The geology of many regions of the country does not include sandstone, limestone, or salt formations suitable for conversion to storage. These regions include the entire eastern seaboard, upper mid-west states such as Minnesota and Wisconsin, and many western states such as Utah, Idaho, Oregon, and Washington.  Without means for local storage, the economics of expanding natural gas use, particularly for electricity generation, are severely burdened. High demand periods must be met in other ways, most commonly through the import of liquified natural gas. To allow all regions of the country to fully enjoy the varied economic and environmental benefits of expanded use of domestic natural gas, NETL is supporting the investigation of gas storage in specially-designed rock caverns.

One area of investigation is Lined Rock Caverns. This technology has been under development in Sweden since 1987.Thus far, development has included extensive technical studies and laboratory and field tests that indicate that the idea is technically sound and economically practical. A facility in construction in Sweden is expected to hold 250,000 barrels and operate at a pressure of 2,900 pounds per square inch (psi). The potential to import this technology to the United States has focused on two regions. The granites near Atlanta, Georgia will be excavated to support a facility with 5.2 billion cubic feet (bcf) of working gas capacity. A similar facility outside of Boston is being designed to hold 2.6 bcf of gas.

A second approach involves the construction of Refrigerated Mined Caverns. This technology attempts to reduce the costs for rock cavern construction by reducing the amount of rock to be removed. To compensate for smaller cavern volumes, chilling units are installed that increase gas density, allowing significantly more gas to be stored. Work is ongoing to evaluate the technical specifications and economics of a 5 bcf refrigerated mined cavern in the Baltimore/Washington metropolitan area.