The windmill, which converts wind into rotational energy to mill grain or pump water, has been around since antiquity. It’s even been claimed that Ancient Babylonians planned to harness wind as early as almost 4,000 years ago, as part of a scheme for one of Hammurabi’s ambitious irrigation projects.
By the end of the 19th century, wind energy took on a whole new meaning as engineers in Scotland, Denmark, and the United States invented the first wind turbines that generated electricity. Many technological improvements have been made since, and now modern wind farms dot the landscapes of countries around the world.
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Today, wind power is an important element of the green energy mix, and its estimated that 432 GW of wind farms are installed globally. In the United States, nearly 5% of all power is now generated by wind.
HOW WIND TURBINES WORK
How do these massive propellers get into motion? Once they are turning, what do they do?
As shown in the animation, it’s all about the lift and drag forces created by the shape of the blades. Lift acts perpendicular to the direction of wind flow and drag acts parallel to the direction of wind flow.
The blades are designed so that when wind passes, a low-pressure pocket of air is created by faster moving wind on the curved side of the blade. This sucks the blade in the downwind direction, creating lift. The blades are then connected to a series of shafts that spin an electromagnetic induction generator, and this creates electricity.
There are some other bells and whistles that help to maximize efficiency in a modern wind turbine as well.
The anemometer measures wind speed, while the controller starts and stops the turbines to operate only at desirable wind speeds (between 8 and 55 kmph). The wind vane measures the wind’s direction and communicates this information to the yaw drive, which helps make adjustments to the turbine’s orientation. Lastly, there is also a braking system installed which can be used for emergency stops when wind speeds get too extreme.