Hydrogen Storage Steps Out of the Lab in Europe

German project shows underground storage working, easing a key hurdle to supply

12 Dec 2025

Europe’s effort to build a viable hydrogen market is beginning to move from planning to practice, as a German storage project demonstrates how renewable hydrogen could be handled under real operating conditions.

The H2CAST initiative, led by Gasunie and STORAG ETZEL, has completed deliveries of hydrogen into underground salt caverns, a method long used for natural gas but still largely untested for low-carbon hydrogen. Project partners say the operation shows that production, transport and storage can be linked in a way that supports more reliable supply.

One of hydrogen’s main obstacles has been timing. Output from wind- and solar-powered electrolysers varies with weather, while industrial users require steady volumes. H2CAST seeks to bridge that gap by storing hydrogen deep underground, allowing fuel produced during periods of high renewable generation to be withdrawn weeks or months later.

That concept moved closer to commercial reality when Plug Power, acting as hydrogen supplier, completed deliveries into the caverns. The companies said the process demonstrated that meaningful volumes could be transported and stored safely outside a laboratory or pilot setting.

The project also offers early insight into production economics. Hydrogen supplied to H2CAST is produced at renewable-powered facilities run by Hy2Gen. Being able to store output allows those plants to run more consistently, reducing downtime and improving utilisation rates. Developers argue that, at scale, this could help lower production costs.

Transport remains a constraint. Europe plans to develop a dedicated hydrogen pipeline network, but much of that infrastructure is years away. For now, H2CAST relies on specialised road transport, which is more expensive but allows early projects to proceed. Gasunie and other network operators view such schemes as interim solutions that generate data for future investment decisions.

Structural challenges persist. Suitable salt caverns are geographically limited, and regulations governing hydrogen storage and transport vary across borders. These factors complicate efforts to build a single European market.

Even so, interest is growing. Analysts increasingly see storage as a critical enabler that could turn hydrogen from a niche technology into a more system-ready energy carrier. As governments look to cut emissions and strengthen energy security, projects such as H2CAST offer a glimpse of how integrated production, transport and storage might support the next phase of Europe’s hydrogen strategy.