[LMB] Energy efficiency

[Mark Allums]

Peter H. Granzeau wrote:
> At 09:14 PM 2/7/2008, Mark Allums wrote:
>> 1. Well-cared-for Hummers probably last 300,000 miles.  A Prius is ready
>> to be put out to pasture by 100,000.  So one would go through three sets
>> of batteries in the life time of one Hummer, at least.  This equation
>> will change if/when battery tech finally is improved to the point that
>> the battery charge/recharge cycle is much better, batteries can be used
>> harder and longer, recycling becomes nearly 100% percent efficient in
>> reclaiming and reusing materials, and the batteries themselves reach a
>> high enough energy density to be an economical storage medium and
>> alternative to gasoline.  Energy density is a problem, in and of itself.
>>   A high energy density battery is a small bomb.  Ask users of Sony-made
>> lithium-ion laptop batteries about that one.
> 
> I believe you have no data whatever on life of a Prius, only 
> supposition.  Since it doesn't have lithium-ion batteries, problems 
> with them don't--and won't--happen to the Prius.  I won't pretend to 
> understand the economics or ecological consequences of building a 
> Prius battery pack, but will point out that even if I were to drive 
> mine as if it were my previous car (a 1999 Saturn SL2), I would get 
> twice the mileage that the  Saturn would give, and what pollution I 
> do put out is much less than the Saturn, as well.

I did not mean to imply that the Prius had LiIon batteries.  It doesn't. 
  Sorry about that.  It has Nickel Metal Hydride batteries, and it never 
completely fully charges them to  100%, nor completely fully discharges 
them to zero.  They stay between 60% and 80% of full capacity.

Lithium-based batteries will probably be in the next generation of 
electric cars, as they are constantly being improved.

I mentioned LiIon batteries as an example of the dangers of a high 
energy density.  That's all. And a high energy density is a desirable 
thing in a compact power source.

I also didn't mean to imply that the Prius is not "green".  Only that a 
Hummer may be even greener, in its own way.

I got the "data" on the relative lifespan of Hummers and Priuses from 
articles I have read.  Would you go all Wikipedia on me, and insist on 
me citing references?  Or smply trust that I didn't completely make it 
up?  Unfortunately, I can't cite the source, because I read the article 
  a few months ago, and did not retain the bibliographical data. 
However, I will be glad to Google around for you, if you like, and try 
to find that article or other, similar ones.

Experience tell us that a Toyota is good for about 200,000 miles.  The 
Prius is not likely to last as long as a Camry, owing to the fact that 
the drvie train in the Prius is much more complex, and that the 
batteries themselves will wear out.  200,000 miles for a Prius sounds 
optimistic.

A Hummer is built off of the same general idea as the real Humvee.  It 
will likely last longer than 100,000 miles.  It is not a Humvee, though, 
so it is not as likely to last as long as one. 300,000 miles is 
optimistic.  However, I have seen that figure quoted a lot.  It makes 
the assumption that the Hummer and the Humvee are made from the same 
mold.  I personally don't have any experience in this area.  I don't 
know if consumer Hummers are as eco friendly as Humvees.

--Mark