Grimsel line: underground installation recommended. Monitoring group makes recommendation for the new Innertkirchen – Ulrichen extra-high voltage line

Bern, 19.05.2022 - A recommendation has been made by the monitoring group appointed by the Swiss Federal Office of Energy for the new extra-high voltage Grimsel line: it should be installed underground between Innertkirchen (BE) and Oberwald (VS), while an overhead line should only be planned for the short line section between Oberwald and Ulrichen (VS). The underground cable would be installed either in existing and newly constructed tunnels or in the multifunctional Grimsel railway tunnel.

Most of the 27-kilometre long extra-high voltage line between Innertkirchen (BE) and Ulrichen (VS), which runs over the Grimsel Pass, is over 60 years old and needs to be replaced. As part of the modernisation, preparations are also being made to increase the voltage from the current 220 kilovolts (kV) to 380 kV. This increase in capacity is necessary in light of the federal government's energy strategy to transport the increasing amount of electricity produced from hydropower in the cantons of Bern, Valais and Ticino to Central Switzerland, and to bolster the security of supply throughout Switzerland.

Thirty-nine criteria evaluated

New extra-high voltage lines must be defined in the federal government's Electricity Transmission Lines sectoral plan. The Swiss Federal Office of Energy (SFOE) launched the procedure for the Innertkirchen-Ulrichen line and appointed a monitoring group in 2020. Various federal offices were represented in this group, as well as the Swiss Foundation for the Protection of the Landscape, and the cantons of Valais and Bern. The monitoring group examined and evaluated a total of six corridor variants based on 39 criteria on the topics of spatial development, environment, technology and economic viability. Corridors denote geographic areas in which a route with a specific transmission technology - an overhead line or underground cable - will later be implemented once the project moves forward.

Underground cable beneath the Grimsel Pass

The monitoring group's recommendation to the SFOE consists of an underground cable between Innertkirchen and Oberwald and an overhead line between Oberwald and Ulrichen. There are two variants for the underground cabling between Innertkirchen and Oberwald, which will cover a distance of around 23 kilometres.

  • In Variant 1, the extra-high voltage line will run from Innertkirchen to Handegg in a new cable tunnel that is yet be built. Between Handegg and the Grimsel 2 power plant, the line will be laid in existing tunnels belonging to Kraftwerke Oberhasli AG (KWO). Between the Grimsel 2 power plant and Oberwald, the line will be again be routed in a new tunnel that is still to be built.
  • In Variant 2, the extra-high voltage line will be laid in the multifunctional Grimsel railway tunnel. The railway tunnel under discussion is to run from Innertkirchen to Oberwald. The plan is to install the extra-high voltage line in a cable tunnel that runs parallel to the railway tunnel.

In both alternatives, the line crosses the valley floor underground in Oberwald. A transition structure is planned on the south side of the valley. From there, the extra-high voltage line runs over a length of 4.5 kilometres as an overhead line to Ulrichen to the existing line over the Nufenen Pass. Both options are equally valid in terms of transfer capacity. Regardless of which variant is implemented, Swissgrid expects the entire line between Innertkirchen and Ulrichen to cost between CHF 210 and 250 million.

Keeping people and the environment in mind

The proposed underground cable will relieve the villages of Guttannen (BE), Obergesteln (VS) and Ulrichen of the current overhead lines, while national and international protected areas will be preserved. These include the Bernese High Alps and the Aletsch-Bietschhorn area of national importance protected by the Federal Inventory of Landscapes and Natural Monuments of National Importance (ILNM), the Grimsel mire landscape included in the Federal Inventory of Mire Landscapes, and the Jungfrau-Aletsch UNESCO World Heritage Site. In addition, the underground cable will protect the extra-high voltage line from avalanches and landslides, especially on the Bern side of the Grimsel Pass. Both alternatives fulfil the requirement to bundle different infrastructures as far as possible.

The underground extra-high voltage line between Innertkirchen and Oberwald would be the longest underground cable in Switzerland. However, the longer the cable, the more complicated it is to control the electricity system. For this reason, the monitoring group recommends that no cabling is installed between Oberwald and Ulrichen.

Decision expected at the end of 2022

In the second half of June 2022, the two variants will be submitted for a three-month public consultation. The relevant documents will be available on the SFOE website. In addition, the draft documentation of the Electricity Transmission Lines sectoral plan will be made available to the public for at least 20 days. All interested parties can take part in the consultation. After evaluating the submissions, the SFOE will make a final recommendation to the Federal Council. The Federal Council is expected to decide on the planning corridor and transmission technology for the future extra-high voltage line between Innertkirchen and Ulrichen by the end of 2022.

Tunnel or multifunctional Grimsel railway tunnel?

If the Federal Council accepts the monitoring group's recommendation, a decision will subsequently have to be made as to whether the tunnel variant or the multifunctional Grimsel railway tunnel variant will be implemented. Various conditions must be fulfilled before the Grimsel railway tunnel variant can go ahead. Firstly, the funding for the railway tunnel must be decided on in national parliament by 2027 at the latest. Secondly, a construction permit will be required by 2030 at the latest. If both conditions are met - in addition to other operating and technical requirements - the extra-high-voltage line will be able to be run through the multifunctional Grimsel railway tunnel, otherwise the line will follow the route set out for the tunnel variant. As Swissgrid cannot wait until the national parliament has made a final decision on the Grimsel railway tunnel, it is pressing ahead with the planning of the variant involving the construction of new cable tunnels and the use of existing KWO tunnels. According to the latest plans, the extra-high voltage line should become operational in the mid-2030s.

In dialogue with the public

Swissgrid and the SFOE are organising two information events to provide the public and the affected communes with first-hand information. The event in Innertkirchen will take place on 1 June 2022, while the event in Oberwald will take place on 2 June 2022. Grimselbahn AG will also be present as the project engineer for the Grimsel railway tunnel.

Swissgrid is the national grid company. As the owner of Switzerland's extra-high-voltage grid, it is responsible for operating the grid safely and without discrimination and for maintaining, modernising and expanding the grid efficiently and with respect for the environment. Swissgrid has more than 600 skilled employees from 28 countries at its sites in Aarau, Prilly, Castione, Landquart, Laufenburg, Ostermundigen and Uznach. As a member of the European Network of Transmission System Operators (ENTSO-E), it is also responsible for tasks in the fields of grid planning, system management and market design in the European exchange of electricity. The majority of Swissgrid's share capital is jointly held by various Swiss electricity companies.

Address for enquiries

Press and Information Service Swissgrid: +41 58 580 31 00,
Press and Information Service SFOE: +41 58 460 81 52,


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