Geothermal potential, chemical characteristics, and utilization of groundwater in Serbia

To collect and unify data about all geothermal resources in Serbia, a database was formed. The database allows us to perceive the geothermal resources of Serbia and their potential for utilization. Based on the data available in the geothermal database, the estimated temperatures of reservoirs, heat power, and geothermal energy utilization were calculated. The database contains 293 geothermal records (springs, boreholes) registered at 160 locations, with groundwater temperatures in the range between 20 and 111 °C. The maximum expected temperature of the reservoir is 146 °C according to the use of a SiO 2 geothermometer. Some thermal water is cooled due to mixing with cold, shallow water. Geothermal resources are mostly used for balneology and recreation, and less for heating, water supply, bottling, fish and animal farms, agriculture, and industrial. 26% of all geothermal resources is used by the local population or has not been used at all. The annual utilization of geothermal energy for direct heat is 1507 TJ/yr, and the estimated capacity of geothermal energy in Serbia is 111 MWt. The results of analytical work were presented in the form of maps with a geological and hydrogeological background. Thermal waters are mostly located within an area of Tertiary magmatism. Three geothermal potential areas are identified in Serbia: Pannonian basin-Vojvodina Province, the Mačva-Srem area and area from Jošanička Banja to Vranjska Banja (southern Serbia). Based on chemical analyses, four hydrochemical facies are distinguished. Thermal water mainly belongs to the NaHCO 3 or CaMgHCO 3 hydrochemical facies, usually depending on the primary aquifer type: karst, karst-fissured, intergranular or fissured.