Practical Research and Collaboration Division
Resilient EICT Research Promotion Office
Dr. Eng

Graduate School of Engineering
Research Subject(s)
We are working on the theory and practice of energy design that drives decarbonization as the basis for transitioning to a carbon neutral society.
Key Words
Energy system design and analysis / Carbon neutral / Renewable energy
Research Activities

The goal is to implement sustainable energy systems in local communities. A "time axis" that extends from the past to the present and into the future, and a "spatial axis" that identifies the characteristics and uneven distribution of energy supply and demand in a community. On this axis, we will develop an integrated optimization method that includes "technology indicators" such as energy efficiency and CO2 emissions, "value indicators" such as decarbonization, affluence, economic efficiency, security, and resilience, and sector coupling of energy system resources, conversion technologies, and demand sectors, to design an energy system that is appropriate for the local society. We will design energy systems that are appropriate for local communities.

Clarify the current status of energy supply and demand in the region by creating an energy flow diagram. Visualize the transition of the flow structure from the past to the present to identify issues in the current energy supply and demand structure. Based on detailed data analysis, we will clarify the degree of dependence on fossil fuels, energy use efficiency, underutilized waste heat, and the amount and quality of underutilized local renewable energy resources.

The energy supply-demand structure is highly uneven across Japan. On the fuel supply side, the difference in gas supply prices increases five-fold depending on whether or not there is a gas pipeline, and on the demand side, there is more than a two-fold difference in energy consumption for air conditioning and hot water supply depending on the outside air temperature. Rather than treating Japan as a uniform country, we objectively analyze energy supply and demand data for each region of the country to develop important evidence for designing sustainable energy systems.

Selected Works

Hiroaki Onodera, Rémi Delage, Toshihiko Nakata (2024), The role of regional renewable energy integration in electricity decarbonization—A case study of Japan, Applied Energy 363 (123118) 1-13, doi:10.1016/j.apenergy.2024.123118

Yoshiki Kusumoto, Rémi Delage, Toshihiko Nakata (2024), Machine learning application for estimating electricity demand by municipality, Energy 296 (131138) 1-10, doi:10.1016/ 

Régis Delubac, Rémi Delage, Toshihiko Nakata (2024), Nonlinear optimization of biomass fueled combined heat and power boilers in district heating systems in Japan, Clean Technologies and Environmental Policy, 1-15, doi:

Toshihiko Nakata (2024), Decarbonized city planning in the context of the local community, Gakushikai Kaiho, 964 67-71
Rémi Delage, Toshihiko Nakata (2023), Directed recurrence networks, Chaos: An Interdisciplinary Journal of Nonlinear Science 33(11) 1-8, doi:10.1063/5.0173394

Selected Memberships
  • The Japan Society of Mechanical Engineers
  • The Japan Institute of Energy
  • The Japan Society of Energy and Resources
  • The International Association for Energy Economics
Selected Awards
  • Japan Society of Mechanical Engineers "JSME Medal for Distinguished Engineers" in 2024
  • Academic Award and the Best Paper Awards, Japan Institute of Energy in 2005, 2017 and 2021
  • Best Paper Award, American Society of Mechanical Engineers, IGTI in 2000