Electric cars have been around since the beginning of the automotive age. Indeed, some of the earliest Automobiles were powered by storage batteries, but the development of a low-cost and reasonably efficient internal combustion (IC) engine captured the market early on in the history of the automobile. Only specialized electric vehicles that are used over short distances, like golf carts and forklifts, have survived.
But now there is a renewed interest in the electric automobiles. Why - at a time when the IC engine has been greatly improved, when oil prices are at their lowest level in more than two decades, and when pollution control devices like catalytic converters have cut automobile emissions down to a few percent of what they were only 25 years ago? There are a number of reasons:
Obviously then, a fleet of properly designed electric cars would solve major environmental problems: urban smog, noise pollution, and the emission of carbon dioxide. A viable electric car would also drastically reduce oil imports and the attendant security and balance of payments problems.
But what has really moved the situation forward in the United States is the recent requirement of the California Air Pollution Board (CARB) that, beginning in 1998, two percent of cars sold in California must be zero-emission vehicles, a percentage that rises to 10 percent by the year 2003. The CARB also requires comparable percentages of ultra-low-emission vehicles, a goal so technically challenging for an IC engine that it might best be reached with electric vehicles.
One can argue about whether the CARB requirement makes sense. There are many who doubt that Los Angeles will ever become smog-free - or that smog is indeed the hazard to human health that some imagine. Be this as it may, there are comparable smog problems in other major cities, like Mexico City and Tokyo, that can be traced to automobile traffic. In fan, air pollution authorities of many northeastern states in the U.S. are moving in the same direction as California by requiring zero emission vehicles - which for all practical purposes means electric propulsion.
Types of Electric Cars
There are many different kinds of electric vehicles. All use storage batteries to run electric motors that power the wheels; but their design depends on the purpose to which they are put. The principal design option: whether to rely exclusively on external power for recharging the batteries or whether to carry the charger on board.
The simplest is the commuter car, which in principle operates much like a golf cart. It would be used during the day for distances of the order of 80 km - or more, if batteries become lighter and cheaper. The batteries would then be slowly recharged at night, at home or in a garage, and be ready for service the next morning. This is what most people imagine when they hear the phrase "electric car."
There are a number of ways to overcome the distance limitation, the chief drawback of the commuter car. One can drive up to a service station, leave the old batteries to be charged and get a new set of batteries. A more acceptable method would be a "quick recharge," say in less than 5 minutes. Unfortunately, as a simple calculation shows, this requires currents of the order of a thousand amperes, many times greater than what normal house wiring would support. In other words, the car would have to go to a service station that specializes in fast recharging.
A further problem with fast recharge is the load it imposes on the electric power system. Electric power companies are very electricity off-peak, generally at night when demand is lowest; but large power surges during the day would be difficult to manage.
There is another option, however: the "hybrid" vehicle, which carries an onboard charger for the running batteries. This is not exactly a new idea either. Every automobile today keeps its battery charged, using an alternator powered by the IC engine by way of a drive belt. The difference is that the hybrid would carry a small gasoline-fueled IC engine whose sole function is to charge its storage batteries, not to turn the wheels.
The hybrid design extends the driving range of the battery-operated car. Range is now no longer set by the number of batteries, but by the size of the gasoline tank. The hybrid takes advantage of the fact that the energy density of gasoline is more than a hundred times greater than that of currently available batteries - an advantage not likely to be lost even when better batteries are developed. Better still, thanks to the high efficiency of electric alternators and motors a hybrid car is more energy efficient - and therefore can have a much greater range - than the auto- mobile using a standard IC engine.
Another advantage of the hybrid lies in greatly reduced emissions, again compared to the standard car. The IC engine - or turbine engine, if preferred - would normally run at a fixed speed and could be "tuned" to maximum efficiency and lowest emission. In addition, the hybrid feature might be turned on only for trips outside of the urban region so that what little pollution is emitted could be dissipated outside of the pollution-sensitive area. There would be no pollution at all from "idling" in congested city traffic.
Of course, the hybrid car would be designed to also preserve the option of battery recharging from the electric power grid. When used as a commuter car, it would be charged slowly at night; but when used for longer trips it would use the onboard charger.
A good many technical options are available for a hybrid automobile; it is difficult to judge at this time which one will be the most successful and capture the market. For example, there is the possibility that high-tech flywheels could replace chemical batteries as the main energy storage medium. Certainly, there are quite a few designers who favor such a choice.
Closer to realization, perhaps, the onboard charger need not be a mechanical engine at all. It could be a so-called fuel cell, which has no moving parts. A fuel cell converts the chemical energy of a fuel, such as natural gas, directly into electric energy at a fairly high efficiency of 60 or 70 percent. Fuel cells are coming into wide use now by electric utilities as storage devices to even out electric power loads and may some day be used to generate electricity directly at decentralized power stations.
A fuel cell suitable for electric car use is not yet available, but the technology is making rapid progress. For example, Energy Partners of West Palm Beach, Florida has just announced the debut of a "Green Card using three of their 7 kilowatt proton-exchange membrane fuel cell stacks. If commercially successful, it will be possible to have an all-electric car, with the running batteries being recharged by fuel cells, which in turn use a fuel such as compressed hydrogen or natural gas.
Electric cars have one further advantage over conventional vehicles: dynamic braking. This is an old technique, in wide use in electric streetcars a century ago. The idea is quite simple. When the operator wants to slow the vehicle, applying the brake pedal turns the electric motor powering the wheels into an electric generator; "regenerative braking" turns the energy of motion of the vehicle back into electric power. Instead of dissipating the energy as heat in the brakes, it is put back into the electric grid (for streetcars) or into the running batteries (for electric cars). The increase in efficiency can be significant for vehicles that start and stop frequently or that travel in mountainous terrain where the gas pedal and brake pedal get frequent use.
