Contact: Bob Ratliff
Electric power generating plants fueled by clean-burning natural gas may help solve the nation's energy shortage, provided the facilities are equipped with safe, efficient storage systems.
Developing an economical natural-gas storage system is the goal of a four-year, $1.2 million U.S. Department of Energy-sponsored project by Mississippi State University chemical engineer Rudy Rogers.
"At times of peak electrical demand, power plants cannot pull enough gas out of pipelines fast enough to meet their needs," Rogers explained. Buying high-cost gas on the spot market or storing enough liquefied or compressed natural gas to meet demands can result in increased electricity prices.
"The amount of natural gas needed to fuel the new electric power plants projected to be built in the next 20 years is likely to far outstrip on-site storage capacity," he said.
Rogers believes one way to solve the problem is the use of gas hydrates to store large amounts of natural gas where it's needed.
"Gas hydrates-essentially ice-can be used safely to store a lot of natural gas in a small space," he said. "For example, more than 180 standard cubic feet of gas can be stored in one cubic foot of hydrate."
Gas hydrates are formed when gas is used to pressurize water and the temperature lowered to near freezing. The pressure causes two reactions-water solidifies at a temperature higher than 32 degrees Fahrenheit and the gas becomes trapped in water molecules within the frozen mass.
Rogers, who was among the first American scientists to research the industrial use of hydrates more than a decade ago, added that the nature of gas hydrates also makes them safer to store in above-ground tanks than pressurized or liquefied natural gas.
"Should a storage tank rupture, there wouldn't be a sudden release of gas because what you essentially have is gas encased in ice," he added. "This type of storage can be especially useful in heavily populated areas, such as the Northeast, where there is strong energy demand and no natural storage sites such as the salt domes or depleted gas reservoirs that exist in the Gulf Coast region."
Rogers is working with colleagues at MSU's Diagnostic Instrumentation and Analysis Laboratory to develop a gas hydrate storage process. The DIAL scientists will design, build and test a storage tank with about a 40-gallon capacity.
"Water in the tank will be pressurized with natural gas to about 550 pounds per square inch and chilled," Rogers said. "Solid gas hydrates will pack on aluminum plates in the tank and the hydrates can be formed or decomposed by either cooling or heating banks of transfer tubing."
If the tank proves successful, Rogers said a larger capacity model for testing at a power plant could be the next step in the research.