For the geothermal heat pump, drilling is required to extract heat from the ground. Therefore, drilling for wells or probes must be planned in advance for groundwater and geothermal heat pumps.
The first thing to be mentioned in this context is the geothermal well, which is required for geothermal heat pumps with geothermal probes. A deep borehole is not required for a heat pump with surface collectors, since the heat is obtained with this variant using a pipe system laid near the surface. If you decide to use a groundwater heat pump, you will need to drill a hole, since the heat is extracted through a well system (suction well and injection well).
With the groundwater heat pump, drilling is required for the installation of the two wells in order to be able to use the groundwater for heat generation. The companies usually drill to depths of around 5 to 20 m, but the exact drilling depth depends on the individual groundwater level on site. A decisive prerequisite for these boreholes is the water quality, which is why test boreholes for pumping tests are common in advance.
For the geothermal heat pump, a borehole must be drilled at a depth of around 50 to 100 m. The exact borehole depth is determined in each individual case by individual factors. The decisive factor in this regard is primarily the required heat demand. Certain aspects must also be taken into account with regard to the number of probes to be inserted into the ground. The most important factors are the subsoil conditions on site and the size of the area to be heated. One or two probes are usually sufficient for a conventional single-family house; a correspondingly larger number may be required for a multi-family house.
Geothermal drilling can primarily be carried out by specialized companies from the fields of well construction and drilling technology. It is important to ensure that the companies have the appropriate certifications:
These certificates are required because the responsible approval authorities require them as evidence. With the certificates, the companies carrying out the tests prove their technical and organizational competence as well as the technical equipment. If the corresponding certificates are available, you as the client can assume that the employees have been trained accordingly and that the work relating to the heat pump and drilling will be carried out in accordance with the official specifications.
For deep drilling with geothermal energy, the costs are highly dependent on the individual factors. As a rule, you can expect costs of around 50 to 100 euros per meter of drilling for deep drilling for geothermal energy. When drilling geothermal energy, the costs of drilling for geothermal heat are largely dependent on the local conditions and the soil conditions. In individual cases, for example, the use of special drill heads for hard rock may be necessary.
For deep drilling for geothermal energy, costs for the drilling itself, the machines used, the employees and other items must be taken into account. On average, you can expect total costs of around 20,000 to 25,000 euros when drilling for geothermal energy. If complications arise, the costs can increase by up to 20 percent. When deciding on a geothermal heat pump, the cost of drilling is therefore a key factor.
In contrast to drilling for geothermal energy, the costs for groundwater drilling are usually significantly lower due to the lower drilling depths. Here, too, the actual effort required is decisive; the soil conditions and the drilling depth are relevant in this regard. The costs for the groundwater drilling for the development and the well drilling vary on average between about 5,000 and 9,000 euros.
Geothermal drilling for a groundwater heat pump or the use of geothermal probes is generally subject to notification and approval. As a rule, a permit under water law is required, which you can obtain from the responsible water authority.
In Munich, a permit is required for the heat pump to be drilled in the ground if it reaches the groundwater. If this is not the case, you only have to report the drilling work to the Munich District Office at least one month in advance. This drilling notification should be made early, as it is not always possible to assess without a doubt whether the geothermal probe will reach the groundwater level. In case of doubt, a permit procedure can then be carried out beforehand. As a rule, within a few weeks you will receive a notification from the responsible authority as to whether a borehole notification is sufficient or whether a permit under water law is required. The approval of the authority is also required for groundwater drilling, you need a water law permit.