Geothermal Development in Slovenia: Country Update Report 2005-2009

Abstract

Direct use of geothermal waters continues to be the only type of use from geothermal reservoir sources in Slovenia, at 29 localities at present. A small progress was achieved in geothermal development during the last five years with four new users appearing in the north-eastern part of Slovenia, belonging to the Pannonian Basin geothermal region. Two of them, still in a testing phase, use thermal water from metamorphic and carbonatic basement rocks respectively, the other two (thermal leisure resort, orchids greenhouses) use the same Upper Miocene-Pliocene aquifer as other users in vicinity. Beside, new reinjection well has been drilled there for a doublet system in Lendava. Due to newish legislation thorough reports on geothermal conditions and present utilization are demanded from the users in recent years, which slowly provoked the monitoring introduction. The installed capacity amounts to 66 MWt and the annual energy use to roughly 773 TJ. Most localities comprise installations that include centralized heating units, thermal spas combined with space heating, and with district heating and greenhouses in a few cases. In addition, ground source heat pumps are also increasingly used, especially in residential applications. There are roughly 3440 ground-coupled heat pump and ground water heat pump units of about 40 MWt capacity removing additional 379 TJ/year in energy use while 13 TJ/yr are rejected to the ground in the cooling mode. The investments were directed for some basic research, but even more for feasibility studies and project implementation with new drillings. Drilling activity reached incredible 23.8 km of new wells, both production and exploration, including the temperature gradient boreholes. Of course, not all wells were successful. For the future prospective geothermal options may include: the adaptation of some abandoned oil wells, small size heat pumps and also groundwater heat pumps of greater capacity, some clusters of ground heat exchangers used for heating or cooling, hopefully some more reinjection wells, and probably multipurpose integrated system.