05/31/2006
Transportation Matters
What to do? With summer coming on and temps already in the 80s, the air conditioning in my trusty 1997 Volkswagen Jetta is kaput, thanks to a leaky condenser. To fix the problem will cost roughly $800. I have three choices: (a) open the windows, (b) spend the $800 or (c) buy another car. If choice (c), should it be a hybrid? Coincidentally, the article in April’s Scientific American following the one on orangutans cited in last week’s column is titled “Hybrid Vehicles Gain Traction”. The authors are Joseph Romm, a former acting assistant secretary of the U.S. Department of Energy, and Andrew Frank, professor of mechanical and aeronautical engineering at the University of California, Davis.
Let’s set the stage for the hybrid automobile, the first to elicit mass appeal in the U.S. being the Toyota Prius. Back in the 1970s, we had an oil crisis caused by an OPEC embargo. There were gas lines and electric vehicles (EVs) were the wave of the future. At Bell Labs, we evaluated a small electric vehicle made by Otis, the elevator company. I was environmental affairs chairman of our Telephone Pioneers chapter and, as part of our Earth Day celebrations, I was in charge of an event in which employees got a chance to ride in a “green” EV. It was a popular event. It was also a fantasy.
The oil crisis spurred many years of very expensive worldwide R&D efforts to find exotic new batteries to power EVs. I’ve probably mentioned earlier my visit to a pilot operation in Europe preparing to manufacture a sodium-sulfur battery. The sodium-sulfur idea died when a sodium-sulfur battery caused a fire and extensive damage in a German auto plant and its management banned sodium-sulfur from that plant forever.
The oil crisis ended and cheap gas returned. We returned to our old ways and the abominable SUV appeared, to the disgust of us small car owners. In the battery field, two types of exotic batteries did not die – lithium and nickel-metal hydride batteries. Both of these, especially lithium-ion batteries, took over the portable electronics applications such as computers and cell phones. Then Toyota began marketing the hybrid Prius with its nickel-metal hydride battery. As they say, the rest is history. Toyota still has trouble keeping up with the demand for the Prius and in 2006 we have at least ten hybrid vehicles on the market. Some 200,000 hybrids were sold in the U.S. in 2005.
The Prius is what is known as a “full” hybrid, which uses a range of measures to save on fuel. How does the Prius achieve its purported 55 miles per gallon combined mileage figure? (Combined mileage assumes 45% highway, 55% city driving.) One important factor in city driving is the fact that the engine turns off when the car is stopped - no wasting of gas or polluting the air while idling. The hybrid has both an electric motor and a gasoline engine. The electric motor can drive the car at low speeds and also kick in to help out the gasoline engine when climbing hills or accelerating. This allows the use of a smaller, more efficient type of gasoline engine.
With the pure electric vehicle, you have to plug in the battery to recharge it. Not so with the hybrid Prius. When you step on the brake, the electric motor essentially runs in reverse and uses the energy of the rotating wheels to charge the battery. This is known as “regenerative braking” and is the major feature that saves on gasoline. There’s also another fuel saving feature. The battery supplies the power to run the air conditioning, power steering and various fans and pumps that in conventional autos are driven mechanically by belts connected to the engine’s rotating parts. Battery power supplies a constant voltage and more efficient operation compared to the mechanical drives, which have to contend with widely varying engine speeds.
These features of a full hybrid yield fuel savings of 60% or more. “Mild” hybrids, such as Honda’s Insight or Civic, employ the start-stop function, use the electric motor to help out the gasoline engine on acceleration and have some regenerative braking. They achieve up to 35% fuel savings, according to the article. “Micro” hybrids include a start-stop feature and use the electric motor to drive the accessories but not the wheels. The micros achieve a 10% fuel savings in city driving but not much in highway driving.
That’s pretty much the situation today as more hybrids are rolled out. What’s next? It may be back to plugging in the battery! Romm and Frank note that Mercedes-Benz has come out with a hybrid Sprinter Van prototype with a larger battery and provision for plugging in the battery and charging overnight. This makes sense if you have a larger battery and are an urban dweller or business with trips typically totaling around 25 miles in a day. For such low-mileage use, the electric motor could power all or virtually all of the load and your cost could be less than a nickel a mile, based on paying the power company about 8 cents a kilowatt-hour to charge your battery. For longer trips the gasoline engine kicks in.
I don’t know whether or not to laugh at a suggestion by Romm and Frank that you might actually use your hybrid to make money. If you charge your battery at night, rates are low because of the reduced demand for power and the desire of the power company to balance its load. So, charge your battery overnight. Suppose you don’t have any trips to make the next day. You’ve got a charged battery and rates are higher during the day. Plug in your battery and sell your stored energy back to the power company at a higher rate than you paid to store it! This may not be as silly as it sounds. Power companies do worry about balancing their load. It costs money to start up or shut down generators to meet changing power demands. If enough individuals and businesses consented to keeping their hybrids plugged in when idle, the power company might go for the idea.
Romm and Frank share my skepticism about the future of hydrogen fuel cells powering our vehicles. In their opinion, a better long-term solution would be a hybrid vehicle combining an electric motor with a flexible fuel option, the fuel being a biofuel blend. With the ethanol now being introduced into our gasoline we’ve started the blending. Ideally, the power we will use to charge our hybrid’s battery will come from solar, wind or some other source that doesn’t send CO2 into the atmosphere.
The Romm and Frank article shows a picture of a small Ford reflex concept car that is a diesel-electric hybrid expected to yield 65 miles per gallon of diesel fuel. As an added bit of “greenness”, solar panels are stated as being incorporated “in” the head and taillights to provide extra power to charge the battery. I’m somewhat mystified by the location of these solar panels in the head and taillights. It seems to me that the roof would be a better location to pick up sunlight. On the other hand, could it be that the solar panels are meant to pick up light from the headlights? If so, shouldn’t the headlights be designed to funnel as much light as possible out to illuminate the road? Hey, I’m just a chemist, not an automotive designer.
Allen F. Bortrum
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