Heating accounts for half of the world’s energy consumption, and the majority still comes from fossil fuels. This challenge calls for new solutions – a rethinking of how we produce heat.
That is exactly what we are doing with our project in Aalborg.
With this full-scale demonstration project, we are testing a new type of geothermal solution, Heat4Ever™, designed to deliver renewable, stable, and local district heating – without significant CO₂ emissions and without visible impact on the surroundings. If we succeed, we will have an alternative that can be scaled – in Aalborg, across Denmark, and internationally.
This project matters to all of us: For you, by providing access to renewable geothermal heat. For Denmark, by adding a new tool to the green transition. And for Green Therma, by taking a crucial step toward making sustainable geothermal heat available to everyone.
At Green Therma, we approach the development of future heating solutions with great responsibility. Our demonstration project in Aalborg is a key step in expanding the use of renewable geothermal energy, and we want to keep you, as a neighbor, well informed along the way. Here is an overview of how we expect the project and its individual phases to unfold.
The drilling and installation phase lasts about three months, during which nearby residents may notice increased activity at the site. For us, it is important to give those affected the best possible experience. That’s why we strive to maintain close dialogue throughout the process.
We use safe, environmentally approved, and recognized drilling methods – the same type used when drilling for drinking water.
Green Therma covers all costs and thus the risk of the project. We have entered into a 30-year fixed-price heat supply agreement with Aalborg Forsyning. Customers of Aalborg Forsyning will not be impacted financially.
We expect seismic surveys to begin in late 2025.
Drilling of the well is expected to start in autumn 2026.
Drilling the well takes about three months. The full construction period with site activity will last about six months.
We expect the facility to be completed in 2027.
We drill the well using proven methods and experienced engineers, operators, and drilling experts. A drilling rig with a 40-meter tower will be installed. The fenced site will cover roughly the size of a football field. The well will be about one meter in diameter at the surface, and drilled in sections that gradually narrow with depth.
No. The drilling is carried out under strictly controlled conditions, and the area will be closed off while work is underway.
The drilling passes through groundwater layers. This is a well-known process, similar to drilling for drinking water, and poses no risk of groundwater contamination.
No, we do not use this technique. In fact, no material extraction takes place underground. The only thing utilized is the naturally occurring heat, which is transferred to the surface through circulating water in a closed system.
The system consists of a closed well with an insulated pipe inside. Water is pumped down along the outside of the pipe.
In the horizontal section, the water is heated through thermal conductivity from the surrounding geology. The hot water is then transported up through the insulated pipe and used for district heating.
No. It is a closed-loop system. Water is pumped down, heated, and brought back up again. The underground functions only as a heat source.
No. The main power consumer is a circulation pump with up to 50 kW capacity, compared to a heating output of up to 2 MW.
When completed, the facility will take up no more space than a 20-foot container, housed in a small building.
We expect the facility to operate for at least 50 years without significant refurbishment.
The facility is expected to provide up to 2 MW of heat. Aalborg Forsyning will distribute this within the overall energy supply.
No. The facility has no CO₂ emissions during heat production and only very low electricity consumption, which comes from certified renewable energy. The closed-loop water system ensures no environmental impact.
No. During operation, there will be no noise, odors, or pollution. The facility requires minimal space and maintenance.
No. Cooling occurs in a cylindrical area with a radius of 100–200 meters around the well at depths greater than 4 km. This has no effect on life at the surface.
No, Green Therma assumes all costs and therefore the full risk of the project. A 30-year fixed-price heat agreement has been signed with Aalborg Forsyning. This means that ordinary district heating customers in Aalborg will not risk paying any kind of bill from a failed project.
Any questions?
Contact project manager Mads Sylvest Eegholm at +45 51 49 22 04 eller e-mail mse@greentherma.com.
