"Pete C." wrote in message
...
Ed Huntress wrote:

"Pete Snell" wrote in message
...
What is it with people? Whenever alternative power solutions are
presented or tested, there is always a Chicken Little faction that has
to
point out that it isn't perfect and we have to look elsewhere or
disaster
looms. It seems that 'someone' thinks that there is a solution out
there
that is universal, safe as apple pie, and could be implemented
perfectly
on a week's notice. Until people change their perception of what
actually
works, and how it should work, we're gonna be stuck with what we have.
Bio-fuels make good sense for certain sectors and countries, but
obviously
not all. Wind power makes sense for on-the-spot power generation, but
not
much as a central power source. Etc, etc.

I'll bet, though, that the OECD is probably right that biofuels, as
they're
produced via the intensive farming we practice in the US and Europe, are
a
net loser in environmental terms, and they're probably worse than the
government claims in terms of net energy production. A lot of energy goes
into making chemical fertilizers.

I did a calculation to satisfy a co-worker last year, based on Chevron's
claim that they had raised the production of soybean biodiesel to 60 gal.
per acre (it was in one of their print ads). I figured it would require
30%
of the arable land in the US to produce enough for our current
consumption
of diesel -- just diesel, not including gasoline.

Of course, that's not the whole story. But it has to make you cautious.

--
Ed Huntress

Did you include all the off road diesel and home heating oil diesel in
your calculation, or just transportation fuel diesel?

I don't know, I just had some DOE figures on total diesel consumption to
work with.


The bottom line is that in some 30 year or so, solar energy is just
barely getting to the point of being viable if not economical for mass
market distributed (individual, not utility scale) use. The new bio-fuel
stuff is just starting out and has a lot of maturing to go both in
technology and in determining what usage is actually appropriate.

It's questionable if, or when, solar is going to be economical. It's pretty
well acknowledged that it's a big loser if you don't have substantial
government subsidies.

There are conflicting stories about whether an honest energy audit would
show any net *energy* gain for PV, even now. The US government has been
saying we passed break-even over a decade ago and I have seen some figures
that suggest a 20% - 25% net energy gain. But _The Economist_ hedged its
conclusion on that as recently as six months ago. They say it's still
questionable whether there's *any* net energy gain with PV, in the real
world and in typical installations. It just consumes too much energy to make
crystalline silicon. And other sources have said that the lifespan used for
the optimistic energy audits (25 years' life for PVs) are 'way too
optimistic on the average.

I don't claim expertise on any of this, just that I've been interested
enough to follow along casually and I'm hesitant to get excited about all of
it. On the other hand, it appears to me that it's almost inevitable that a
very large portion of our energy over the latter part of this century will
come from nuclear fission. When you see the numbers on breeder reactors, it
looks like no contest anywhere.


Solar does poorly with attempts at utility scale use due to the large
areas of environmental impact necessary for utility scale use, while
individual use on existing rooftops works well without the environmental
impact. I expect bio-fuels to ultimately be found to be viable mostly
for farms where they can be produced from waste to provide fuel for use
on those farms and not to be sold elsewhere.

Maybe. The big wild card in the longer term is cellulosic ethanol. Will it,
or won't it?

--
Ed Huntress