THE FLYWHEEL REVISTED

The idea is to store energy available now, but needed later, by making a flywheel spin; when the energy is needed again, the spinning flywheel drives an electric generator.

An old fashioned flywheel would, of course, soon come to a stop by friction in the bearings and air resistance, but magnetically suspended flywheels spinning in vacuum can spin for several months.

Nor could an old fashioned flywheel withstand the high velocities needed in practice: Metals would shatter under the centrifugal forces. But modern, composite, varying-thickness "superflywheels" use fibrous laminations able to withstand these great stresses, and if they can't, they won't "fly to pieces," but disintegrate into harmless dust.

The machine that makes the flywheel useful for energy storage is the electric motor/generator, whose funcion is reversible: Turn its shaft, and it will produce electricity (generator); send a current through it, and it will turn (motor). The motor geared to the shaft of a flywheel will spin the flywheel, but will generate electricity when spun by it.

There are many uses for such a storage device some day electric power plants will rev up the flywheels during the night, and then tap their energy during the peak hours the next day. But the most important use awaits them in transportation, where they can truly conserve energy - the energy that now goes to waste as heat in the brake linings every time a vehicle brakes. To bring up the tons of metal to their former velocity when the vehicle accelerates again, totally new and precious energy must be used - whether it is gasoline for a car, or diesel oil for a truck, or coal or uranium for an electric train. Only to be wasted once more at the next traffic light or downhill grade, and to be replaced once more by totally fresh energy.

Barry Commoner has a simple solution: Stop wasting the energy individually in cars, and start wasting it collectively in trains, preferably nationalized ones.

The flywheel, on the other hand, would stop wasting these vast quantities of energy in both cars and trains. To brake the vehicle, the energy is not channeled into heat, but into a spinning flywheel (by a generator geared to the wheels, which drives a motor geared to the flywheel); at the next acceleration, the energy stored in the flywheel is tapped (the flywheel generator drives the wheel motor). The energy is not wasted, but conserved.

And that is what true conservation means: conserving energy instead of wasting it. Conserving energy instead of using it is like a 50% reduction in crime and disease by annihilating half the population.