R and D of hydrogen production by HTGRs

In future energy system, hydrogen energy will play a very important role as well as electric power. Global environment problems of greenhouse effect due to accumulation of carbon dioxide and acid rain due to sulfur oxides are caused mainly by consumption of a large amount of carbon-contained fossil fuels. To solve the problems, it is essential to decrease the dependence on fossil fuels and to develop both nuclear energy and renewal energy. In Japan, about 40% of primary energy is supplied to a power generation sector. Nuclear energy and renewal energy produce about 30% and 10% of electricity, respectively. Nuclear energy has a potential not only to share larger part in electricity production but also to share large energy supply in the non-electricity sector. Hydrogen production using nuclear energy is a key technology for energy supply in non-electricity sector. In order to develop hydrogen production technology as a heat utilization system of HTGRs, we are conducting studies on the following three processes. (1) Thermochemical hydrogen production process: The Iodine-sulfur process has been studied to demonstrate chemical feasibility with a laboratory-scale apparatus. Continuous hydrogen production is achieved by cyclic operation of the process. (2) High temperature electrolysis of steam: The steam electrolysis is one of the new technologies for hydrogen production. Both tubular-type and planar-type cells with solid oxide electrolyte(YSZ), are fabricated and tested to clarify features of electrolysis for further scale up. (3) Steam reforming process of natural gas: Studies are being carried out in order to lower the steam reforming temperature aiming at extensive utilization of heat energy from HTGRs. (author)