is it true that once the wind reaches a certain speed, wind farms are turned of?

Question

thus making them seem pointless. Surely that is when they willl make and store the most amount of energy.

Answer 1

Wind generators (which is actually the visible blades plus the mechanical gear plus the electric generator) have both maximum AND minimum operating speeds. This is primarily due to mechanical stress on the system (for overspeed conditions), and to electrical losses (at low speeds).

Overall efficiency is a function of speed; the electric machine has a limited range for producing usable power. The variable pitch of the blades (if employed) can extend the usable range somewhat by 'feathering' ... i.e. allowing more air to pass the blade without doing useful work. The bottom limit, which occurs when the wind speed is low and the blades are as 'closed' as they can be, is more or less fixed.

Basically, it isn't worth it to try and generate power when the system efficiency is below a certain level (approximately 70 percent for slow speed operation). And the extra risk of mechanical failure makes operating at overspeed conditions prohibitive from a cost perspective.

It's a good bet to assume that a wind farm will only generate about 50% of its total kilowatt output, if averaged over 12 months.

That puts it in the same ballpark as a solar collection system, by the way. And still better than the 30-40 percent efficiencies of the fossil-fuel-powered thermal systems.

Oh yes, I almost forgot ... the wind generator does not "store" the energy it produces - at least, not for commercial wind farms. Its production capacity is always dumped onto the grid, to allow reduced operation of other generating sources.

Answer 2

But the research found wind generation was below 20% of capacity more than half the time and below 10% of capacity over one third of the time. I've been by wind farms in Wyoming with a 20 mph wind blowing and not one turbine turning, or they were at zero capacity. You know why? They would have put too much power on the grid and blown it. Any energy producing device will not produce at full power 100% of the time and will produce at much less than full power if placed in the wrong location. Try putting a nuke plant on top of a mountain and see how much cooling water it can get- it won't be able to produce anywhere near 100%.

Answer 3

Windmills in windfarms are built to not go over a certain speed, regardless of how strong the wind is. This is to protect them from burning out, they can only produce so much power for every rotation so there is no need to have them spinning round like a plane propeller.

Answer 4

yes there is a big one near here and they stopped it during the high winds. I was thinking the same thing.