Thermochemical H 2- Production with Sulfur-Iodine Process and Solar Energy Adaptation

A thermochemical cycle for hydrogen production is a process in which water is used as a feedstock along with a non-fossil high temperature heat source to produce H₂ and O₂ as product gases. The water splitting process is accomplished through a closed loop sequence of chemical reaction steps in which the chemical reagents are continuously recycled and reused in the process with essentially no loss of material. Practical thermochemical cycles, as currently envisioned, require input temperatures of 1200K for the highest temperature chemical step, and operate at a thermal efficiency of about 50%. Here, the thermal efficiency is defined as the higher heating value of the H₂ produced divided by thermal heat per mole of H₂ delivered by the high temperature heat source. High temperature gas-cooled reactors have been considered as heat source for these cycles. Electrical energy for process equipment is required in addition to high temperature heat for operation of thermochemical hydrogen plants.