Green Therma has successfully deployed its Heat4Ever technology under real geothermal operating conditions at the GFZ Helmholtz Centre for Geosciences’ geothermal research site in Groß Schönebeck, Germany.
The Danish geothermal technology company said in a statement that the demonstration marks an important step from installation to operation.
Water is now circulating through the closed-loop system, vacuum integrity of Green Therma’s DualVac insulation technology has been established, and geothermal heat is being brought from more than three kilometres underground to the surface at temperatures suitable for direct use, according to Jørgen Peter Rasmussen, the company’s founder and CEO.
“The heat is already there, right beneath our feet. We need to get better at using this enormous natural resource and bringing it to where people and industries need it,” he said.
“What we have demonstrated at Groß Schönebeck shows that we can access deep geothermal heat and bring it to the surface at temperatures that can be used directly without heat pumps. We are turning the heat beneath our feet into a new source of baseload heat – available around the clock and with very little electricity use.”
Deep geothermal heat has extensive potential as a stable, local source of renewable energy, but its deployment has traditionally been limited by the availability of suitable underground hot-water reservoirs.
Green Therma’s Heat4Ever system takes closed-loop geothermal technology one step further by delivering more heat to the surface at higher temperatures.
The company believes this could significantly expand where geothermal heat can be produced, bringing it closer to cities and industrial sites without relying on underground hot-water reservoirs.
With its system now operating, continued testing at Groß Schönebeck will generate further data on long-term performance, stability, and heat-extraction potential under different operating conditions.
The project is being carried out in collaboration with GFZ at its Groß Schönebeck geothermal research site north of Berlin.
“Groß Schönebeck provides a unique opportunity to investigate this technology under real-world subsurface and operating conditions,” said Prof. Dr. Hannes Hofmann, Leader of the Helmholtz Young Investigator Group Advanced Reservoir Engineering at the GFZ Helmholtz Centre for Geosciences.
“The operational test will now generate valuable scientific data on long-term performance and help us evaluate the potential and integrity of closed-loop geothermal systems.”
Prof. Dr. Ingo Sass, Head of the Geoenergy Section at the GFZ Helmholtz Centre for Geosciences added that data from full-scale operations will be essential to turning promising geothermal concepts into proven solutions.
“Groß Schönebeck helps bridge the gap between research and application by generating the data that will allow us to challenge assumptions, improve our models and advance the next generation of closed-loop geothermal systems.”
Green Therma is already taking its technology to full scale in Denmark with a project developed in partnership with Aalborg Forsyning.
This project will bring Heat4Ever from demonstration to commercial-scale operation, delivering geothermal heat directly into the local district heating network under a 30-year heat offtake agreement.
Preparation is underway, and drilling will begin in early 2027.