The energy from hydropower cannot be fully transported to the centres in Central Switzerland without expanding the existing lines. This requires an increase in voltage between the Chippis (VS) and Bickigen (BE) substations from the current 220 kilovolts to 380 kilovolts.
The project provides for an increase in voltage along the 106 kilometre, 220 kilovolt line between the Bickigen (BE) and Chippis (VS) substations with a 380 kilovolt line. The 220 kilovolt line from Chippis to Bickigen was constructed between 1963 and 1965. The Federal Inspectorate for Heavy Current Installations (ESTI) had already approved this line for an operating voltage of 380 kilovolts, but to date it has only been operated at 220 kilovolts.
The transmission grid has structural bottlenecks in the Valais and in other regions and Swissgrid already regularly needs to instruct power plant operators to restrict production. To increase the capacity of the existing 220 kilovolt line between Chippis and Mörel, the entire line will be converted to a voltage of 380 kilovolts. 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.
To enable the full extent of the energy to be transported between the Chippis (VS) substation and the Bickigen (BE) substation, the entire line will be increased from the current voltage of 220 kilovolts to 380 kilovolts.
The line between Chippis and Bickigen is now to be operated on a voltage of 380 kV. It will be refurbished and modernised for this. The construction project is extensive: Changes are planned for more than 294 pylons. However the construction activities will be undertaken on the already existing pylons and lines. The original line route will therefore not be changed.
Before the line can be operated with 380 kV, it is mandatory that it be adapted to today's legislation – for instance stricter ordinances with regard to protection from noise or from non-ionising radiation. The voltage increase and modernisation activities contain among other things
The construction work will last a total of about two years. The construction period per pylon location will last between 3 and 15 days depending on the activity.
| Route lengths | Chippis – Wimmis about 49,5 km Wimmis – Bickigen about 57,1 km |
| Number of pylons | 297 |
| Number of strands | 2 |
| Number of bundles | 2 |
| Electric conductors | 600 mm2 Aldrey |
| Voltage before / after | 220 kV / 380 kV |
| Amperage before / after | 1920 amperes / 1500 amperes |
| July 2015 | Planning approval dossier submitted to ESTI |
| November – December 2015 | Public circulation in the municipalities |
| February 2017 | ESTI sends the dossier to the Swiss Federal Office of Energy (SFOE). The SFOE then enters into conciliation negotiations with legitimate objectors. |
| February 2022 | The SFOE issued the planning approval decision, giving the green light for the voltage increase. Various appeals against this decision were filed with the Federal Administrative Court. |
| January 2024 | The Federal Administrative Court dismissed the majority of the appeals in January 2024. However, the planning approval dossier was referred back to the SFOE to examine possible solutions for additional noise reduction. This is expected to delay the voltage increase of the Bickigen – Chippis line by another two years. |
| 2029 | Commissioning |
The Federal Council has authorised a temporary voltage increase to 380 kV as a measure against a possible electricity shortage in the winter months. Swissgrid carried out test operations at 380 kV in January/February 2023. This showed that import capacity from abroad was increased and congestion in the Swiss transmission grid was significantly relieved. The planned line modifications required for the permanent voltage conversion to 380 kV are currently in the approval process.
Two 220-kV electricity systems are currently connected via the electricity pylons along the Bickigen – Chippis route. A line consists of three phases of alternating current that run one above the other on the three pylon cantilevers. The ground conductor runs at the top of the pylons and is for grounding, which means that it protects against direct lightning strikes. For the temporary voltage increase, the live conductors of the 380-kV line were transposed so that the 220-kV line is on the lowest cantilever. This will minimise the impact on people and the environment as much as possible and ensure that the safety distances between the conductors and the ground, houses or cableways can be observed.
The construction project is extensive, but only has a minimal effect on the environment and landscape. Lasting environmental impact will occur in relation to the landscape, however the changes compared to the initial state will only be perceptible in the planned increase to the height of the pylons. The heights of 7 pylons will be raised between 2 and 6 metres, primarily in the Alpine region between Leukerbad and Kandersteg, but isolated pylon height increases will occur along the entire line. Targeted measures will minimise the negative impact on the soil, flora and fauna, and the initial state will be restored following the completion of the construction work.
The renovation work will reduce the magnetic field load along the entire line and significantly improve the current state. While operation at 380 kilovolts will increase noise emissions, the measures that have been introduced ensure that the emission limits are complied with across the board.
Swissgrid always observes the statutory limits when constructing lines. The Ordinance on Protection from Non-Ionising Radiation (NISV) is always complied with. Swissgrid also reserves the right to operate the line at the previous intensity of current of 1920 amperes. This is based on the version of the NISV revised in July 2016. Increasing the voltage from 220 kilovolts to 380 kilovolts requires the heights of isolated pylons to be raised, certain foundations to be reinforced and the wire rope hoists to be tensioned in certain sections. These measures reduce the magnetic field without significantly restricting the operating current.
