Because landfi ll gas (LFG) contains an abundance of methane, the utilization of LFG as a renewable energy source is becoming popular in many countries. LFG, however, contains various trace constituents, some of which may pose problems during utilization. For example, siloxanes and halogenated volatile organic compounds (VOCs) can cause diffi culties when present in the fuel of gas engines. In addition, many VOCs and mercury have harmful effects on human health, especially on the health of workers at landfi ll sites and people living near the landfi lls. Energy recovery from LFG is expected to make great progress in the near future, particularly in Asia, but we found little information on the trace constituents of LFG in this region. Therefore, we sought to characterize the trace components in LFG generated in two landfi ll sites in China and one site in Japan, to determine the typical concentrations of these trace components in LFG, and to compare their concentrations among landfi ll sites in Asia. We concluded that the trace components in LFG at the sites studied were mainly siloxanes generated from sewage sludge and harmful benzene, toluene, ethylbenzene, and xylene compounds from petroleum products.

Osaka Gas started joint development of the residential SOFC CHP system with Kyocera in FY2004, and Aisin Seiki Co., Ltd. and Toyota Motor Corporation also took part in out development. Development for commercialization was completed at the end of the 2011 fiscal year, and product commercialization was started. Most significant issue for commercialization was durability.　 Osaka Gas has conducted durability verification of a large number and long time test for stacks, material, and SOFC generation units in order to establish 10 years life time. As these results, we judged that durability SOFC power generation unit which uses latest stack, hot module design, and control reached durability target.

Osaka Gas began selling the second-generation residential SOFC CHP “ENE-FARM type S” in April 2016, which was developed in collaboration with Aisin Seiki, Kyocera and Noritz. In April 2018, power efficiency when the rated output can be stably is improved 53.5 % (net AC, LHV) from 52.0 % (net AC, LHV). The cumulative sales volume of Osaka Gas’s the residential fuel cell CHP system as in March 2019 was over 100,000. The cumulative number of SOFC-type was more than half. We have been trying to improve its quality and specifications, and reduce its cost. For example, we have improved the merchantability by adding a self-sustaining power generation function and using the Internet. ENE-FARM type S performed at approximately 2,000 customer homes though a power failure occurred mainly in Osaka due to Typhoon in 2018. It was an opportunity that one of the benefits in residential CHP was socially recognized.

We developed the high durability coating for SOFC metal interconnectors. The method is anion type electrodeposition coating, and the material of coating is spinel type oxide. Generally, electrodeposition coating is used to form the resin based coating, but we successfully increase the amount of ceramics in the film and enable this method for coating of SOFC metal interconnectors. This coating method enables the uniform coating thickness regardless of the structure of metal interconnectors. We demonstrated the high durability data of interconnector tests in terms of the degradation rate of ASR and Cr poisoning. This coating method is available for any ceramics and quite economical.