Steam electrolysis using micro tubular ceramic reactors

  • Dr Shin-ichi Hashimoto, Central Research Institute of Electric Power Industry, Japan
  • Dr Yu Liu, Central Research Institute of Electric Power Industry, Japan
  • Dr Masashi Mori, Central Research Institute of Electric Power Industry, Japan
  • Dr Yoshitaka Kawamura, Central Research Institute of Electric Power Industry, Japan
  • Mr Yoshihiro Funahashi, Fine Ceramics Research Association
  • Dr Yoshinobu Fujishiro, Advanced Industrial Science and Technology

    • Steam electrolysis is one of promising technologies for hydrogen production since its high production efficiency and effective heat utilization will be expected compared with usual water electrolysis. On the other hands, micro tubular structured SOFCs widely attracted attention because of the rapid startability and high electrochemical performance. Such cells will be applied to not only SOFCs but also high performance electrochemical devices including steam electrolyzers.
    In this study, micro tubular ceramic reactors were produced experimentally, and steam electrolysis was carried out using the ceramic reactors. Electrode-supported cell structure was introduced to the ceramic reactors, and one of the cell configurations was La0.6Sr0.4Co0.2Fe0.8O3(LSCF) - Ce0.8Gd0.2O1.9 (CGO) electrode / CGO buffer layer / (ZrO2)0.89(Sc2O3)0.1(CeO2)0.01(ScSZ) electrolyte / Ni-ScSZ electrode supporting tube. The prepared cell dimensions were 1.8 mm in diameter, 500 mm in length and 1.75 cm2 in active area. 10%H2-Ar mixture gas was used as steam carrier gas, and 18% steam was supplied to inside of the ceramic reactors. Reversible cell operation in between SOFC mode and SOEC mode was confirmed on this ceramic reactor, and power density: 0.04 Wcm-2 at SOFC mode and cell voltage at 0.1 Acm-2: 1.43 V at SOEC mode was observed at 650oC. During the steam electrolysis, hydrogen production has proportionally increased with current density increasing, and heat generation from low current density was observed by electro-chemical technique. It is suggested that the micro tubular geometry of ceramic reactors is one of potential structures for self thermal sustainable electrolyzers.