"Ed Huntress" wrote in message
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"ATP*" wrote in message
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"Ed Huntress" wrote in message
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"Wes" wrote in message
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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
I see now that the original question referred to energy input/payback, not
dollars. Hopefully we will see much greater efficiencies in the production
of solar cells as the technology evolves, which will reduce the cost and
energy input. The potential for improvement through innovation in solar
cells is probably much higher than in corn to ethanol. I think wind power
installations are a hideous blight on the environment, I don't see
technology changing that aspect much.