Geothermal Isn't Expensive: The Reservoir Always Has the Final Say Somewhere beneath a volcanic ridge, a drill bit is turning through rock that has not moved in two million years. It costs money every second it turns. And nobody on the surface — not the engineer, not the financier, not the minister who announced the megawatts — knows yet whether that well will produce steam or silence. That single moment explains almost everything people get wrong about geothermal energy. Geothermal is routinely described as expensive, slow, capital-hungry and haunted by drilling risk. Investors are reminded that tens of millions can disappear underground before a single megawatt reaches a grid. All of that is true. But it is not the whole truth. The uncomfortable question the industry keeps avoiding is this: is geothermal expensive, or is the way we develop geothermal making it expensive? Those are two completely different problems. One is geology. The other is us. Why Geothermal Refuses to Be...
Ahnsbeck Breakthrough: Lower Saxony’s First Deep Geothermal Project Set to Become a Flagship for Clean Energy
First Deep Geothermal Project in Lower Saxony About to Be Implemented – LBEG President Carsten Mühlenmeier: “Ahnsbeck Could Become a Flagship Project”
Sven Krueger, Managing Director of Baker Hughes, shows LBEG President Carsten Mühlenmeier and SVO Managing Director Holger Schwenke (from left) the drilling rig in Ahnsbeck.
“We are now here else in Lower Saxony as far along as we are here.” With these words, Carsten Mühlenmeier, President of the State Office for Mining, Energy and Geology (LBEG), made it clear during his visit to the drilling site near Ahnsbeck (Celle district) that just twelve kilometers east of the former ducal residence city, the first deep geothermal project in the state could soon become reality. Baker Hughes has encountered rock layers at around 2,500 meters depth that register temperatures of 113 degrees Celsius. In the future, this heat could be used, for example, to supply buildings with heating.
“Up to now, we have issued 42 exploration permits for geothermal energy, 32 of them in Lower Saxony,” explains Mühlenmeier, whose authority also oversees Schleswig-Holstein, Hamburg, and Bremen. But until now, it has not been foreseeable anywhere whether or when a successful deep geothermal project would develop.
A permit issued by LBEG as the mining authority only grants a company the right to search for a specific mineral resource. Over time, however, it usually becomes clear whether and how such projects can be implemented technically. Yet, in deep geothermal projects, the so-called discovery risk often poses a major hurdle. Whether the rock layers deep underground have high enough temperatures and whether these can be tapped can only be determined once drilling is carried out usually requiring investments in the tens of millions of euros. This is often a stumbling block.
“But in Ahnsbeck, it’s exactly the other way around,” notes the LBEG president. The drilling already exists and is showing very good results. “There is now an almost infinite amount of energy available here,” he says. “Ahnsbeck could become a flagship project.” The discovery risk practically no longer plays a role; instead, the focus is now on how to bring the heat to end users. Enough reason for him to inspect the project in person. Representatives from the Federal Ministry for Economic Affairs, the University of Göttingen (which is supporting the project scientifically), the city and district of Celle, and the local utility company SVO also joined the visit.
Host Prof. Dr.-Ing. Sven Krueger readily agreed with Carsten Mühlenmeier’s assessment. “We’ve turned everything upside down here and eliminated the discovery risk. This is unique for an energy supplier,” says the Managing Director of Baker Hughes INTEQ GmbH. “Our DemoCELL project has exceeded all expectations so far,” he adds.
Project manager Dr. Oliver Höhne from Baker Hughes backed this up with numbers. “We have a reservoir temperature of 113 degrees Celsius,” he explains. Normally, at 2,500 meters depth, one would only expect about 75 degrees Celsius. Because Baker Hughes had previously tested numerous drilling tools at this site, the experts already suspected they were on a hot spot. But the current results exceeded all expectations.
Dr. Matthias Franz from the University of Göttingen, which is accompanying the project as a research partner, explained why the values turned out so favorable. At this location, the underground contains a more than 40-meter-thick layer of Rhaetian sandstone, which is particularly well-suited for deep geothermal use. Just a few kilometers further south, this quality of rock is no longer found. This geological formation is similar to that in Mecklenburg-Vorpommern, where deep geothermal projects in Waren an der Müritz (since 1984) and Neustadt-Glewe (since 1994) have been successfully supplying thousands of households with geothermal energy. “Towards Unterlüß, similarly good conditions are likely,” Franz adds, giving an idea of how the formation extends.
That leaves the question of how to get the heat to end users answered by Holger Schwenke, Managing Director of SVO (Stromversorgung Osthannover) Holding GmbH. The head of the regional utility outlined how households in Celle could, in the future, be supplied with district heating from deep geothermal energy. First, the nearby towns of Ahnsbeck and Lachendorf would be connected. There, the waste heat from a paper mill could serve as a “booster” to help bridge the roughly twelve kilometers to Celle without significant heat loss. With its medieval city center, Celle has a strong need for such centralized supply due to space and heritage preservation constraints. Turning to the Federal Ministry representatives, Schwenke summarized the next steps: “Now we’re just waiting for your funding approval, and then we can start our feasibility study.”
Highlighting the importance of geothermal energy, Mühlenmeier concluded that LBEG would showcase it during the “Day of Geothermal Energy” on Friday and Saturday. “At Lower Saxony’s largest geothermal fair for homeowners, builders, craftsmen, municipalities, and utilities, everyone can learn about all aspects of geothermal heating and systems,” he explained.
Further Information:
- More details on the DemoCELL project are available online from Projektträger Jülich, the project sponsor of the Federal Ministry for Economic Affairs and Energy.
- Geothermal energy extracted from more than 400 meters depth is considered a “free-to-mine” resource and falls under federal mining law. By contrast, near-surface geothermal energy up to 400 meters depth remains unaffected.
- LBEG is the responsible mining authority for Lower Saxony, Schleswig-Holstein, Hamburg, and Bremen.
- Currently, there are 42 exploration fields for geothermal energy within the LBEG’s jurisdiction: 32 in Lower Saxony, 7 in Schleswig-Holstein, 2 in Bremen, and 1 in Hamburg.
- In addition to its role as mining authority, LBEG also functions as the Lower Saxony Geothermal Service (NGD), providing neutral and independent expertise on both near-surface and deep geothermal energy, while also developing and maintaining geoscientific foundations.
- LBEG regularly highlights the importance of geothermal energy as a renewable energy source by hosting events for both the public and professionals—such as the “Day of Geothermal Energy” on September 12–13, 2025, at LBEG’s headquarters in Hanover: Day of Geothermal Energy 2025 – Experience Geothermal!
Press contacts:
Eike Bruns, Tel.: 0511 643 2274
Björn Völlmar, Tel.: 0511 643 3010
Email: presse@lbeg.niedersachsen.de
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