Karlovac Geothermal DHS

Karlovac, Croatia

Project overview

The main objective of the Karlovac Geothermal Project is to improve energy efficiency and increase the share of renewable energy in the city’s district heating system by utilising local geothermal resources. The exploration licence for the “Karlovac 1” block was granted in 2019, and the required technical documentation has since been prepared. Initial site preparation works for the new geothermal well, located approximately 6 km from the City of Karlovac, were co-financed by the EEA and Norway Grants under the Energy and Climate Change Programme, in cooperation with the City of Karlovac. Despite this progress, further project development has been delayed due to insufficient funding. The geothermal reservoir is expected to reach a temperature of around 120°C, with an anticipated flow rate of approximately 50 l/s. Based on these parameters, the estimated installed geothermal capacity is 15 MW, with expected annual heat production of approximately 75,000 MWh.

Project Developing Company

GeotermiKA Ltd., Karlovac, Croatia

Background of the project

The geothermal potential of the Karlovac area was already confirmed in the 1980s through the drilling of two geothermal wells located approximately 10 km north of the City of Karlovac, with recorded reservoir temperatures of up to 138°C. Today, Gradska toplana Ltd., the district heating company of Karlovac, is the main provider of thermal energy in the urban area, serving a population of approximately 50,000 inhabitants. Heat is currently produced primarily from natural gas as the dominant energy carrier. In 2024, the district heating system supplied approximately 46,237 MWh of heat to around 7,701 consumers, with a total of about 8,000 residential and commercial users connected to the network. Between 2021 and 2023, the system underwent a significant modernisation programme, including the replacement of approximately 15.7 km of ageing distribution pipelines, thereby improving network efficiency and reliability.

Impact and Strategic importance

  • Integration of geothermal energy into the district heating system
  • Reducing reliance on natural gas
  • Substantial reduction in CO2 emissions, between 50% and 80%, particularly with the addition of a heat storage system+
  • Supplying geothermal heat to at least 50% of the city’s population, and about 300 commercial entities