The goal of this project is to investigate the commercial potential of storing refrigerated natural gas in mined hard rock caverns to meet seasonal gas peaking needs in market areas that do not have conventional gas storage options.
PB KBB, Inc.
Houston, TX 77079
The high cost of hard rock gas storage caverns has prohibited their wide spread construction in the United States. However, in many parts of the country where salt deposits are not available, storage in hard rock formations are feasible. Refrigeration of natural gas can significantly reduce the physical space required to store a given quantity, by reducing costs associated with mining the cavern to expand its use for natural gas storage. This project investigated five regions of the United States for underground storage development and reviewed the literature to determine if the geology of these regions were suitable for siting hard rock storage caverns. Area gas market conditions in these regions were also studied to determine the need for such storage.
This study concluded that the conceptual refrigerated-mine rock cavern facility would cost $173 million to construct or approximately $34.5 per million standard cubic feet of gas stored. The capital costs of the project was higher than the comparison group. However, refrigerated-mined cavern storage provides multiple, high capacity, peaking cycles per year compared to the single cycle provided by the others in the comparison group, such as liquefied natural gas. The ability to cycle several times per year allows cost to be spread over a larger unit of gas, reducing unit costs of service.
A number of factors were analyzed to determine the selection of a possible storage site within one of five regions that does not have favorable geological conditions for underground storage: New England, Mid-Atlantic (NY/NJ), South Atlantic (DL/MD/VA), South Atlantic (NC/SC/GA) and the Pacific Northwest (WA/OR). These factors included available gas transmission pipelines, proximity to metropolitan areas, accessible power and water, proximity to environmentally sensitive areas, rock types, potential disposal sites for excavated material, and a sufficient water table for the storage formation. Based on this analysis, suitable geology for a possible site was found in Howard and Montgomery Counties, Maryland. Areas in this region have sufficient extent, are isotropic in nature, and are of high quality with excellent mechanical and physical properties for mined storage caverns. This area is also near commercial gas transmission lines that serve both Baltimore and Washington D.C.
Design parameters for a storage facility were developed based upon the general site selection. The final conceptual design consisted of a mined cavern of approximately 37 million cubic feet (Mcf) at a depth of 3000 feet. A working storage gas volume of five billion standard cubic feet (Bcf) would be provided with this design for gas stored at a temperature of –20° F and a maximum pressure of 1250 psig. Using this conceptual design, capital and operating cost estimates were developed for a comparative market analysis of this type of gas storage system to other systems that are commercially used in the region of the study.
This project has been completed and the final report is available.
NETL - Gary Sames (412-386-5067 or email@example.com)
Final Report [PDF] (OSTI - external website)