Hydrogen in Germany: Infrastructure is needed for storage. © Fabian Sommer / dpa
Green electricity and the hydrogen produced with it are the main pillars of the climate-neutral energy system of the future. But how can the hydrogen be stored? This is shown by the first model projects.
Essen - Hydrogen as a beacon of hope: In the climate-neutral future, the lightest element should play a key role. Produced CO₂-free, it can generate electricity in new gas-fired power plants, for example when there is a lack of wind and sunlight. Federal Minister of Economics Robert Habeck even recently flew to Namibia for a cooperation for green hydrogen.
And large quantities of hydrogen are needed. To ensure that there is always enough, however, hydrogen must be stored temporarily. But where? Are the existing natural gas storage facilities, of which Germany has a great deal, suitable for this?
Storing hydrogen: natural gas storage only partially suitable
Yes, but probably not all. This is the conclusion of a study published last summer by associations of the energy industry. According to this, cavern storage facilities with their large cavities are "particularly well suited", explained Ingo Forstner, Head of Storage & Geothermal Energy at the Federal Association of Natural Gas, Petroleum and Geoenergy (BVEG) at the time. In the case of the other type of storage, pore storage, the suitability must be examined on a case-by-case basis. The study assumes that only four out of sixteen porous storage systems can be used for hydrogen storage.
Hydrogen storage is a major issue for the operators of natural gas storage facilities. The industry association Ines is aware of 23 pilot projects: "They are usually at an early stage of the project without a final investment decision and hold significantly smaller volumes than usual for commercial gas storage facilities," says Sebastian Bleschke, Managing Director of the Energy Storage Initiative (Ines).
Pilot project in Brandenburg
One of the most advanced pilot projects is being built in Rüdersdorf near Berlin in Brandenburg under the sleek name HyCAVmobil. The operator is the energy company EWE. On a site where EWE already has two natural gas storage facilities, a cavity about the size of a house, around 1000 cubic metres in size, was flushed out in an underground salt dome at a depth of 500 metres for three months until the beginning of March. In the meantime, technology is being installed above ground. EWE plans to fill in the first hydrogen and start test operation from late summer.
One focus is on the quality of the hydrogen after it has been withdrawn: According to EWE, almost 100 percent purity is particularly important for applications in the mobility sector. EWE wants to transfer the findings from the operation of the small cavern to large caverns with 1000 times the volume.
A pilot plant is also coming to Lower Saxony
Uniper, Germany's largest storage operator, is also working on a pilot plant. It is to be built in Krummhörn in Lower Saxony and will be 1000 cubic metres in size. According to Uniper, the approval process is still underway there. "The construction of this cavern is planned for the course of this year. We want to start filling with hydrogen for the first time at the end of the year/beginning of next year," said Matthias Schnadwinkel, project manager at Uniper Energy Storage, at a recent event organised by the Zukunft Gas industry association. Uniper also wants to transfer its experience to large storage systems at a later date.
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At the Bierwang storage site in Unterreit, Bavaria, Uniper wants to investigate the suitability of porous storage systems in more detail together with several companies. Starting in June, different methane-hydrogen gas mixtures are to be stored in a former natural gas reservoir in three phases and withdrawn after a certain period of time. HyStorage is the name of the research project.
RWE starts commercial use of cavern storage facilities
The energy company RWE wants to use large caverns commercially right from the start. To this end, an existing natural gas cavern storage facility in Gronau-Epe, North Rhine-Westphalia, is to be made fit for hydrogen by the end of 2026. The storage volume that can be used by customers is expected to be 28 million cubic meters of hydrogen. Commercial operation will not be possible until 2027 at the earliest, says RWE spokesman Olaf Winter. In a second construction phase, the capacity could be further increased later.
"The development of our hydrogen storage facility in Gronau-Epe is only a first step, which must be followed by many more," says Sopna Sury, RWE hydrogen board member, in response to a dpa request. "A round-the-clock supply of green hydrogen to industrial customers is only possible with sufficiently large storage capacities."
But what does "sufficiently large" mean? The storage association Ines refers to long-term scenarios of the Federal Ministry of Economics. They assume that hydrogen storage with a capacity of 2045-72 terawatt hours will be needed to implement the energy transition in the target year 74. "Our studies have shown that 32 terawatt hours of hydrogen storage capacity can be provided from today's gas storage facilities," says Ines Managing Director Bleschke. "To achieve this capacity, it would be necessary to convert a large part of today's gas storage facilities."
Bleschke: Storage is an infrastructure task
But according to Bleschke, this is far from enough: Implementing the energy transition in accordance with the long-term scenarios would require more than doubling the storage potential that can be used for hydrogen today. Bleschke calls this an "infrastructure challenge" and emphasizes: "So far, not a single commercial hydrogen storage facility has been in operation in Germany." Accordingly, there was still no conclusive experience with planning, approval and implementation processes. In recent years, storage capacities have been reduced rather than built up. "For the development of extensive new projects in the field of hydrogen, the entire value chain will have to be rebuilt to a large extent." (dpa, lf)