ETH and PSI Study: New Nuclear Power Plants in Switzerland Only Competitive with State Aid

High Construction Costs Hamper Profitability

According to the calculations, new nuclear energy would only become economical if construction costs fell to at most around 8,000 francs per kilowatt. This would not be unrealistic, according to Andreas Pautz, professor at ETH Lausanne and PSI staff member, provided manufacturers learn from cost overruns in earlier projects. Pautz pointed to the differing experiences: «Wir haben in Europa eine Handvoll von Neubauprojekten, die zum Teil deutlich aus dem Ruder gelaufen sind. Es gibt aber im nicht-europäischen Ausland zum Teil Projekte, bei denen die Baukosten sehr günstig ausgefallen sind. Es ist also relativ schwierig, sich dort auf eine Zahl festzulegen».

The study also notes that Switzerland can reach its net-zero target by 2050 even without new nuclear power plants. The prerequisite is efficient electricity trading with neighboring countries. ETH professor and co-author André Bardow said that a stable and affordable system requires this exchange to continue. Without new nuclear power plants, solar energy would have to feed between 36 and 43 terawatt-hours per year into the grid from 2050 onwards – a significant expansion compared to 8 terawatt-hours last year.

Security of Supply Remains an Import Question Even with New Nuclear Plants

According to the models, Switzerland would remain a net importer even with new nuclear plants. The Gösgen nuclear power plant was shut down for maintenance work last winter, the researchers explain; Switzerland imported a net 7 terawatt-hours of electricity – more than Beznau's annual production. New nuclear power plants would reduce winter imports by 1 to 6 terawatt-hours, corresponding to at most 20 percent of current winter production.

The authors also note that nuclear power and solar energy are «in einem gemeinsamen System technisch und wirtschaftlich kompatibel». For the economic viability of new nuclear plants, the study sees similar support instruments as are already in place for renewable energies: loan guarantees or contract-for-difference models, in which the state pays operators a fixed electricity price over an agreed period.

Support Models: Contract for Difference as an Option

Albert Rösti, who, like the entire Federal Council, wants to lift the existing ban on new nuclear power plant construction, described the contract-for-difference model as «ein sehr spannendes und gutes Instrument». The Federal Office of Energy under his leadership aims to present a report on the possible financing of new nuclear plants by the end of the year.

Reactions outside the research community were divided. Hans-Ulrich Bigler, President of the Swiss Nuclear Forum, said that lifting the construction ban was the right path and that nuclear power could be part of a future energy system. Nils Epprecht, Managing Director of the Swiss Energy Foundation (SES), on the other hand, saw the study as an argument against new nuclear power plants: «Sie bräuchten massive Bundessubventionen – und so tiefe Baukosten, wie sie für die Schweiz nicht realistisch sind».

Political Debate and Societal Decision

Christian Schaffner, Managing Director of the Energy Science Center at ETH Zurich, emphasized at the media event that the study should provide a scientific basis for the debate: «Wir werden aber kein Plädoyer für oder gegen Kernenergie geben». The decision for or against new nuclear plants is in any case «eine gesellschaftliche Frage».

The study appears amid the political debate about a possible lifting of the statutory ban on new construction. Even if voters lift the ban, hydropower and solar energy will remain the backbone of Switzerland's future electricity supply, according to the researchers. Without new nuclear plants, the study projects net imports of 5.4 to 12.4 terawatt-hours in the future.

The authors' conclusion: new nuclear power plants could in principle be technically integrated into the system, but their economic viability hinges on the stronger lever – lower construction costs, state support, and clear framework conditions. The model calculations thus deliver neither a verdict for nor against new nuclear plants, but rather a range of preconditions under which the numbers could work out.