"jeff" wrote in message
news:W6zue.2318$HU.623@trnddc03...

The "close to 50%" was from a casual conversation some 15 years ago with
an engineer in the precision engineering lab at Livermore when I was out
there on a CRADA. It was in large measure based on the 80000 mile throw
away Detroit junk of the late 70s. I haven't been able to lay my hands
on them, but ANL did a lot life cycle modeling of work in that era as
well. Most of the current analysis I see is based around "green" vehicles.

Here's one that gets it down to 10% by claiming a 14 year life cycle for
a 1990 Taurus: http://www.ilea.org/lcas/macleanlave1998.html

The "14 year life cycle" assumes consumption of only 6,700 gallons (878
thousand megajoules at 130 megajoules/US gallon of gasoline), so it's in
line with the others: an assumption of a 120,000-mile life. MIT uses a
figure of 300,000 kilometers.

I don't remember what SAE used as the "life" of a car, for their life-cycle
analyses. When I was materials editor at AM, the SAE and AISI (not to
mention the aluminum and plastic makers) flooded us with statistics on
life-cycle costs of cars, both current and hypothetical. That was in the
'70s and early '80s. SAE was saying then that the energy cost of manufacture
and materials was around 4.5%. AISI said it was less. I reported the SAE
figures. d8-)

The PDF I pointed to in an earlier message shows some graphs that come in
around those old SAE figures, but it appears the independent, scholarly
analyses have moved up to around 8%, by opening the range of upstream
activities they're counting in the total energy audit.

I just spent some time reading the extensive analysis that MIT did a few
years ago, "ON THE ROAD IN 2020: A life-cycle analysis of new automobile
technologies." It's 160 pages that lay the subject out in detail. They
include a 1996 Toyota Camry for comparison with the new technologies (it's
not their "baseline" vehicle, which actually is one that hasn't been built
yet). There is much of a chapter devoted to how difficult it is to pin the
figures down, because you have to make a lot of assumptions no matter how
you do the analysis. Their bottom line, however, is around 8% (page 113).

Unfortunately the two examples you posted that I looked at don't explain how
they did their accounting, but the "couple of percent" comment at the
co-design site, regarding the energy recovered from recycling, should make
you suspicious. The example I posted a day or two ago
(http://eerc.ra.utk.edu/ccpct/pdfs/2000-01-0595.pdf -- an SAE paper from the
Center for Clean Technologies project at U of Tenn.) goes into more detail
on the accounting. They have graphs but no numbers; still, take a look at
it.

But the MIT paper is the motherlode:
http://lfee.mit.edu/public/el00-003.pdf. For anyone interested in this
subject, as well as projections of where the trends are headed, it's worth
downloading it.

Look at Chapter 4, especially pages (in the PDF) 110 - 113.

Happy reading. If you want to discuss the accounting, I hope you find
someone who also reads the MIT report. I have a load of work to catch up on
and have to drop it here.

--
Ed Huntress