The 27-kilometre-long line section between Innertkirchen (BE) and Ulrichen (VS) is to be replaced and increased from 220 to 380 kilovolts. The Federal Council has defined the planning corridor with extensive underground cabling between In-nertkirchen and Oberwald. The multifunctional Grimselbahn tunnel is an underground cable variant.
Most of the extra-high-voltage line between Innertkirchen and Ulrichen, which covers a distance of 27 kilometres over the Grimsel Pass, is over 60 years old and must be brought into line with the current state of the art. The modernisation will also encompass an increase in voltage from the existing 220 kilovolts (kV) to 380 kV throughout. The increase in the capacity of the line between Mettlen (LU) and Ulrichen is an important project in Swissgrid’s «Strategic Grid 2025».
The expansion of electricity production from hydropower is a central pillar of the Energy Strategy 2050. The replacement and increase in voltage of the line between Innertkirchen and Ulrichen is important for the transportation of the growing electricity generation from the cantons of Bern, Valais and Ticino to the conurbations in Central Switzerland. The distribution of energy flows along several north-south axes also increases grid stability. The increase in capacity is necessary in light of the federal government’s energy strategy, in order to transport the increasing electricity production from hydropower in the cantons of Bern, Valais and Ticino to Central Switzerland and to permanently enhance security of supply throughout Switzerland.
At the start of July 2020, Swissgrid submitted an application to establish a planning corridor between Innertkirchen and Ulrichen to the Swiss Federal Office of Energy (SFOE) in the federal government’s sectoral planning process for transmission lines (SÜL). As a first step, Swissgrid developed a range of possible corridors, i.e. geographic areas in which a route can be established with a certain transmission technology – overhead line or underground cable – during the further course of the project.
Each of the variants has specific advantages and disadvantages with respect to regional planning, the environment, technology and economic viability. The SFOE set up a monitoring group to assess and evaluate these aspects as objectively as possible. This monitoring group incorporated various federal offices, the Swiss Foundation for the Protection of the Landscape, the cantons of Valais and Bern, and Swissgrid. 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».
On 25 February 2023, the Federal Council defined the planning corridor in the sectoral plan, with extensive underground cabling over a distance of approx. 23 km between Innertkirchen and Oberwald. In both variants, the line crosses under the valley floor in Oberwald as an underground cable and runs as an overhead line corridor to Ulrichen. There are two variants for the underground cabling between Innertkirchen and Oberwald, which will cover a distance of around 23 kilometres.
Once the Federal Council has defined the planning corridor and the transmission technology in the sectoral plan, a decision will have to be made on whether to implement the tunnel variant or, alternatively, the variant with the multifunctional Grimselbahn tunnel. Various conditions must be fulfilled before the Grimselbahn tunnel variant can go ahead. Firstly, the funding for the railway tunnel must be secured in the 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 the operating and technical requirements – the extra-high-voltage line will run through the tunnel parallel to the Grimselbahn tunnel. Otherwise, the line will follow the route set out for the tunnel variant. According to the latest plans, the new extra-high-voltage line should become operational around the middle of the 2030s.
Swissgrid is aware of the advantages of bundling large, linear infrastructures, particularly in the area of landscape protection. It examines the corresponding synergy potential in all line projects. With the proposal to combine a railway tunnel and an underground cable, a variant on the Grimsel is now available that is technically feasible and is suitable for approval. Grimselbahn AG has demonstrated this in a feasibility study (2015) and in an in-depth technical analysis (2019).
Further information: www.grimseltunnel.ch
All the corridor variants submitted by Swissgrid have one thing in common: they reduce the burden on residential areas in and around Innertkirchen, Guttannen and Obergesteln. Today’s 220 kV line runs partly through the middle of these villages and restricts their development. National and international protected areas will be preserved. These include the Bernese High Alps and Aletsch-Bietschhorn area of national importance that is 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. The current line will be removed in all variants.
On 25 February 2023, the Federal Council defined the planning corridor in the sectoral plan, with extensive underground cabling over a distance of approx. 23 km between Innertkirchen and Oberwald.
| Completion of sectoral planning process | 25 February 2023 |
| Development of construction project | Q3 2025 |
| Approval procedure | Q4 2027 |
| Tendering process, construction, commissioning | Q4 2033 |
| Dismanteling of the 220 kV line | Q4 2034 |
Schedule in the best case scenario. If it comes to legal proceedings, the timetable will be delayed by two to four years.
Swissgrid is planning a new line lead-in into the Innertkirchen substation to relieve the village of the current overhead lines. In addition, Swissgrid has replaced the outdated outdoor switching substation in Innertkirchen with a modern gas-insulated switchgear (GIS).
As is well known, Swissgrid is planning a new line lead-in into the Innertkirchen substation to relieve the village of the three current overhead lines. According to the SFOE, the line lead-in will now be included in the Innertkirchen – Mettlen (LU) sectoral planning process in order to avoid any delays. Three variants are currently being examined. According to the current planning, the new line route will be in place by the end of 2028. The dismantling of existing lines is scheduled for 2029.
Swissgrid commissioned a 220 kV modern, gas-insulated switchgear (GIS) in the Innertkirchen substation in September 2020 following a construction period of around two years. Nine line bays, two transformer bays, two longitudinal separations and a cross-coupler form the core of the new 220 kV plant. The switchgear was prepared for all technical variants of the new line from Innertkirchen (underground cable or overhead line). Housed in the building of the substation, the modern GIS system replaces the outdated outdoor switching substation, which further relieves the burden on Innertkirchen’s landscape.
The substation in Innertkirchen is an important grid node in the Swiss transmission grid. It is very important for security of supply in Central Switzerland as well as for regional supply. The switchgear serves as the feed-in point for the Oberhasli power plant.
