Investigation on a new hydrogen production process for FBR

A new thermochemical and electrolytic hybrid hydrogen production process (thermochemical and electrolytic hybrid hydrogen process in lower temperature range: HHLT) is under investigation to realise the hydrogen production from water by using the heat generation of coolant in fast breeding reactor (FBR). HHLT is based on sulphuric acid (H2SO4) synthesis and the decomposition processes developed earlier (Westinghouse process), and sulphur trioxide (SO3) decomposition process at about 500degreesC is facilitated by electrolysis with ionic oxygen conductive solid electrolyte which is extensively utilised for high-temperature electrolysis of water. Decomposition of SO3 were confirmed with the cell voltage lower than 0.5V at 500-600degreesC using 8 mol yttria stabilised zirconia (8 mol YSZ) solid electrolyte and platinum electrode, furthermore, oxygen permeation rate through YSZ into N-2 purge gas agreed well with the calculated permeation rate from measured cell current. Preliminary measured oxygen permeation rate through La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) in air supplied experiments were higher than the rate through 8 mol YSZ. These results show the possibility of development of higher performance electrolytic cell using other solid electrolytes than YSZ. Thermal efficiency of HHLT roughly estimated based on chemical reactions was 47.3% with no heat recovery. Further investigations are planed on durability of the solid electrolytes and electrodes in SO3 atmosphere at about 500degreesC, and on laboratory scale experimental apparatus to substantiate whole process of HHLT.