(Etzel) – Storag Etzel GmbH, together with six consortium partners, is investigating whether salt caverns in Lower Saxony can serve as storage for hydrogen. In 51 of the artificially created cavities in Etzel, Frisia, half an hour's drive southwest of 
Wilhelmshaven, there are currently around 4,3 billion cubic meters of gas and around ten million cubic meters of crude oil stored in another 24 caverns, the company explained. Among other things, a large part of Germany's crude oil reserves are stored in Etzel.
Potential of 99 caverns
In addition to the 75 caverns currently in existence, further storage cavities could be created in the salt dome. According to Storag Etzel, there is potential for expansion to 99 locations. According to the plans, the caverns could hold up to 72 terawatt hours of hydrogen in the future. A shuttle operating system between two caverns ensures that the storage volume and pressure can be variably adjusted.
The investigations are scheduled to begin in the first quarter of 2022. The storage of hydrogen in research operations is planned for 2024. The project, called “H2 Cavern Storage Transition” (H2CAST), is financially supported by the Lower Saxony Ministry for the Environment, Energy, Building and Climate Protection.
The consortium partners
In addition to Storag Etzel GmbH, Etzel-Kavernenbetriebsgesellschaft mbH & Co. KG (EKB Storage) is involved. It has been operating a natural gas storage facility at the site since 2012, currently with nine caverns for national and international customers. The consortium also includes the engineering company DEEP.KBB GmbH, which is said to be responsible for planning, 
is involved in the construction and operation of underground storage facilities in 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.
The Oldenburg Institute for Networked Energy Systems, part of the German Aerospace Center (DLR), is also on board, as is Hartmann Valves GmbH, based in Celle, which is a provider of special ball valves, wellheads and associated services, including solutions for the underground storage of hydrogen.
Also involved is Socon Sonar Control Kavernenvermessung GmbH, which specializes in geophysical surveying of caverns, boreholes and underground cavities. The Chair of Geomechanics and Multiphysical Systems at Clausthal University of Technology is supporting the project scientifically and is dealing with the stability and tightness of salt caverns for storing energy raw materials such as natural gas and crude oil, for compressed air storage and for brine production.
Photo above
Cavern complex in Etzel. © Storag Etzel
Photo middle
In Etzel, experts in the H2CAST joint project are investigating whether the local salt domes are suitable for storing large amounts of hydrogen. © Storag Etzel / DEEP.KBB
Graphic below
Gas pipelines that can be repurposed for H2 operations. A hydrogen pipeline to the possible H2 import terminal in Wilhelmshaven could also be realized. © Storag Etzel
