Storing Renewable Energy | Green Energy News

April 21, 2002 – Vol.7 No.4

STORING RENEWABLE ENERGY.

Everyone knows the Sun doesn’t shine all day, nor does the wind blow around the clock. Renewable energies such as wind and solar can work in consort with energy storage devices to save energy generated in off-hours, or to save energy for use when the sun goes down.

Flywheels are one possibility for energy storage.

The Flywheel Safety and Containment Program, through the U.S. Defense Advanced Research Projects Agency (DARPA) has announced the successful completion of 100,000 test cycles for a high speed composite flywheel. The flywheel has been operated at speeds between 27,000 and 36,000 revolutions per minute with a very fast tip speed (the speed of the wheel at the outer rim of the wheel) of 825 meters (more than 2700 feet) per second.

At issue with flywheels is safety. Considerable damage can be done to the surroundings if a flywheel breaks free of its containment enclosure.

Flywheels are more efficient energy storage devices than batteries, but still too expensive for most renewable energy applications, such as storing solar and wind generated electricity. Mass production techniques, however, should bring costs down. The flywheel being tested could be used for stationary distributed power, or in vehicles such as hybrid electric vehicles. Visit the Southern Coalition for Advanced Transportation (SCAT) which is administering the program at http://www.advtrans.org/ .