GM's 2005 Hybrid Silverado might be called "fake" because it's really a gas truck
with an electric plug for powering chain saws and other tools. The engine stops when the truck stops, instead of
idling, giving slight gas savings. It's started again by the beefed-up battery. On other days, it might be charitably
be called a "mild hybrid", which also
use tricks like "Displacement on Demand" for mild mpg savings.
"Weak" parallel hybrids are just one small step above real "fake" (sic) hybrids such as the
mild hybrid.
But in 2006-7 almost every company will be offering scads of new "hybrids", trying to duplicate Toyota's
success with the Prius. Many of these new offerings are as confusing as the mild
hybrid.
Here's one classification scheme for hybrids.
FAKE HYBRIDS:
Hybrid is little more than a name. Some of these have plugs that feed power from their battery
to power tools, others have Combustion on Command. The electric motor is sort of a beefed-up starter motor that
can assist a big engine perform a little big more efficently.
PARALLEL HYBRID (WEAK):
Parallel means the Internal Combustion ("ICE")
gas engine is integrated into the power train. Weak
means it cannot run on the motor alone, without the ICE, perhaps under the fiction that the ICE is needed for "real
power". Motor and ICE contributions to power demand are controlled by a complicated computer.
The key example is the Honda Insight, which only has 72 "D" cell batteries. But the Insight is the most
aerodynamic production car on the road, and gets the best gas mileage. Insight, like the Prius, has a vociferous
fan base. |
PARALLEL HYBRID (STRONG):
Larger battery or ultracap can store energy derived from regen braking. Stores far more energy than a weak parallel
hybrid because it can run on the electric motor alone
as the primary traction power, although the ICE is still primary. The Toyota Prius, for example, has 1.3 kWh of battery and can run on the drive motor alone (until the computer turns
on the ICE at 43 mph, or when the smog gear is cold). Toyota was first to market with this idea..
PLUG-CAPABLE HYBRID (PHEV, WEAK):
Battery is slightly larger, often about 9 kWh, and can be charged via external power ("plug-capable").
Can run on electric traction power up to a certain speed, but needs ICE for higher speeds or torque demands. Still
working with the bass-ackward idea of putting the ICE first, and the electric motor second; but now, we are complicating
that model by beefing up the battery and adding a charger you can plug into the wall.
Examples of this Frankenstein car is be the plug-capable Prius, that can drive up to 43 mph in stealth mode. It
would be so much easier to make the Prius plug-capable if it were designed for that configuration. Prototype versions
get up to 180 miles per gallon, providing a symbolic
example of how to seamlessly move some of our energy use from gas to off-peak electric..
PHEV (STRONG, SERIAL)
This is in essence the "Long Ranger" by AC Propulsion, an EV with an added-on gas engine-generator that
can charge the batteries or directly run the motor. Any EV can be turned into a strong PHEV just by adding on a
small generator.
The electric motor is the only traction power. That's
the key idea, eliminating layers of compexity. Electric is fed to the motor from a battery, which is capable of
running the car for a substantial period of time. The battery is charged by an ICE motor-generator, which |
only comes on when the battery is low; in general, the battery is charged from the grid,
as it's "plug-capable". Big advantage, like a diesel-electric locomotive, is that the connection between
the engine-generator and the battery-motor is all electric, no mechanical linkages, clutch or gearing to fool with.
Backers claim this configuration can allow
the average person to drive 500 miles for each gallon of gas bought.
BEV ELECTRIC CAR
As the strong PHEV, but without a built-in motor-generator. On-board electric battery
storage of enough electric power to travel significant distances (at least 100 miles).
In this classification scheme, a Fuel Cell Vehicle ("FCV") would be a "strong PHEV" of sorts
with a fuel cell stack in place of the ICE motor-generator.
The FCV might still be at the diesel-electric configuration class, because you still have to make the H2 gas via
electric power (H2 is the medium of transmission, instead of the battery); however, FCV folks would argue that
FCV is, under certain conditions, completely ZEV, and that even BEV require battery recycling. And no one is proposing
getting rid of all gasoline or fueled vehicles, at least for a while. Every FCV uses only the electric motor for
traction power, just like an EV.
Some would say that the ultimate vehicle might be the strong PHEV (serial hybrid), because it can serve all missions
and all requirements seamlessly to the driver, except for not being completely ZEV.
Others might say that the ZEV requirement is the "gold standard" and makes avoiding the serial configuration
worthwhile, or at least making it only an add-on. For example, you could fit the optional engine-generator into
a dock on the EV when you need to go long distances, otherwise use it as a cargo area.
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