technology � McIntosh project
Alabama Electric Cooperative's (AEC's) generating units at McIntosh, Alabama, include the compressed air energy storage (CAES) unit and twin gas-fired combustion turbines.
Designated McIntosh unit 1, the CAES unit was declared commercial May 31, 1991, and officially dedicated September 27, 1991. The 100-megawatt CAES unit uses air compressed and stored in an underground cavern in the generation process. When the compressed air is needed for generation, it is mixed with natural gas in a convention gas turbine combustion process to generate electricity. The plant uses off-peak electricity to pump air into the cavern, then uses the air in the generation process during peak periods.
In June 1998, contractors completed work on two single-cycle combustion turbines at the McIntosh site. The units have a generation capacity of 226 megawatts, and are designed as McIntosh units 2 and 3. While these units are not CAES units, they have increased the total power generation capacity of the McIntosh facility to over 326 megawatts.
Facts about the Nation's First Compresses Air Energy Storage (CAES) Power Plant
AEC's CAES plant was declared commercial in McIntosh, Alabama on May 31, 1991.
Officially dedicated September 27, 1991.
Second commercially owned in the world. World's first CAES plant is a 290 MW facility located in Huntdorf, Germany.
First CAES plant in the United States.
First in the world to use fuel-efficient recuperator, which reduces fuel consumption by 25 percent.
One full charge from the 110 MW CAES plant provides enough electricity to supply the demands of 11,000 homes for 26 hours.
Off-peak electricity is used to compress air in the cavern.
Top of solution-mined salt cavern is 1,500 feet underground. Bottom of cavern is 2,500 feet underground.
10-million-cubic-foot air storage cavern is 220 feet in diameter and 1,000 feet tall.
At full charge, air pressure is 1,100 pounds per square inch. At full discharge, cavern air pressure is 650 pounds per square inch.
The cavern walls do not move as the pressure changes inside. The cavern walls have a strength of 50 times that of the maximum air pressure produced by the CAES plant.
Compressed air flows through the CAES plant generator at a rate of 340 pounds of air per second, which is as fast as a wide-body jet engine.
The fuel consumption during generation is equal to 4,600 Btu (HHV) per kilowatt-hour (kWh) of electricity. There are about 20,750 Btu in each gallon of gasoline.
The electricity consumed during compression is 0.82 kWh of peak load generation.
Constructor: Harbert International, Birmingham, Alabama Plant construction time: approximately 2 years, 9 months Engineer: Gibbs & Hill, New York, NY
Machinery and equipment made by Dresser-Rand, Wellsville, NY (includes expanders, compressors, motor-generator, control system, clutches, gears).
Alabama Electric Cooperative provided funding of the majority of funding for the $65-million CAES plant.
| ||The Electric Power Research Institute (EPRI), the research and development arm of the electric utility industry, provided an additional $5 million for plant hardware and $3 million for engineering support. The National Rural Electric Cooperative Association (NRECA) contributed $660,000 toward the cost.|
|For more info:
Phillip Burgess, AEC, Andalusia, Alabama
Laury Olson, EPRI, Palo Alto, California