Perspective of Shallow Geothermal Systems in the Republic of Croatia

¹ University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Zagreb, Croatia
² University of Zagreb, Faculty of Mining, Geology and Petroleum Engineering, Zagreb, Croatia

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Abstract

Owing to its favourable geological and hydrogeological conditions, the Republic of Croatia possesses substantial potential for the exploitation of shallow geothermal energy. This potential has been acknowledged in the national energy policy framework, particularly within Croatia’s Integrated National Energy and Climate Plan, which outlines strategic directions for the wider deployment of geothermal heat pump technologies. Early systematic research on ground-source heat pump systems was conducted within the project Heat Pumps Coupled to the Ground as a Renewable Energy Source (2007–2013). Further in-situ investigations were carried out through the IPA IIIC project Research and Promotion of the Use of Shallow Geothermal Potential in Croatia – GeothermalMapping (2013–2015), during which soil thermal properties were determined at eight representative locations using the advanced Distributed Thermal Response Test (DTRT) method. The resulting dataset provided a valuable national reference for assessing shallow geothermal potential and supported both technology promotion and stakeholder education. Subsequently, several international initiatives, including Interreg, Horizon and EED projects, have further contributed to the development and dissemination of shallow geothermal technologies in Croatia.

The first comprehensive assessment of heating and cooling systems utilizing shallow geothermal energy in Croatia was conducted within the PLIGES – Mapping of Shallow Geothermal Systems in the Republic of Croatia project (2023–2024). The project established a national database of installed geothermal heat pump systems, complemented by a continuously updated interactive GIS platform. The collected data indicate a nearly equal distribution of systems using groundwater and soil as heat sources or sinks. Annual thermal energy production from shallow geothermal installations is estimated at approximately 70,000 MWh, corresponding to a reduction of about 12,000 tonnes of CO₂ emissions. The project was implemented by the University of Zagreb and funded by Iceland, Liechtenstein and Norway through the European Economic Area (EEA) Financial Mechanism 2014–2021.