June 27, 2008 3:59 AM PDT
Another option for relatively long-term storage (several hours or days) is compressed air energy storage. There are two compressed air storage facilities now operating, one in Germany and one in Alabama.
The idea is to use power generators to compress air and store it underground at off-peak times. During peak times when demand for electricity is highest--and most expensive--the air is released to run a gas turbine.
Here's a diagram of one of the plants in McIntosh, Ala., where a facility has been operating since 1991. According to its developers, the system reduces fuel consumption by 25 percent. This illustration shows the various components needed for CAES, including a limestone cavern or some other geological feature to store compressed air.
Photo by CAES Development Company
Caption by Martin LaMonica
