Stadtwerke Flensburg and Innargi A/S to explore potential for geothermal energy

Both companies signed an initial letter of intent on May 11, 2023, which defines the further steps to convert part of Flensburg’s district heating supply to climate-neutral geothermal energy.

Dirk Thole, Managing Director of Stadtwerke Flensburg, sees geothermal energy as a suitable building block for climate neutrality:

Assessment of the subsurface

This will also include determining an optimal location for the potential deep drilling and integrating the heat into the district heating system of Stadtwerke Flensburg. Together with all other planned investigations, it will take about a year until all the necessary data is available. Then the project partners will evaluate whether the Flensburg geothermal potential is sufficient to be able to produce enough district heating at a competitive price.

If the result is positive, nothing should stand in the way of a contractual agreement on the construction and operation of a geothermal heating plant by Innargi.

Innargi carry capital costs and drilling risk

In principle Innargi A/S will be responsible for all exploration work and the construction of the geothermal heating plant and its operation as part of the project. Innargi also shoulders the investment costs and carries the risk for the well.

Stadtwerke Flensburg can accept the climate-neutral geothermal energy for their district heating customers and feed it into their heating network, but they can also use cheaper heat sources at their own discretion.

The Danish company Innargi is known worldwide as an expert for medium-deep to deep geothermal energy and has the necessary know-how from comparable projects. Experienced teams of geologists, reservoir, plant and drilling engineers will take on the planning and implementation of the project on site. Innargi relies on partnerships with district heating companies and cities across Europe. The company is currently building the EU’s largest geothermal heating plant in Aarhus, Denmark.

Geothermal energy:

Geothermal energy originates from the Earth’s core. From a depth of two to three kilometres, water with a temperature of 40 to 75 degrees is extracted via a production well. On the surface, the water would have to be heated to the temperature necessary for the district heating network with the help of high-temperature heat pumps. The cooled geothermal water would then be pumped back underground via another well and the cycle would be repeated. Experts assume that the potential for geothermal energy is higher in southern Germany because the water in the subsurface there has higher temperatures, but sufficient heat potentials cannot be ruled out in the north of the republic either. Geothermal energy is available day and night, whether the sun shines or the wind is blowing. It is therefore ideal as a carbon and emission-free base load energy source.

About Stadtwerke Flensburg:

As an environmentally responsible energy supplier, Stadtwerke Flensburg supplies around 60,000 households in the Flensburg region with electricity, district heating and drinking water. By 2025, the Flensburg energy supplier will expand its fiber optic network throughout the city.

The company sells electricity to private and business customers nationwide, as well as natural gas in Schleswig-Holstein. 682 employees, including 54 trainees, work for one of the largest employers and training companies in Flensburg. Stadtwerke is one of the most important heat suppliers in Germany. More than 90% of all Flensburg residents receive their heat in an environmentally friendly way using combined heat and power from the public utility company.

Stadtwerke Flensburg is a 100% subsidiary of the city of Flensburg. Decarbonization and digitization are core topics of the business. Stadtwerke Flensburg wants to become climate-neutral by 2035, if all the general conditions permit.