September 16, 08
Supersonic Flywheel Could Revolutionize Energy Storage

Beacon Power Corp. has developed a new energy storage technology that it thinks could revolutionize power storage for everything from individual homes to large industrial complexes. The technology uses massive rotating flywheels that store power while spinning at twice the speed of sound.

These high tech flywheels are "charged" when power demand is low, by using electric motors to spin the flywheels. Then the whirling wheels are connected to generators to release the power when it's needed. The company currently building a massive commercial scale system that is capable of storing 5 million watts of power.

Beacon Power flywheels are 2,500-pound cylinders made of carbon fiber and fiberglass, and bonded with epoxy. Each is mounted on bearings that generate a magnetic field to support the flywheel, so it floats inside its steel casing. Friction is almost nonexistent. When the flywheel is spun to its full speed of 16,000 revolutions per minute, it can store the energy for hours with little loss.

The surface speed on this thing would be Mach 2, or twice the speed of sound, but these flywheels don't generate a sonic boom, because they operate in a vacuum to reduce friction even more.

At the base of each flywheel is a motor-generator system like those found in hybrid cars. When electricity is added to the system, it acts as a motor, speeding up the rotation. To release power, the system acts as a generator, translating the rotation to electric power and feeding it into the grid.

Each flywheel can store enough power to run a typical US home for a full day.