Winter 2023/2024

The responsibility for security of supply in Switzerland is shared by various players. As the national grid company, Swissgrid is responsible for ensuring the non-discriminatory, reliable and efficient operation of the transmission grid. Swissgrid works closely with partners in Switzerland and abroad and does everything in its power to contribute to Switzerland’s secure and reliable supply of electricity. Ensuring secure grid operations is an absolute priority for Swissgrid.

In 2022, the Federal Council enacted various measures to increase security of supply in the short term and assigned new roles to Swissgrid. The ordinance on the establishment of a power reserve for the winter (Winter Reserve Ordinance, WResV) came into force on 15 February 2023.

Hydropower reserve

In accordance with the ordinance on the establishment of a power reserve (WResV), Swissgrid procured the volume of energy specified by ElCom by means of a tendering procedure. Swissgrid accepted tenders from all operators of storage hydropower plants that feed energy into the Swiss control area who are in a position to offer a product that complies with the relevant benchmarks. In accordance with ElCom Directive 3/2023 («Benchmarks for the establishment of a hydropower reserve in the hydrological year 2023/2024»), procurement took place in staggered partial tenders between May and September 2023. The Federal Electricity Commission ElCom examined the tenders and awarded the relevant contracts.

The three auctions took place in late May, early July and mid-September. For the winter of 2023/24, a total volume of 400 GWh (2022: 400 GWh) has been procured at an average price of EUR 138.67/MWh (previous year: EUR 739.97/MWh). The hydropower reserve will cost 81 percent less in the current year than in the previous year. The costs for the reservation of water are financed through Swissgrid’s tariffs.

The hydropower reserve requires storage power plants to retain, in exchange for a fee, a certain amount of energy that can then be requested when needed. The reserve is intended to bridge a period of a few weeks towards the end of winter when there are fewer import possibilities and lower availability of domestic production.

In exchange for a fee, storage power plants will retain a certain amount of energy, the hydropower reserve.
In exchange for a fee, storage power plants will retain a certain amount of energy, the hydropower reserve.

The Federal Council has transferred the operational management of the hydropower reserve to Swissgrid by ordinance. Consequently, Swissgrid has taken on a new role that goes beyond its previous legal mandate. In specific terms, Swissgrid provides the IT systems for handling the auction and the requests. Swissgrid is also entrusted with defining and organising training for all processes, conducting the auctions and overseeing the accounting.


Voltage increases

To prevent congestion in the transmission system, the Federal Council allowed a temporary increase in the operating voltage of the two transmission lines between Bickigen and Chippis (Gemmi line) and Bassecourt and Mühleberg from 220 kilovolts (kV) to 380 kV for the winter of 2022/23.

It will be possible to operate the Bassecourt – Mühleberg line at 380 kV on a permanent basis from the end of 2023. In addition, the existing transformer capacities of the transmission system in the Berne/Jura region have been expanded to strengthen security of supply.

The construction project for a definitive voltage increase of the Bickigen – Chippis extra-high-voltage line (Gemmi line) is still in the approval phase. Commissioning is planned for 2027. In 2022, Swissgrid made the necessary technical preparations to operate the line at 380 kV on a temporary basis. Two 220 kV lines are currently connected via the electricity pylons. For the temporary voltage increase, all phases have been shifted by one position so that the 220 kV line is on the lowest cantilever. The line systems on four electricity pylons in the vicinity of the Bickigen, Chippis and Wimmis substations have been transposed especially for this purpose (see information sheet). The line lead-ins to the Bickigen and Chippis substations have also been modified. The aim was to minimise the impact on people and the environment as much as possible and to ensure that the safety distances between the conductors and the ground, houses or cableways can be observed. Test operations in the winter of 2022/23 clearly showed that bottlenecks in the Swiss transmission grid were relieved and the exchange of energy within the country and across borders was improved. Subject to approval by the federal government, Swissgrid will be able to temporarily operate the line at 380 kV in the winter of 2023/24 if required to ensure grid-related security of supply.


Grid connection of the reserve power plant in Birr

Eight modular, mobile gas turbines, each with around 30 megawatts of power, totalling almost 250 MW, have been installed on the premises of General Electric (GE) in Birr (AG). The turbines can be operated with various gaseous and liquid fuels. The Federal Council has issued an ordinance to govern the deployment of these reserve power plants. The use of energy is managed by Swissgrid. In addition to the grid connection for the reserve power plant in Birr, Swissgrid is responsible for managing the use of energy of the reserve power plants in Monthey and Cornaux. These energy reserves can be used as needed in extraordinary shortage situations until the end of April 2026.

A grid connection in record time

Swissgrid had to establish a new grid connection in order to feed the energy from the mobile gas turbines into the transmission system via the 220 kV substation in Birr. The grid connection for the Birr reserve power plant has been ready since 24 February 2023 after a construction period lasting just six months. The process usually takes several years. Implementing a project of this kind under extreme pressure in just a few months was a huge challenge for the project team and the commissioned suppliers and service providers.

Control energy for secure grid operation

Electricity cannot be stored in the transmission grid, so the amount of electricity fed in must always be the same as the amount of electricity fed out. This means that the production and consumption of energy must always be balanced. This equilibrium guarantees the secure and stable operation of the grid at a constant frequency of 50 hertz. If unforeseen fluctuations arise, the operators in the grid control rooms use control energy, a reserve that power plants keep available for Swissgrid and that can be retrieved as required. The power plants either increase or decrease their power to compensate for any missing or excess electrical energy. Even if electricity becomes scarce in the winter of 2023/24, Swissgrid must be able to provide sufficient control power. For this reason, procurements were made at an early stage to prepare for the winter.

Swissgrid Control
The employees in the two control centres in Aarau and Prilly monitor the entire Swiss transmission grid around the clock.

Emergency power groups

The use of emergency power groups as an additional reserve for the coming winter was substantiated in the Winter Reserve Ordinance. As with the hydropower reserve, Swissgrid is responsible for operational management.

The Confederation has signed four-year contracts with Axpo, BKW and CKW for a total contract sum of CHF 1 million. The aim is to contract emergency power groups to provide a total capacity of around 280 MW.

As poolers of emergency generators, these three companies are tasked with setting up a national virtual reserve power plant consisting of emergency generators that are voluntarily made available by their owners in return for remuneration. Registration with the three poolers is possible with immediate effect.

Interconnection with Europe

The Swiss transmission grid is part of the continental European interconnected grid and is connected to neighbouring countries via 41 cross-border lines. The close meshing of the electricity system and the existing cooperation with European partners make a significant contribution to Switzerland’s security of supply. Close cooperation with partners in Europe is also of the utmost importance for ensuring system security in Switzerland and its neighbouring European countries in the winter of 2023/24. Electricity self-sufficiency would not mitigate the risk of a power shortage.

Close cooperation with European partners requires a political or intergovernmental solution.

An island solution would jeopardise both secure grid operation and security of supply. The legislator took the importance of interconnection with Europe into account in the Electricity Supply Act. Cooperating with the European transmission system operators and ensuring sufficient international interconnection of the Swiss transmission grid represent an explicit legal mandate for Swissgrid (Art. 20, para. 2(f), StromVG).

Close cooperation with European partners requires a political or intergovernmental solution. This is the only way to establish a stable framework for secure cooperation with the EU in the long term, and hence for a high level of security of supply in Switzerland.



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