The idea of storing energy by compressing air in underground mines may sound like science fiction, but it's already being done in Alabama and within a few years residents in Ohio will have their own compressed air plant.
"The world's first compressed air energy storage plant was in Germany," says Lee Davis, plant manager for the Compressed Air Energy Storage (CAES) Power Plant in McIntosh, Alabama. "The Alabama CAES plant was the first in the United States when it opened in 1991."
The Alabama Electric Cooperative CAES plant works like this: On nights and weekends, air is pumped underground and compressed, using low-cost electricity, at pressures up to 1,078 pounds per square inch. (Average air pressure at sea level is 14.7 pounds per square inch.)
During the day, at peak times, air is released and heated using a small amount of natural gas. The heated air flows through a turbine generator to produce electricity.
In conventional gas-turbine power generation, the air that drives the turbine is compressed and heated using natural gas. On the other hand, CAES technology needs less gas to produce power during periods of peak demand because it uses air that has already been compressed and stored underground.
With the success of the Alabama plant, developers began to look for other suitable locations. "We looked at several other states before we decided on an abandoned limestone mine in Ohio, but soon we hope to explore some of the other promising CAES sites around the country and begin constructing," says Michael McGill, Vice President of business development at Norton Energy Storage.
"The proposed plant in Norton, OH, about 35 miles south of Cleveland, will be the world's largest CAES plant," he says. "At peak operation, the plant will store enough electricity to provide 675,000 homes with electricity for just over two days."
While the idea of compressed air energy storage has been in existence for the last decade, it is only now gaining popularity and support as researchers look for energy alternatives.
"I think that it is important for all states to look at their alternative energy generation resources and ways of storing energy," says John Turner, a researcher at National Renewable Energy Laboratory. "Compressed air energy storage is definitely one."
[Contact: Lee Davis, John Turner, Emilie Lorditch]