The energy source of the future is hydrogen. It can be produced from renewables and used as a raw material or an energy source in multiple industries. The biggest challenge industrial companies face with hydrogen is also key to implementing energy systems integration in general.

The challenge is: How to store the gas? Since clean electricity is not available 24/7, green hydrogen output will fluctuate. However, large hydrogen consumers in industry and transportation cannot rely on volatile renewable sources for their energy needs. A solution could be to store green hydrogen in salt caverns, as they can provide reliable, long-term and centralized gas supply. As part of HYPOS, two project teams are now working on implementing this idea.

Typically, underground rock formations provide a suitable environment with a sufficiently large capacity to store and retrieve fluids. HYPOS’ H2-Forschungskaverne project is investigating a salt cavern in Bad Lauchstädt in Saxony-Anhalt, Germany. Salt caverns are created artificially by pumping water into salt deposits several thousand feet below ground. The salt dissolves, leaving behind cavities that can hold gases long term.

Since the 1970s, the oil and gas industry has set up well over 200 of these caverns, a testament to its decades-long experience in building and operating underground storage facilities. In Bad Lauchstädt, VNG Gasspeicher operates multiple natural gas storage sites, including salt caverns. The goal of HYPOS’ H2-Forschungskaverne is to develop and design a safe, efficient and large-capacity green hydrogen storage system inside one of these caverns. The system envisioned for the project will have a working gas capacity of around 50 million normal cubic meters, the energy content equivalent of around 150 gigawatt-hours, making it the largest of its kind to date.

Plans for the following years include preparing a large-capacity cavern for hydrogen storage. Storing hydrogen in caverns is a strategy that has not yet been pursued in Germany. Still, this storage technique is not completely unknown. There are underground caverns storing gray hydrogen, such as Moss Bluff, Spindletop and Clemens Dome in the United States and Teesside in the UK. These supply local industry. However, it will be very difficult to adapt their cavern design or geological specifications to meet green hydrogen storage requirements.

Pairing green hydrogen produced from renewables via water splitting with underground storage poses special challenges for cavern operators. For example, equipment needs to be faster and more responsive when storing and retrieving gas to closely match the load profiles of solar and wind energy systems, as well as electrolyzers.

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read more in H2-international August 2020

Author:
Stefan Bergander
HYPOS – Hydrogen Power Storage & Solutions East Germany e.V., Leipzig, Germany