The ongoing integration of renewable energy sources requires a major expansion of the power grids in Germany. The grounding systems required for overhead lines and substations are very cost-intensive due to the quantities of grounding material (copper or stainless steel) and groundwork required, and they also have a negative impact on the environment. Grounding systems are always dimensioned on the basis of measurements of electrical soil conductivity, in which metallic electrodes have previously been galvanically coupled—i.e., driven into the ground surface. This is particularly labor-intensive in stony soils and leads to high transition resistances to the rock, which can often only be overcome by very high measuring voltages.

As a result, the accuracy of the measurement results is reduced on the one hand, while on the other hand, the effort required to ensure occupational safety increases due to the high voltages. With good coupling to the ground, galvanically coupled measurement methods offer sufficient accuracy, but due to the limited penetration depth of the measurement principle, they only provide a highly simplified picture of the upper soil conductivity. As climate change is expected to cause the soil to dry out steadily, a decrease in average soil conductivity is also to be expected. This means that deeper areas of the subsoil must also be taken into account when designing earthing systems.

Due to the limitations and uncertainties of the measurement methods used to date, grounding systems are often oversized. To avoid this, a novel system for determining the electrical conductivity in the ground using electromagnetic mapping methods is to be developed. Coupling via electromagnetic waves eliminates the need to insert electrodes into the ground at the measuring points, which is particularly advantageous in stony or built-up areas. In addition, the time required for a single measurement is reduced, enabling larger areas to be mapped with the same amount of effort. Furthermore, the electromagnetic method, by its very nature, ensures conductivity mapping to greater depths than with the previous galvanically coupled methods.

The aim of the project is to build a demonstrator that can determine soil conductivity more accurately, with higher resolution, and at greater depths than the methods used to date. This will enable grounding systems to be designed more precisely and in a more targeted manner, minimizing material costs and environmental impact (such as soil sealing).