There are three types of experimental vehicle (EV) propulsion technologies 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.
One of the most recent and exciting developments in electric-vehicle technology is the fuel cell. The fuel cell generates electricity through a controlled reaction between hydrogen and oxygen atoms, utilizing a special membrane. Unlike batteries, which store electricity, fuel cells actually produce it. Inside a fuel cell, hydrogen and oxygen 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. This 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 any carbon monoxide produced as a byproduct would be processed in additional chambers that would convert it to harmless carbon dioxide. Another departure from chemical-based battery technology is the flywheel.
All flywheels, including those presently on vehicle engines, act as a sort of mechanical battery, storing energy by spinning. 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. The 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.
Hybrid vehicles typically feature two different power sources, working either in parallel or in series, to propel the vehicle. Much research is underway 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 needs only to 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 could be charged by a generator operated by a small internal combustion engine. Such a combination could extend the range of an EV considerably. There has already 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 spun two turbines providing electricity. A flywheel generated additional power. The electricity was controlled by a computer that delegated which power source to draw from and directed that power to the motor driving the wheels. The turbines and flywheel produced about one megawatt of energy, allowing the Patriot to reach speeds approaching 200 mph.
These new power sources will revolutionize the transportation industry. They will replace gasoline as the predominant energy source of our vehicles.
