Engineering Research Center  People

Engineering Research Center  People

Associate Professor  Ryoichi Komiyama
Division: Energy System Resilience



List of Research Topics

1. Simulation analysis of energy security

Energy security concerns have highlighted the significance of formulating an energy contingency plan, and studies on assuring energy system resilience of the country’s energy system are indispensable for developing sustainable energy pathways leading to an energy market transition. In consideration of contingency risks such as disasters and fuel supply disruptions, this research aims at providing quantitative implications for energy security improvements using an energy system model allowing us to evaluate energy policies and technologies contributing to an enhancement in the redundancy, multiplexing, and diversification of energy systems. Faced with an increase in fossil fuels imports owing to the nuclear shutdown after the Fukushima nuclear disaster in Japan, with the emergence of geopolitical risk in resource-rich countries and with a rapid growth in energy demand in developing countries, Japan has again found itself as a country whose energy security is quite vulnerable. As one item of the research agenda, we have thus far developed a mathematical energy model for an energy security evaluation using stochastic dynamic programming, and are currently engaged in an analysis of the economic rationality of fuel stockpiles for an abrupt energy disruption. This model can deal with relative uncertainties such as fuel price volatility and fuel import disruptions, as well as an unexpected shutdown of a nuclear power plant, and can be used to analyze the economic validity of fuel stockpiles including crude oil and liquefied natural gas (LNG) in a consistent way.

  • Kawakami, Y., Komiyama, R., Fujii, Y., Development of energy security evaluation method using mathematical programming and analysis of optimal strategy for fuel stockpile operation, Journal of Japan Society of Energy and Resources, Vol. 34, No. 5, 21-30 (2013) [in Japanese]
  • Komiyama, R., Li, Z., and Ito, K., World energy outlook in 2020 focusing on China's energy impacts on the world and Northeast Asia, International Journal of Global Energy Issues, Vol. 24, Nos. 3/4, 183-210 (2005)

2. Formulation of optimal energy policy in Japan

This research analyzes the impact of energy and environmental policies such as energy-saving standards and innovative technology introduction on the energy market, as well as greenhouse gas emissions on the basis of mathematical programming techniques and an econometric analysis, which provide the implication for an optimal energy demand and supply structure for realizing a low-carbon society in an efficient manner. In Japan, the maximization of renewable energy in the country’s energy mix has become a crucial agenda after the Fukushima Daiichi nuclear accident. As one research example thus far, we analyzed the PV and wind installable potential that can be technically integrated into the Japanese power grid using a high time-resolution optimal power generation mix model. This model enables us to explicitly consider the actual PV and wind output intermittency for a 10-minute time resolution throughout the year, and is expected to contribute to a successful economic integration of PV and wind power in policy-making situations, and may provide additional insight regarding its massive deployment. One of the simulation results implies that, as installed PV increases, the growth of PV integration into the grid exhibits a saturated trend when the installed PV capacity is more than the scale of the peak demand, despite Japan having an immense deployable potential of PV capacity equivalent to 40-times the peak. In addition, it has also turned out that a large-scale integration of PV in a power grid potentially decreases the usage ratio of thermal plants such as an LNGCC during specific months or seasons, revealing the challenge for utility companies to assure LNGCC operation while serving as a profitable complementing generator for PV intermittency.

  • Komiyama, R. and Fujii, Y., Assessment of massive integration of photovoltaic system considering rechargeable battery in Japan with high time-resolution optimal power generation mix model, Energy Policy (2013)
  • Komiyama, R., Shibata, S., and Fujii, Y., Simulation analysis for massive deployment of variable renewables employing an optimal power generation mix model, Journal of Energy and Power Engineering, Vol. 7, 1604-1615 (2013)
  • Komiyama, R. and Fujii, Y., Assessment of Japan's Optimal Power Generation Mix Considering Massive Deployment of Variable Renewable Power Generation, Elect. Eng. Jpn., Vol. 185, 1-11 (2013)

