To protect against global warming, a massive influx of renewable energy is expected. Although hydrogen is a renewable media, its storage and transportation in large quantity has some problems. Ammonia fuel, however, is a hydrogen energy carrier and carbon-free fuel, and its storage and transportation technology is already established. In the 1960s, development of ammonia combustion gas turbines was abandoned because combustion efficiency was unacceptably low . Recent demand for hydrogen energy carriers has revived the interest in ammonia as fuel [2, 3]. In 2015, ammonia-combustion gas turbine power generation was reported in Japan using a 50-kW class micro gas turbine [4, 5]. It consists of an ammonia supply system, a gas turbine, selective catalytic reduction (SCR), and loading equipment. Since ammonia combustion emits high concentrations of NOx, low-NOx combustion technology has been investigated. A rich-lean, two-stage combustion technique for ammonia gas turbine combustor was researched and developed , which operates in the high-temperature region of the gas turbine combustor. To improve the high-temperature resistance of materials, materials were researched under ammonia combustion conditions. Finally, to obtain a larger system, a 300-kW class ammonia gas turbine power generation system has been designed, using newly developed, high-temperature, and high-efficiency SCR.
This work was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), “Energy Carriers” (Funding agency : Japan Science and Technology Agency (JST)). Final reports of Energy Carriers program are now available .
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 Kobayashi, H., Hayakawa, A., Somarathne, K.D.K.A. and Okafor, E.C., “Science and technology of ammonia combustion”, Proceedings of the Combustion Institute, 37 (2019) 109-133.
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 Iki, N., Kurata, O., Matsunuma, T., Inoue, T., Suzuki, M., Tsujimura, T., Furutani, H., Kobayashi, H., Hayakawa, A., Arakawa, Y. and Ichikawa, A., “Micro Gas Turbine Firing Ammonia”, The 12th Annual NH3 Fuel Conference, Chicago, September 20-23, (2015).
 Kurata, O., Iki, N., Inoue, T., Matsunuma, T., Tsujimura, T., Furutani, H., Hayakawa, A. and Kobayashi, H., “Performances and emission characteristics of NH3-air and NH3-CH4-air combustion gas-turbine power generations”, Proceedings of the Combustion Institute, 36 (2017) 3351-3359.
 Kurata, O., Iki, N., Inoue, T., Matsunuma, T., Tsujimura, T., Furutani, H., Kawano, M., Arai, K., Okafor, E.C., Hayakawa, A. and Kobayashi, H., “Development of Wide Range-operable, Rich-lean Low-NOx Combustor for NH3 Fuel Gas-turbine Power Generations”, Proceedings of the Combustion Institute, 37 (2019) 4587-4595.
 JST, Final reports of Energy Carriers program (in Japanese)