Determine the feasibility of using gas hydrates to store natural gas above ground, for peak-load use in electric power plants and other commercial applications.
Mississippi State University(MSU)
Mississippi State, MS 39762
Previous efforts to store natural gas as hydrate have been limited by several negative factors, including: 1) free water, when trapped between forming hydrate particles, becomes isolated from gas and unreactive; 2) mechanical stirring required for rapid formation creates scale-up problems; 3) hydrate formation is too slow in an unstirred system; and 4) filtering and packed hydrate particles from a cold, pressurized slurry is economically difficult. This project investigated the development of a cost-effective system using a surfactant to overcome these problems. A conceptual large-scale process design for the formation, storage, and decomposition of gas hydrates was developed.
The results of the economic analysis of a large-scale process concluded that the development costs per 1,000 standard cubic feet (scf) for gas hydrate storage can be competitive with liquefied natural gas (LNG), salt caverns, and depleted reservoirs. This can be done by using at least 4, 14, and 54 cycles/year, respectively. Operational costs can be competitive with conventional storage options above 13 cycles/year; above 125 cycles/year hydrate costs are superior to all gas storage alternatives.
Laboratory studies have demonstrated the feasibility of storing natural gas in hydrates. Results, using a sodium dodecyl sulfate surfactant (SDSS) solution, formed micelles to solubilize the hydrocarbon gas included: 1) the rapid formation of hydrates (approximately 700 times faster than without surfactant); 2) the full utilization of free water trapped between hydrate particles, yielding a high bulk density; 3) the adequate distribution of hydrate forming particles, throughout the solution, and hydrate packing on the chamber walls; and 4) 155 volume gas/volume hydrate (86% of theoretical capacity) being stored at 550 pounds per square inch/gauge at 36°F within 3 hours of hydrate initiation.
Based on the laboratory findings, a conceptual design of a larger-scale process was developed (to form and dissociate hydrate on a 24 hour cycle) and an economic analysis was performed.
This project is complete and a final report is available.