Questions and Answers

GeoLaB (Geothermal Laboratory in a Mine) is a research project focused on the future use of geothermal energy from crystalline rocks. GeoLaB aims to investigate how this heat source can be used safely and sustainably in an underground research laboratory. The project is divided into different phases: The initial phase is the site exploration phase, during which the subsoil is examined in more detail to determine whether the location is suitable for the research laboratory. If the decision is made in favor of the Tromm region (which is planned for late spring 2026), the planning and approval phase will begin. If approved, the construction phase and operational phase are expected to follow starting from 2029.

The world's greatest potential for geothermal energy lies in crystalline rock. To use the heat deep beneath the Earth’s surface in this less permeable rock more effectively — and above all safely — fundamental research is still needed. This is why GeoLaB was initiated.

The goal of the project is to study geothermal energy utilization and develop new technologies to reduce dependence on oil and gas for heating. Additionally, GeoLaB contributes to a better understanding of the geological and hydrogeological properties of the Tromm region. For instance, hydrological monitoring is conducted from the exploration phase onward to analyze the Tromm’s water cycle in detail.

Geothermal energy is a key building block in the global transition toward a climate-neutral energy supply. It plays a crucial role because — unlike wind or solar power — it requires little land, is independent of weather conditions, and offers storage potential. To use this energy source safely and sustainably and to integrate it into heat supply systems, extensive research is essential.

As with any complex field, advancing geothermal energy requires persistence and collaboration among many research teams — much like the development of photovoltaic technology, which became an efficient and widely adopted renewable energy source through decades of continuous research and improvement. Different teams approach the challenges with diverse methods and ideas, and each contributes to creating innovative solutions in the long run.

The GeoLaB research project is part of an internationally connected research landscape, where ongoing exchange of knowledge drives major progress. Germany can take a pioneering role and make important contributions to unlocking the vast energy potential hidden deep within crystalline rock.

Beyond its ecological benefits, large-scale use of geothermal energy also holds economic potential: it can create new jobs, train skilled professionals, and build value chains. In this way, GeoLaB’s research not only supports the heating transition but can also contribute to Germany’s economic development.

The development of geothermal energy involves many different fields: from the rocks that store heat, to technical components such as drilling systems, pumps, and heat exchangers, to economic questions — and finally politics and society, which want to use this energy. Geothermal energy use can therefore be understood as a complex socio-technical system.

Such a system requires research across a wide range of disciplines: production technologies must be environmentally friendly, pumps need to be adapted to new demands, drilling must be made as safe as possible, regulations must be developed, and the heat must be delivered efficiently to consumers.

That is why geothermal research depends on the collaboration of many disciplines — including geosciences, natural sciences such as physics, materials science, process engineering and mechanical engineering, computer science, and the social sciences.

Moreover, such a broad research topic cannot be handled by individual teams or a single laboratory. For example, to ensure that geothermal technologies can be applied to different geological settings, researchers must study various types of rock under different conditions. This is why the GeoLaB team works in close exchange with other underground laboratories and research drillings worldwide. Studying the same challenges in multiple labs accelerates technology development and — especially important — increases the safety of new technologies.

Research at GeoLaB thus adds another important piece to the larger puzzle of climate-friendly energy production from geothermal sources.

The Tromm Massif in the Odenwald region of Germany has crystalline rock that is particularly close to the surface, making it a promising site for investigation. This means that the planned research laboratory will be able to directly observe processes that normally take place deep below the earth's surface when geothermal energy is used. Whether these assumptions are correct and whether the Odenwald is indeed suitable for the research laboratory will be tested during the exploration phase. Only after this phase will a final decision be made on the Tromm site for GeoLaB.

Since June 2024, parts of the area where GeoLaB conducts research are subject to regulations from the general decree of the Bergstraße district for combating African Swine Fever (ASF).

To carry out our measurement campaigns and all related activities, we are in close communication with the General Veterinary Administration of the Bergstraße district. Each measurement campaign and activity is assessed for feasibility. This means that we may need to adjust our campaigns accordingly. The execution of each individual measure must be approved by the Veterinary Office. Only then can the measurement campaigns be conducted in compliance with the rules imposed by the Veterinary Office.

We cannot answer this question yet during GeoLaB’s current exploration phase. Until about the end of 2025, we are still examining whether the Tromm is geologically suitable at all for an underground laboratory. Only if this question can be answered with “yes” will it be possible to identify a specific target area within the Tromm for the underground lab. At that point, the groundwork for the next stage — the planning and construction phase — will be laid.

During the planning phase of a potential GeoLaB tunnel, we will work closely with the affected local communities. It is clear that construction may cause disturbances for residents. We will look for ways to reduce or sensibly manage traffic and minimize impacts wherever possible.

Both the Odenwald and the Black Forest are generally suitable for the study of crystalline rock, as it occurs close to the surface in large areas of both regions.

However, exploring a site to determine its suitability for the research laboratory is complex and costly, meaning it can only be conducted for one area at a time. The decision is based on various scientific criteria as well as political framework conditions. In terms of logistics, the region offers favourable connections to the coordinating research institutions. As a result, the current research efforts for GeoLaB are focused on the Tromm, although the Black Forest is not entirely ruled out as a potential site.

