Geothermal potential in the Romanian Part of the Pannonian Superbasin

The Pannonian Basin is a large sedimentary basin complex situated in southeast Central Europe, covering parts of Bosnia-Hercegovina, Croatia, Slovenia, Austria, Hungary, Slovakia, Ukraine, Romania, and Serbia. Average geothermal gradients in the Pannonian Basin vary strongly with depth from 60°C/km in the first 1500 m to 45°C/km on average in the deeper parts. The geothermal potential of the eastern part of the Pannonian Basin is seen primarily in the use of low-medium enthalpy systems mainly focusing on heat production for district heating systems. Other industrial processes like food processing, greenhouses also require an operating temperature of about 90-150°C. Similarly, the Romanian segment of the basin displays significant low enthalpy geothermal resources (<125°C) that are suitable mostly for direct heat utilization and balneology, both already established around Oradea. Currently, geothermal energy production in Romania plays only a minor role in the national energy mix despite of its considerable potential, given by geothermal gradients ranging from 40 to 60°C/km. Our evaluation shows that the existing geothermal plays like Triassic and Cretaceous are not the only ones to be targeted since they are not present everywhere in the region. Other plays, like the Upper Pannonian clastic series in the right depth interval or the crystalline basement, can be a potential geothermal play. To unlock the full geothermal potential of the Romanian Pannonian Basin, all potential geothermal technologies need to be considered depending on their feasibility based not only on the geological settings, but also on the usage demand and available infrastructure. Given the prevailing high thermal gradients the required technological solution may include all possible geothermal systems, from ground water heat pumps to geothermal doublets, and even enhanced to advanced geothermal systems.