(Rüdersdorf) – The Oldenburg energy supplier EWE AG has stored hydrogen for the first time in its underground test cavern in Rüdersdorf, Brandenburg. The salt dome developed there holds six tons of the energy source. According to the company, this amount is enough to fill up 1.000 hydrogen cars.
Sketch of the underground cavern: Over the next few months, EWE will test the interplay between the storage and withdrawal of hydrogen © EWE / Litho Niemann, M. Steggemann
Last November EWE started with the extraction. The cavity is around 1.000 meters underground. The hydrogen now stored there was, as it is said, delivered by tanker trucks “from common industrial gas suppliers”. With the storage, the brine - a mixture of salt and water that is still in the cavern from the construction of the cavity - is evenly displaced and brought to the earth's surface. According to previous information, EWE transports a total of 500 cubic meters of the aqueous solution to the brine sinking station in Heckelberg via an existing brine transport pipeline. The rock layers there are suitable for sinking brine.
Testing storage and withdrawal
After filling, test operations and research begin as part of the project called “HyCAVmobil”. “Above all, the interplay between the storage and withdrawal of hydrogen” will be tested.
In addition to operating the system, the aim is to test the quality of the hydrogen after withdrawal and prepare it for use. What is particularly important is proof of how much moisture the hydrogen absorbs underground and how the drying system needs to be adjusted. “A purity of almost 100 percent is important for future applications, especially in the mobility sector,” explains project manager Hayo Seeba. EWE also wants to optimize the technical processes with which hydrogen can be successfully integrated into the German energy system. A digital connection also makes continuous measurements in the cavern possible.
Gas purity testing
The Institute for Networked Energy Systems of the German Aerospace Center (DLR) examines the quality of the gas samples in its laboratory in Oldenburg. The gas purity and the brine are tested in order to draw conclusions about the possible microbial influence on the hydrogen quality.
“The results are incorporated into the assessment of whether the stored hydrogen is directly suitable for use in fuel cell vehicles or whether cleaning is required after withdrawal for these or other applications,” explains the company.
Can be transferred to larger caverns
The tests are expected to last one year. EWE then wants to use the findings in large-scale storage projects in Huntorf, Lower Saxony. This is part of the large-scale “Clean Hydrogen Coastline” project, which brings together the production, storage, transport and use of green hydrogen in industry and heavy-duty transport.
According to EWE's own information, with 37 salt caverns in Huntorf, Nüttermoor, Jemgum and Rüdersdorf, it has 15 percent of all German cavern storage facilities that would be suitable for storing hydrogen in the future. This means that hydrogen produced from renewable energies can be stored in large quantities and used as needed.
The investment volume for “HyCAVmobil” amounts to around ten million euros. Six million of these come from the Federal Ministry of Transport and Digital Infrastructure's National Innovation Program for Hydrogen and Fuel Cell Technology.
Photos
View of the cavern site: Only the surface technology of the H2 cavern is visible. © Jörg Schattling