In 2024 and 2025, the project will be in the exploration phase, during which the Tromm area will be examined: What is the geological structure of the Tromm, and is the rock massif suitable for the geothermal research laboratory? To “look inside” the mountain, various exploration measures will be carried out on the Tromm ridge:

• Seismics: The geology is investigated using sound waves generated by vibrations (seismics). Measuring devices (geophones) capture the reflected waves.
• Exploratory Drilling: Exploration drilling involves drilling from the surface with drilling equipment to explore the geological layers in more detail. So far (as of December 2025), two drillings have taken place: The first exploration drilling was vertical and reached 500 meters deep from the Tromm. Core samples were taken along the entire drilling length. The second exploration drilling was carried out from the same drilling site, but at a slight angle, drilling more than 700 meters diagonally into the subsoil.

  The goal of the second drilling was to verify whether the findings from the first drilling also apply to a larger area and to gain a better understanding of the hydraulic and structural properties. After the drilling, tests and extensive measurements were also carried out in the borehole. Therefore, the data collected from this second drilling will be analyzed after its completion.

• Additional Geophysical Measurements: Electrical and magnetic properties of the subsurface will be determined (geo-electrics and geomagnetics). Additionally, the density of the rocks will be examined through gravity measurements (gravimetry).

If the area proves suitable for the research laboratory, the construction phase will begin in 2026, involving an extended planning and approval process. The potential tunnel will then be built into the rock massif from the side.

GeoLaB is a project of the Helmholtz Association, Germany's largest research organisation, which promotes and funds research in various fields, including energy and the environment.

The project is coordinated by the Karlsruhe Institute of Technology (KIT). Helmholtz partners include the German Research Centre for Geosciences (GFZ) in Potsdam and the Helmholtz Centre for Environmental Research (UFZ) in Leipzig. Scientists from these institutions specialising in geology, hydrogeology and geophysics are contributing their expertise to the region.

The research consortium is completed by TU Darmstadt and BGE. The Federal Company for Radioactive Waste Disposal (BGE) is involved as a cooperation partner to gain experience in the development of underground infrastructure. However, its involvement will end when GeoLaB becomes operational. No repository for nuclear waste will be built at the GeoLaB site. The Technical University of Darmstadt is contributing its regional geoscientific expertise, particularly in hydrogeology, to the project.

The Federal Company for Radioactive Waste Disposal (BGE) is involved in the exploration and construction phases of GeoLaB as a cooperation partner. Its participation aims to gain experience in the development of underground infrastructure. However, BGE’s involvement will end once the research laboratory becomes operational.

No nuclear waste repository will be built at the GeoLaB site. The legally regulated site selection process for a final repository is conducted independently of BGE’s fundamental research within GeoLaB.

For more information: New BGE classification 
BGE Site Selection Process

GeoLaB is a project of the Helmholtz Association, Germany’s largest research organization. The project is funded with approximately 35 million euros from the Federal Ministry of Education and Research (BMBF). Additionally, the Federal Company for Radioactive Waste Disposal (BGE) contributes 15 million euros.

This funding covers the exploration phase, the construction, and the operation of GeoLaB. Research activities within GeoLaB are project-based and supported by various public funding sources.

The approval process is a multi-stage process within the framework of the Federal Mining Act (BbergG) with step-by-step individual approval. Reviews and approvals are carried out by the Hessian Mining Inspectorate (RP Darmstadt / Department of the Environment Wiesbaden / Department IV/Wi 44 Mining Inspectorate).

On 15 February 2024, KIT was granted the exploration permit for the Tromm permit area.

This is merely the basic right to prospect for a specific raw material in a defined area. The holder of the exploration licence is not yet permitted to take any technical measures. It is linked to a work programme that serves the geological exploration of the permit area.

In July 2024, an operating licence under mining law for the exploration was applied for and approved in september 2024. This approval includes the application for seismic surveys, geophysical investigations such as geo-electrocs, geomagnetics and gravimetry, two exploratory boreholes and hydrogeological observation measurements.

IAs part of the procedure, the Hessian Mining Inspectorate consults specialist authorities and public bodies (including the affected municipalities and nature conservation organisations). The municipalities are entitled to submit a statement. The authorisation procedure includes, among other things, an examination of the operator's reliability and existing expertise, an examination in accordance with water law, immission control law (regarding possible noise and pollution) and nature conservation law. The Hessian Mining Inspectorate prepares and publishes the authorisation notice.

If the assessment for the Tromm site is positive, the planing and approval phase of the GeoLaB project will begin in 2026: extensive planning and necessary detailed investigations of the subsoil are carried out, the documents for the permits to build the tunnel are prepared and submitted to the Hessian Mining Inspectorate. This authority reviews the documents and again involves the affected communities, among others. Construction of the tunnel can only begin once the licences have been granted.

Citizens affected by mining damages are entitled to compensation from the mining company that caused the damage or the holder of the underlying mining licence (in this case KIT). This also applies to seismic surveys, exploratory drilling or geophysical measurement campaigns.

Further information:

Lexicon of geothermal energy, Federal Geothermal Energy Association: www.geothermie.de/bibliothek/lexikon-der-geothermie/b/bergschadensvermutung

Federal Mining Act: Laws on the Internet: https://www.gesetze-im-internet.de/englisch_bbergg/index.html

The GeoLaB project offers various information services such as this website and a newsletter. Here we report on the latest news, but also provide background information in the form of reports on the topic of geothermal energy, for example.

We organise public events, such as information evenings or participation in markets, in order to engage with the public. Information on past and current events can be found here.

In addition, GeoLaB regularly offers excursions to the exploration sites (construction site for exploration drilling, measurement campaigns) so that interested citizens can be present on site and ask questions to the project team.

Other formats for different target groups (e.g., students) serve to convey knowledge and foster exchange. For example, at the end of June 2025, school classes were invited to a construction site tour at Tromm.