Heat supply starts from deepest geothermal borehole in Estonia
Opening of the Arbavere geothermal pilot plant in Estonia (source: K. Viikoja / Geological Survey of Estonia)
Carlo Cariaga
13 Oct 2025
The Geological Survey of Estonia has started heat supply from a 712.5-meter borehole in Arbavere in Estonia, currently the deepest thermal borehole in the country.
The Geological Survey of Estonia (EGT) has built the deepest geothermal borehole in Estonia, drilled to a depth of 712.5 meters. The borehole is located in the village of Arbevere in Lääne-Viru County, where it now provides heating and cooling to the buildings of the Geological Survey’s research center.
The Arbavera pilot project uses a coaxial pipe, which is the first time that such a pipe architecture was used in Estonia. Water flows along the middle of the pipe which then goes through a heat exchanger before the water is reinjected through the annular space. The thermal capacityof the borehole is 40 kW.
Three geothermal heat pumps have been installed in the building to increase the temperature, and a cooling system has been installed in one building. The heating and cooling network is equipped with a 5G-based smart control system, enabling advanced energy management.
The drilling work was carried out by OÜ Inseneribüroo Steiger in cooperation with the Finnish company QHEAT. The installation of pipelines and equipment, including heat pumps, and automation work were carried out by Coron O, AindPRO, and K&S Torutööd. Tests are also ongoing to evaluate the feasibility of using the borehole to store residual heat generated during summer.
The Arbavere geothermal pilot plant is one of the three projects under the GEOENEST program, launched in 2021, of the Geological Survey of Estonia. The first two project have already started operations – the semi-deep geothermal pilot in Tallinn, and a pilot geothermal district heating network in the small township of Järva County in Roosna-Alliku. The total cost of the Arbavere pilot was EUR 1.3 million, while the total cost of the GEONEST projects is EUR 3.8 million.
The use of geothermal energy solutions in Estonia has grown rapidly in recent years – in 2024 alone, over 1,500 new thermal wells were built. According to EGT, geothermal energy is one of the key technologies that helps ensure the independence of Estonia’s heat supply from fossil fuels. “Together with increasing the energy efficiency of buildings and upgrading heating systems, the use of geothermal energy is an opportunity to reduce both energy consumption and costs,” commented Helena Gailan, Head of the Geothermal Energy Department at EGT.
Source: ERR and Geological Survey of Estonia
