High Quality Content by WIKIPEDIA articles! Underground hydrogen storage is the practice of hydrogen storage in underground caverns, salt domes and depleted oil/gas fields. Large quantities of gaseous hydrogen have been stored in underground caverns by ICI for many years without any difficulties. The storage of large quantities of hydrogen underground in solution-mined salt domes, aquifers or excavated rock caverns or mines can function as grid energy storage which is essential for the hydrogen economy. By using a turboexpander the electricity needs for compressed storage on 200 bar amounts to 2.1% of the energy content. The ConocoPhillips Clemens Terminal in Texas stores the hydrogen since the 80's in a solution-mined salt cavern with the cavern roof ~2800 ft underground.