Why Do Wind Turbines Spin When There Is No Wind?
The wind turbine mechanism is very misunderstood, which gives rise to question such as why do wind turbines spin when there is no wind? Let’s answer that very question.
A wind turbine is a fairly simple machine. The basic idea is you have the blades that are connected to an axle. This axle has a gear on the end of it. As the blades turn, the axle rotates against a second gear. That second gear is connected to a generator. When the generator cranks, it produces electricity. The electricity is then sent down the main pole of the wind turbine to a line that takes it to the utility grid, a battery or a structure for direct use. There are more complicated approaches, but this is the basic idea.
The commercial wind turbines you see out in the country are obviously huge. This is one situation, however, where size doesn’t equate to power. While these turbines will produce a lot of power, they don’t require a lot of power to turn. The initial reason has to do with balance. The blades are balanced perfectly so that even the slightest gust can get them moving. Ah, but wouldn’t the gear stop them since there needs to be power to turn that gear? This brings us to our second part of the equation.
Wind turbines are tuned to their conditions. If an area is going to produce low winds, the turbine can be tuned through a multi-gear system to rotate at gusts at very low speeds. If things really get slow, then turbines actually “shift” down into a low wind gear where they do one of two things – they either are disengaged from the gear and rotate freely or a brake is applied and do not rotate at all even if gusts come up.
You are still probably thinking that you’ve been places with no wind and yet still seen blades moving. Well, there is always some wind. Wherever sun hits the ground, it heats it up. The air is heated and it rises. This causes cooler air to sweep in and you have wind. That doesn’t mean, however, that wind is going to occur uniformly across a field or in noticeable gusts. It could be a tiny little current, but wind turbines are so sensitive that they will rotate a bit. This small rotation, however, does not produce electricity because it is too weak to turn the gears in the turbine.
Okay, what about the opposite. It might be a windy day, but you’ll notice a few wind turbines in a commercial field are not spinning at all. What gives? The answer is simple. They’ve been locked into a no-spin gear. This is somewhat akin to pulling the parking brake on your car. The reason is usually that the particular turbine is in need of repair.
