> Wikipedia - Toyota Prius: Each battery pack uses 1015 kg (2233 lb) of
> lanthanum. As each electric motor in Prius also contains 1 kg (2 lb) of
> neodymium.
Somebody screwed up the battery pack figures. :) NOT EVEN.
The Electric motor magnet amount is also a misleading figure. BOTH
electric motors in the Prius have a total of 2 pounds of neodymium.
What isn't mentioned is that most new vehicles have alternators and
starters with around a pound of neodymium. Or how about the speakers
for the sound systems? Your home stereo possibly has more neodymium in
just ONE speaker.
The battery pack does use lanthanum. Sure. But would anybody care to
think about all the rare-earth elements INCLUDING lanthanum in the
NiMH batteries we put in our camera flashes? Or what about all the
stuff in our Lithium Ion battery camera batteries? Let's not single
out JUST the Prius here. Anybody getting that nit-picky better start
growing their own hair-shirts.
Besides, another thing the anti-Prius crowd totally neglect to mention
is that the magnets in the motors and the battery packs are recycled,
recovering for reuse all of these rare-earth elements. However, in the
case of Toyota, this is a slight problem. These Prius are lasting too
long and not wearing out. The GM products should not be a problem in
that regard, though. The Hondas have also been short-term casaulties
of their own design. (The only hybrid that is giving vehicle lifetimes
on the batteries is the Prius).
A parallel to all this is aluminum. The amount of energy required to
convert alum to aluminum is massive. It is extremely inefficient and
when you factor in the carbon-footprint which a billet of new aluminum
has, steel looks mighty environmentally friendly indeed. No need to
save 50% the weight on anything because you'll never recoup that
savings in carbon-footprint. But the moment that aluminum is recycled
and reprocessed for its second use, the carbon-footprint argument
completely disappears.
As to vehicle weight, the weight of a vehicle today is completely
governed by two things: Safety and Sound-Level. Bumpers, crush-zones,
side-impact beams, air-bags, sound-proofing and more rigid body
structures have caused a massive increase in vehicle weight. Oh, and
seats, dashboards, sound systems, thicker/heavier glass, rollover
structures to top it out. Not to mention catalytic converters,
improved exhaust systems, safer gas tanks...
I did mistype the other day. Each measured unit of energy recovery in
the Prius is 50Wh. I did a little bit of experimentation this weekend
to see what that equates to understandable terms. From a standard
highway speed of 55mph (USA 2-lane road standard speed limit), the
Prius will typically recover 50Wh in coasting the vehicle to a stop
without the use of friction brakes. If you are careful, you can
actually stop the vehicle without ever using the friction brakes,
except for the final 5mph where you need to be a little more abrupt
and also the vehicle does use the friction brakes to hold position.
Discounting the loss of energy through conversion, that 50Wh is
applied to either accelleration or speed maintenance--energy not
required to come from the ICE (internal combustion engine). In-town
driving results in a typical recovery of 100-150Wh of energy over a 5
minutes period of time. (recovered energy denotes wasted energy and
hyper-milers will attempt to reach a point of zero energy recovery
through normal highway driving).
When there isn't enough coasting or slowing to regenerate enough
electricity, the ICE will produce just enough extra power required to
recharge. As the ICE has several specific points of maximum efficiency
(no need to build an engine with a broad power/torque curve, just need
a couple points of maximum power-per-measurement of gas), the battery
is either being used to boost output power to make up the deficit, or
recovering excess energy from the overabundance of power.
The Prius isn't too picky about where the battery charge level is at.
It seems to work in about five minute averages. Over a five minute
period of time, if you are stuck in stop-and-go traffic, for example,
it'll just let the battery run things, until the level gets too low
and then the ICE will kick in for just long enough to keep it from
getting any lower. When you start moving again, it'll use the ICE to
produce just enough energy to get it back in the middle someplace and
will use recovered energy to take it up the rest of the way. After a
few minutes of regular driving the battery is back up a ways and it
only take a couple of good coasts to top it back off.
There are two motors in a Pruis hybrid drive system. One is more
directly coupled to the ICE itself and is used to start the motor and
then is used as a generator. The second is more directly coupled to
the drive-shaft and is used to provide power to the wheels, but also
dynamically switches to the role of generator if the torque is coming
from the wheels. Everything is intertwined, though and all four things
are kinda meshed together in some sick kind of way that makes about as
much sense as a bumblebee flying. A lot of the electrical energy
produced by the ICE goes directly to the propulsion electric motor,
which would technically be wasted energy through the
double-conversion, but the electric motor is much more efficient in
regards to torque and this allows the ICE to be pretty wimpy. In the
end, it all works out well.
So, to wrap this up, when you consider the recycleability of
everything in a Prius AND use a proper apples-to-apples comparision
with other vehicles (my aluminum vs. steel example), there is no
ignoring that the Prius is truely "green". It'll just take a long time
before they wear out enough to get recycled, but it will eventually
happen.
I've been a little upset about our gas mileage the past couple of
weeks. When the heat gets way up in the '90s, the air-conditioner has
to run more. When the temp is about 98 degrees, this translates to
about a 10% loss of gas mileage as compared to peak performance around
72 degrees. My wife is tired of my grousing that we only got 46.5 MPG
on the last tank. (That's a fully overloaded Prius driven on hilly
highways in very high heat using marginal gas in windy conditions).
I will complain about two things, though. Legroom for me is pitiful.
The car is painful to me, but that is not atypical these days. The
other thing is my taillights. The way the taillights are designed, the
bulbs overheat and burn out. I'm going through a bulb a week right
now.
AG
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