flywheels

A flywheel is an interesting device to store energy in, theoretically it can store unlimited power, all you need to do is speed it up. In practice, of course, engineering limits of the materials used and physical limits temper that theoretic capacity.

The main use of flywheels in energy conversion systems is to store large amounts of power to be used in a very short period of time, such as in 'ride-through' systems that provide hospitals and computing facilities with power in emergency situations just after a power failure but before the generators have had time enough to start up and come online. Typical ride-through systems will provide their power during a period shorter than one minute.

Another use of flywheels is to power vehicles.

Flywheels have the same properties as batteries and other storage systems, such as self discharge (the rate at which the flywheel loses energy when no power is drained by a consumer), power density and so on.