This is a unique feature of the Freeport LNG terminal, made possible by the terminal’s proximity to the Stratton Ridge salt dome. Approximately one mile from the company's Stratton Ridge meter station, Freeport LNG developed a natural gas underground storage cavern in the salt dome to be able to store natural gas in its gaseous rather than liquid form. The cavern, which has a working capacity of around 4.5 Bcf of gas and maximum injection/withdrawal rates around 500 MMcf per day, is integrated into the operation of the LNG receiving facility.

Integrating underground storage in the operations of the terminal achieves numerous cost and operational benefits. Salt cavern storage is cheaper to build than an LNG tank and it makes it possible for LNG terminal operators to maximize the utilization of the LNG facilities and provide maximum flexibility to terminal customers. For example, LNG tanks can be emptied at a higher rate, thereby allowing ships to unload in quick succession, while smoothing out gas deliveries into the market.

Gas redelivery from underground storage, combined with gas from the LNG vaporizers, allows for significant variations in gas deliverability and cost-effectiveness. Customers are able to profit from the high daytime peak gas demand on the power generation market. For Freeport LNG, the advantages include injecting gas during low nighttime demand periods and paying low nighttime electricity rates.

The solution-mining process of creating the cavern was completed and the cavern was placed into service in late 2011. The Freeport LNG facility now has the equivalent of over 11 Bcf of gas storage, which represents a very favorable ratio between the storage capacity and the throughput capacity sold to customers.