A new 380 kilovolt line is being constructed between Mörel and Ulrichen. The construction of this line is necessary to ensure that all of the energy generated from hydropower in the Valais can reach Central Switzerland and Ticino.
The extra-high-voltage line between Mörel and Ulrichen will be newly constructed with a voltage of 380 kilovolt. Without connecting the transmission lines in the Valais to the 380-kilovolt grid, it will only be possible to transport around two thirds of the Valais production from hydropower once the new Nant de Drance pumped storage power plant commences operation. The construction of the SBB's new 132 kilovolt railway power line is also critical for the secure operation of the New Railway Link through the Alps (NRLA) at the Gotthard.
The existing 220 kV line between the Elektra Massa power plant in Bitsch and the switchgear in Mörel-Filet will be converted. The valley crossing between the Bitsch substation and Termen with four new pylons has already been constructed. Now, 7 pylons will be replaced to accommodate the 132 kV railway power line, which will also be 8 metres higher. The main pylon and cable installation activities are expected to be carried out in the autumn and winter months between 2022 and 2023. Swissgrid is also renewing the switchgear in Bitsch. Construction started in April 2020. The construction activities will continue in November and are expected to be completed in the spring of 2022.
| Construction of access paths | H2 2020 – H1 2021 |
| Clearing | Q3 2020 – Q2 2021 |
| Construction of foundation | Q1 2021 – Q4 2021 |
| Installation activities | Q4 2021 – Q3 2023 |
| Commissioning | Q4 2023 |
| Dismantling of 220 kV and 65 kV lines | H1 2024 – H2 2024 |
| Recultivation | H2 2022 – H1 2024 |
57 new pylons were built and the existing 220 kilovolt and 65 kilovolt overhead lines will be dismantled between the Ernen and Ulrichen substations. The main work (foundation and pylon construction, rope installation) took place between 2017 and 2020.
The total costs for the new Mörel – Ulrichen extra-high-voltage line amount to approximately 100 million Swiss francs.
The existing 220-kilovolt overhead line between Mörel and Ulrichen will be taken down after the new line has been commissioned. The existing 65-kilovolt Mörel – Ernen 1, Mörel – Ernen 2 and Ernen – Ulrichen overhead lines will also be dismantled.
Steel lattice pylons and plastic insulators will be used for all pylons.
1,000 mm2 Aldrey conductors are used for the transmission and railway power lines; twin conductors will be used in the transmission line. The 65-kilovolt line will be equipped with 600 mm2 Aldrey single conductors. The ground conductor has a diameter of approx. 350 mm2 and contains an integrated fibre-optic cable.
A modern 220-kilovolt substation will be built at the new location in Niederernen. The old substation in Fiesch and the line connection will be dismantled. This prevents the crossing of the Rhone and relieves the burden on the settlement area. The centrepiece of the new 220 kV Ernen substation is the gas-insulated switchgear. A second 220/65 kV transformer will also be installed to increase the regional security of supply.
A bridge solution to the Binna crossing is being considered for cable version 1. The cable bridge is a version in the topologically difficult area of the Binna crossing with steep drops on both sides.
The cable bridge could be used as a pedestrian connection. Special consideration must be given to the magnetic field on account of the proximity of the pedestrians to the cable arrangement. An aluminium panel could be attached above the cable arrangement to shield the magnetic fields.
A total of 19 buildings within the study perimeter were classified as OMEN. The magnetic field was calculated for all OMENs. In 18 OMENs, the system limit value of 1 microtesla was maintained. In one OMEN, the system limit was exceeded slightly – a dispensation has been granted for this.
The new line routing is used in the entire project perimeter south of the existing building zones and residential areas. By moving the line from the banks of the Rhône and out of the open agricultural land to the wooded hillsides, the potential conflict of the existing 220 kV line from the construction zones in several communities will be resolved. In terms of the landscape, there will be a general improvement over the existing situation.
Due to the bundling with the 132 kV railway power line and the 65 kV line on the same pylons as well as to the higher voltage, however, the pylons will be taller than the existing 220 kV line.
The majority of the pylon sites are located in the forest. Other locations are used intensively for agriculture or include semi-dry meadows and extensively grazed areas.
Along the Ernen – Ulrichen section, the clearing work along the line route was carried out in the spring of 2018. This was necessary to ensure safety on the construction site and safe operation of the line. An approximately 30-metre-wide corridor was cleared over a distance of around 16 kilometres. Trees and shrubs are beginning to grow again in this area. Over time, this will allow the line to blend into the landscape better.
A total forested area of 15,288 m2 had to be cleared to install the line at the pylon locations along the Ernen – Ulrichen section. The temporary clearing of 22,572 m2 is required to provide access to the building sites and pylon locations. Suppression is necessary for an area of 292,471 m2.
After every forest-clearing measure, Swissgrid checks whether additional safety measures are required to protect people and the environment. For example, snow barriers and timber tripods are erected to protect against avalanches. Moreover, Swissgrid also plants young trees in glades along the line route. These kinds of precautions were taken in the municipalities of Ernen, Goms and Obergoms. They guarantee the safety of the roads, which are used year-round, during winter. Besides this, they also support the growth of the forest in the vicinity of the line. The measures allow the forest to fulfil its long-term role of unrestrictedly protecting against avalanches.
In the section stretching from Mörel to Ernen, the forest-clearing activities along the line route are expected to be carried out by the spring of 2021. In this section Swissgrid will once again review whether additional protective measures for avalanches and snow slides are necessary. A definitive assessment of the situation and the agreement upon suitable measures is possible only after deforestation.
The construction of the extra-high voltage line will have an impact on nature. By way of compensation, Swissgrid will implement various renaturation projects in the affected municipalities between Mörel-Filet and Ulrichen. For instance, on the Tunetschalp, Swissgrid has created a wet habitat while also contractually assuring that the Tunetschalp and Gorneralp will be regularly maintained over the next 20 years to protect against overgrowth.
As another compensation measure, Swissgrid also intends to protect dry meadows and pastures from overgrowth. A total of seven meadows and pastures will be cleared of overgrowth between Ulrichen and Ernen alone. The associated activities started in autumn 2019 and will last until the end of 2021. The overgrowth in these areas will continue to be managed in the future in order to preserve their ecological value.
