I've always wondered about the impact on the environment from the operation of the windmill itself. For every action there is an equal and opposite reaction. So wouldn't large numbers of these slow down wind currents? Would that stop seeds, pollen, birds, etc... from traveling as far?

Especially for charging EVs, wind beats pv hands down.

A recently opened stage of a windfarm in Palmerston North, New Zealand, on a very good wind site has showed it will generate 55 to 60 times more energy over 20 years than the
energy consumed in its manufacture, construction and de-commissioning.

http://www.windenergy.org.nz/documents/2007/070913-NZWEA-Tararua-3-carbon-neutral-in-months.pdf

In fact it was carbon neutral two weeks before the last turbine was commissioned.

Benjamin

That's a tremendous figure. If correct it makes a very strong case for supporting massive expansion of wind generators.

It would be instructive to see all forms of energy production similarly given a life cycle analysis. Makes you wonder how solar photovoltaics compare, for instance.

It also shows an enormous gulf between wind and ethanol, where the best figures for cellulosic ethanol have a 5x ratio and food crop ethanol is

This shows where we should be putting our public policy, investment and incentives, and our purchasing.

BTW, the link is broken. I found the article cited at:
http://www.renewableenergyaccess.com/rea/news/story?id=25113

The german Wikipedia has a good article about this here:
http://de.wikipedia.org/wiki/Windkraftanlage#Energier.C3.BCcklaufzeit
it states a time between 2.1 and 6.1 month regarding brand and position of the turbine.
Interesting is the short english couterpart at wikipedia. Way to go, dudes!

About how far seeds and the like travel-- the decrease caused by wind turbines is far less than what would be caused by a forest... and huge chunks of the planet were forested only a thousand years ago.

Also when you consider these things next to coal plants and nuke stations, they must be better for us all in many other ways besides outweighing the energy used in their production.
Pollution, dangerous chemicals. I think they are nicer to look at than a nuclear or coal power plants.
The big drawback is the surface area needed to have a good number of them.

I believe any good sized city blocks more wind than all of the turbines already put into place. Acid rain from coal plants and day glow fish and 6 legged frogs near nuclear plants (sorry, I am exaggerating) I think are worse to deal with than some blades spinning around.

Fun factoid... from my days of flying little airplanes around... 'they' say a windmilling prop on a plane produces more drag and turbulence than a solid disk of the same size.

vsk

Bryan - Good thinking, but I don't imagine it'd be a problem.

Birds, obviously, have to deal with both head and tail winds, the effect of a turbine on their actual progress will be minimal. There was, however, some concern during the earlier phases of wind power development w.r.t birds hitting the blades. This is still frequently cited as a reason for limiting development by the various anti-wind groups, but monitoring of operating farms has shown it to be a non-issue.

As for seeds/pollen - I'm not sure. There might be a bit of an impact in the region of the turbine, but I think it'd be fairly small as the fill factor is quite low (not that many turbines compared to atmospheric cross section).

As to slowing down wind currents on a global scale - nothing to worry about at all. Even the biggest wind turbines these days only poke into the very lowest layer of the atmosphere, pretty much all the wind energy exists out of reach, and causes the low level winds by a wide range of interactions. Also, the actually energy flux in question is astronomical - you've probably heard the figure of "a cat5 hurricane releases the same amount of energy in 10 mins as all the worlds nuclear weapons would".

I realise this is hardly a scientific analysis, but I don't think it'll ever cause a problem.

The real question should be..

How long does a coal power plant take to DOUBLE the impact of building itself?

Some literature on the subject:

http://www.windpower.org/media(444,1033)/The_energy_balance_of_modern_wind_turbines%2C_1997.pdf

L. Schleisn, "Life cycle assessment of a wind farm and related externalities", Renewable Energy
Volume 20, Issue 3, 1 July 2000, Pages 279-288

Manfred Lenzen and Jesper Munksgaard, "Energy and CO2 life-cycle analyses of wind turbines—review and applications", Renewable Energy
Volume 26, Issue 3, July 2002, Pages 339-362

Milborrow, Dispelling the Myths of Energy Payback Time, as published in Windstats, vol 11, no 2 (Spring 1998).

I would really be interested in an accurate figure showing how long a PV panel takes to "pay" for itself energy-wise. I was told by someone at my company (we make PV manufacturing equipment) that they generate the energy required to produce them in one year, but I have doubts about the accuracy of that statement. Most of the time people speak in terms of money, as when the cost of the panel equals the market cost of the energy it produces, but that is such a sliding slippery figure. Silicon stock is overpriced, grid energy is subsidized indirectly etc, price varies by location. I want to know watts in and watts out.
Figure the energy costs: energy used to "mine" and refine the silicon (and energy cost for the steel, graphite, argon, ceramics etc to make the equipment along with that) energy cost of casting the silicon, testing, sawing, assembling and shipping and installing, along with the inverter and batteries (or infastructure to transport the energy back to the grid)
I guess calculating this could be a fun project for me at work...but I don't have the time.

a few points:

firstly, i think it's fair to suggest that this photo is not real, am i correct? as someone who drives by REAL wind-farms regularly, this is a misleadingly idyllic rendering of a visually and environmentally horrific abuse of wilderness.

real desert windmills are crammed together, side by side, nearly as far as the eye can see, with giant transformers and 200+ foot power line towers. they kill almost all living creatures and vegetation, prevent natural drainage, and perpetuate the utility industry chokehold over OUR power through outdated remote generation and transmission. they require service roads and sometimes natural gas to get them going. as much less important points, they also destroy the innate peacefulness (scientifically proven) that comes from viewing nature, and are LOUD, which, ok, so is wind. they are not small, sparsely planted, unobtrusive, wireless "trees" dotting the otherwise pristine landscape! the ones shown here are roughly 20% of actual scale...

