Katsuya Hirata

SOFC Module and System Development by Means of Sealless Metallic Separators with Lanthanum Gallate Electrolyte

The third-generation 1-kW e -class module was developed with an automatic control system. A conversion efficiency of 48% ac/lower heating value [ac/LHV] was achieved with an exhaust heat recovery unit. An endurance test using the third-generation 1-kW e module was done for over 1000 h and no degradation of the power generation performance was observed. In parallel, a single-cell unit, which includes one cell and two metallic separators, was tested for over 10000 h and the degradation rate of the terminal voltage was found to be 1-2%/1000 h. In the direction of scale-up, a triple-stack module of 3-kW e output was developed. A partial load as well as excess loads on the module were tested and the output power of 1-5 kW e was attained under thermally self-sustainable conditions. It was found that a high efficiency of 55% dc/lower heating value [dc/LHV] was obtained under stable operation. Ongoing research of the fourth-generation 1-kW e module has resulted in the conversion efficiency of 58% [dc/LHV].

Development of IT-SOFC Based on Lanthanum Gallate Electrolyte

The Kansai Electric Power Company, Inc. and Mitsubishi Materials Corporation started a joint research project for developing intermediate temperature (600{degree sign}C to 800{degree sign}C) solid oxide fuel cells (IT-SOFC) in 2001. High performance disk-type cells with lanthanum gallate-based electrolyte and a seal-less cell-stack design enable high efficiency operation at temperatures below 800{degree sign}C. The development of 10 kW-class CHP system under a project supported by NEDO (New Energy and Industrial Technology Development Organization) was started in FY2004. In 2007, the performance test of the 10 kW-class system using town gas as fuel has been undertaken. In this test, the electrical efficiency of 41%HHV on AC power output of 10 kW and the overall efficiency of 82%HHV by recovering 60aC hot water have been achieved. And the voltage degradation rate per 1,000 hours was 1.08% after 3,000 hours operation has been observed during the field test of the 10 kW-class system. Furthermore, after making some refinements to enhance the performance of 10 kW-class module, the second long-term stability test for 3,000 hours were carried out in 2008. Efforts to enhance cell and module durability have been made with 1 kW-class modules operated for 5,000 hours, and with the cell-stack units operated for 15,000 hours. The voltage degradation rates per 1,000 hours were 0.51 % for the 1 kW-class modules, and 0.23 - 0.48% for the cell-stack units.