Stress-testing the Swiss power system: what ETH and ZHAW say about hydrogen’s role

In January 2025, a team of researchers from the Energy Science Center at ETH Zurich and the ZHAW Winterthur published a follow-up to earlier work on the role of synthetic fuels in a climate-neutral Swiss electricity system. The new study – titled “Thrive in sunshine, brace for thunder” – stress-tests the 2050 Swiss power system against shock scenarios: drastic reductions in cross-border electricity trade, and disruptions in gas imports. The results clarify, soberly, what hydrogen and synthetic fuels can and cannot do for Swiss security of supply.

The model and the starting point

The research builds on the Nexus-e modelling platform developed at ETH’s Energy Science Center, which integrates electricity market dynamics with capacity expansion, transmission and storage decisions for the Swiss system. By 2050, under Switzerland’s Climate and Innovation Act, the national energy supply is to be CO₂-neutral. Demand will rise as transport and heating electrify. The existing nuclear fleet will be retired. The remaining supply mix in the model rests primarily on hydropower, solar and wind, complemented by imports.

The question the new study asks is sharper than the earlier work’s: not just what mix is cost-optimal under normal conditions, but how resilient that mix is to disruption.

The key finding: the system is more resilient than often assumed

The headline result is reassuring on its own terms. The model calculations show that a future Swiss electricity system can absorb up to a 70 percent temporary reduction in cross-border electricity trade without requiring additional measures. The main reasons are Switzerland’s substantial hydropower reservoir capacity – around 9 TWh of seasonal storage – and a generation mix in which a significant share comes from domestic rooftop PV, Alpine PV, wind and biomass.

In other words, the system has substantial buffers built into its current and planned structure. Imported electricity is important but not load-bearing for ordinary operation.

Where hydrogen fits in

This is where the study is most interesting for the Power-to-X community, and where the findings deserve careful reading.

Under ordinary conditions and moderate shock scenarios, the cost-optimal way to handle import disruptions is liquid fuel reserve power plants – not green hydrogen. Gas-fuelled or liquid-fuelled reserve capacity, used rarely, is cheaper than expanding hydrogen production and storage infrastructure that sits idle most of the time. The economics of capital-intensive hydrogen capacity with a low capacity factor are unforgiving.

Sustainably produced hydrogen, in the model, is only deployed as an offsetting power supply in shock scenarios where electricity and gas imports break down completely on a frequent two-to-ten-year cycle. Even then, the total contribution is modest – the researchers indicate a maximum of around 2.5 TWh, equivalent to roughly 3 percent of Swiss electricity demand.

The 2024 study from the same group reached compatible conclusions: hydrogen and e-methane imports become part of cost-efficient electricity supply only at low import prices (below roughly 3 CHF per kg of hydrogen). Domestically produced hydrogen for power generation faces a competitive disadvantage compared to Swiss hydropower storage. At very low import prices of 1 CHF per kg, hydrogen could cover up to 12 percent of annual electricity demand – but that price level is, today, well below realistic forecasts.

What this does and does not say

Two clarifications are essential.

First, the studies analyse hydrogen as a fuel for electricity generation in Switzerland. They do not analyse hydrogen as an industrial feedstock, as a feedstock for synthetic fuels and chemicals, or as a fuel for heavy-duty road transport, aviation or shipping. Those are different questions with different answers. Power-to-X projects in Switzerland are not primarily targeting the power sector – they are targeting the hard-to-electrify segments where hydrogen and its derivatives have genuine competitive advantages.

Second, the studies analyse cost-optimised system design under stated assumptions. They are not forecasts of what will happen. The model also notes that domestic Swiss hydrogen production faces diseconomies of scale: costs rise with higher production targets, reflecting limited renewable resources and high land costs. This is an empirical observation, not a verdict.

SPIN Perspective

The ETH/ZHAW findings reinforce a point the Swiss Power-to-X community has emphasised consistently: domestic green hydrogen production in Switzerland is not the most cost-effective lever for defossilising electricity. Hydropower storage already covers most of the seasonal flexibility needs. Imports of electricity – not hydrogen – are the practical bridge for residual demand.

Where Switzerland’s Power-to-X opportunity actually lies is in two adjacent spaces. The first is hard-to-electrify demand: heavy transport, aviation, shipping, high-temperature industrial heat, chemicals feedstocks. Hydrogen and synthetic fuels for these segments cannot be substituted by hydropower or grid electricity. The second is the value chain: Swiss engineering, equipment, project development, certification and finance for Power-to-X projects deployed in regions with better renewable resource availability – Patagonia, North Africa, Iberia, Norway, Scandinavia.

Power-to-X derivatives like synthetic diesel or petrol (eFuels) can play an important role in bringing down CO₂ emissions from passenger cars, faster than through electrification alone (see the Porsche Consulting report we wrote about).

These ETH and ZHAW studies are useful precisely because they de-mystify a debate that has, at times, conflated two distinct questions: should Switzerland produce hydrogen for its own electricity grid (probably not, at scale), and should Switzerland be active in the global hydrogen economy (clearly yes, across multiple value chain positions). Mixing these up serves no one.

Sources: ETH Zurich, ZHAW, Nexus-e Syngas Report (2024), ETH Energy Science Center.