Green hydrogen has been produced at the Kubel hydropower plant in St. Gallen since November 2022 – so far mainly for fuel cell vehicles. Now SPIN member OST – Ostschweizer Fachhochschule (IET Institute for Energy Technology) is examining whether part of it could also be fed into the gas grid of St.Galler Stadtwerke. According to the IET, the study was commissioned by SN Energie AG and covers the technical, regulatory and economic feasibility of blending the hydrogen with natural gas. The aim: to open up additional uses and make hydrogen sales more flexible.

Hydrogen from the Kubel hydropower plant

The hydrogen comes from Wasserstoffproduktion Ostschweiz AG (WPO). The St.Gallisch-Appenzellische Kraftwerke AG (SAK) and the Osterwalder Group (AVIA Osterwalder) founded the company in September 2019 to produce green hydrogen from renewable energy. In July 2022, SN Erneuerbare Energie AG – a wholly owned subsidiary of SN Energie AG, the client of the OST study – joined as a third shareholder, as Hydrogen Central reported at the plant’s opening.

The electrolyser draws its electricity directly from the neighbouring Kubel hydropower plant, which SAK describes as Switzerland’s oldest storage power plant. At its commissioning on 17 November 2022, the plant was specified as follows:

  • Electrical output: 2 MW
  • Production rate: 36 kg of hydrogen per hour
  • Annual output: about 250 tonnes, depending on how much electricity is available for hydrogen production
  • Offtake: delivered by container to the AVIA hydrogen filling stations in St. Gallen and Gossau for fuel cell cars and trucks

What the OST study examines

The IET team wants to find out at which points, in what quantities and under which conditions green hydrogen could be fed into the existing grid. The study has four focus areas:

  • Technical feasibility: possible injection points, connection requirements and the amount of hydrogen the grid could absorb under different operating conditions – especially in summer and in winter.
  • Regulation: the applicable requirements for hydrogen injection, in particular permissible hydrogen shares and gas quality.
  • Economics: the main investment and operating costs and the economic framework for injection.
  • Potential and scalability: future development options and the factors that support or limit implementation.

The result is meant to be a sound basis for deciding whether the gas grid can serve as an additional sales channel for regionally produced green hydrogen, together with recommendations for next steps. The IET has not published a timeline or first results. The contact at the institute is Prof. Dr. Dariusz Nowak.

What the rules allow

In Switzerland, the permissible hydrogen content of natural gas is set by the SVGW guideline G18 on gas quality. According to the revised July 2026 edition, published as a consultation draft, up to 2 mol-% hydrogen requires no additional safety assessment of the grid and connected users. Between 2 and 20 mol-%, blending is possible in a delimited network area if the grid operator first assesses hydrogen compatibility. In that area, the operator must also ensure that all of the gas distributed is consumed and that none flows back into upstream grids. Limits on combustion characteristics such as the Wobbe index can cap the hydrogen share further.

This is why the season matters: where less gas is consumed, less hydrogen can be blended in. The OST team explicitly looks at summer and winter operation.

One physical fact puts the percentages into perspective. Per cubic metre, hydrogen carries far less energy than methane: SVGW gives a lower heating value of 2.995 kWh/m³ for hydrogen and 9.971 kWh/m³ for methane. Based on these values, a blend of 20 per cent hydrogen by volume supplies only about 7 per cent of the energy in the gas.

SPIN’s view

An electrolyser that depends on a single offtake channel has to throttle back whenever that channel is weak. A second outlet through the gas grid could help the Kubel plant run more steadily – the kind of system question we discussed earlier with Markus Friedl, head of the OST IET, in «Is hydrogen coming or not?». And every kilowatt-hour of renewable hydrogen that ends up in the grid replaces fossil natural gas: a small but real contribution to defossilisation.

Blending should nevertheless be seen as a buffer, not as the destination. Renewable hydrogen is most valuable where it replaces fossil energy that is hard to electrify – heavy transport, industrial processes, chemical feedstock. And if the gas grid is to take up larger volumes in the long run, there is an alternative without a blending ceiling: methanation. Synthetic methane made from renewable hydrogen and recycled CO₂ – from biogenic, atmospheric or industrial sources – counts as H-gas under G18 and can therefore replace natural gas one to one.

We look forward to the results. The question of where green hydrogen can go when the primary market falls short is one that many Swiss producers face.

Join SPIN: Companies, research institutions and associations that want to advance Power-to-X in Switzerland are welcome to become members of SPIN. Questions? Write to info@power-to-x.swiss.

Sources: OST IET, “Einspeisung von grünem Wasserstoff in das St. Galler Gasnetz”; SAK, “SAK und AVIA Osterwalder gründen die Wasserstoffproduktion Ostschweiz AG” (24 September 2019); Hydrogen Central, “Opening of the hydrogen production plant in the Kubel power plant” (21 November 2022); SVGW, Richtlinie G18 Gasbeschaffenheit, Ausgabe Juli 2026 (Entwurf Vernehmlassung); SVGW, “Erneuerbares Gas aus Strom” (September 2021).

🤖 AI transparency: This text and its visual were created using AI, reviewed and approved by a human.