Grid project Mettlen – Ulrichen

Swissgrid is reviewing a number of options for increasing the voltage from 220 kilovolts to 380 kilovolts between Innertkirchen and Ulrichen. The construction of a new overhead line, an underground cable as well as the laying of the cable in the Grimsel Tunnel are being discussed.

Overview

The Mettlen – Ulrichen project will convert the existing 87 kilometre, 220 kilovolt overhead line to 380 kilovolts. The new line will be operated at 220 kilovolts for the time being.

The Mettlen – Ulrichen section is 61 kilometres long and does not meet the current technical requirements. The largest section of the line (51 kilometres) is over 60 years old and 10 kilometres of the line was converted to 380 kilovolts in 1992.

The upgrading of the existing 220-kilovolt line between Innertkirchen and Ulrichen (Grimsel line) to 380 kilovolts throughout is a key element in the 2025 strategic grid planning. The Innertkirchen – Ulrichen project will convert the existing, roughly 27.8 kilometre-long, 220 kilovolt overhead line and prepare it for subsequent operation at 380 kilovolts.

The planning approval procedure is expected to be concluded by mid-2027. Swissgrid is very reliant on efficient planning and approval processes to do this. Swissgrid endeavours to find the most logical and sensible solution for all projects with regard to environmental compatibility as well as with respect to regional planning and technical and financial aspects. Potential synergies with other linear infrastructure, such as SBB rail power, distribution grids or motorways are systematically reviewed and considered where appropriate. As is the case for all projects, Swissgrid is required to develop several versions. At least three versions exist for the Grimsel line: the version with an overhead line over the pass (in this case, the existing line would be replaced), the version that exclusively uses underground cabling and the version with cabling through the Grimsel Tunnel. The Federal Council reaches the final decision on the version after careful consideration of regional planning, technical, economic and environmental aspects by the authority administering the process.

Project

The 220 kV line between Innertkirchen and Ulrichen (Grimsel line) was created in 1951. The project aims to upgrade the existing 220 kV line between Mettlen and Ulrichen, which is 27.8 km in length, to 380 kV. Two 380 kV extra-high-voltage lines or cable systems are planned for the Innertkirchen – Oberwald (Ulrichen) section. For the Innertkirchen – Oberwald section, the possibility of laying a cable in the Grimsel tunnel, 22.3 km in length, will be investigated. The connection of the Handegg and Grimsel power plants is also part of the laying of the cable in the Grimsel tunnel. The possibility of a 220 kV power plant connection from the Handeck and Grimsel substation to the Innertkirchen substation via a cable laid in the Grimsel tunnel will be investigated.

As part of the Mettlen – Ulrichen programme, but also outside this project, a new 220 kV switching substation will be constructed on the site of the existing switching substation in Innertkirchen. The necessary space will be reserved for the later construction of a new 380 kV switching substation and a grid coupling transformer.

Links

Grimseltunnel (in German)