Another milestone reached

Following the successful completion of the conversion and leak tests with hydrogen in two caverns in 2024, STORAG ETZEL began injecting the first quantities of a planned total of 90 tonnes of hydrogen at the turn of the year. The injection is part of the ‘H2CAST Etzel’ research and development project, which is developing the technical implementation of hydrogen storage in salt caverns. ‘This represents another milestone in the conversion of existing caverns for the storage of hydrogen in Etzel,’ says Carsten Reekers, project manager of the “H2CAST Etzel” research and development project.

The gaseous hydrogen delivered at a pressure of 300 bar by truck trailers displaces the brine from the caverns during storage via the cavern head and borehole piping suitable for hydrogen. The brine is transported away via the STORAG ETZEL brine system.

‘After the expected start-up difficulties in the procurement of hydrogen - it is clear that the hydrogen market is still in its infancy - several tonnes have now been safely stored underground at a maximum pressure of 170 bar as of the end of January,’ Reekers continued. ‘We are proud of what we have achieved so far and have now shown that the existing facilities in the Etzel cavern field are suitable for hydrogen storage. Our specialist colleagues in gas operations have the process steps for hydrogen filling under control.’

STORAG Etzel is continuously pursuing its hydrogen storage strategy. The Etzel caverns are scalable and flexible, meaning that existing local underground gas and oil storage facilities can be quickly converted for the use of hydrogen. ‘We'll be ready to go when the H2 market is,’ says Reekers.

In 2025, STORAG Etzel and its project partners still have some challenging milestones ahead of them in the H2CAST project. The focus will then be on the construction and commissioning of the hydrogen purification plants. Different processes and their efficiency will be tested. Preparations for this are already in full swing. ‘We are very confident that we will also succeed in this step as a team effort with

with our employees and partners,’ continues Reekers. ‘The fact that we can manage the operation and maintenance of the systems with specialist personnel from our existing organisation is proving to be an advantage. Our decades of experience in underground storage will help us here,’ concludes Reekers.

Due to the lack of an H2 pipeline connection, the hydrogen still has to be delivered to Etzel by lorry. Up to three lorry loads of hydrogen will arrive in Etzel every week until the summer. A total of around 200 lorry trailer loads will be required to fill the roof area of the caverns with hydrogen. Smaller quantities of hydrogen were already injected into the caverns at the beginning of 2024 as part of upstream tests to prove the hydrogen-tightness of the caverns and the drilling equipment under maximum gas pressure. In future, the Etzel site will be supplied with hydrogen via pipeline after connection to the already approved H2 ‘core network’.

The storage of hydrogen was authorised by the supervisory authority, the State Office for Mining, Energy and Geology (LBEG).

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