In May 2026, Finnish energy company Fortum launched an innovative heat plant in Kolabacken, designed to eventually run on waste heat from a nearby Microsoft data centre. The installation is already supplying heat to the network, though the full synergy with the server farm is expected after 2026.
The plant is located in Kolabacken, near Kirkkonummi and the Helsinki-Espoo metropolitan area. A twin unit without a heat storage tank was also commissioned in Hepokorpi, Espoo. Fortum is investing in these low-emission solutions to serve a 900-kilometre district heating network that supplies around 250,000 residents, moving away from coal and gas.
The centrepiece of the project is a 20,000-cubic-metre hot water accumulator – a giant 43-metre-high thermos. The plant also includes two 50 MW induction boilers and 36 water-to-water heat pumps (16 already operational, the rest being phased in). Additionally, 20 air-to-water heat pumps are installed on the roof, currently the primary source of heat alongside the boilers.
A symbiotic model for waste heat recovery
The concept is straightforward: once Microsoft’s data centre is fully operational, its waste heat will be captured and fed into the Fortum plant. Heat pumps will raise the temperature, and the hot water will enter the district network. According to Fortum, over 75% of the data centre’s waste heat can be reused.
– Over 75% of waste heat will be reused – said a Fortum spokesperson.
The system intelligently switches between sources: when electricity prices are high, the accumulator supplies heat; when prices drop, the boilers and heat pumps run, also topping up the accumulator. Financial details of the heat purchase agreement between Microsoft and Fortum have not been disclosed.
Investment costs and decarbonisation targets
The total investment, including land acquisition, reached 20–30 million euros, partially financed by the EU’s NextGenerationEU programme. This makes the project a potential blueprint for similar initiatives elsewhere.
– The heat remains affordable despite the complexity – said the spokesperson – especially because, just like in Poland, we have to watch not only the price but also security of supply.
Fortum aims to produce 95% of its heat using electricity or biomass by 2029. The Microsoft partnership is key to meeting this target, as the waste heat from servers will replace fossil fuels. Until the data centre is ready, the plant relies on air-source heat pumps and induction boilers.
Źródło: WNP.PL, Fot. PTWP
