The most favourable areas for geothermal energy in Germany include

• Southern German Molasse Basin

The region in the foothills of the Alps that has absorbed the weathering debris of the rising mountains is known as the "Molasse Basin". The South German Molasse Basin stretches from Switzerland via Baden-Württemberg to Bavaria and Austria.
How warm? Temperatures between 100 and 155 °C with correspondingly high permeability are possible south of Munich and in the area of Lake Chiemsee (depth: approx. 4,000 m).
Suitable are: The Jurassic carbonates are particularly suitable, as they are partially dissolved and therefore permeable.
 

• Upper Rhine Graben

The Upper Rhine Graben stretches along the Rhine between the Swiss Jura in the south and the Taunus in the north.
How warm? At comparable depths, the Upper Rhine Graben has the highest underground temperatures measured in Germany to date, e.g. over 170 °C at a depth of 3000 m in the Karlsruhe/Mannheim area.
Suitable are: Sedimentary rocks and transitional horizons in the bedrock with 130 to 180 °C hot thermal water. In the Oberrheingraben, fissured areas of the bedrock also have excellent reservoir properties in some cases.
 

• North German Basin

The North German Basin extends from southern Lower Saxony to below the North and Baltic Seas. From a geothermal point of view, it is particularly advantageous that this structure contains at least six different layers with hydrothermal deposits, e.g. in Potsdam at a depth of 1200 metres, temperatures of 45 degrees are already reached with high productivity, and at great depths (4,000-5,000 m) temperatures of 130-160 degrees. Due to the strong movements of the salt formations in the North German Basin, which took place in geological time, the North German Basin is tectonically highly fissured and therefore highly permeable in many areas, making it very interesting for geothermal development.
How warm? Temperatures of 130 to 160 °C are found at 4,000 to 5,000 metres.
Suitable are: Conglomerates and sandstones down to a depth of 5,000 metres.
 

• Bedrock = 95% of the geothermal energy potential

Bedrock is the term for the geologically old, tectonically deformed (folded) crustal areas of a continent. It is the focus of petrothermal energy, which still requires basic research in some areas. The GFZ is involved in this, e.g. with the GeoLAB research infrastructure and the GeoReal project. In this way, the GFZ is contributing to the development of this enormous resource with a medium-term perspective.
How warm? Temperatures of 130°C to 220°C can be found at a depth of 5,000 metres.
Suitable are: Older crystalline rocks belonging to the bedrock, such as granite, gneiss or marble. In most parts of Germany, crystalline rock is found in deep underground German low mountain ranges, from the Sudeten Mountains to the Black Forest and the Eifel.

The strategy paper makes five recommendations for the expansion of geothermal energy:

• Define expansion targets for deep geothermal energy

Politicians must formulate clear expansion targets and legislators must back these up with regulations. This includes accelerated approval procedures with a concentration effect as well as reviewing the adaptation of laws (e.g. BBergG, WHG, BauGB, UVPG, GEG) and the designation of preferred areas in the regional development plans of the federal states and in municipal land use plans. At the same time, policymakers must make CO₂ avoidance costs a key regulatory tool and the system of charges and levies for municipal and industrial producers and operators must be levelled and simplified.

• Minimising the risk of discovery

Effective instruments are needed in the short term to minimise the risk of discovery: in economic terms, these are financial tools and a noticeable increase in the annual funding volume of the "Federal Subsidy for Efficient Heating Networks (BEW)" to well over EUR 1 billion. Technically, this includes
geophysical investigations in metropolitan areas as part of the geological surveys and an exploration drilling programme to reduce the exploration risk, as well as demonstration and pilot plants with close scientific support.

• Invest in key technologies

Investments in 10-year key technologies for expansion to a large industrial scale by industry and accompanying government funding programmes; e.g. in drilling and reservoir technologies (incl. engineered geothermal systems), borehole pumps, high-temperature heat pumps, development of large heat storage systems, the expansion of trans-municipal heating networks and cross-sectoral system integration. Comprehensive digitalisation must become the basis for the analysis, planning, integration, control and monitoring of complex energy systems.

• Train skilled labour

Activation of the high value creation and labour market potential of 5 to 10 people per megawatt of installed capacity along the value chain of research and development, component production, administration, plant construction and operation through innovation and business promotion measures. Accompanying education policy measures (curricula, further training, inter-company training centres, recruitment programmes) are needed to eliminate the lack of personnel capacities.

• Interact with citizens

Broad public outreach must be initiated and proactively supported politically. The promotion of positive anticipation and acceptance in society requires a targeted strategy for interaction with citizens and stakeholders, especially at municipal level, which creates participatory opportunities.