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...
Deutsche Erdwärme Starts Long-Term Geothermal Test in Graben-Neudorf
By: Robert Buluma
After months of inactivity, the geothermal project in Graben-Neudorf (Karlsruhe district) is springing back to life. Deutsche Erdwärme has initiated a long-term test to evaluate the productivity of its 3,600-meter-deep borehole. The test, expected to run for two to three weeks, is seen as a critical step in determining the feasibility of large-scale geothermal energy production at the site.
The central question: Is the geothermal well as productive as Deutsche Erdwärme anticipates? According to reports by SWR, water will be pumped into the underground reservoir, followed by seismological measurements and pressure tests. These activities aim to determine the operational conditions required for safely running a future geothermal plant.
Herbert Pohl, CEO of Deutsche Erdwärme, noted that such a long-term test is unprecedented in Germany and in the Upper Rhine Valley. While geothermal exploration in Graben-Neudorf has been ongoing for decades, this advanced stage of the project focuses on securing sustainable heat extraction and simulating plant operations. Systematic geothermal studies at the site date back more than 30 years.
During the test, significant amounts of water will be injected into the hot underground reservoir. Pressure will be applied carefully to avoid triggering significant seismic events, preventing incidents similar to those experienced in Basel or Landau.
A key goal of this long-term test is to ensure a reliable supply of heat for a regional district heating network. At a minimum, the communities of Graben-Neudorf and the city of Bruchsal are expected to benefit. Deutsche Erdwärme is also in discussions with additional municipal utilities. Further drilling is planned nearby in Dettenheim, although regulatory conditions are still being finalized.
If everything goes according to plan, a second borehole will follow next year in Graben-Neudorf—essential for the eventual operation of the geothermal plant. However, exact dates are not yet confirmed. Only a few specialized drilling rigs in Europe are capable of reaching these depths, so work will resume once equipment becomes available.
With temperatures exceeding 200°C at around 3,600 meters deep, Graben-Neudorf is considered Germany’s hottest thermal water source. Extracting this extremely hot water requires specialized heat-resistant technology, which was not part of the original design. Deutsche Erdwärme aims to begin routine extraction of hot thermal water by 2029. Meanwhile, a geothermal power plant will be constructed on-site to process the heat efficiently.
Deutsche Erdwärme’s long-term test marks a significant milestone in Germany’s geothermal energy sector. Success in Graben-Neudorf could not only provide clean, sustainable heat to local communities but also set a benchmark for geothermal projects across the Upper Rhine Valley.
Source: SWR
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