Study warns of the costs of overhead line expansion

30.04.2026

Source: E & M powernews

A study predicts significant delays and additional costs for the SuedWestLink if there is a switch from underground cables to overhead lines

A possible switch from underground cables to overhead lines in the "SuedWestLink" grid expansion project would significantly delay the expansion and cause additional costs in the billions. This is the conclusion of a recent study by Frontier Economics in cooperation with the law firm Görg and the consulting firm "ef.Ruhr".

The study, commissioned by cable manufacturers NKT and Prysmian, considers the entire life cycle of a grid expansion project for the first time and therefore goes beyond the pure investment costs that have often been the focus to date, according to a press release from NKT.

Südwestlink is intended to transport wind power from Schleswig-Holstein to Baden-Württemberg. According to the study, a change in technology to overhead lines would require new planning. This could delay commissioning by at least four to seven years.

According to the authors, this delay would have a direct economic impact. For every year without the additional grid capacity, additional costs of around 180 to 190 million euros would be incurred. The main reason for this would be additional redispatch measures, which would be necessary to balance supply and demand in the electricity system. Over the entire delay period, the avoidable additional costs would total up to 1.3 billion euros, according to the study.

Commissioning planned for 2037

In the 2023 version of the grid development plan, priority was still given to underground cabling. At that time, commissioning was announced for 2037.
The analysis also calls into question widespread assumptions regarding the costs of underground cables. While significantly higher investment costs compared to overhead lines are often cited in the public debate, the study arrives at an additional cost factor of around two when considering the entire life cycle. This puts the difference over the operating life into perspective.

In addition to the costs, the study also refers to other aspects such as acceptance and system stability, which play a role in the choice of transmission technology. However, the decisive factor is the overall cost consideration over the service life, which is significantly influenced by delays. The study also emphasizes the importance of planning security for large infrastructure projects. A change of direction could not only cause time losses, but also additional costs that could be avoided.

The background to the debate is a planned amendment to the Federal Requirements Plan Act, which is to be discussed by the Federal Cabinet in the coming days. The draft provides for greater use of overhead lines. However, the authors of the study conclude that such an approach could fail to achieve the goal of accelerating grid expansion.

The Federal Requirements Plan Act refers to projects "for which the energy industry necessity and the urgent need to ensure secure grid operation" have been determined. A number of projects are direct current projects for which priority implementation with underground cables was originally planned, some of which were to be implemented in underground sections.

The second legal basis for grid expansion is the Energy Line Expansion Act (EnLAG). This contains projects at the 380 kV level that have been classified as "necessary for the energy supply in Germany" and are the responsibility of the federal states.

The Frontier Economics study is currently not available online.

Author: Fritz Wilhelm