Materials compatibility was examined for the environments of hydriodic acid solution containing iodine (“HI_x” solution) in the iodine-sulfur water splitting process. The testing environments were (1) HI_x solution environment in the Bunsen reaction step, and (2) HI_x solution environment in the high pressure distillation column. Ta and Si0₂ showed excellent corrosion resistance in the former environment. Ta and Nb did in the latter environment.

Catalytic dehydrogeno-aromatization of cyclohexane has successfully been demonstrated in the liquid-film state of carbon-supported platinum fine particles under boiling and refluxing conditions. From the viewpoint of thermal / chemical energy conversion, endothermic hydrogen production from cyclohexane at mild reaction temperatures is important. By coupling with well-established catalytic hydrogenation of benzene, a safe and energy-saving tool of hydrogen storage and transportation is proposed, which uses chemical tunker and track vehicles for cyclohexane and benzene to and fro.

Thermal efficiency of the proposed chemical heat pump system has been enhanced extensively by adopting a liquid-film state under boiling conditions for the dehydrogenation catalysts, which are composed of Ru-Pt fine particles supported on carbon. Increase of rate for 2-propanol dehydrogenation as well as decrease of retardation caused by adsorbed acetone were ascribed to higher active-site temperatures than the boiling point of the solution. Characteristics of heat and mass transfers as correlated irreversible processes are discussed on the thermodynamical basis.

JAERI has been developing a high temperature chemical heat pump, which can amplify thermal energy of the temperature 500°C to a maximum temperature above 1000°C as well as store mass hydrogen taking advantage of the metal-hydrode reaction. To testify the concept of this type of heat pump desingned, the heat pump element test facility are constructed to be tested its performance.

Present paper reports the resent research activities of the chemical heat pump system, including R&D on metal-hydride materials.

Hydriding characteristics of LaNi_2.5Co_2.5 were measured by electrochemical and gas reaction processes.The equilibrium characteristics measured by the electrochemical process were found to be identical with the results by the gas reaction process.Under a constant potential, electrochemical hydriding processes exhibited similar results to those by the gas reaction process.This study aimed to bridge the results between both electrochemical and gas reaction process.

The world energy demand and supply were projected up to 2100 using a long-term world energy model. Several types of environmental cost were taken into account on the assumption of costs of fossil fuels. The projected energy mix showed that market penetration of renewable energy is accelerated when environmental costs are included in the fuel cost evaluation.

In -recent years, there has been renewed interest in the use of hydrogen as an environment friendly energy source. Biological production of hydrogen is one approach that has been extensively investigated. This report is on aspects of hydrogen photoproduction by marine microorganisms.