There are three types of experimental vehicle (EVs) propulsion technologies on
the currently being tested. Batteries are currently the most popular power
source for modern EVs but they are by no means the only available technology. A
number of alternatives are under development and they, too, are well positioned
to rival batteries as an effective EV power source. 1.Fuel cells Some of the
most recent and exciting news in electric-vehicle development has centered
around a new power source, called the fuel cell. The fuel cell utilizes a
special membrane to generate electricity through the controlled reaction between
hydrogen and oxygen atoms. Unlike batteries, which store electricity
rather than generate it, fuel cells actually produce electricity through a
controlled chemical reaction between hydrogen and oxygen. Inside a fuel cell,
the two elements are fed to opposite sides of a porous membrane. As hydrogen
atoms pass through the pores, they are stripped of their electrons. This results
in a negative charge on the membrane’s hydrogen side and a positive charge on
the oxygen side. Stacking fuel cells in series produces enough power to operate
a vehicle. Unfortunately, there is a downside to this innovative
system—hydrogen is extremely volatile. It is also difficult to store and
unavailable at local filling stations. Chrysler Corporation is currently working
on a fuel cell that eliminates some of these obstacles, notably storage and
inconvenience. Their efforts may make fuel cells a viable option in the near
future. One of Chrysler’s plans is to use small amounts of gasoline in fuel
cells. Doing so would eliminate the dangerous proposition of storing hydrogen
onboard an EV before converting it to electricity. A series of reaction chambers
in the system would convert the gasoline to hydrogen as needed, and carbon
monoxide—produced as a byproduct—would be processed in additional chambers
that would convert it to harmless carbon dioxide. 2.Flywheels Another departure
from chemical-based battery technology is the flywheel. All flywheels, including
those presently on vehicle engines, act as sort of mechanical batteries, storing
energy by spinning. Friction, of course, is their enemy. In new flywheel
technology plans are to create a nearly frictionless environment—essentially a
vacuum—around the flywheel by enclosing it in a shell and mounting it on
liquid or magnetic bearings. To create electricity, magnets mounted on the
flywheel would pass close by tightly wound wires lining the shell’s interior.
Drawbacks are that charging such a system requires some initial force to get the
flywheel up to operating speed (which can be as high as 100,000 rpm) and that
lightweight but strong composites instead of common metals must be used to
construct the flywheel to prevent it from breaking apart. 3.Hybrids Hybrid
vehicles typically feature two different power sources—working either in
parallel or in series—to propel the vehicle. Much research is under way
combining gasoline or diesel-fueled internal combustion engines with
electrically powered motors to get the job done. In a parallel setup, both power
sources drive the wheels. For example, an electric motor may accelerate the car
to highway speeds, whereupon a small internal combustion engine, or ICE, then
takes over to power the wheels for cruising. With this system, the ICE need only
be large enough to maintain speed, and the energy supply for the electric motor
need not provide long range. In a series setup, power from both engine sources
is sent to a single additional motor or controller that drives the wheels. In
such a vehicle, an electric motor might run on batteries that in turn could be
charged by a generator operated by a small internal combustion engine. Such a
combination could extend the range of an EV considerably. Already there has been
an example of a hybrid vehicle, albeit extreme: the Chrysler Patriot race car
project of the early ‘90s. The Patriot used liquefied natural gas to fuel an
internal combustion engine that, in turn, spun two turbines providing
electricity. A flywheel generated additional power. All the electricity was
controlled by a computer that both delegated which power source (turbines or
flywheel) to draw from and then directed that power to the motor driving the
wheels. In all, the turbines and flywheel produced about one megawatt of energy,
which was how the Patriot was expected to reach speeds approaching 200 mph.
These new power sources will revolutionize the transportation industry. They
will replace gasoline as the predominant enegy source of our vehicles.