A Study for the Use of Low Enthalpy Geothermal Water for District Heating

Abstract

Low enthalpy geothermal water in Japan was deposited in generally new sedimental basins (Tertiary and Quaternary). Such basins are found widely, in plains and mountain areas. In particular, many low enthalpy geothermal water resources are in Northern Japan, where the winter climate is very cold. Therefore, the said low enthalpy geothermal water resources are anticipated to be attractive sources of energy, though, so far, they have not been utilized much. The said resources generally exist in layers at over I,OOOm depth. To use these resources, we have to drill geothermal wells, of which the depth may be between I,OOOm to 2,OOOm, and the drilling'costs are estimated at several tens of millions of yen to 2 hundred million yen. Therefore, the district heating will have to be on a large scale so as to utilize an effective system and with a stable heat demand over the long term, because in the case of a smaller scale system an economical system will be unobtainable.