Battery Technology
So with all these advantages: high efficiency, near-zero pollution, low-noise or no-noise, and reduced oil imports-what's holding up electric cars? The main obstacle, according to many experts, is battery technology.
Battery technology is crucial for a commuter type vehicle where charging is external, but not nearly as important for the hybrid vehicle where range does not depend on the number of batteries. According to the Advanced Battery Consortium (ABC), set up jointly by the major car companies, the Electric Power Research Institute (EPRI), and the U.S. Department of Energy, the ideal car battery should meet or exceed certain specifications on energy content per unit weight (specific energy) and power content per unit weight (to be able to supply peak power and accept high charging rates); it should survive about a thousand charging/ recharging cycles before failure (corresponding to a replacement after about 100,000 miles of driving) - and, of course, it should have low cost.
There are many candidates for electric car batteries out there, all competing to meet the criteria set by the ABC. Ford Motor Company has incorporated its sodium-sulfur battery into the Ford Ecostar Van, a small, front-wheel drive delivery vehicle. Ford claims to have tripled the range of conventional batteries. The Ecostar has regenerative braking in addition to power-assisted hydraulic brakes, solar power-assisted ventilation, and other advanced features. More than 100 vehicles were built to be tested by late 1993.
This was encouraging news, but a more recent release from Ford announced a scaling back of plans to build an all-new electric car until a breakthrough on batteries can be achieved. Ford's director of electric vehicles, Dennis Wilkie, said: "The fundamental challenge in electric vehicles is in the batteries and propulsion technology."
The problem is really the cost.
"Even with our most advanced experimental power packs, operating costs would be unacceptable to the vast majority of buyers," he said. According to newspaper reports, the Ecostar minivan currently would cost more than $350,000.
Another approach to the battery problem is the nickel-metal-hydride "Ovonic" battery developed by Energy Conversion Devices, Ind. of Troy, Michigan. A 1993 report published in Science magazine claims that the battery exceeds ABC specifications in nearly all respects except cost. In March 1994, ECD announced a joint project with General Motors to bring the battery into production and lower its cost. If this effort is successful, it will give a big boost to GM's plan to bring affordable electric vehicles onto the market. It should be noted, however, that the Ovonic battery uses expensive metallic ingredients.
About 100 GM-built G-Vans are on the road today, mostly in fleets operated by electric utilities. In 1993, General Motors announced plans to build 50 limited-production units of its electric powered two-seater Impact car and team up with electric utilities to let customers test-drive the car in different parts of the country. The Impact is a commuter car with a range of about 80 miles, to be recharged at night at a low rate. While the car uses currently available lead-acid battery technology, it has impressive new technical features which could also be carried over to other advanced car concepts: lightweight magnesium seats; an aluminum structure 40 percent lighter than steel; a heat pump that heats and air-conditions; tires with 25 percent lower rolling resistance; an aerodynamic drag coefficient of only 0.19, about 30 percent better thanany current production car.
The Chrysler Corporation has also entered the field of electric vehicles, and in 1993 constructed 50 TEVans, a minivan for passengers or light cargo; 25 units used nickel-iron, and 25 used nickel-cadmium batteries. A number of other car manufacturers have constructed pro- totypes, often with quite innovative features. Perhaps the most unusual is the Zoom car by Renault, which can actually shorten its overall length for parking. Mercedes-Benz has built a research car using exotic sodium/nickel chloride batteries, while Toyota, Fiat, and Volkswagen employ more conventional batteries in specially constructed lightweight passenger cars.
Perhaps the most promising new battery is EPRl's improved lead-acid battery,developed by Electrosource, Inc. in Austin, Texas. Its "Horizon" battery uses a horizontal-plate system, with lead plates replaced by extruded lead fibers woven into filament grids. Compared to the current lead-acid battery, the Horizon battery shows substantial improvements in specific energy and energy density, and exceeds the ABC specs in specific power (and therefore recharge time) and in the number of cycles (cycle life). For example, recharge time is less than one hour, compared to six hours required by the ABC, and more than 10 hours for the current lead-acid battery. At the same time, the Horizon retains the traditional advantages of low cost and materials recycling of the lead-acid battery.
A Peek into the Future
It's been said, jokingly, that forecasting is very difficult - especially about the future. In the case of electric cars, however, matters are a little easier. If current laws and regulations remain unchanged, there will be a government-decreed market for such vehicles by 1998. The only real obstacle is cost -specifically the cost of storage batteries. This situation provides a powerful incentive for entrepreneurs to develop cost-effective technology. With so many promising candidates in the field, it's really a horse race. And there may be more than one winner; it's big market out there, a quarter-million vehicles a year - and one that's sure to grow.
The breakthrough may come from an entirely unanticipated direction, and may not even involve the major carmakers. A lot of technology companies - aerospace, defense, electrical manufacturing - are vying to get into what could be a commercial bonanza. They may turn out to be more nimble than the established automobile companies. New technology can be bought from smaller firms and transferred quickly even across national boundaries, giving rise to possible multinational ventures.
In all this ferment, governments can and probably will play an important role by providing the proper incentives to manufacturers and to consumers. The most talked-about are various tax incentives for those who purchase electric vehicles, but other incentives may help also: the use of normally restricted high-speed lanes on highways and of course, special parking privileges in congested urban areas.
In all this ferment, governments can and probably will play an important role by providing the proper incentives to manufacturers and to consumers. The most talked-about are various tax incentives for those who purchase electric vehicles, but other incentives may help also: the use of normally restricted high-speed lanes on highways and of course, special parking privileges in congested urban areas.
We may all be surprised by the speed with which electric cars will carve out a share of the automobile market as we enter the 21st century. ~