The St1 geothermal pilot project in Otaniemi, Espoo, makes its geothermal wells available for research use, as a research group led by the University of Helsinki carried out measurements at the wells.
Two geothermal wells were drilled between 2016 and 2020 for St1’s geothermal heat plant pilot project in Otaniemi, Espoo. The wells are over six kilometres deep, and the bedrock in them reaches a temperature of about 120 degrees Celsius. The project was halted due to an inability to generate a sufficiently high flow rate between the wells, and the output of the planned heat plant would not have been commercially viable.
The deepest wells in Finland, drilled into hard Finnish bedrock, have garnered much interest as a research subject, so to make the wells as useful as possible, St1 wants to make them available for research use. The actual work began in autumn 2024 when the University of Helsinki, in cooperation with the Finnish research institution VTT and the German Research Centre for Geosciences (GFZ), measured the well temperatures to a depth of five kilometres and collected numerous water and gas samples for microbiology and geochemistry research at different depths for two weeks. The wells provide an international and completely unique research environment for the development of geothermal energy and other Earth sciences to deep microbiology.
"Our research project combines the study of bedrock temperature, the composition of groundwater and microbiology. The highly saline groundwater of the bedrock, which contains up to 170 grams of salt per litre of water, is home to a wide variety of microorganisms that are studied in the project. The temperature at a depth of five kilometres is around 100 degrees. Undisturbed temperature measurements and sampling have not previously been possible at such a depth in Finland. One exciting thing is that you can still see the cooling effect of the ice age in the temperature data. Our research brings new perspectives to basic research and improves baseline knowledge on rock conditions for the future use of geothermal energy. Next, we will carry out a more detailed analysis on what the measurement results and samples tell us," says project leader Ilmo Kukkonen at the University of Helsinki’s Department of Geosciences and Geography.
"The geothermal pilot project in Otaniemi was a significant investment for St1 in which we created something completely new. It's great that the special environment created by the Otaniemi project can be utilised for research purposes, and we hope that the data obtained from the site can contribute to the creation of new innovations," says Erkki Mäkelä, CEO of St1 Lähienergia, a company focusing on geothermal heating at St1.
The research work carried out in Otaniemi was a test project, and St1 wishes to also enable research work at the site in the future. The international research group led by Kukkonen has already made preliminary plans on how to make use of the wells.
The Otaniemi project as a trendsetter in the development of geothermal energy
We have been able to bring the expertise gained from Otaniemi into the development work for shallow geothermal wells, which is producing even more competitive results than before for larger properties, such as the heating of housing companies and shopping centres. The advanced geothermal heat solutions will play a significant role in the transition to low-emission heat production. The energy transition requires both open-minded innovation work and significant investments in new low-emission energy solutions.
Photos from St1's geothermal wells in Otaniemi, Espoo, during the research project:
Main image of the news: St1's two deep geothermal wells (inside the construction fences) from the Otaniemi geothermal pilot project in Espoo. (Photographer: Veikko Luukkonen)