GEOTHERMAL RESOURCES AND DEVELOPMENT IN THE REPUBLIC OF KOREA

摘要

Geothermal in Korea is characterized by an absence of high-temperature resources for power generation. Hot springs are associated with localized, deeplyconnected fracture systems mostly in granite areas. Geothermal utilization in Korea has, therefore, been of direct-use only, mainly in public baths with lowtemperature geothermal water from a hundred wells hitting deeply-connected fractures. Recently a high heat flow anomaly was identified in the Tertiary sediment area in the south-eastern part of the Korean Peninsula The first low-temperature geothermal development project is currently being carried out at this location by the Korea Institute of Geoscience and Mineral Resources (KIGAM) for the purpose of district heating. Geothermal heat pump installation is now booming; the number of installations and total produced energy approximately double annually. There are strong government subsidizing programs for fostering renewable energy and the total estimated subsidy for geothermal heat pump installations in 2006 reached US $11.8 million, twice that of the previous year. One reason for the increasing number of geothermal heat pump installations is that the fluctuation in groundwater temperature and amount of extractable water varies little throughout the year. In Korea, for example, the amount of groundwater used for residence and industry in 2007 was 5.5 million m3/day, which can be utilized for heating and cooling buildings nearby with groundwater-source heat pump system. The fact that it does not require any drilling cost when connecting heat pumps to existing groundwater well heads or pipe lines, offers great opportunity for expanding geothermal utilization. There are also several ongoing Research, Development and Demonstration (RD&D) works for utilizing thermal energy of alluvial groundwater in urban and suburban areas. The fact that the thermal properties of subsurface such as thermal conductivity and volumetric heat capacity are the main factors controlling heat exchange rate in borehole heat exchanger was the motivator to initiate a nation-wide thermal property compiling program in which a total of 1,560 rock samples have been collected, measurements been done and then compiled into database system. First geothermal assessment ever tried in Korea has been recently made and the result shows that the total amount of heat down to 5 km beneath Korean territory reaches 105 EJ which corresponds to ten thousand times the annual primary energy consumption.