if, say, a wind farm and all its transmission lines were built on the footprint of what used to be a coal plant or other previously developed land (abandoned airfields, warehouses or industrial areas, retired oil platforms, over-grazed or dehydrated agricultural land), i would be all for it. if it involves annihilation of wilderness, however i think we all need to agree that it cannot be a "green" solution to anything.

please, let's all draw the very real distinction between remote, utility-profiteering and wilderness-killing power generation and transmission, and local, decentralized, wilderness-saving power generation which profits individuals. we need our government policy to encourage the latter, not the former, and things are not headed in that direction, thanks to the Big Power lobbies.

thanks!

For solar PV payback times have a look at a paper by Bankier and Gale reproduced in EnergyBulletin:

http://www.energybulletin.net/17219.html

Times are clustered round the 3-year mark, with two models at 12 years and one at 25(!) years.
A typical lifetime is stated as 25 years but, with replacement of some parts (not the actual panels) could last a lot longer.

In the North-Sea, large (300MW) windpower plants are being built off-shore. Large parts of the north-sea can be used to install these turbines. The impact on the ecosystem is beneficial, since the area can not be used for (over)fishing anymore, providing a breeding place for the fish. Moreover, the foundation provides an ecosystem for many creatures. Between the foundations of many towers, mussels will be cultivated in very large quantities (which compensates the economic losses for the fisheries) in hanging cages.
(These cages don't touch the ground, so they don't damage the seabed environment, and provide high-quality mussels)

So on top of the obious green energy, many other advantages are created for the environment.
Until recently the advantage of off-shore turbines (higher wind-speed, less 'visual polution',...) was lower than the disadvantage of more expensive infrastructure. But with the advent of larger turbines and new technologies, this will change dramatically.

Q Sheila : It apears your experience is limited to wind parks erected in the eighties. Much has changed since than.

@ Sheila:

It appears your experience stems from wind parks which were built during the great Californian wind rush of the 1980's. Since then, wind turbines have become more powerful, bigger, quieter, are placed further apart and have less impact on birds.

I think it would be a good idea to retrofit these old parks with new wind turbines*, and then you can see how beautiful wind turbines can be.

*Preferably by wind turbines from Enercon or Siemens-Bonus, because these look the most elegant.

Wind power is a great resource compared to solar PV for large scale projects the payback period is much shorter. I just saw a report on how some wind farms are killing off certain species of birds, although the owners of the wind farms are doing all the can to mitigate this risk. Wind Power isnt made for common household or small business (PV works better in their case) but wind power does have the ability to help large scale projects. I wonder since there are moving parts in a wind turbine, how much maintainence is required over its 20 year life span. If anyone wants to see a cool wind farm, drive up to palm springs, CA....you can see giant wind turbines there.....

-Deep Patel
www.gogreensolar.com

well, i have to say that many of the windmills i am referring to have been put up in the last 2 years in the Whitewater, Desert Hot Springs area, and they are very close together, and are all the things i say.

i should be clear, aesthetics are the least of my worries. it is the permanent, irrevocable obliteration of previously healthy ecosystems which really upsets me. there is no need to kill off our pristine spaces just to hand over more money to utilities. when every roof in CA has panels and aggressive conservation is underway, i will reconsider whether the outdated remote power plant makes sense. at this time, it is simply a way to make sure WE have to pay tax dollars for utilities to use OUR federal wilderness (super cheap) to bottle OUR sun and wind and manipulate its supply to us, while making really large profits. why shouldn't those resources be available to us, the taxpayer individuals, to generate and sell our own power back to the utilities through a 100% buyback guarantee like they get?

this strikes me as a pretty lousy NEW paradigm. meet the new boss, same as the old boss except instead of killing the planet with CO2 emissions, they kill the planet with dynamite, bulldozers, concrete and steel. and throughout it all, they get paid and we get screwed...

don't other people want the opportunity to be a part of something sustainable which will really change things AND make us all money?

How long (on average) would it take to get one of these things up and running, and I dont mean that it is already standing, but how long would it take to build the thing?

I don't think anybody here read the stats of Vestas turbines correctly, it states "The life cycle assessment of a 3.0 MW wind turbine indicates that it would have to generate electricity for only 6.8 months" that is 6.8 months of constant wind, you would be lucky to get that over 5 years if not more

I worked in the California wind turbine fields in 1990 and 1991. Those were the lean years for the industry. I can tell you a story about the scam artists who have now become the old men leaders of the California cabal. Those of you who feel that Wind energy is just an extention of the old monopolistic electrical grid system are correct. The old men who run the wind turbine industry in California are just that, monoopolists and con men. Its not your wind, Its the wind that passes over their ground and is therefore their wind. SO it is like one of your sagatious readers remarked in January,08, meet the NEW BOSS, just like the old boss. The exception being that they are doing it without the heavy CO2 tax. They salivate over the price differentiation between wind power and natural gas power. And you dear consumers are the source of their gravy. Do you think the price of supplying power to your home will go down. to the cost of wind. NO. If they could charge for sunlight they would have done so long ago. Thats why PV's are lagging behind so. The monopolists don't want you to cut loose and be free. Big Oil, big cars and big power griids want you to remain as slaves regardless of CO2 levels and global warming.