Plug-in Cars Will Give Commuters a Charge

Abstract

0 AS YOU back out of the garage on your way to work, a prong on the front of your car detaches itself from a socket in the wall. When you park at your destination, the prong is driven into another socket, this time in what otherwise appears to be an ordinary parking meter. The rest of your driving routine is not unusual, except-no gas stations. The milk routes of England and the golf courses of the U.S. already see heavy traffic in vehicles that are the forerunners of such an idea. The secret: electricity. The source: batteries. There are problems, of course. The British electric milk carts are slow; golf carts are even slower and most have barely enough power for two rounds of golf-hardly the commuter's dream. In fact, even with a 500-pound battery of the conventional variety, an average American compact car with an electric motor would last for about 10 miles of driving around in city traffic before it stopped dead, Dr. J. E. Goldman, director of Ford Motor Co.'s scientific research laboratory, said. A silver-zinc battery is more than three times as efficient, but it would be almost prohibitively expensive in passenger-car sizes. In addition, it wears out, as do most batteries, from being charged and discharged over and over again. Now, however, thanks to the holes in a new form of aluminum oxide crystal, batteries are being developed that may offer eight times the range and 15 times the efficiency to the charged-up commuters and shoppers of tomorrow. The closest thing to a miles-pergallon figure for a battery is called energy density, measured in kilowatthours of power per pound of battery weight. Today's lead-acid car batteries have an energy density of about 10. The exotic nickel-cadmium and silvercadmium batteries used in hearing aids, portable radios and other miniaturized electronic equipment rate about 14 and 24, respectively. Even silver-zinc only gets a 50. A new battery, just announced by Ford and still literally in the test-tube stage (the prototypes are all built in glass vials), has a conservative rating of 150, Dr. Goldman reported. Driving downtown in that electric compact, the battery would be good for at least 82 miles, while at a steady 40 mph the car could travel 132 miles without recharging. The battery is just the opposite of the version in today's cars. Instead of having solid electrodes immersed in a bath of sulfuric acid, it has liquid electrodes (liquid sodium and conducting sulfur) separated by a solid ceramic made of aluminum oxide. Because of the unique shape of the ceramic crystals, which resulted from basic research that had nothing to do with batteries, only sodium ions can pass through the ceramic. These ions are formed when an external circuit such as an electric motor steals an electron from a sodium atom, leaving it as an ion. The ion goes through the ceramic and combines with the sulfur, producing the chemical reaction that is the source of the battery's power. The battery reportedly does not deteriorate from repeated charging, and its storage life is apparently indefinite, though its development was so recent that scientists are not yet sure. When it becomes standardized, says Dr. Goldman, it may ultimately outlast the cars it is used in. In addition, it is cheap. Our hearts fill with glee when we think of sodium, Dr. Goldman says. Detroit, hub of the auto industry, sits on deposits of the stuff, and all the salt in the U.S. is a usable source. Sulfur is no more of a problem. There is actually little comparison with present car batteries, since the sodium-sulfur cell will not be doing the same job. While today's battery, which is constantly being recharged by the generator, needs relatively little power to start the car's internal combustion engine, a battery that must run the entire car by itself needs 30,000 or 40,000 watts on tap. Stoking up a battery with 30 kw would seem to require quite a bit of recharging time. Not so, according to Dr. Neil Weber, co-inventor with Dr.