Vol.5 No.1 2012

Research paper : Durable polymer electrolyte fuel cells (PEFC) for residential co-generation application (K. Tanimoto et al.)−62−Synthesiology - English edition Vol.5 No.1 (2012) the cathode or anode gases. Also, high potential of about 1.6 V could be induced depending on the condition of gas switching according to the model cell experiment, and this could offer the rationale for the accelerated test protocol by gas switching. The decrease of gas diffusion in the catalyst layer was thought to arise from the electrochemical reaction of the catalyst supported carbon. The dissolution of ruthenium of the anode catalyst was confirmed in the analysis and observation of the electrolyte membrane and the electrode catalyst layer after cell operation. These behaviors were thought to decrease the CO poisoning resistance of the Pt-Ru alloy catalyst over time. The increase of anode potential was confirmed in the anode gas switching condition. It was thought that such aging condition would not occur under normal operation, but since the local distribution of the gas composition caused the potential increase, the dissolution of ruthenium of the anode catalyst was accelerated.The PEFC residential cogeneration system uses the fuel cell of about 1 kW as the power source. The durability was evaluated by applying the accelerated test protocol to this fuel cell by gas switching method. As a result, for the fuel cells of the various fuel cell system manufacturers, about seven-fold acceleration rate was obtained in the cathode gas switching method, and about 100-fold acceleration effect was observed for the anode gas switching method. In this project, the companies that manufactured the PEFC residential cogeneration system were able to confirm the 40,000-hour durability through the accelerated test, and the commercialization in market was initiated. As part of the attempt to spread the PEFC residential cogeneration system, the energy supplier and the fuel cell system makers gave the name “ENE-FARM” to this commercialized product system. This name is a combination of energy and farm. The ENE-FARM was commercialized in May 2009, and it is spreading all over Japan as shown in Table 1. 6 ConclusionFor the authors who have been engaging in research of the fuel cells as the next-generation technology, the fact that the fuel cell, which was always called the technology of the coming generation, became commercialized as ENE-FARM was a satisfactory event. The factors that allowed the fuel cell to become commercialized were that the initial stage of the residential cogeneration market was formed as society became increasingly eco-minded, and that there was excellent generation efficiency of the fuel cell compared to the gas engine technology that has already been in this market. Since the electricity-main heat-sub tendency was increasing in the home energy consumption, the generation efficiency was highly adaptable in terms of the balance of electricity and heat with electricity being main. The fuel cell cogeneration system is clearly adaptable as a commercial product compared to the gas engine cogeneration. Also, the interest in reducing the emission of carbon dioxide, preparing against disaster and saving energy accelerated the formation of the residential cogeneration market. The technology development in the industry-academia-government collaboration was important in the commercialization of the ENE-FARM. For a product that was so close to commercialization, there was very little incentive on the part of the companies to engage in joint technological development while sharing the unique corporate information. In this case, vertical collaboration with the energy supply companies was done aiming for the new market formation for residential cogeneration. AIST managed the unique technological information, the sharing of developed information progressed, and the positive incentives such as lowered risk of R&D functioned well.Currently, the ENE-FARM is spread widely due to government’s subsidies. For autonomic market growth, further decreased cost and increased reliability and durability are necessary. To do so, research and development must be conducted from the designing aspect of residential cogeneration system by the fuel cell system makers, and at the same time, it is necessary to engage in researches to increase the performance and durability of the PEFC as well as to decrease the cost. AIST wishes to contribute as much as possible.AcknowledgementThe industry-academia-government collaboration project “Fundamental Research of Degradation of PEFC Stacks” was conducted from October 2004 to March 2008, under the subcontract by New Energy and Industrial Technology Development Organization (NEDO). We are thankful to the people involved. We also express our thanks to the following participants of the project: Toshiba Fuel Cell Power Systems Corporation, Sanyo Electric Co., Ltd. (now part of Panasonic Corporation), Matsushita Electric Industrial Co., Ltd. (now Panasonic Corporation), Tokyo Gas Co., Ltd., Osaka Gas Co., Ltd., Nippon Oil Corporation, Kyoto University, Yokohama National University, and Doshisha University. Table 1. Introduction of ENE-FARM by subsidy3,6811,3495,030FY 2009FY 2010FY 2011TotalTotal / unitLP gas type/ unitCity gas type/ unit(For FY 2011, the number is for the application received by December 27, 2011)3,96910,52618,1764,98512,43722,4521,0161,9114,276NoteNote 1) http://www.fujielectric.co.jp/about/news/11041101/index.html


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