Salt Cavern Storage

In the context of clean energy, hydrogen primarily serves as a storage mechanism for solar, wind and hydropower, similar to a battery.  For utility scale projects, hydrogen also has beneficial attributes that allow for the storage of massive amounts of energy over long periods of time. Thus, hydrogen might be used to store solar energy in the summer when it is plentiful to be used in the winter when solar energy is scarcer.

However, hydrogen gas takes up a lot of space (low volumetric energy density). It can be compressed but that uses up some of the energy that could otherwise be stored and the more compression, the more energy used up. In addition, hydrogen tanks and other storage vessels can be expensive to manufacture given the use of advanced materials.

A promising solution is to store hydrogen with relatively low compression in vast underground caverns that can be carved out of salt beds inherent to certain areas around the world including North America, northern Europe and the UK.  Often constructed at 500-2,000m below the surface, these salt caverns benefit from relatively low maintenance costs as well as the inert nature of salt which can prevent contamination of stored hydrogen.

In the US, Linde has stored hydrogen in a Texas salt cavern for over a decade to serve customers that primarily use hydrogen for chemical processes rather than energy. Hydrogen from the cavern is then released into a specialized regional pipeline network to meet peak demand. Similar infrastructure has existed in the UK since the 1970s.

The Advanced Clean Energy Storage (ACES) project (see article below) will initially provide 150GWh of storage capacity in salt caverns near Delta, Utah. This compares to ~2GWh of installed utility scale battery storage in the entire US currently and would be enough to power 150,000 homes for 1 year according to a separate article about the project published by CNBC. Moreover, it is believed the site could support up to 100 additional caverns.

In Europe, the HYPOS consortium is developing a similarly sized salt cavern hydrogen storage facility in Saxony-Anhalt, Germany that could begin operations in 2023/24 and other projects are underway in the UK, France and elsewhere.

Transitioning to clean energy depends on the availability of storage in order to smooth the intermittency of solar and wind.  Salt caverns can potentially address a meaningful portion of our renewable energy storage requirements in a safe, space efficient and cost-effective manner.