BI,

These suckers are slewed by a motor and pinion gear arrangement, controlled by a system that determines average local wind direction and speed. Rotors face upstream to avoid the problems with the tower/mast wake disturbance.

As for turbines not spinning, see http://www.greentechmedia.com/articles/read/why-ar...

I figured it might have directional control.

Curtailment ... if you can't get it through the grid to where it's needed, no point in making it. Isn't a lot of power gen capacity in the US Midwest stranded power?

The 40% capacity factor for the best wind sites would be really good. I've found that as you increase the area of "the site" to an area as large as Spain, the capacity factor drops to 10-20%.

One manufacturer [if not most of them?] uses suspended cables as opposed to slip rings to connect the nacelle to the switchgear at the tower's base; there is a monitoring system in place to keep track of how many degrees of slewing / nacelle rotations, in which direction, have occurred from "neutral" since the latest time the tower began generating, and unless the twist in the cables draws too close to what they can absorb without damage the unit will continue to produce until its next shutdown due to failing wind. Once the tower is idle the restoring system will slew the tower around as many turns as needed to get it back to within 360° of "neutral..." or something like that; I'm going from memory from when I was given a tour of a ~200 MW wind farm.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

"Curtailment ... if you can't get it through the grid to where it's needed, no point in making it. Isn't a lot of power gen capacity in the US Midwest stranded power?"

CapX2020 alleviated a lot of that in the upper Midwest. In my locale, just 45 minutes north of the "Buffalo Ridge", this has been a hot topic for many years.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

Yes. You are right.
In general, the wind turbine "business" relies on the manufactoring and construction tax write-offs and government-mandated rebates and government-mandated "electrical favored buy-in" rates to even pretend to make a profit.

The wind turbine average capacity = 0.17 to 0.22. Meaning you have to build 6x to 5x wind turbines to get the rated nominal power output of 1 over a full year's service. But half the time, you are getting no power out at all.

Also a very quick way to get your tax credits and total generating capacity numbers up.

Racookpe1978,

A capacity factor of 17-22% percent is very low. If you go look up the EIA's yearly report on the LOCE (levelized cost of energy), you'll see the total cost of different forms of generation's all said and done cost, including fuel, maintenance, spinning reserves, everything. Wind generation is near competitive or is competitive in some regions against everything with the exclusion of natural gas.

Total cost of everything is a start, but what you really need to know is how much money a given installation will make, hence capacity factor is equally important. It is the other half of thee equation.

Yes 12% (lowest yearly average over the total area of Spain) to 22% (higher yearly average over the same area) are low numbers, which is why wind turbines can compete with other forms of energy generation ONLY when they are located in areas where the local capacity factor is very high (say 35-40% or more to equal solar PV). Those areas are not as common as one thinks. Most of these already have wind turbines working there. What I have noticed explains that not all wind turbines are located on hilltops where winds are best. That is why, as you increase the area you analyze, the regional capacity factors drop to numbers so low. That is also something that the WTMA doesn't like to talk about. I made a detailed comment on their online magazine a few years ago, giving specific actual examples showing reducing capacity factors as area increases and they promptly removed the whole article.

Anyway, all of that indicates that many wind turbines have been built up on land with poor wind generating characteristics, probably only for the tax credits. Why else would you do it. I certainly would not put one up if I was only expecting to get a max 20% return on my nameplate capacity... during a very windy year. You need a really great hilltop, Cape Cod, or tax credits to make most of them work. Santa Ana winds don't blow anywhere near 40% of the time over a year.

Another thing that needs to be taken into account when talking about capacity factors is going rate of electricity. In places like California, the price per a kwh is high, near $0.20. My electric bill in Texas for comparison is $0.11 per kwh. This offers a lot of margin that can be used to offset low capacity factors. A capacity factor in Oklahoma of 30-35% might be equivalent to 20-25% in California in terms of economics. California is a green state with its own mandates but green energy will and can make inroads in expensive markets. Looking at the map, I kind of suspect that the wind energy in Hawaii is economical even with low wind capacity factor due to Hawaii not having the resources or access to cheap generation.

Yes I believe wind is economic there and other remote locations with no oil, because the cost of importing oil to fuel conventional generators adds a few cents per kW, so even a lo cap wind farm can compete. Big problem with wind, and all renewables for that matter, is usually, if you need reliable power and who doesn't, you wind up building the same amount of conventional power plant to back it up, or you will need to add mucho, mucho batteries. Another big cost.

"Anyway, all of that indicates that many wind turbines have been built up on land with poor wind generating characteristics, probably only for the tax credits."

That's pretty much exactly what's happening in this area. The wind farm companies are chasing government money, not wind.