Presently, approximately 30 % of the electricity consumed in Switzerland comes from nuclear power. According to the objectives stipulated in the Energy Strategy 2050, this share is to be replaced by electricity from renewable sources. However, this entails new risks: the flow of electricity from solar power plants or wind turbines is prone to fluctuations, and the public can endanger development, for example by opposing the construction of power lines or wind turbines. In this research project, the scientists wanted to determine how much renewable energy Switzerland should aim for, and where it should come from. The findings are intended to support decision-makers. To this end, the researchers analysed the listed risks for the four most promising renewable energy expansion options: wind power in Switzerland, solar power from Swiss rooftops and solar farms, offshore wind turbines in the North Sea and solar thermal power stations in North Africa.
The analysis shows that Switzerland can switch from nuclear power to renewable energies without compromising security of supply. For the experts, it is clearly possible to switch from nuclear power to renewable energy without resorting to gas-powered plants to fill in the gaps. Forgoing gas makes the switch even cheaper, provided the electricity production costs of wind and solar energy remain as low as those fixed in supply contracts in 2017. However, the country should not rely exclusively on photovoltaics (PV): in the wintertime, when sunlight is weak, the yield from hydropower plants, which supposedly ensure a constant flow of electricity, is also reduced, as a large amount of water is bound in the form of snow and thus cannot flow through the turbines. It therefore makes sense to also import offshore wind power from northern countries, as this source is particularly abundant in winter. However, this strategy increases imports and it is therefore crucial to operate several transmission corridors in parallel, in case one of them fails.