Could Switzerland’s run-of-river hydropower plants become hydrogen factories? A new study by researchers at HES-SO’s School of Engineering and Management Vaud (HEIG-VD) in Yverdon-les-Bains — a SPIN member — says yes, but with a twist nobody was expecting: the biggest revenue stream isn’t hydrogen at all. It’s oxygen.
A real Swiss case: the Lavey plant on the Rhône
The team around Matthieu De Lapparent, Selin Ataç and Massimiliano Capezzali built a detailed optimisation model (a so-called mixed-integer linear programme) and applied it to the Lavey run-of-river plant on the Rhône — a 67 MW installation owned by the municipal utility of Lausanne, which is contractually obliged to supply 40% of the city’s power consumption at all times.
The model decides, hour by hour across a full year, whether electricity should be sold to the grid or diverted to a 10 MW electrolyser producing H₂ — and, inevitably, O₂ as a co-product. What makes the framework stand out is its realism: it accounts for electrolyser degradation from on/off cycling, minimum up-times, on-site H₂ storage and compression, reconversion to electricity via fuel cells, and — a first in the literature — hydrogen delivery contracts with penalties for non-compliance. The calculations use real 2023 electricity prices (ENTSO-E) and hydrogen market prices (Hydrix index).
The surprising result: O₂ beats H₂
In the baseline scenario, the hybrid plant generates roughly 74 million EUR in annual net profit. The breakdown is remarkable: around 41 million EUR comes from oxygen sales — for example to hospitals, water treatment plants and industry — about 22.5 million EUR from net electricity revenues, and only some 12 million EUR from hydrogen itself.
In other words: the gas that electrolysis operators routinely vent into the atmosphere may be the key to making green hydrogen projects financially viable. The authors are careful to note that this hinges on sufficient local O₂ demand, which is site-specific — but in densely populated or industrialised regions, the case is strong.
Further lessons for project developers
The sensitivity analyses hold additional insights. One large electrolyser outperforms several smaller units of the same total capacity, thanks to economies of scale. More H₂ storage does not increase profit — it mainly buys operational flexibility. And hydrogen delivery contracts only become fully reliable once the penalty for non-delivery reaches about 6 EUR per kilogramme; below roughly 3.5 EUR/kg, the model happily accepts shortfalls and pays the fine.
The electrolyser itself runs almost continuously: in the baseline case it is switched off for only about 2.4% of the year, mostly in late winter when electricity prices peak and selling power to the grid beats making hydrogen.
Why this matters for Power-to-X in Switzerland
Run-of-river plants account for a substantial share of Swiss hydropower, and many face summer periods when abundant solar power depresses electricity prices. This study shows a credible path to “upgrading” such plants into hybrid producers of electricity, defossilised fuels and industrial gases — and it delivers a fully parametrised decision-support tool that operators can adapt to their own site. For the defossilisation of Swiss industry and mobility, that is a very practical contribution.
Source: Ataç, S., Marques Mendes, D., de Lapparent, M., Capezzali, M. (2026): A multi-period MILP approach to run-of-river hydropower integration for green hydrogen supply: An optimization framework. International Journal of Hydrogen Energy 254, 156003. https://doi.org/10.1016/j.ijhydene.2026.156003 (Open Access, CC BY)
🤖 AI transparency: This text and its visual were created using AI, reviewed and approved by a human.
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