A HYBRID FLYWHEEL CAR

It seems like a sure sign of progress that such optimistic reveries are being replaced by talk about cost, markets, and potential for early development. Unless a drastic breakthrough occurs in the development of a new electric battery, the electric car has no hope of competing against the heat engine not in a free market, where consumers want better than a range of 80 miles, top speed of 50 mph and acceleration best left unmentioned.

A flywheel is superior to a battery in energy density, but not by an awful lot; the real advantage is its high power density, that is, it can discharge its energy very much faster, enabling a flywheel car to accelerate more quickly.

But only in the pages of the Scientific American, not on the streets of Suburbia Americana. Why not? Because, says P.M. Newgard of Stanford Research Institute, the transition must be evolutionary, not demanding the simultaneous development of new industries and major facilities.

An SRI study reported in the November Symposium looked for a flywheel system with potential for early development, yet competitive with the traditional automobile in its four salient advantages over the battery-driven car: instant mobility, infinite range, good acceleration, and low cost.

What they came up with is a hybrid car whose internal combustion engine drives an electric generator, coupled to the motor on the drive shaft either mechanically via an oldfashioned clutch, or electrically with flywheel storage between the two, or via both in parallel.

The flywheel is charged overnight with about 10 kWh of utility power. During the following day's travel, the flywheel energy is discharged first (clutch open); when it is nearly depleted, the ICE- powered generator provides average motive power, with the flywheel providing load leveling, and above all, regenerative power for braking and acceleration. This mode is used for low-speed and stop-go urban driving. Above a set speed (35 to 40 mph), the clutch closes and provides the drive train from heat engine to wheels with a more efficient link for extended high-speed driving, while using the flywheel load-leveling energy reservoir.

And the four trump cards of the traditional car are maintained.

Although the main advantage of the flywheel car is energy conservation, there is some fringe benefit in pollution control. Not only is the burst of pollution as the traffic light turns green eliminated, but the pollution is moved from the car exhaust to the power plant stack, where there is less of it and it is more easily curbed. It is not, however, entirely eliminated unless the plant is nuclear.