On Monday, Nov 17, 2003, at 15:44 US/Pacific, Jake Anderson wrote:
>
> you say that USA uses 100 times the energy of the incident sunlight?
>
Actually, I think he said that fossil fuel consumption is equivalent to
100 times the incident sunlight energy, after assuming horrendous
(but not necessarilly incorrect) conversion factors for each of the
stages
from sunlight->biomass->...->fossilfuel.  This is a way of including the
difficulties (ie inefficiency) of creating the fossil fuels; we're using
up the fossil fuels at a rate 100 times that with which they could
possibly
be replaced...

But I'm not sure it's relevant.  The whole point of alternative energy
sources,  including solar and biomass, is to replace those inefficient
steps with more efficient ones, or eliminate them entirely.  So a solar
cell converts sunlight directly at better than 10% efficiency (not
counting
manufacturing/etc, which you do need to count sooner or later), which is
better than solar to biomass efficiency, and much much better than solar
to fossil fuel to electricity conversion.  Biomass research presumably
includes finding plants that are more efficient than "average", and I
assume the point of the original posting was that someone was claiming
that willow trees were more efficient that some other fuels.  (Willows
make great charcoal for fireworks, btw...)

So the article claims that there's about a 10:1 payback for willow
biomass,
and the counter-argument is that if that "1" HAS to be fossil fuels,
it's
not nearly efficient enough to reach a steady state...  But we don't
really
know how much of the "1" needs to be fossil fuels, because there isn't a
lot of effort directed at running willow harvesting appliances off of
willow wood.  Yet.  Presumably, willow is better than "something else",
or there wouldn't be a paper.  At least in some growing conditions.

Personally, I want direct ethanol fuel cells, at the end of a grow,
ferment,
fuel cell chain that's both shorter and more efficient than fossil fuel
generations.  The whole Bush "hydrogen fuel cell" thing is a bit
depressing,
because large scale hydrogen generation currently uses ... fossil
fuels.  I
guess he had to keep his oil buddies happy :-(

BillW

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu