Development of a New Thermochemical and Electrolytic Hybrid Hydrogen Production System for Sodium Cooled FBR

Abstract

A new thermo-chemical and electrolytic hybrid hydrogen production system in lower temperature range is newly proposed by the Japan Nuclear Cycle Development Institute (JAEA) to realize the hydrogen production from water by using the heat generation of sodium cooled Fast Breeder Reactor (FBR). The system is based on sulfuric acid (H 2 SO 4 ) synthesis and decomposition process developed earlier (Westinghouse process), and sulfur trioxide (SO 3 ) decomposition process is facilitated by electrolysis with ionic oxygen conductive solid electrolyte to reduce the operation temperature 200-300• C lower than Westinghouse process. SO 3 decomposition with the voltage lower than 0.5 V was confirmed in the temperature range of 500 to 600• C and theoretical thermal efficiency of the system evaluated based on chemical reactions was within the range of 35% to 55% under the influence of H 2 SO 4 concentration and heat recovery. Furthermore, hydrogen production experiments to substantiate the whole process were performed. Stable hydrogen and oxygen production were observed in the experiments, and maximum duration of the experiments was about 5 hours.

Calculation of X-ray absorption near edge structure of CeO2 using a model cluster

“…As one of them, we are developing a hybrid thermo-chemical process, which utilizes SO 3 electrolysis with solid electrolyte [1]. This hybrid is based on sulfuric acid (H 2 SO 4 ) synthesis and decomposition, and sulfur trioxide (SO 3 ) decomposition facilitated by electrolysis.…”

“…This heat supplied by an Fast Breeder Reactor (FBR). We have succeeded in production of hydrogen continuously for up to 5 h with this thermo-chemical process, using YSZ as electrolyte [1]. However, in order to improve the energy efficiency of hydrogen production, it is necessary to investigate solid electrolyte of higher conductivity at 500-600°C.…”

Clarification of the Mechanism of Sulfur Trioxide Electrolysis—Evaluation of SO3and O Atom Adsorbed on Pt Surface—

“…We have been investigating the Feasibility Study on Commercialized fast breeder reactor (FBR) Cycle System of the Japan Nuclear Cycle Development Institute (JNC) to clarify the promising concepts for commercialized FBR cycle system since 1999, 1) in order to carry out the necessary R&D and to establish the FBR cycle technical systems as a future energy source. In Phase II of this study, one of the promising concepts is a multipurpose small-sized FBR with various requirements, such as safety and economic competitiveness.…”

“…As a new hydrogen production process utilizing the heat supplied by FBR, we are developing a hybrid thermo-chemical process. 1) This hybrid thermo-chemical process is based on sulfuric acid (H 2 SO 4 ) synthesis and decomposition processes, where the decomposition process of sulfur trioxide (SO 3 ) is facilitated by electrolysis using the electrolysis cell at the temperature of about 500 C, which is supplied by FBR. With this hybrid thermo-chemical process, we have succeeded in the continuous production of hydrogen for up to five hours, and thus, we have demonstrated the practical application of the process.…”

The refinement of the rate determining process in sulfur trioxide electrolysis using the electrolysis cell

“…We have succeeded in production of hydrogen continuously for up to 5 h with this hybrid thermo-chemical process, thus demonstrating its practical usefulness, though hydrogen generation rate was 4.5 ml/h [4][5][6]. The electrolysis cell used in SO 3 electrolysis is composed of an electrolyte and an electrode similar to the solid oxide fuel cell (SOFC) which has recently been extensively developed.…”