Re: the real answer to transportation

On May 8, 1:17 pm, Still Just Me <stillnoEm...@xxxxxxxxxxxxxxxxxx>
wrote:
On Thu, 7 May 2009 23:10:04 -0700 (PDT), Chalo

I'm pretty sure that what Peter Cole was talking about, and probably
Tom Sherman too, was the fact that gross efficiency for internal-
combustion engines in cars (as defined by joules of heat in the fuel
compared to joules of work at the crankshaft) approximates 25% to
begin with, thus you take the big efficiency hit right off the top.

Chalo

That's more reasonable... but the numbers are somewhat misleading
since no energy conversion to mechanical power mechanism is all that
efficient when you look at the whole process from finding fuel in the
raw to producing power at the rear wheels.

In addition, each alternative has non-desirable output e.g. if you
burn coal at a power plant to produce electricity for electric cars,
is that more desirable than the gasoline engine producing pollution?
In fact, looking at the entire cycle, form finding to using various
fuels (oil, coal, nuke, organic) and what's generated along the way in
undesirable side-effects then it builds a much more complex picture.
FOr example, if you want to use CF and build lighter cars, what is the
cost of manufacturing CF and or other plastics (and is using fossil
fuel that way any better)? Is bio-fuel any better considering the
downside we've seen to massive farming for bio-fuel and the effect on
world food markets?v

If you look at the entire equation, you realize we have to make more
global observations as to the "best" solution. Most people are focused
on the trees instead of the forest.

As long as we're discussing various effiiciencies: Does anyone know
the efficiency of a charge - discharge cycle of the various battery
chemistries? IOW, if you put 100 Joules in via a plug-in charge or
via regenerative braking, how many do you get back out?

I imagine it varies depending on the rate of charge and discharge,
among other things; but I've never come across even rules of thumb.
That includes when I asked a young engineer who was trained to answer
questions about the GM EV1 he was standing in front of.

- Frank Krygowski
.

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