Patriot Flywheel/Turbine Hybrid
Slide 10 of 13
Click image to enlarge.
For top quality images and fast viewing,
download the native PowerPoint file from the contents page.
The 200-mph Patriot is another Chrysler hybrid, but its at the other extreme in
combustion conversion and storage technology. It uses a turbine genset that runs on
liquefied natural gas (LNG). The built-in alternator runs at turbine shaft speed,
which means that it delivers lots of power from a relatively small and lightweight
Allied Signal has turbines that are about the size of a loaf of bread and develop more
power than three V-8s. But more development is needed in order to achieve the high
efficiency and low costs necessary for a hybrid-electric automobile.
And of course the next step beyond these combustion systems would be to replace the
genset with a fuel cell, which operates at over twice the efficiency and produces only
water vapor as emissions. The only problems with fuel cells today is that they are
too large, too heavy, they cost too much to build, and they need hydrogen in order to
operate. But remarkable progress has been made in the last few years on all fronts,
and fuel cells may be feasible for automotive application in as little as ten years.
Patriots flywheel energy storage system, which uses a 61 kg (135-lb)
carbon-composite rotor, is also relatively small and lightweight. A flywheel,
however, is a very testy device. The biggest problems, aside from high costs, are the
gyroscopic effects of the rotor, and the effects of the sudden release of energy on rotor
failure. Gyroscopic forces, if they are not correctly oriented, are enough to cause
a vehicle to roll over in a turn, and the flywheel has to be well protected from road
shocks. The energy released during the failure of a 1 kW-h flywheel is enough to
lift a mid-size car 100 feet into the air.
Ultracapacitors are another high-tech storage device that should be much more benign
than a flywheel. Both ultracapacitors and flywheels can accept and deliver energy
many times more rapidly than a battery. In a hybrid automobile, high specific power
is the most important attribute, and specific energy is secondary.