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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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