© project management Jülich / Jülich research centre GmbH (Background: Baker Hughes)

Successful geothermal drilling tests in Lower Saxony

Researchers successfully harvested more than 1,000 cubic metres worth of boiling water from a hot spring situated some 2.5 kilometres below the surface in Celle, Lower Saxony. A promising outcome for the future use of geothermal energy.

Geothermal energy is climate neutral, abundant, safe and reliable – and it does not have to be imported. It is therefore considered a key component of Germany’s future climate-neutral heat supply. The Federal Ministry for Economic Affairs and Energy targets funding towards exploration projects to increase this technology’s share in the country’s energy supply. Promising geological characteristics are a prerequisite for this.

At present, a team of researchers is studying the Rhaetian sandstone below the surface in Ahnsbeck, close to Celle. The aim of the project entitled DemoCell is to demonstrate the feasibility of using geothermal heat in the wider Celle area. The sandstone is situated some 2.5 kilometres below the surface, and the stratum is more than 40 metres thick. Initial results confirm that there is indeed potential for the use of geothermal energy.

^{Positive interim results from drilling tests and geological studies}

Dr Oliver Höhn, leader of the DemoCELL project, reports on successful drilling tests: “When reaching the surface, the water temperature still exceeded 100° Celsius. Other findings also suggest that there is actual potential for geothermal energy: the water continued to flow for various hours and at varying rates of intensity. The results are still being analysed, but the initial impression, Dr Höhn said, is positive.

Georg-August University in Göttingen also reports positive findings. Prior to the tests, more than one hundred metres of high-quality drill cores were taken for analysis of the potential reservoir.

“The average permeability rate we found is around 832 millidarcies – suggesting that the Rhaetian sandstone is good for our purposes”, explained Dr Matthias Franz. Again, the analysis has yet to be completed.

^{Why does the ground have to be studied so thoroughly?}

Rhaetian sandstone is already being used in the production of geothermal energy at other sites, including ones in Waren and Neustadt-Glewe (Mecklenburg-Western Pomerania). However, it is not possible to simply transfer the findings from these projects to others: not all sandstone reservoirs are suitable and any geological disruptions can result in stark differences in conditions between sites that are only a few kilometres apart from each other.

If the latest findings can be corroborated, concrete planning for the demonstrator project will begin, with the objective of establishing a local heat network using geothermal energy in the wider Celle area.