Grid project Grynau – Siebnen
Swissgrid will replace the existing 220 kilovolt line between Grynau and Siebnen with a new 380 kilovolt overhead line. This will improve the security of supply in the Lake Zurich/Linth Plain region.
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Overview
The existing 220 kilovolt overhead line between Grynau and Siebnen will be replaced by a new 380 kilovolt line. At the same time, Axpo will increase the voltage of the existing 50 kilovolt distribution grid line to 110 kilovolts.
The grid project is necessary due to the constantly increasing load development in the Upper Lake Zurich/Linth Plain region. The increase in voltage of the Grynau – Siebnen line to 380 kilovolt will ensure the international and regional security of supply and increase the import capacity from the north by about 500 megawatts. The project is also important for transporting energy from new pumped storage power plants.
Project
The line for the Swissgrid Grynau – Siebnen grid construction project has already been insulated to 380 kilovolts between the Siebnen substation and pylon no. 15 (along motorway A3 in the municipal region of Tuggen). A section roughly 5 kilometres long between pylon 15 and the Grynau substation has not yet been upgraded to 380 kilovolts. The line will be adapted to the status of the applicable regulations for electrical and magnetic fields as well as noise along the entire route.
In its ruling from 21 September 2011, the Federal Administrative Court returned the project to the Swiss Federal Office of Energy (SFOE) and decided that the underground cabling in the Tuggen region needed to be reassessed. The cable study will be submitted to the SFOE together with the overhead line project. The SFOE will then undertake an extensive weighing of interests between the cable and the overhead power line versions. Assuming an optimal course of proceedings, Swissgrid expects to convert the line to 380 kilovolts in 2020 at the earliest. The 110-kilovolt line was implemented as a separate underground cabling project for compelling scheduling reasons.