3. Assessment for installable potential of innovative end-use technology

For multiplexing, decentralizing, and diversifying an energy system, the deployment of an innovative technology and system in the end-use sector (final demand sector) is essential for improving the energy system resilience. Employing an energy-economy model, we analyze the possibility of introducing a smart community, distributed power generation, clean energy vehicles such as electric vehicles (EVs), a cogeneration system (CGS), and renewable energy. As one of the research topics tackled thus far, we evaluated the impact of an extensive introduction of EVs and plug-in hybrid vehicles (PHEVs) on the energy supply mix in Japan. The energy consumption in Japan’s transport sector has been dominated by petroleum, and CO2 emissions in this sector account for twenty-percent of Japan’s CO2 emissions. Hence, the deployment of clean energy vehicles, such as EVs and PHEVs, is expected to play a significant role in addressing the nation’s energy security and environmental concerns. To assess the energy and environmental benefits of using EVs and PHEVs, we developed an energy system model integrating an optimal power generation mix model and a vehicle penetration model, considering the optimal electricity charging profile of such advanced vehicles. The results suggest that massive EV penetration serves as an energy conservation measure in Japan owing to the significant petroleum reduction exceeding the growth of fuel input into the power generation sector derived from significant EV and PHEV penetration. When evaluating the CO2 emissions per mileage by automobiles, however, carbon emissions per mileage for an EV is almost equivalent to that of a gasoline hybrid vehicle (HEV) for the case of decommissioning a nuclear power plant, causing an increase in carbon-intensity of the power supply.

  • Komiyama, R. and Fujii, Y., Analysis of energy saving and environmental characteristics of electric vehicles in regionally disaggregated world energy model. Elect. Eng. Jpn., Vol. 186, 20-36 (2014)
  • Komiyama, R. and Fujii, Y.: Assessment of energy saving and CO2 mitigation potential by electric vehicle and plug-in hybrid vehicle under power generation mix, IEEJ Trans. PE, Vol. 133, No. 1, pp. 10-18 (2013) [in Japanese]
  • Komiyama, R., Hayashi, T., Fujii, Y., and Yamaji, K., Feasibility evaluation of on-site generator network by cooperative game theory. Elect. Eng. Jpn., Vol. 150, 23-35 (2005)

4. Analysis of sustainable energy pathway in developing countries

China and the whole Asian region will account respectively for about 30% and 60% of the world’s incremental growth of CO2 emissions in the upcoming decades. Considering this rapid increase in CO2 emissions in emerging economies, it is obvious that reducing the environmental burden through international transfers of advanced energy-efficient technologies to these emerging countries will contribute to an improvement in the energy and environmental problems in developing regions and around the globe. This research investigates the impact of the penetration of energy-saving and innovative energy supply technologies in emerging economies such as Asia and the Middle East on global energy security improvement and CO2 mitigation. An energy modeling framework adopted for the energy demand and supply projection was mathematically formulated using an econometric and optimization method for a detailed assessment of the impact of low carbon technology on the energy supply and demand around the world. As an existing research topic, we develop a long-term projection model on energy supply and demand for up to 2035, with a particular focus on the Middle East, based on an analysis of world trends that are already evident or expected to emerge in the future. Using this model for the Technologically Advanced Scenario, which assumes that all Middle East countries will take on technological advanced measures and that accelerated R&D will encourage the global deployment of advanced technologies, the primary energy consumption in the Middle East will decrease by 13% compared with the reference scenario for 2035.

  • Gan, P.Y., Komiyama, R., Li, Z.D., A low carbon society outlook for Malaysia to 2035, Renewable and Sustainable Energy Reviews, Vol. 21, 432-443 (2013)
  • Sharma, S., Komiyama, R., and Fujii, Y., Assessment of sustainable energy strategy with long term global energy model incorporating nuclear fuel cycle, Journal of Environmental Science and Engineering, Vol. A1, 1215-1232 (2013)
  • Komiyama, R., Sofukuwaki, M., and Matsuo, Y., Forecast analysis on energy demand and supply in Middle East countries by 2035, Journal of Japan Society of Energy and Resources, Vol. 33, No. 2, 44-53 (2012) [in Japanese]


・R.Komiyama, Y.Fujii, J. Ene. & Pow. Eng. (Accepted)
・S.Sharma, R.Komiyama, Y.Fujii, J. Env. Sci. & Eng., A1, pp.1215-1232 (2013)
・P.Y.Gan, R.Komiyama, Z.Li, Renewable & Sustainable Energy Reviews, Vol.21, pp.432-443  (2013)
・小宮山, 藤井, 電学論B, Vol.133, No.3, pp.263-270 (2013)
・(分担執筆) 「日本の将来を変えるグリーン・イノベーション」第5章, 中央経済社 (2012)