Green Therma to evaluate feasibility of closed-loop geothermal solution for Wismar, Germany
Harbor in Wismar, Germany (source: Jo Vert, CC BY-SA 4.0 
Carlo Cariaga
14 May 2026
Green Therma will be working with the municipal utility company in Wismar, Germany to evaluate the feasibility of deploying a closed-loop geothermal solution.
Danish geothermal technology company Green Therma has signed a letter of intent with municipal utility Stadtwerke Wismar GmbH to jointly examine the potential of using closed-loop geothermal to supply the local district heating network in the city of Wismar in Mecklenburg-Vorpommern, Germany.
The project will specifically evaluate the feasibility of deploying Green Therma’s Heat4Ever technology, a single-well closed-loop geothermal solution that is said to deliver heat without the requirement of underground water reservoirs or special geology. Demonstrations projects for this technology are already underway in Aalborg, Norway and in Groß Schönebeck, also in Germany.
The project will follow a structured, step-by-step approach, beginning with a preliminary feasibility study that includes a geological survey, a technical assessment, and an initial economic evaluation. If the results are positive, both parties intend to conduct a full feasibility study. The collaboration could form the basis for a future geothermal project that will support the utility’s goal of decarbonizing its heat supply and diversifying energy sources.
“Utility companies are looking for reliable and scalable solutions to decarbonize district heating. Together with the Wismar municipal utility, we are pursuing a structured approach to integrate our Heat4Ever™ technology into existing heating networks and enable a reliable, low-carbon heat supply,” said Jørgen Peter Rasmussen, CEO of Green Therma.
“We are committed to transforming Wismar’s heat supply into a more sustainable and future-proof system. This collaboration allows us to examine how geothermal energy can become a reliable and long-term component of our district heating network,” added Uwe Rühleman, Managing Director of Stadtwerke Wismar.
Source: Green Therma
