Geothermal potential and sustainable use of karst groundwater in urban areas–Belgrade, capital of Serbia case study

The increase in energy demand due to urban expansion and migration to urban areas has a negative impact on the environment and the city budget. Development plans of cities are more frequently based on the implementation of energy efficiency measures, which among other things include the use of renewable energy sources. In the area of Belgrade, research was conducted aiming for assessing the geothermal potentiality of the field and defining the possibility of groundwater exploitation. The research has been directed to groundwater formed in karst aquifers. Geothermal field evaluation was preceded by the formation of geological and hydrogeological bases, then, the development of a conceptual model of karst distribution in the city area and the systematization of data measured in the observation well network. The potentiality assessment is followed by defining of the conditions and possibilities of the exploitation of karst water as a form of geothermal energy in heat pump systems. In the exploitation of karst water in the city, it is significant to establish mechanisms of sustainable management, especially in terms of protection of resources. In recent years, there has been recorded a constant increase in the number of heating and cooling systems of buildings using groundwater as an energy source in the territory of Belgrade. Potential causes of the negative impact of exploitation of karst water are the overexploitation of resources, creating of the effect of "thermal feedback" as a result of incompetent disposition, namely restoring of groundwater to the aquifer.