demonstration will be presented. An update flowsheet incorporating the new processing information will also be introduced.