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Covenant of Mayors - Europe
News article10 October 2023

Stockholm, Sweden : Heat recovery from data centres

Stockholm’s initiative to attract data centres to the city and capture their excess heat in the city’s district heating network has allowed it to boost its IT industry while reducing the system’s emissions by 50g of CO2 per kilowatt hour.


New tech for an old network

Stockholm has positioned itself at the forefront of climate action, striving for climate positivity by 2040. This goal necessitates innovation, and repurposing excess heat plays into this by promoting energy efficiency and reduced waste. The strategic redirection of excess heat from data centres into district heating is an important step along this road.

With a robust district heating network that began in the 1950s and now spans 3,000 km, and a district cooling system covering 300 km, Stockholm’s infrastructure capacity for heat recovery is significant. By 2030, Stockholm Exergi aims for its district heating to be generated entirely from renewable and recovered sources. Open District Heating, introduced in 2014, assists in this by facilitating industries that produce excess heat to feed that heat into the network, rather than wasting it.

Since the inception of Open District Heating, the initiative has seen the integration of various heat-producing entities into its network, notably data centres. Due to their constant need for cooling, these facilities are prime candidates for heat recovery. By 2022, Open District Heating had partnered with 20 suppliers, recovering enough heat to warm 30,000 modern apartments annually, thus reinforcing the concept’s viability and efficiency. This initiative was essential in setting the stage for the more expansive Stockholm Data Parks project, which started discussions around three major sites in 2017.

Mutual effort, mutual benefits

The Stockholm Datapark initiative didn’t emerge in isolation. It was the outcome of collaborative endeavours involving multiple stakeholders, including the municipality. Stockholm Exergi, a joint venture, is 50% owned by the city and 50% by an investment consortium, Anchiale. 

Key collaborators in this initiative include Invest Stockholm, the Planning Office, Ellevio (the power company), Stokab (a fibreoptic cable company) and Stockholm Exergi. Together, they’ve established a cohesive system allowing data centres to easily navigate the complexities of establishing themselves in Sweden, connect to the district heating network and contribute to Stockholm’s sustainability goals.

The municipality’s motivation stems from its commitment to becoming both an energy-efficient city and a city with a strong local economy that benefits from international investment. 

Lesson learned 

Collaboration between the city, Stockholm Exergi and data centre companies demonstrates the importance of a cohesive approach to sustainability. 

The success of Stockholm's initiative has garnered international interest, While the model offers an appealing roadmap for urban sustainability, it is contingent on existing infrastructure, particularly a district heating network. However the recent elimination of a Swedish tax break on electricity for data centres has reduced the incentives for new centres to pen, and the initial investment costs for both parties are very high.

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Publication date
10 October 2023