"ATP*" wrote in message
...

"Ed Huntress" wrote in message
...

"Wes" wrote in message
...
Is there someplace that has an analysis of how much energy is put into
making, erecting,
and commissioning a windmill vs typical energy output. I'm wondering
how long it takes to
recover the energy used to put it in place.

Since wind is a bit variable, we can assume it is somewhere in the wind
corridor that T.
Boone Pickens was pitching.

I know solar cells have a lousy break even point unless the technology
has changed
drastically.

Thanks,

Wes

Do you need something precise, with documentation, etc.? If so, there are
lots of studies, using different methods of measurement. Search on "wind
power embedded energy," wind power embodied energy," or "wind power life
cycle analysis."

I did this a few years ago. At that time photovoltaic was showing a
worst-case payback of around 24 years, while wind power showed a payback
in 6 months or even less.

Just grabbing one from a Google search, without checking it for accuracy,
here's something that shows how it's calculated and some specific
numbers. There are better studies that you can find, I'm su

www.rogerhelmer.com/sustainability.pdf

--
When I analyzed small solar installations to be constructed under a
prevailing wage scenario, the installations generated such a small amount
of electricity that they would not even cover the interest on tax-free
municipal bonds, and that is after generous utility rebates and other aid
had been applied. Of course homeowners can get the panels installed for
less using small contractors employing illegal aliens. Wind power is only
feasible in areas where there is sustained wind available:

http://www.eia.doe.gov/cneaf/solar.r...nds/fig13.html

The cost issue is one thing, and the embedded energy can be quite different.
One thing to watch out for in the optimistic assessments of photovoltaics is
that they sometimes mix-and-match technologies. For example, I saw an audit
of monocrystalline photovoltaics, which make up most of today's
installations, that didn't include the energy cost of growing the
crystals/ingots. The rationale was that the cells are made from rejected
ingots from the semiconductor industry, and thus cost nothing in terms of
energy. ! Those ingots are a large part of the embedded energy in the
cells.

I also saw a quick energy payback claimed for thin-film photovoltaics, which
may or may not be true, but they used the 25-year lifetime figure often used
for monocrystalline cells. But apparently the thin-film cells, so far, have
much shorter lives.

So it pays to be careful in reading the evaluations. That's why I put the
disclaimer in that note to Wes, above. I'd want to see the complete
methodology and a detailed accounting of any report on photovoltaic payback.

In terms of dollars, most people acknowledge that they're a loser.

Wind, on the other hand, keeps looking better. I don't know enough to
evaluate the construction costs and so on, but the numbers from a variety of
sources look very promising. Of course, there are a lot of variables. So
far, the costs work out best when wind is just a small percentage of a
system's input.

--
Ed Huntress