Windfarms take up far too much land for the power they give. What? If Windmills were located in the center of Los Angeles, this would be a valid statement. But windmills are usually located in deserts, or even in pylons in the ocean. No land loss there.
The way you should figure out if windmills are efficient or not is simply this: don't give any tax breaks for building them, and allow private companies to build them. If windmills aren't efficient, they won't be built. If they are, they will be. In some cases, windmills will exist in farm areas, taking very little ground space. In the desert, the land can't be used for much else. Now, I know that there are certain tax abatements and other things that mess up (or, in John Kerry's parlance, "F--- up") the analysis a bit. But overall, I think you'll find that even without tax breaks, windmills make sense for some power. Surely not all power. Not even 10%. Probably not even 5%. But for a few percent, yes. It's low hanging fruit. Build some windmills in the middle of the desert. Check on them every now and then for failure due to turbine breakage, etc. In the meanwhile, they generate electricity. Probably not always, but if you locate them in a sensible place, almost always.
Environmentalists think that we can all have just solar, or just solar and wind and other renewables. We can't. There's not enough. Most other places can't. But a few places can, like Iceland, which has vast stores of geothermal energy, and a small population base. Makes sense for them to use geothermal. Just like for us, in the desert, makes sense to make use of the wind. But also use coal, natural gas, oil, nuke plants. Wind power isn't necessarily a bad thing.
I live in one of those deserts, it's lost land. Other stuff COULD be done with that land, if nothing else you could build more efficient forms of energy.
The lack of tax breaks thing wouldn't work. For one thing it would create an uneven field that wieghs heavily against the windmills since just about every other method we use to generate electricity gets some form of tax break, as it should electricity generation is one of the most important things we do. It's the building block to Western culture and American wealth, and often interstate commerce (one of the duties of the fed as outlined in the Constitution).
Wind farms are a lot higher maintenance than you think. Those things are tall and potentially quite dangerous if something goes wrong. In the mean time you've to have them tuned to different wind speeds for smooth operation, and they need to be kept very clean. They aren't a fire and forget energy source, not even close to it.
Actually in the chunk of the desert I live in wind power makes no sense at all. We don't have the kind of consistent winds needed to set that up. Tucson suffers from dead air outside the monsoon season (really DEAD, only place I've ever been where the air outside around 9 AM can be described as stuffy), and during the monsoons the wind is horribly violent, way too fast for a windfarm. Probably get about 4 days a year of good windfarm weather. We kick butt for solar though.
I'm not saying wind power is a bad thing, I'm saying it's not ready for primetime. I envision a day when it actually can be a major if not primary energy source for large chunks of America, but that day isn't here yet. Our turbine technology isn't geared towards how windmills work, it's geared towards how gas or coal engines work; it's aimed at a much higher RPM and not efficient at lower speeds.