Appalachia's First Multi-Cycle Natural Gas Storage System
Evaluating chilled natural-gas storage in bedded salt storage caverns.
The United States Department of Energy funded research to evaluate the feasibility of storing chilled natural gas in bedded salt storage caverns to dramatically increase their working-gas capacity. Previous research had determined that storing chilled natural gas in a mined hard-rock facility may be feasible. However, the cooling loads required to maintain the stored gas at low temperatures may be substantial in salt storage caverns because the thermal conductivity of salt is typically significantly higher than the thermal conductivities typical of hard rocks, such as granite. The thermal expansion coefficient of salt is also much higher than most hard rocks, which will result in larger thermally induced stresses and strains.
The purpose of this study was to evaluate both the economic and technical feasibility of converting typical natural-gas storage caverns in bedded salt deposits to refrigerated natural-gas storage. To determine the economic feasibility, RESPEC conducted laboratory tests to determine the thermal conductivity of salt at low temperatures and performed numerical modeling to estimate cooling loads and costs to maintain the low gas temperatures. To evaluate the technical feasibility, RESPEC conducted laboratory testing to determine the mechanical properties of salt at low temperatures and numerical modeling to evaluate cavern stability during refrigerated storage.
The conceptual design used to evaluate chilled gas conversion of a natural-gas storage facility in bedded salt is based on the design for a conventional natural-gas storage facility in Steuben County, New York. The design is typical of storage caverns that are being, and will be, developed in the salt beds of the Appalachian and Michigan Basins in the northeastern United States. Converting the facility to chilled gas storage would increase the working-gas capacity by approximately 70 percent.