General Atomic sulfur-iodine thermochemical water-splitting process

Abstract

Thermochemical water-splitting has the potential to provide an energy-efficient, low-cost process for the production of hydrogen utilizing a renewable energy supply in conjunction with nonfossil resources. The General Atomic Company (GA) sulfur-iodine cycle which has been under investigation at GA since 1974 is compatible with the heat characteristics projected for three of the major energy sources of the future. These heat sources, which have the capability to achieve the necessary high temperature conditions required for the process, are: the high-temperature gascooled reactor (HTGR), the fusion reactor, and systems for concentrating solar energy. GA is working on developing the first two of these heat sources and has carried out an engineering design effort that matches the sulfur-iodine cycle to all three of these heat sources. In these equations, HI /SUB x/ represents the average of several HI /SUB n/ compounds formed in the initial solution reaction. Separation of the H/sub 2/SO/sub 4/ and HI /SUB x/ takes place under gravity, since the two acids are nearly immiscible. The upper phase contains most of the H/sub 2/SO/sub 4/, and the lower phase contains most of the HI /SUB x/ . The main attributes of this cycle are its expected high thermal efficiencymore » (50%) and that it can be conducted as an all-liquid and a gas-phase process. The total process development at GA has been historically divided into several areas: Basic chemical investigations, Material investigations, Process engineering studies, Bench-scale testing. Recently, GA has carried out engineering studies to couple the existing sulfur-iodine process to solar heat sources and, in cooperation with the Lawrence Livermore National Laboratory (LLNL), to a Tandem Mirror Fusion Reactor.« less