Electric Car Future
In the not-so-distant future, if the stories in the media are of any indication,
we are all going to be driving around in electric cars. We are told how this
technology showed promise early in 20th century but was soon replaced by the
fossil-fuel guzzling, evildoing internal combustion engine. Electric cars,
the story goes on, are quiet, efficient, non-polluting, responsive and just
need to be plugged in during the off-hours when electricity is plentiful.
All that is now needed for this exciting electric future to come to pass is
more funding for research and infrastructure. So far so good? Not exactly!
Electric cars have a number of formidable problems to overcome. Overall
efficiency of the electric car must take into account efficiency of power
generation, transmission and battery charge/discharge cycle. The product
of all these efficiencies place the electric car overall efficiency below that
of the IC engine. The environmentally friendly, zero-emission reputation of
the electric car becomes questionable when we factor in the impact of
high-performance battery manufacture and eventual disposal. We are not
talking lead-acid here but some serious alchemy. The zero-emission label
only applies if the generating plant is also zero-emission. Since the
electrical grid is a melting-pot of all types of generators, it cannot
be called zero-emission. These are all factors that make the electric car
less than ideal. However, the primary factor that will continue to keep the electric
car from our garages is its unacceptable driving range.
Provided we can invent high-tech batteries, the driving range problem boils
down to the charge rate. Electric vehicles cannot be charged in our garages in 8 hours or
less. EV proponents keep stressing "infrastructure" as something that is needed
to make the EV a reality. They are right. An EV in all ways comparable to today's
midsize sedan with a driving range of 600km and a charge cycle of, say 1 hour,
would require not only new and exotic batteries but a massive electrical charge
system designed by Nikola Tesla! The average home garage simply cannot get the
job done. Charging thru a measly 110 volt outlet for 8 hours will produce
approximately 12 hp-hr of energy. Assuming that a car uses an average of
40 hp to get around, a 110 volt outlet charge will keep us going 18 minutes. Things
get a little better if we were to plug the car into the dryer outlet. After an
8 hour charge, we could drive for about an hour and travel maybe 60 km. Sound familiar?
These are exactly the electrical-only range specs for the Chevrolet Volt!
These figures are going to be lower if we resort to rapid acceleration,
defrosting the windows, running air conditioning, steering a lot
(electrical power assist), running the heater, having the lights on,
listening to a premium sound system, etc.
The solution to the short driving range is to equip the car with a small
gas engine. Once the batteries give up, the 850cc gas engine takes over
and gets the car to its destination at a (much) reduced level of performance.
This is the philosophy behind the yet-to-be-unveiled Chevy Volt. Better to skip
the electrics all together, save the environment and just run the 850cc 24x7.
YK - June 9, 09
© Transdynamics Engineering Limited
June, 2009.
