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Research paper : Development of a small-size cogeneration system using thermoelectric power generation (R. Funahashi et al.)−91 Synthesiology - English edition Vol.1 No.2 (2008) added value to the system to which the thermoelectric module is installed. In oxide thermoelectric module, since the temperature on the low side can be set high, waste heat can be used efficiently by topping heat recovery. Using this concept, we expect improvement of total heat efficiency of heat conversion and energy conversion devices such as boilers and fuel cells. Also, high power density, an advantage of thermoelectric conversion, is excellent for application to mobile objects such as automobiles and power sources for cell phones. The Co-349/Ni-113 thermoelectric element can produce about 2 MW/m3 power density.By installing the thermoelectric system developed by technological integration described here to heat engine so waste heat can be used effectively, new value can be provided to users who were waiting for this, and great contribution can be made to solve the energy issues.Some of the results described here were presented in other journals[10].AcknowledgementWe express our gratitude to Yoshinori Hisazumi, Senior Engineer and Akeshi Kegasa, Senior Engineer of Energy Technology Research Center of Osaka Gas Co., Ltd. for their useful advice in manufacturing the pipe-type module. Also, part of this research was conducted under NEDO Industrial Technology Research Grant (ID06A39002d).TerminologyTerm 1.Exergy: effective energy that can be converted to other energy.References[1][2][3][4][5][6][7]K. Hirata: Sho enerugi ron (Energy Conservation Theory), Omsha, Tokyo (1994) (in Japanese).K. Okuma et al.: Collection of Papers of Thermoelectric Symposium 99, 96 (1999) (in Japanese).L. D. Hicks and M. S. Dresselhaus: Effect of quantum-well structures on the thermoelectric figure of merit, Phys. Rev. B, 47, 12727 (1993).R. Funahashi, I. Matsubara, H. Ikuta, T. Takeuchi, U. Mizutani and S. Sodeoka: An oxide single crystal with high thermoelectric performance in air, Jpn. J. Appl. Phys., 39, L1127 (2000).R. Funahashi, S. Urata and M. Kitawaki: Exploration of n-type oxides by high throughput screening, Appl. Surf. Sci., 223, 44 (2004).R. Funahashi, S. Urata, K. Mizuno, T. Kouuchi and M. Mikami: Ca2.7Bi0.3Co4O9/La0.9Bi0.1NiO3 thermoelectric devices with high output power density, Appl. Phys. Lett. 85, 1036 (2004).S. Li, R. Funahashi, I. Matsubara, K. Ueno, S. Sodeoka and H. Yamada: Synthesis and thermoelectric properties of the new oxide materials Ca3-χBiχCo4O9+δ (0.0 < χ < 0.75), Chem. Mater., 12, 2424 (2000).R. Funahashi, M. Mikami, S. Urata, M. Kitawaki, T. Kouuchi and K. Mizuno: High-throughput screening of thermoelectric oxides and power generation modules consisting of oxide unicouples, Meas. Sci. and Tech., 16, 70 (2005).R. Funahashi, T. Mihara, S. Urata, Y. Hisazumi and A. Kegasa: Preparation and properties of thermoelectric pipe-type modules, Proc. of 2006 Int. Conf. Thermoelectrics, 58-61 (2006, Vienna).R. Funahashi and S. Urata: Haiki netsu o yuko riyo suru sanka butsu netsuden hatsuden mojuru no kaihatsu (Development of oxide thermoelectric generation module for efficient use of waste heat), Oyo Butsuri, 77, 45-48 (2007) (in Japanese).Received original manuscript December 25, 2007Revisions received February 19, 2008Accepted February 19, 2008[8][9][10]AuthorsRyoji FunahashiCompleted masters course at Graduate School of Science, Nagoya University in March 1992. Joined the Government Industrial Research Institute Osaka, Agency of Industrial Science and Technology (current AIST Kansai) in April 1992. Obtained doctorate (engineering) from the Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University in December 1998. Has worked on research of functional oxides for superconductivity and thermoelectric. In this paper, mainly worked on development of material and joining technologies.Saori UrataGraduated from Department of Chemical and Biological Engineering, Sasebo National College of Technology in March 1999. Worked as dispatch researcher to AIST Kansai in June 2002. Became technician at Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency in April 2006. Has worked on search for new thermoelectric materials and development of manufacture technology for high-performance power generation module. In this paper, mainly worked on development of element technology and manufacturing and assessment of module.Discussion with reviewers1 Greatest difficulty in this R&DQuestion (Naoto Kobayashi)I see that you were engaged in a series of significant R&D with a strategic vision toward the development of small-size gas cogeneration system, with a basic research including search and development of materials, an intermediate integration technology that combined with know-how, and a power generation by pipe-type module installed in a water heater. What was the most difficult point? And how did you overcome that?Answer (Ryoji Funabashi)The most difficult point technologically was material development. Discovery of a new substance cannot be planned beforehand, and one must be blessed with luck to succeed. We were able to discover Co layered oxide for p-type material, but we are still struggling for n-type material. I feel that the research for (19)−

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