EWE has completed its HyCAVmobil research project at the gas storage site in Rüdersdorf near Berlin. Together with the German Aerospace Center (DLR), the energy service provider demonstrated that hydrogen can be stored in underground salt caverns. Moreover, the purity of the hydrogen barely changed during storage. This is particularly important for mobility applications.
DLR and EWE started the HyCAVmobil project in 2019. In autumn 2023, hydrogen was first stored in the newly constructed salt cavern. The test cavern has a volume of 500 cubic meters and is located approximately 1,000 meters underground. The partners have now successfully concluded their research project, as stated in the press release dated December 5th.
By storing hydrogen in the test cavern and starting operations, the energy service provider gained experience in hydrogen input and output at different pressures. DLR researchers conducted extensive measurements of gas composition. For the HyCAVmobil project, DLR established a new laboratory in Oldenburg to determine the quality and purity of hydrogen from the Rüdersdorf salt cavern.
DLR investigations showed that the hydrogen purity changed minimally during storage. There were no significant contaminations, with the hydrogen only being slightly more humid after extraction. Hydrogen quality is especially crucial for fuel cell applications. Dr. Alexander Dyck from DLR emphasized that the quality of the extracted hydrogen remains high enough that simple purification is sufficient for further use.
"Hydrogen Can Be Stored in Salt Caverns"
During the project, the team faced several challenges, requiring adjustments to planned project steps. Ralf Riekenberg from EWE's hydrogen team in Rüdersdorf noted this as typical for research projects. Particularly challenging was ensuring the tightness of the drilling to a depth of 1,000 meters. After multiple leak tests, the EWE team successfully resolved hydrogen-specific sealing issues between the rock and steel casing.
"With proof of safe hydrogen storage, we've made significant progress toward climate protection and renewable energy supply security," emphasized EWE CEO Stefan Dohler.
The HyCAVmobil project costs were nearly 14 million euros. EWE invested about 8 million euros itself, with an additional 6.5 million euros in funding from the Federal Ministry for Digital and Transport.
Transferability to Large-Scale Storage
The partners now want to use their insights from building and operating the test cavern for future projects. For DLR, being able to conduct measurements on a real cavern was a "gain," allowing them to provide essential baseline knowledge for future hydrogen infrastructure in Germany. EWE plans to transfer the gained insights to salt caverns with 1,000 times the volume.
The energy service provider owns 37 salt caverns, representing 15% of all German cavern storage facilities suitable for hydrogen storage. The company's goal is to establish large-scale caverns for hydrogen storage for industrial use, enabling the storage of green hydrogen in large quantities.
The test cavern cannot be used for industrial hydrogen storage but will be utilized for further testing.
Perspectives for Industrial Hydrogen Storage
At the cavern site in Huntorf in the Wesermarsch, the company is currently converting a natural gas cavern for hydrogen storage. However, the purity after hydrogen extraction in the 500,000 cubic meter Huntorf cavern must be carefully examined. Previously, EWE stored natural gas in this cavern, which could not be completely removed, Riekenberg explained.
The Huntorf project is part of the larger "Clean Hydrogen Coastline" project, which combines green hydrogen production, storage, use, and transport. EWE received funding approval from Federal Minister of Economics Habeck this summer for this four-part IPCEI major project. The company is currently engaged in detailed planning and intends to start hydrogen storage within the next three to four years.
