In Etzel, experts in the H2CAST joint project are investigating whether the local salt domes are suitable for storing large quantities of hydrogen. ©STORAG ETZEL


Energy storage facilities play a central role in security of supply. In Lower Saxony, there are underground salt caverns that have so far been used as oil and gas storage facilities. The joint project H2CAST in Etzel is now investigating whether these can also function as storage facilities for hydrogen and what conversions may be necessary for this. The project is financially supported by the Lower Saxony Ministry for the Environment, Energy, Building and Climate Protection.

News (23.10.2023): Arbeiten zur Umrüstung der Kavernen für die Wasserstoffspeicherung haben planmäßig begonnen

Die Umrüstung der zwei Kavernen hat erfogreich gestartet. „In eine Kaverne wird in die Zugangsbohrung eine Gasspeicherkomplettierung und ein Solependelstrang eingebaut. Zudem wird ein neuer für Wasserstoff geeigneter Kavernenkopf aufgebaut.“ Das Einspeisen von 80 Tonnen H2 soll im Sommer 2024 beginnen, nachdem weitere erfolgreiche Tests abgeschlossen sind. Ab 2026 soll der Standort „H2-Ready“ sein. Mehr Infos hier.

News (02/17/2023): Successful completion of the first leak test with hydrogen at cavern in Etzel

Within the framework of the research project H2CAST has STORAG ETZEL together with project partners successfully completed the first gas tightness test with hydrogen on a cavern borehole.

Extensive material testing was carried out in preparation for the test and during the test phase. In total, the team introduced several thousand standard cubic meters of gaseous hydrogen from sustainable, "green" production into the well. The test period wassignificantly longer, at over two months, than is the case with comparable tightness tests under nitrogen. More

News (01/17/2023): Gasunie becomes partner in the H2CAST Etzel project

As STORAG ETZEL and Gasunie announced on 17.01.2023, Gasunie will become consortium partner in the project "H2CAST Etzel". Within the framework of the project, hydrogen storage in the Etzel salt caverns is to be made possible together with project partners. In a first step, two existing salt caverns will be upgraded for H2 storage and connected by an aboveground facility. Gasunie will be responsible for this aboveground facility. The pilot project is scheduled for completion in 2026.

Gas and oil are stored in so-called caverns at a depth of over 750 metres in the massive Etzel salt dome. These are artificially created cavities in underground mining. The hydrogen research & development project H2CAST Etzel aims to show that these caverns can store not only oil and gas, but also large quantities of hydrogen. The existing caverns will then hold up to 22.5 TWh of hydrogen. A sophisticated shuttle operation system between two caverns will help to variably adjust the storage volume and the pressure, among other things. The project on an industrial scale could lead the way for many other salt caverns in Europe.

H2CAST is the abbreviation for H2 Cavern Storage Transition, and stands for the conversion of existing caverns and facilities for the storage of hydrogen.

Boris Richter, STORAG ETZEL

"We want to make the Etzel site in Lower Saxony "H2-ready", i.e. prepare it for the foreseeable ramp-up of the hydrogen economy, which will help to decarbonise German industry, i.e. make it more CO2-free and climate-friendly. In this way, security of supply with CO2-free energy will be guaranteed in the future. The location is of crucial importance for north-western Europe in this regard.

The energy transition will need these large-scale storage facilities by 2030 at the latest, as H2 supply and demand will diverge in time and space. Our goal is to make the location sustainable for future generations!

Christian Rode, EKB Storage

Christian Rohde adds, "that extremely flexible, large-volume underground storage facilities are essential for the energy transition, as they act as a variable buffer to secure the supply chains and can be used between hydrogen production or

-import and the consumers on the market. The Etzel site is particularly predestined for this due to its existing infrastructural importance."

Olaf Lies, Energy Minister

"Hydrogen will be an integral part of the future energy economy. Without storage, this will not succeed. With H2CAST Etzel, we are promoting a pilot project on an industrial scale. A competent and experienced project consortium from industry and science has come together for this. What is special is that for the first time in Lower Saxony, existing caverns intended for oil and gas storage are to be converted for hydrogen. The intended brine shuttle operation has also not yet been implemented in this way. The pilot project is also the starting point for a possible local value chain. We are creating knowledge that is likely to be in demand elsewhere. With the funding, we are helping to ensure that we will continue to have a secure energy supply in the future, ultimately without oil and natural gas, and that we will maintain local value creation in the energy hub of Lower Saxony."

H2CAST Etzel Project Team 

  • STORAG ETZEL (supplier of cavern storage facilities)

STORAG ETZEL builds, maintains and leases underground storage capacity for gas and oil at the Etzel site in East Frisia. Tenants are national and European oil storage organisations and international companies from the energy sector. Among other things, a large part of the German crude oil reserve is stored in Etzel.

    • Gasunie (responsible for the surface plant)

    Gasunie is a European energy infrastructure company. Gasunie's network is one of the largest high-pressure pipeline networks in Europe, comprising over 17,000 kilometers of pipelines in the Netherlands and northern Germany. With its cross-border gas infrastructure and services, Gasunie enables the TTF, which has become the leading European gas trading point. Gasunie also offers other gas infrastructure services, including gas storage and LNG.

    • KBB (planning, construction and operation of underground storage facilities)

    DEEP.KBB is significantly involved in the planning, construction and operation of underground storage facilities in the salt for the storage of natural gas, mineral oil, gas and oil products as well as the storage of renewable energies, in particular compressed air and hydrogen. Main focus: Geology, rock mechanics, drilling and completion engineering, thermodynamics, brine engineering, tightness testing, cavern flooding, gas filling and reservoir engineering.

    • DLR - Institute for Networked Energy Systems

    The Institute for Networked Energy Systems joined the German Aerospace Center (DLR) in June 2017. The primary research goal of the three scientific departments Urban and Building Technologies, Energy Systems Engineering and Energy Systems Analysis is the development of technologies and concepts to shape the energy transition.

    • Hartmann Valves

    Hartmann Valves is a supplier of special ball valves, wellheads and related service and testing, including solutions for applications and underground storage of hydrogen.

    • Clausthal University of Technology

    The Chair of Geomechanics and Multi-Physical Systems at Clausthal University of Technology is concerned with the stability and tightness of salt caverns for the storage of energy raw materials such as natural gas and crude oil, for compressed air storage and for brine extraction. For the performance of its tasks in research and teaching, the chair has an extensively equipped laboratory (currently 25 rock mechanical testing facilities), a powerful computer pool and various numerical programme systems.

    • SOCON

    SOCON Sonar Control Cavern Surveying specialises in the geophysical survey of caverns, boreholes and underground cavities.