Swissgrid estimates the current grid situation and the supply of energy for winter 2015/16 as tense. Energy reserves are tight, due to a number of interconnected special circumstances. As a result of the drop out of the nuclear power plants Beznau 1 and 2, a large proportion of the base load is missing from the 220-kV grid. This will have to be replaced primarily from Swiss storage reservoirs, as imports can only be used to a limited extent to compensate.
More energy is consumed in the winter in Switzerland than in the summer. Some of these additional energy requirements are imported from abroad. The energy providers also use the water reserves from the reservoirs to cover part of consumption.
Lack of base load leads to tense energy situation
Due to a number of interconnected special circumstances, these energy reserves are in short supply for the winter of 2015/16:
- As a result of the dry summer and autumn, rivers are carrying considerably less water than the long-term average and this reduces power production from run-of-river generation.
- The reservoir fill level curve published by the Swiss Federal Office of Energy shows that the reservoirs are currently filled to a below-average extent, compared to the long-term average.
- The nuclear power plants Beznau 1 and 2 are currently out of service. As a result, a feed-in of 720 MW into the 220-kV grid is missing in northern Switzerland. Consequently the corresponding proportion of base load, which covers the basic demand for electricity throughout the whole day, is lacking.
The missing base load has to be compensated for by means of production elsewhere, for example from storage power plants, which leads to the relevant reservoirs emptying more quickly than in previous years.
The situation on the transmission grid is becoming acute
The missing energy generation on the 220 kV grid and on the distribution grids is resulting in the need to transform more energy from the 380 kV grid to the lower grid levels. However, the capacity of these transformers is limited. In order not to get into an overload situation, Swissgrid must already intervene in power station deployment planning (taking 'redispatch measures') more often then usual. In this way, the transformers are relieved at certain times.
Imports are only possible to a limited extent for compensation
Around 90 percent of the exchange of energy with foreign countries is carried out via the 380 kV grid. As a result of the limited 380/220 kV transformer capacity, imports can only be used to a limited extent to compensate for the missing constant energy on Switzerland's 220 kV grid and distribution grid. This means that there are adequate energy reserves available abroad in the current situation and there is adequate import capacity at the borders, but these cannot be fully exploited to supply Switzerland.
Swissgrid recognised the current situation early on, and has conducted detailed analyses and calculations, as well as taking measures on the transmission grid to exploit the capacity of the transformers as effectively as possible. The competent authorities have been informed.
Swissgrid is monitoring the energy and grid situation continuously and providing information about further developments on this page.