(Strausberg) – The Oldenburg energy supplier EWE AG has started cleaning out the hydrogen cavern in Rüdersdorf, Brandenburg. The underground cavity will cover around 500 cubic meters - roughly the volume of a single-family home.
Cavity at a depth of 1.000 meters
With the project called “HyCAVmobil”, EWE wants to research how hydrogen storage works under practical conditions. To do this, EWE is building a cavity around 1.000 meters underground. Rüdersdorf offers the geological conditions for this: around 150 million years ago there was a sea there, which is now remembered by an underground salt rock formation that is thousands of meters thick, according to the company at the start of the project last year.
EWE already operates caverns to store natural gas at the Rüdersdorf site. © EWE
According to EWE estimates, the extraction will last until around the beginning of February. This layer of rock salt beneath the site where EWE has already built two large cavern storage facilities and has been storing natural gas there since 2007 begins at a depth of around 600 meters and extends to 3.200 meters below the surface of the earth.
5.000 cubic meters of water required
To brine the cavity - i.e. to flush out the rock salt - 5.000 cubic meters of water are used over a period of three months, which comes from the company's own pond and the nearby mill flow. “We pump the salt water created during the brining process via an existing underground pipeline to our immersion station in Heckelberg,” says EWE project manager Hayo Seeba. There the brine is piped into sandstone formations 1.000 meters deep, which already naturally contain salt water.
Protected from the weather: surface solar plant on EWE's cavern site in Rüdersdorf. © EWE / Jörg Schattling
After completion of the underground cavity, EWE will build a temporary above-ground facility for hydrogen storage. The initial filling with hydrogen and the start of extensive testing of storage operations with injection and withdrawal scenarios are planned for mid-2023. However, the supplier is significantly behind its own schedule. In January 2021 it was announced that the cavern should have been filled with hydrogen for the first time “in spring 2022” as part of a six-month test phase.
Hydrogen storage quality test
The aim of the research project is to test not only the operation of the system but also the quality of the hydrogen after withdrawal. The findings should be transferable to large volumes. In the future, caverns with 500.000 cubic meters could be used for large-scale hydrogen storage. With 37 salt caverns, EWE has 15 percent of all German cavern storage facilities that would be suitable for storing hydrogen in the future.
In the project, EWE is cooperating with the Institute for Networked Energy Systems of the German Aerospace Center (DLR), which will, among other things, examine the quality of the hydrogen after it is removed from the cavern and the materials used. The investment volume amounts to around ten million euros. Of this, six million euros come from the Federal Ministry of Transport and Digital Infrastructure (BMVI) from the pot of the National Innovation Program for Hydrogen and Fuel Cell Technology.
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The test cavern for hydrogen storage is to be built at a depth of 1.000 meters © EWE
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EWE already operates caverns to store natural gas at the Rüdersdorf site. © EWE
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Protected from the weather: surface solar plant on EWE's cavern site in Rüdersdorf. © EWE / Jörg Schattling
