The influence of sulfur compounds on Ni-YSZ anode of SOFC cell was investigated by measuring cell voltage under a constant current density for Ni-YSZ anode / YSZ electrolyte / (La,Sr)MnO 3 cathode cell. Two-step degradation of cell voltage was observed by supplying H 2 S containing fuel. The first-step degradation of cell voltage was recovered completely by switching to sulfur-free fuel, while the cell voltage wasn't recovered completely once the cell voltage went down under 0 V. After the cell with irreversible degradation was cooled down under pure N 2 atmosphere, it was analyzed by FE-SEM, EDX and Raman Spectroscopy. The results of these analyses revealed nickel sulfides formation in H 2 S containing fuel. It is supposed that melted nickel sulfides diffused in the anode and electrolyte layer. The irreversible cell poisoning might be caused by these nickel sulfides.

Electric Power Development Co., Ltd. (JPOWER) started Tubular Type SOFC system development in collaboration with Mitsubishi Heavy Industries, Ltd. (MHI) in 1991. Stability of our improved structure featured with higher durability and lower cost has been verified using the 5kW-class Cartridge with 104 cell-tubes and 25kW-class Sub-module which consists of 4 Cartridges. As our new SOFC module structure was well established through great success in 5kW-class Cartridge and 25kW-class Sub-module test in collaboration with MHI, the prototype 150kW-class atmospheric SOFC co-generation system (SOFIT) development was planned by JPOWER. The system was installed at JPOWER's R&D Center in Chigasaki in 2006, and its verification test is started in January 2007. Our main purpose is definitely to verify and evaluate system durability and operation ability through more than 10,000 hours operation.

Electric Power Development Co., Ltd. (JPOWER) started Tubular Type SOFC module development in collaboration with Mitsubishi Heavy Industries, Ltd. (MHI) in 1991. Since 2001 proof of concept of module structure, which was designed through the various trial and error, has been verified using the 5kW class cartridge and the 25kW class Sub module composed of 4 cartridges. The concept of module structure was verified with more than 1,400hrs operation using the 5kW class cartridge in 2003, followed by more than 500hrs operation of the 25kW class Sub module in 2006. Then the verification demonstration of the 150kW class atmospheric SOFC CHP system using accomplished module structure was planned. The prototype system was installed in 2006 and commissioning and operation test were started at the beginning of 2007. In this paper, the prototype atmospheric SOFC CHP system development and its operation test result are introduced.