Potentials of transboundary thermal water resources in the western part of the Pannonian basin

In this paper we investigate hydrogeological aspects of eleven geothermal aquifer types in four countries in the western Pannonian basin, and their development potential. Most thermal waters outflow with temperature below 50 °C, and are used for bathing, drinking, industrial water supply, space and water heating. Geothermal electricity is produced only in Austria at a small pilot plant. Low share of direct use is coupled by small number of reinjection wells. Waste thermal water is produced at 149 user sites and by 307 objects, and shows rather low thermal efficiency of exploitation. Annual production of thermal water sums to approximately 40 million m3, and the Pannonian-Pontian clastic and the Mesozoic carbonate rocks form most productive and transboundary aquifers. The innovative approach and field investigation enabled identification of potential of inactive wells which sums to 4.7 million m3 of thermal water per year, while the legislative potential is estimated to be approximately 58.8 million m3 per year. Since depletion of many geothermal aquifers is already evident, such increase in production might be hydrogeologically unfeasible, at least if no improvements in utilization technology are made. In order to exploit the vast identified potentials without major investments in new production wells, we recommend optimization of exploitation and extensive implementation of reinjection wells in this transboundary region.