成果報告書詳細
管理番号20160000000539
タイトル*平成27年度中間年報 再生可能エネルギー熱利用技術開発 再生可能エネルギー熱利用のポテンシャル評価技術の開発 オープンループ型地中熱利用システムの高効率化とポテンシャル評価手法の研究開発  
公開日2016/9/7
報告書年度2015 - 2015
委託先名国立大学法人岐阜大学 東邦地水株式会社 株式会社テイコク
プロジェクト番号P14017
部署名新エネルギー部
和文要約
英文要約1. Developments on the optimized backwash technology and the heat exchange unit for groundwater use.
Two 20 m circulation wells (Y-1, Y-2) and a 50 m heat exchange well (Y-BH1) have been installed in Yokkaichi site, in where the aquifer consists of a sand layer including finer sediments and the other sand layer including gravels. The pumping-up and injection capacities of Y-1 are higher those that of Y-2. From the temperature measurements, Y-2 shows a uniform temperature from the earth surface to the bottom, while Y-1 exhibits a lower temperature of ca. 15.2 ‹C along the screen. From the inside observation of the wells using a borehole camera, groundwater is muddy below the top of the screens, especially in Y-2. The reasons of lower temperature of Y-1 and muddy groundwater of Y-2 may be caused by the pumping-up of the pre-existing well. Lower temperature of Y-1 suggests the presence of the localized groundwater flow, and this should be resolved before the groundwater circulation experiments. The continuous groundwater monitoring will be performed to understand the reason of the lower temperature. The muddy groundwater of Y-2 indicates the presence of finer grains in groundwater. These are considered to be a possible material clogging injection wells. The effective thermal conductivity (ƒÉs) is estimated to be 1.80 W/mK from a thermal response test.
2. Development on the application technology of driven wells and water infiltration inlets, and development on the combined system of tank heat exchangers and water infiltration inlets
A 20 m observation well with water level and temperature sensors has been installed in the site with a pre-existing water infiltration inlet to monitor the temperature change due to the heated and cooled groundwater injections. The underground geology is clarified to be mainly gravel layers, and a sand layer with a thickness of ca. 1 m is intercalated.
3. Development on potential assessment technique for open-loop systems of geothermal heat pumps
A simulation study was performed to estimate the underground temperature change accompanied by heated and cooled water injections. The target is Gifu site, in where an open-loop system of the geothermal heat pump will be installed for a demonstration experiment in next fiscal year. The result of this study shows that slight temperature change (e.g. 0.2 ‹C) occurs widely in the downstream side of groundwater and that severe change (e.g. 1.0 ‹C) is limited near the injection wells. This result is considered to be caused by a rapid groundwater flow in Gifu area, and is treated as a basic understanding to decide the well locations for a demonstration experiment.
For the development on the inversion technique of thermal response test, pre-existing publications have been collected to understand the present understanding for the groundwater flow and hydrogeolocial conditions in the alluvial fan of the Nagara River. Based on this literature survey and site survey, three possible sites for thermal response tests were selected.
Cooled water injection tests were performed to understand temperature changes in two aquifers intercalating a thin sand layer. When cooled water was injected into an aquifer, temperature change was recognized not only this aquifer but also the other.
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