Geothermal plants are designed so that after 50 years of operation, a cooling of less than/equal to 1°C can be measured at the production well. The plant will then continue to function with little loss of overall performance. If this field is abandoned, warm water will flow in from the earth’s inexhaustible reservoir, so that the condition of the reservoir will not change over the long term.
The earth’s interior contains fracture points, i.e. areas where different rock layers are offset relative to each other. In zones that are still active, such as the San Andreas Fault in California, increasing stresses naturally build up at those points as the rock continues to shift. If the tension is greater than the friction, the rock slips, tension is released and the earth shakes.
A similar mechanism can also cause quakes here in Germany, but on much smaller scales and with much less energy. The difference between the interfaces in Germany and the San Andreas Fault, for example, lies in the fact that Germany is only home to old, inactive plates. The rock is no longer actively moving. However, there are plate boundaries, or offsets, of rock here (“remnants” from when the Alps formed) where tension can build up due to external, anthropogenic activities, but because the friction is much lower. Tension here is discharged much faster and can therefore only lead to very slight, often imperceptible movements of the ground.
No. On the one hand, it is a closed circuit: extracted water is pumped back into the ground in equal amounts. On the other hand, the extracted water volume is so large that water from the surrounding rock immediately flows in behind it, thus filling any potential hollow spaces.
In preparation for construction projects, extensive measurements of the subsurface help provide information about the geology to be encountered below and the associated subsurface models.
If there are large anhydrite deposits in the subsurface, for example, there is a risk that they will interact with water. When anhydrite layers interact with water they soak it up like a sponge and expand greatly, forming gypsum.
Environments with a high groundwater level and boggy subsoil are also not ideal for deep geothermal energy drilling projects.
The rock beneath Munich consists mainly of gravel, sandstone, mudstone and limestone – good load-bearing layers. These do not pose any danger in terms of geothermal energy.
Note: The FAQ list is preliminary and may be extended over the course of the project.