News / 28.11.2019

Helen investigates possibilities of geothermal heat in Helsinki

Helen is investigating the possibilities for utilising geothermal heat. Central Park (Keskuspuisto) is one of the areas where geological explorations will be carried out jointly with GTK. This is the first time a geological survey is conducted in an urban area to such depth.

Helen is charting potential areas that are geologically suitable for extracting geothermal heat and lend themselves to possible deep drilling. Helen is starting the geophysical exploration of the bedrock in the Central Park area jointly with Geological Survey of Finland (GTK)in early December. The aim is to investigate the bedrock structure to the depth of about 5-8 kilometres.

Such a deep geological survey has never been conducted in urban areas in Finland, and the survey is an important step in making geothermal energy a possibility.

"We are currently investigating various technological solutions from geothermal heat solutions to medium-depth geothermal wells. In the early stages, the coverage of the solutions would be about a block. We are also following the progress of the Otaniemi geothermal heat project – however, we are not planning a similar pilot study," says Senior Vice President Heikki Hapuli.

The exploration method applied at Central Park is reflection seismology. The seismic waves for measuring are produced by two specially equipped trucks vibrating the ground. The vibration creates seismic waves, and their reflection from the bedrock structures is recorded by receivers, geophones, installed on the ground. The field explorations will take a few weeks, and the results will be available in the early part of 2020.

Solutions not based on combustion are sought for replacing coal

Helen will close the Hanasaari power plant in 2024 at the latest, and it will also discontinue using coal in Salmisaari by the end of 2029.

Helen is seeking methods that are not combustion-based to replace the heat production from the Salmisaari power station. Heat may be produced by methods like heat pumps from various waste heat sources and environmental heat, such as sea water and geothermal heat. One of the potential solutions is deemed to be geothermal energy.


  • Helen will launch geophysical explorations in the Central Park area jointly with GTK in early December.
  • At Central Park, the method applied is reflective seismology, with the seismic waves for measuring produced by two specially equipped trucks vibrating the ground.
  • Once the suitable locations for utilising geothermal energy have been mapped, Helen will investigate the most suitable technology for drilling.
  • One of the challenges of geothermal energy is Finland's cold ground, which is why the drillings must be deep.
  • A further challenge is finding the right kind of know-how for making a geothermal heating plant a reality.

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