Eli5: windmills
Why is it that in an entire group of windmills all facing the same direction and all right next to each other, you sometimes only see one or two moving and the other windmills aren’t moving at all?
I’m driving through California and noticed this, which is prompting my question. I would expect all of them should be turning, so I think they’re either immobilizing most of them, or manually spinning those windmills somehow. In either case, why? Or am I wrong in my assumptions?
In: 43
Wind turbines can be shut down/locked, either because they’re under maintenance, or because the entire field of turbines is projected to produce too much power for the electrical grid on any given day and so only some are allowed to produce power.
Wind turbines can be turned off. The reason you would do this is that if you are generating more power than can be used by the grid, that can cause problems. So if you have a bunch of turbines and they’re generating too much power, you will want to stop a couple of them.
Wind turbines can be turned off. Other comments are correct but another aspect is who owns the land that the windmill is on.
If the government does not own it, they likely have to pay the owners for time that the windmill is on. If you have a specific number to hit, you turn off unnecessary windmills to save money.
Electricity, when produced, needs to go somewhere. It needs to be used. It runs through the wires on a loop, basically. Produce a lot more electricity than the system is using, it starts to cause problems.
Turning off a windmill and stopping production of excess energy helps avoid the problems.
To add still more – turbines can be ‘turned off’ by:
* a brake of some sort on the shaft
* increasing the resistance between the electrical/coil and the magnets until the turbine locks up
* de-coupling the blades from their “pointers” so the blades just blow with the breeze instead of sticking out into it
The last one requires the least amount of wear and tear, and on its own or in conjunction with a brake is usually enough. You *don’t* want to leave the blades locked-out and just use the brake though, because then the turbine will try to keep turning and you put a lot of extra stress on the brake mechanism. And I do mean just the blades here, they are on a separate “pointer” from the housing which can also turn. The blades can be angled forward/backward to increase or decrease the rotations per wind speed, by decoupling this the blades just ‘feather’ like a windsock rather than provide resistance (which is what makes the turbines turn). When the housing turns, that is to point the face of the turbine in the desired direction, which can change depending on the primary wind direction.
I’m not sure how common it is to use resistance as a method and can’t comment on that.
There can be many reasons.
1. Windmill is down for maintenance.
2. Windmill is down because thre is currently no need for energy. Shutting it down means less maintenance will be needed and reduces running costs. (Having an excess of non-reduceable power sources is often the cause.)
3. Because of the current winddirection, another windmill upstream is causing turbulence which reduces efficiency and causes more stress on that windmill. Shutdown is sometimes preffered.
I know this thread is about modern windmills, but old windmills were used to work giant millstones. If you did not have grain to mill, there was no point in grinding the stones.
Anyone else find it intriguing that these huge windmills can be spinning even with seemingly no wind whatsoever, or maybe a very slight breeze. Perhaps the windmill is tall enough and there’s more wind the higher you go? It’s all conjecture on my part.
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