18.3 Flywheels
070403
http://www.et.anl.gov/sections/te/research/flywheel.html
lFlywheels store energy
as angular momentum
lBest suited to storage
periods of 1 second to 10 minutes
lHigh temperature
superconducting bearings reduce bearing friction to 2% of
speed drop per day
lBall bearings are so inexpensive that the performance gains
of magnetic bearings are irrelevant
lThe flywheel case is designed
with a shield to contain a failed rotor and its pieces if it
shatters and blows up
lBatteries are much
cheaper than flywheel systems
lTest buses used
flywheels that were spun up by electricity at bus stops; no
wires along streets