When new nuclear power plants are worth it in Switzerland

Should we forge ahead with the existing energy strategy or return to building new nuclear power plants again in the future? Since the Federal Council’s counter-proposal to the “Blackout Initiative”, this question has been at the heart of Swiss energy policy and will ultimately be decided on by the Swiss electorate.

A new study by 19 energy experts from ETH Zurich and the Paul Scherrer Institute (PSI) is investigated under which conditions the construction of new nuclear power stations may make financial sense for Switzerland’s future energy system. The findings of the study are based on four different energy models. These models calculate which technologies Switzerland could use by 2050 to cover significantly higher electricity demand as cheaply possibly and in a carbon-neutral way.

Speaking on behalf of the research team, André Bardow, Professor at ETH, explains: “Each of these models is based on a range of assumptions that are associated with uncertainties and simplify the complexity of the energy system. In cases where these models point in the same direction, there are robust findings that could form the basis for discussion by society and in the sphere of politics. As for whether to decide for or against nuclear power, this is ultimately a question for society.”

Nuclear power under present political conditions

The study by PSI and ETH researchers shows that new nuclear power plants might not be financially viable under present fiscal conditions. Proceeding on the assumption that the state will continue only to subsidise renewable electricity sources such as photovoltaics and wind as part of its target to expand power generation to 45 TWh in future and not provide any funding for the construction of new nuclear power plants, nuclear power would still be too expensive under the majority of model calculations used in the study. This remains the case even with low to moderate construction costs of CHF 5,000 to CHF 8,000 per kW of installed capacity.

The study also shows that Switzerland can achieve its net-zero target using existing and planned technologies without the need for new nuclear power plants. Efficient electricity trading with foreign countries is among the essential factors for the stability of a system that does not include nuclear power. Depending on the model, the net electricity imports in winter range between 5.4 TWh and 12.4 TWh. All models show that Switzerland would still be just as dependent on net imports in winter in 2050 as it is today. For example, Switzerland imported around 7 TWh of electricity net between October 2025 and March 2026, when Gösgen Nuclear Power Plant had been powered down to undergo an inspection. By way of comparison, Beznau and Leibstadt nuclear power plants generate around 6 and 10 TWh of electricity per year respectively.

In a future energy system without nuclear power, solar energy would supply between 36 and 43 TWh of electricity depending on the model, which would cover around 50 percent of total energy consumption in 2050. Taken together, hydropower and photovoltaics would make up around three quarters of the electricity supply, thus forming the backbone of the system. Other additions would include wind power, biomass, and storage technologies such as pumped-storage power plants, chemical energy storage plants (hydrogen and methane) and batteries. In order to hit the expansion targets for these generation and storage technologies, government support is required. The Swiss electorate accepted the statutory basis for this support in 2024.

Nuclear power in a future energy system

According to the authors of the study, new nuclear power plants are technologically compatible with a future energy system based primarily on solar and wind power. But in order for nuclear power to be economically competitive compared to the renewable electricity sources that are already being supported, three things are needed: firstly, the government would have to decide to support nuclear power as part of the 45 TWh target too. The details of how to implement this are outside of the scope of the study. The models calculate only the cheapest technology mix for Switzerland’s energy supply in 2050 in keeping with the 45 TWh target. The models adjust the financial support required for this as appropriate.

Secondly, politicians would have to decide on risk reduction measures in order to lower the financing costs of new nuclear power plants from its estimated market rate of 8 percent to 5 percent, in line with the interest rate for other large-scale carbon-neutral plants. This is another point where the models do not specify how this target could be achieved – for example, it might be possible for the government to award loans or certain guarantees for agreed fixed prices such as contracts for difference.

Thirdly, construction costs for new nuclear power plants must not be too high. With construction costs of CHF 12,000 per kW, which are similar to costs recently observed in Europe and the US, building new nuclear power plants will no longer be worth it in three of the four models – even if the government awards subsidies and bears a portion of the financial risk. But in the hypothetical scenario where construction costs of CHF 5,000 per kilowatt could be achieved, which is rather cheap, it would be profitable to build between 2.6 and 4.9 GW of new nuclear power plants. And even with moderate construction costs of CHF 8,000 per kW, two out of four models still predict an installed power plant capacity of 2 GW (see Figure 1 below). By comparison, the four reactor units currently running at Beznau, Gösgen and Leibstadt have a total capacity of around 3 gigawatts.

“This goes to show how crucial construction costs are for nuclear power plants to be competitive. Prices for new nuclear power plants recently seen in the US and Europe can also be attributed to the fact that they are the first projects of their kind. At best, nuclear energy will only be competitive in Switzerland if manufacturers successfully learn the lessons of these cost overruns and limit the costs of future plants to around CHF 8,000 per kW,” says Andreas Pautz, Head of the PSI Center for Nuclear Engineering and Sciences, Professor of Reactor Physics and Systems Behaviour at EPFL and one of the study’s authors.

Nuclear power would mean lower electricity imports in winter

Even in an energy system that includes nuclear power, hydropower and photovoltaics form the backbone of the electricity supply of the future in the majority of the models. And in most of the models, solar energy is expanded drastically, even where new nuclear power plants are built. If the costs of construction for new nuclear power plants increase from CHF 5,000 to CHF 8,000 per kW, electricity from nuclear power will be replaced by photovoltaics and, to a much lesser extent, by wind power too.

The models also show that new nuclear power stations would reduce net electricity imports in winter overall, but not eliminate them entirely. Depending on the model, net electricity imports in winter could be reduced by 1 to 6 TWh, i.e. 3 to 20 percent of the electricity currently generated between October and March. “In order to maintain a stable and affordable energy system, efficient electricity trading with neighbouring countries remains indispensable, even if new nuclear power plants are built,” adds Bardow, Professor at ETH.