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Green
Transportation: Solar-powered Vehicles
by Chuck Hall
 One
of the great dreams of the alternative energy revolution is to
create a car that runs totally on solar power. Unfortunately, with
our present state of technological development, cars that run only
on sunlight must remain a dream…for now. The principle behind a
solar vehicle is to create enough energy to drive the car by
converting sunlight into electricity through the use of photovoltaic
cells. The problem is that the amount of energy available to run a
vehicle depends on the surface area of the car itself. More surface
area exposed to the sun means more sunlight and therefore more
electricity, but it also means added weight. And added weight means
more electricity is needed to move that weight. There is an optimal
ratio of surface area to operating weight, and at the present time
that ratio only allows for one person per vehicle. Most solar-only
vehicles seen in competitions and at universities are basically
glorified bicycles, with no room for passengers or cargo.
 By
putting batteries onboard the vehicle, additional stored energy is
available for the motor, but once again the batteries contribute to
the overall weight of the vehicle. There is also another problem to
consider, however, if you leave the batteries off in order to
conserve weight. If there are no batteries at all on the vehicle,
then it can only operate when the sun is shining. This means that if
you are out on a date in your solar car, you have to be home before
sunset! And don’t even think about driving on a rainy day!
Races
for total solar vehicles like the World Solar Challenge (www.wsc.org.au/)
and the North American Solar Challenge (www.americansolarchallenge.org/)
promote the use of solar vehicles by offering a yearly competition
where the best and brightest (no pun intended) of solar engineers
throughout the world can show their stuff. While the designs on
these state-of-the-art solar vehicles are aesthetically pleasing,
they leave a lot to be desired in terms of practical highway use.
The main problem with having the solar cells attached directly to
the vehicle is that photovoltaics work best when facing the sun.
Since vehicles constantly move, the cells on these cars will very
rarely be at an optimal angle for power generation. In terms of
efficiency, if solar power cells were to be used at all, it would be
better for them to remain in a stationary location facing the sun.
So if solar-powered vehicles were to become a reality, it would be
far more practical to charge the vehicle by leaving the solar panels
at a fixed location. These solar panels would then have a hookup
that could be attached to the car to charge the onboard battery pack
when the vehicle is not in use.
Although
the days of onboard photovoltaic vehicles are still a long way off
in the future, that doesn’t mean that we can’t operate electric
vehicles by using sunlight. It just means having the solar panels as
a separate ‘filling station,’ no different from buying gasoline
today.
Chuck
Hall is a Sustainability Consultant and author. His latest book, Green
Circles: A Sustainable Journey from the Cradle to the Grave, is
now available at Booklocker.com.
You may contact Chuck by email at: chuck@cultureartist.org or visit
the Culture Artist Web site at www.cultureartist.org.
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