| Title | Suitable Areas for Geothermal Heat Pumps Inferred from Geological and Hydrological Features: a Case Study in the Nobi Plains, Central Japan |
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| Authors | Tomoyuki Ohtani, Kohji Kamiya, Satoru Kojima |
| Year | 2010 |
| Conference | World Geothermal Congress |
| Keywords | Geothermal heat pumps, suitable areas, geology, hydrology |
| Abstract | Distribution of the suitable areas of the Geothermal Heat Pump system is studied. For the closed loop system, the distribution of the Darcy velocity of groundwater flow in aquifers in the Nobi plain is estimated. The velocity of groundwater flow is calculated from hydraulic gradient and permeability coefficient of aquifers. Distribution of hydraulic gradient is estimated from interpolated distribution of water table of wells using kriging. In the most part of the alluvial fan area, the gravel is dominant in the formation and the velocity is >10-6m/s. In the southwestern area, the velocity is ≤6.3×10-7m/s. This difference of groundwater velocity would affect effective heat conductivity of formations and heat transfer under the ground. For the open loop system, distributions of aquifers and groundwater yields are studied using a well database to evaluate the potential installation of the open loop systems in the Nobi plain of Gifu prefecture. The distribution of two aquifers is deduced from that of well screens, and these are getting deep gradually toward the south. The distribution of the groundwater yields indicates that the open loop systems using pre-existing wells have a potential installation in the whole of the study area. The distribution of the groundwater yields drawn from the aquifers shallower than 50m depth shows that the northern part of the study area is a suitable area for the installation of the open loop systems with a well drilling. The potential installation of the open loop systems using the groundwater drawn from the total depth and shallower than 50m depth are 52.9% and 26.0% for the houses in the study area, respectively. These results suggest that the study area has a large potential for the installation of the groundwater heat pump systems. |