Aalborg CSP supplies heat pump station to EU’s largest geothermal project

Danish renewable energy specialist, Aalborg CSP, has partnered with the Danish geothermal heating company, Innargi, to supply an integrated heat pump station of approx. 18 MW for a large geothermal project in Aarhus, Denmark. The heat pump station, equipped with a 10 MW electrical heat pump, will capture energy from underground geothermal water, which will then be transferred to the client’s supply area in the northern part of Aarhus.

Solar and wind energy have proven to be valuable assets in the green energy transition, but how do we produce energy when the sun is not shining, and when there is no wind? The answer lies beneath our feet. The Earth's core holds infinite amounts of renewable energy in the form of geothermal heat.

Geothermal district heating for the second largest city in Denmark

Both Innargi and the Danish utility company Kredsløb have recognized the potential of using geothermal energy for district heating purposes and have therefore entered into a collaboration to bring geothermal heating to the city of Aarhus. The parties are currently working on a project that, when completed, will consist of 14-17 geothermal wells distributed across seven locations in Aarhus. With a total capacity of 110 MW, the geothermal system will cover up to 20% of the district heating need within the Kredsløb supply area. This is equivalent to the annual heat consumption of 36,000 households. The entire facility is expected to be completed by 2029 and will be the largest of its kind within the EU.

Customized heat pump solution optimized for geothermal heat

The groundbreaking ceremony has already taken place in Skejby, Aarhus, where the first geothermal plant is expected to deliver its first sustainable energy during the second half of 2025. Following a tender process, Aalborg CSP was selected by Innargi as partner on the project. Aalborg CSP has designed a modular hydrocarbon-based heat pump, capable of handling the - at times - fluctuating flow of the geothermal water while delivering the desired high supply temperature. The complete heat pump station in Skejby will be able to provide up to 18 MW of heat and a temperature of up to 95° C to the local district heating network.

"Innargi brings fantastic know-how and deep expertise in geothermal energy, and we share their ambitious goal of creating the most affordable district heating possible. We are extremely honoured and proud to contribute with our experience in heat pumps, integration, and project management in realizing a groundbreaking piece of district heating infrastructure together with Innargi. This will potentially benefit cities not only within Denmark but also across Europe," says Svante Bundgaard, CEO of Aalborg CSP.

In addition to a heat pump station optimized for geothermal energy, it has been crucial to design and construct a building standard that both Innargi and Kredsløb can utilize for future geothermal plants. Moreover, the building design is required to meet specific visual and architectural demands to ensure that it blends into the local environment at the location.

“We are very pleased with the solution – and not least the collaboration – we have developed with the team at Aalborg CSP over the past few months. The facility on Skejbyvej will be the first of its kind in Aarhus. Finding the best and most long-term solutions has been a central element throughout the collaboration process. This will enable us in delivering stable, green district heating to the people of Aarhus for many years to come,” says Lars Bjørn Heineke, Project Manager at Innargi.

As a result, Aalborg CSP has developed a building design as well as an optimized design for the technical installations in close collaboration with Innargi's technical team.

The building is expected to be completed by January 2025, after which the installation of the heat pump and technical systems will commence. The heat pump station will be operational in the fall of 2025.

Project facts

  • Client: Innargi
  • End client: Kredsløb
  • Capacity:
    • Heat pump: 10 MW at a temperature of up to 95° C
    • Complete plant: 18 MW at a temperature of up to 95° C
  • Refrigerant (natural): Hydrocarbons (isobutane and propane)
  • System supplier: Aalborg CSP A/S in collaboration with Solid Energy A/S (heat pump), Svend Aage Christiansen A/S (building) and Soft & Teknik (electrical)
  • Scope of supply: Heat pump station including building, heat pumps, and technical installation
  • Location: Skejby, Aarhus, Denmark
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