Most regions in Germany are suitable for the use of deep geothermal energy to help achieve climate neutrality while also reducing dependence on imported energy. Heat from underground is available regardless of the season or the time of day, which means geothermal energy is baseload-capable. It is also renewable since thermal characteristics and transport processes ensure that heat is replenished in the reservoir.

"Geothermal energy has huge potential. In Germany alone, we could use it to replace a third of the gas we need for heating. Given the climate crisis and the geopolitical situation, we can no longer afford to do without it," says Professor Holger Hanselka, President of KIT and Vice President of the Research Field Energy at the Helmholtz Association. "But to ensure that we can also use the required technologies safely while keeping the environmental impact minimal, we will now continue our development of geothermal energy using GeoLaB."

Doin???????g the Experiments UndergroundGeoLaB, which is short for "Geothermal Laboratory in the Crystalline Basement," will provide innovative large-scale research infrastructure for investigating fundamental questions of reservoir technology and borehole safety underground – at the source of the energy. The Helmholtz Association project partners, along with external partners headed by KIT, will open a new mine in the Black Forest or the Odenwald range. On completion of the mine, a tunnel about a kilometer in length will lead to caverns that will house the world's first underground deep geothermal energy research laboratory. Controlled high-flow experiments (tests in rock at relevant flow rates for geothermal energy) will be performed under a layer of rock at least 400 meters thick.

The Helmholtz Association is making a strategic expansion investment of 35 million euros in GeoLaB to provide research infrastructure for the joint use of its Energy and Earth & Environment research fields. To build GeoLaB, KIT (as the coordinating Helmholtz center and on behalf of the partners GFZ and UFZ) is entering into a partnership with the Bundesgesellschaft für Endlagerung GmbH (BGE), a government-owned company tasked with nuclear waste management.

BGE's involvement is intended to make use of synergies between the energy transition and nuclear waste storage, two major societal challenges. The mining expertise for building GeoLaB will also be made available to BGE. However, there are no plans to build a repository at the GeoLaB site; an earthquake-prone region in or near the Upper Rhine Graben would be unsuitable for that purpose. Instead, BGE's aim is to gain essential experience and expertise in driving a mine in crystalline rock.

Basic Research and Fast Knowledge Transfer"With this underground laboratory, we're breaking new scientific ground and taking a major step forward for geothermal energy research," says Professor Oliver Kraft, Vice President for Research at KIT. "Using advanced methods, we can measure and record thermal, hydraulic, chemical and mechanical parameters to gain a fundamental understanding of geothermal transport processes that will enable us to make valuable contributions to safety research for geothermal energy."

With a view to rapid transfer from research results to practical applications, Professor Susanne Buiter, Scientific Director of the GFZ, adds, "Heat from the ground is a resource that we haven't researched enough yet, let alone put to use. To do this, we need not only data but also fast approval processes and open dialogue with the public. These are also areas where research at GeoLaB will make valuable contributions and enable a knowledge-based approach. Then various forms of geothermal energy could soon begin to contribute to the transformation of the heating supply in many cities."

Research Helps Minimize RisksOne of the reasons geothermal energy has only found isolated use in Germany thus far is concern among citizens about human-induced earthquakes. "Those mainly happen when fluids are injected into a reservoir improperly," says Professor Thomas Kohl from KIT's Institute of Applied Geosciences (AGW), who is the project's scientific coordinator. In principle, however, the use of such enhanced geothermal systems (EGS) is needed in order to make geothermal energy economically feasible at any location, including regions with crystalline bedrock. These rock layers have the best potential for geothermal energy and are essential to future energy security.

According to Kohl, the required flow rates can usually be reached there only with appropriate stimulation measures. "A crucial mission for GeoLaB's research will be to improve our understanding of induced seismicity and to experimentally demonstrate measures for preventing it," he says. Kohl expects the GeoLaB experiments to considerably expand our knowledge of complex processes in crystalline rock at high flow rates. The findings could then be applied to other crystalline reservoirs worldwide.

Applied Research with Modern Methods This is also one of the reasons GeoLaB is being built specifically in crystalline basement rock, according to Professor Ingo Sass, who heads the GFZ's Geoenergy section and is Professor of Geothermal Science and Technology at the Technical University of Darmstadt. "That's because we know that this kind of rock can be reached by drilling from most major German cities," he says. "Knowledge transfer from GeoLaB could be crucial to the heating transformation in conurbations."

"We also want to set new standards for the digitalization of underground labs with GeoLaB," says Professor Olaf Kolditz from the UFZ. "With a digital twin (virtual GeoLaB), we will have modern data management combined with integrated process models so that experiments can be planned and analyzed better to give us a clearer look into the future. We'll also use virtual reality methods, which have already been proved in other underground labs, to make the complex underground processes visible and understandable."

GeoLaB as an Investment in the Future"The use and development of leading-edge observation and analysis methods with GeoLaB will shape the safe and ecologically sustainable use of geothermal energy and underground spaces for generations to come," says GeoLaB's technical coordinator, Professor Eva Schill, who heads the Geoenergy Cluster at KIT's Institute for Nuclear Waste Disposal (INE) and works on GeoLaB with the Technical University of Darmstadt. "As an interdisciplinary and international research platform, GeoLaB will generate synergies and set standards in research in cooperation with our research partners, industry and public agencies."

GeoLaB will also help to educate a new generation of researchers and technicians; a variety of relevant measures is in planning. In addition, a wide range of options will be provided for interaction with the public; activities can be developed and implemented in cooperation with the public and regional interest groups in a co-design process.