Underground storage facilities are strategic infrastructure in which natural gas reserves are kept in order to match supply and demand and meet consumption peaks that may occur throughout the year due to seasonal variations and other factors. Gas is stored underground taking advantage of depleted gas fields or injected into deep aquifers or cavities created in saline formations.

The injection and extraction of gas from underground wells is carried out from these facilities, as well as the drying and odorisation of gas for subsequent injection into the gas pipeline network. Once the natural gas has been delivered to the national grid, the Enagás Main Control Centre, also known as Dispatching, is in charge of distributing it throughout the Gas System according to demand in different parts of the country.

Enagás manages three underground storage facilities in Spain, located in Serrablo (Huesca), Gaviota (Bizkaia) and Yela (Guadalajara).

The maximum pressure on entering the facilities is between 72 and 80 bar, depending on the design pressure of the pipeline to which they are connected. The minimum pressure in all of them is 45 bar.