Compressed Gas Storage
While small compressed gas cylinders may be stored indoors in small numbers, outside storage is generally considered safer and is required for large amounts of gas. Stationary storage should be located outside at a safe distance from structures and ventilation intakes, and protected from vehicle impact.
Hydrogen storage separation distance requirements are typically based on the quantity and pressure of the hydrogen or the piping diameter, depending on the type of storage. Consideration should be given to distances between multiple containers to prevent interaction during an unintended hydrogen release. More detailed guidance can be found in the applicable codes and standards such as NFPA 2 Hydrogen Technologies.
An example outdoor bulk storage system for a fueling station is shown in the figure below.
(Pacific Northwest National Laboratory)