Under the city of Erfurt lies a little-known underground. The rock beneath the Thuringian state capital and the Erfurt Basin region is considered underexplored. This is one reason why deep geothermal energy is not yet being utilised to provide heat. A new project by Stadtwerke Erfurt is now set to shed light on the situation. It is being scientifically supported by a team from the TU Bergakademie Freiberg. The aim is to create the data basis for the first large-scale geothermal plant in Erfurt: Using a new type of 3D seismic method that will provide precise images from deep underground.
Erfurt and the surrounding area are located in the Central German Crystalline - geologically speaking. And crystalline is a subsurface that presents challenges: "It is primarily the steeply inclined deep faults that make mapping this region difficult," explains Professor Stefan Buske, who is leading the project at TUBAF. Faults are changes in the rock, faults, fractures or fissures. "We want to localise these faults using seismic waves that are emitted into the subsurface during 3D seismics," explains Stefan Buske.
Look deeper with a wide angle
His team and he have further developed the actual 3D seismic method and have already tested it in other projects: it is a 3D wide-angle seismic component that is specifically geared towards great depths of five to seven kilometres. "Wide-angle seismics as an extension of 3D seismics makes a significant contribution to refining the structural geological models at great depths," summarises Stefan Buske. This is an important decision-making aid when it comes to finding the optimal location for the deep boreholes and ultimately the large-scale geothermal plant.
The big goal: a large-scale geothermal plant for Erfurt
Buske and his team will monitor the measurements in the first half of 2026, focusing on the municipalities of Erfurt, Riethnordhausen, Alperstedt, Großrudestedt, Nöda and Udestedt - an area of around 136 square kilometres - and then evaluate them. The data required for further planning of the deep geothermal boreholes should then be available. The main aim of the overall "SeismikEFfizienz" project is to build a commercially viable large-scale geothermal plant to supply district heating to the city of Erfurt. It would be the first large-scale deep geothermal energy project in central Germany.
Erfurt as a pilot project
What is now beginning as an experiment has the potential for follow-up projects. Possible further sites for deep geothermal energy are located in the immediate vicinity of an already extensive district heating network. But you can think even bigger: crystalline rocks (e.g. granite, gneiss) are widespread in Germany, but have not yet been utilised for geothermal heat supply. The 3D wide-angle method can be an important building block in seismic exploration for deep geothermal energy in crystalline rock, even in places where it was previously unthinkable - and is therefore another important step towards a successful heat transition.
Information on partners and financing (total + university share)
SWE Energie GmbH, Dr Ingo Raufuss
Financing: cost estimate € 5.8 million, funding € 2.4 million
DMT GmbH & Co. KG, Dr Boris Dombrowski
Involved in the development of ideas for vibro-wide-angle measurement
Geofizyka Torun, Poland as contractor for the seismics with Geo-Service K. Bittner as subcontractor for the so-called permitting
