Must-read highlights from FrHyGe – July 2025

Hydrogen storage in salt caverns is increasingly recognised as a practical component of Europe’s low-carbon energy strategy. 

Supported by the European Commission and national governments, this solution enhances the resilience and flexibility of future hydrogen infrastructure. It is also being incorporated into the European Hydrogen Backbone, the cross-border network designed to connect production hubs with areas of high demand. With their ability to store large volumes and respond to supply-demand fluctuations, salt caverns provide a reliable way to stabilise the hydrogen system. Several Member States are now integrating large-scale storage into their national hydrogen strategies.

In Germany, major investments are underway to convert existing gas storage sites into hydrogen-ready infrastructure. According to a white paper by the Federal Ministry for Economic Affairs and Climate Action (BMWK), the country’s salt caverns have the potential to meet long-term hydrogen storage needs not only domestically, but also at the European scale. In this context, both salt caverns and porous reservoirs are expected to play a central role.

One concrete example of this effort is the SaltHy project led by Storengy Deutschland.
On June 18, Storengy Deutschland signed a grant agreement with the European Commission, securing up to €4.5 million in funding from the Connecting Europe Facility (CEF) – Energy for the SaltHy hydrogen storage project, aimed at hydrogen storage in Harsefeld. The funding will cover predefined work packages in the following areas: engineering, permitting procedures, stakeholder management, risk management, health, safety and environment (HSE), and quality management.

In France, current developments are moving in the same direction. The national hydrogen policy is being revised to place greater emphasis on large-scale underground storage as a key lever to balance supply and demand, in addition to short-term and local storage solutions.

Meanwhile, in Spain, Enagás recently launched the Public Participation Plan for the Hydrogen Backbone Network in Castile-La Mancha, the company’s largest deployment to date. The European Commission has also approved a €400 million Spanish State aid scheme to support renewable hydrogen production, as part of the second round of the European Hydrogen Bank’s Auctions-as-a-Service mechanism, which closed in early 2025.

On the technical side, recent publications — including work by RTE and NaTran (formerly GRTgaz) — confirm the growing need for medium-term hydrogen storage solutions, especially in France. The flexibility of electrolysis, essential to integrating renewable electricity, requires buffer systems. In this context, salt caverns stand out for their ability to support regional hydrogen hubs both technically and economically.

HyPSTER is the first salt cavern hydrogen storage demonstrator which has been subsidised by the European Union (Clean Hydrogen Partnership). It aims at testing and validating the role of hydrogen storage in the hydrogen value chain, with the perspective to eventually replicate it on a larger scale and support the development of the hydrogen industry in Europe. Launched at the end of 2024 for a period of four months, the cycling tests have now been completed.

They provided an assessment of the salt cavern and the stored hydrogen while facing different pressure cycles and validated the ability to commercially operate hydrogen storage in salt caverns. A key milestone that laid the groundwork for the FrHyGe project, now progressing towards TRL8 and building on these results through further R&D and detailed economic and environmental assessments.