5:15 PM - 7:15 PM
[U05-P05] Case study on Renewable Thermal Energy Research of Local Government
Keywords:Renewable Energy, Renewable Thermal Energy, Shallow Ground Source Heat Energy, Solar Thermal Energy, Saitama Prefecture, Local Government
To achieve a decarbonized society, it is essential to transition from conventional fossil fuels to renewable energy. In household energy consumption, approximately 70% is used as thermal energy (for hot water supply, heating, cooling, cooking, etc.), and utilizing heat directly-thus avoiding energy conversion losses-makes "renewable thermal energy" a promising option.
The spread of renewable thermal energy is an important issue for local governments, and research and information dissemination efforts are underway to promote its adoption. In this presentation, we report on a research case in Saitama Prefecture. The Center for Environmental Science in Saitama has evaluated the geothermal potential of various regions based on subsurface environmental data and disseminated the map via GIS. This evaluation method is based on borehole stratigraphic data from 4,800 sites in the prefecture and an empirical relationship between typical geological formations and their corresponding heat extraction rates. Each site was evaluated based on the average heat extraction rate per meter of depth (up to 100 m).
Furthermore, demonstration tests were conducted at five locations in the prefecture by installing small-scale systems comprising closed-loop shallow ground source heat pumps and air-source heat pumps. The results derived from actual operational data showed that shallow ground source heat pumps exhibit an efficiency approximately 1.5 to 2 times higher than that of air-source heat pumps.
In addition, given the promising potential for geothermal energy in agriculture, demonstration tests using open-loop shallow ground source heat pumps were performed in collaboration with local farmers, including strawberry growers in Kumagaya City and herb cultivators in Kuki City. These tests not only confirmed the energy-saving effects of shallow ground source heat pumps but also indicated additional cultivation benefits such as improved product quality and extended harvesting periods.
Regarding research on solar thermal energy, temperature variations were monitored and data were collected throughout the seasons using a vacuum-tube-type solar thermal system installed at the Research Center. Owing to its reduced sensitivity to ambient air temperature, the vacuum tube system was shown to achieve high temperatures even in winter, with an energy conversion efficiency exceeding 50%, thereby confirming its high efficiency. Because solar thermal energy is inherently variable depending on weather and installation location, high-density, hourly data on regional solar irradiance are crucial. Therefore, we are also conducting regional analyses of solar radiation.
Part of these results were obtained through a project funded by the New Energy and Industrial Technology Development Organization (NEDO).
The spread of renewable thermal energy is an important issue for local governments, and research and information dissemination efforts are underway to promote its adoption. In this presentation, we report on a research case in Saitama Prefecture. The Center for Environmental Science in Saitama has evaluated the geothermal potential of various regions based on subsurface environmental data and disseminated the map via GIS. This evaluation method is based on borehole stratigraphic data from 4,800 sites in the prefecture and an empirical relationship between typical geological formations and their corresponding heat extraction rates. Each site was evaluated based on the average heat extraction rate per meter of depth (up to 100 m).
Furthermore, demonstration tests were conducted at five locations in the prefecture by installing small-scale systems comprising closed-loop shallow ground source heat pumps and air-source heat pumps. The results derived from actual operational data showed that shallow ground source heat pumps exhibit an efficiency approximately 1.5 to 2 times higher than that of air-source heat pumps.
In addition, given the promising potential for geothermal energy in agriculture, demonstration tests using open-loop shallow ground source heat pumps were performed in collaboration with local farmers, including strawberry growers in Kumagaya City and herb cultivators in Kuki City. These tests not only confirmed the energy-saving effects of shallow ground source heat pumps but also indicated additional cultivation benefits such as improved product quality and extended harvesting periods.
Regarding research on solar thermal energy, temperature variations were monitored and data were collected throughout the seasons using a vacuum-tube-type solar thermal system installed at the Research Center. Owing to its reduced sensitivity to ambient air temperature, the vacuum tube system was shown to achieve high temperatures even in winter, with an energy conversion efficiency exceeding 50%, thereby confirming its high efficiency. Because solar thermal energy is inherently variable depending on weather and installation location, high-density, hourly data on regional solar irradiance are crucial. Therefore, we are also conducting regional analyses of solar radiation.
Part of these results were obtained through a project funded by the New Energy and Industrial Technology Development Organization (NEDO).