The flow of heat from the Earth's interior provides fundamental insights into the geodynamic and tectonic development of the Earth's crust and forms the basis for evaluating renewable geothermal resources. Scientists at the GFZ German Research Centre for Geosciences in Potsdam have now evaluated and quality-checked all available heat flow data for Germany. It turned out that much of the old data is highly uncertain and new data must be collected. The researchers created new maps and showed that the heat flow is on average 20 % higher than previously assumed. The results have now been published in the journal Earth Science Reviews.

Legacy data not recommended for further use

The strict application of basic scientific criteria on documentation and methodological quality precludes, on one hand, the future use of the majority of former legacy data and reveals, on the other hand, a high demand for the determination of high-quality heat-flow data. These are two conclusions of a paper just published in Earth Science Reviews by a GFZ team of scientists of the section Geoenergy.

New Database

The researchers have compiled a new database and heat-flow map consisting of all heat-flow determinations for Germany. Their work involved a systematic screening of all available legacy measurements since the 1950sand also the inclusion of observations not considered in data compilations before. The current database consists of data from 595 locations, from which only 121 are recommend for future use.

New high-quality heat flow maps

Based on the quality-assessed heat-flow data, the researchers created new heat-flow maps of Germany and discussed the heat-flow pattern of geological sub-regions. The area-weighted mean heat flow of Germany is 78 mW/m² (milli Watt per square meter), which is about 20% higher than expected by previous compilations. “The new database is a significant improvement for Germany and a strong contribution to the revision of European heat-flow data in the context of the ongoing Global Heat Flow Data Assessment”, says GFZ researcher Sven Fuchs, who led the new paper and who is also maintaining the IHFC Global Heat Flow Database at the GFZ. The improved database will also build the core of a new heat-flow research infrastructure, developed by GFZ scientists from section Geoenergy and the Library and Information Services in the frame of the DFG funded World Heat Flow Database project.

Need for future efforts: Heat flow data only very patchy in Germany

For many regions, heat-flow data are simply missing, for example in Northwest Germany, North Saxony, South Brandenburg and Thuringia, as well as in parts of Bavaria. For some of these regions data did not pass the quality evaluation, but in most cases there was no heat flow determined at all. Thus, an important parameter for understanding the thermal field of the subsurface is missing. “With the drastically increased demand of utilizing the subsurface for different geoenergy applications, we need to speed-up our efforts to fill these large data gaps in Germany. These efforts will help to complete our picture of the geothermal resources in Germany,” says Sven Fuchs. To better understand possible processes affecting the heat-flow determination and in order to provide new heat flow data for the blank areas, the team is preparing a new heat-flow measurement campaign across Germany. This will allow the map to be further filled in and strengthen the analysis of the subsurface thermal field.

Data and publication

Find the research paper ‘Evaluation of the terrestrial heat flow in Germany: a case study for the reassessment of global continental heat-flow data’ at https://doi.org/10.1016/j.earscirev.2022.104231

Find the data publication ‘The German Heat Flow Database 2022’ at https://doi.org/10.5880/GFZ.4.8.2022.015

Find the GFZ World Heat Flow Database project (GFZ PI: Sven Fuchs, Kirsten Elger) at http://project.heatflow.world

Find the IHFC Global Heat Flow Database at http://database.ihfc-iugg.org