• This screenshot, taken from the U.S. Wind Turbine Database, shows the location of wind farms across the country up to 2017.

Over a third of Kansas's electricity now comes from wind. But how do turbines work?

If you’ve driven up from Oklahoma City, or across I-70 in western Kansas, or even through Burlington, you’ve surely noticed the fields of wind turbines. It makes for quite a sight. But wind turbines don’t just create a scenic view for drivers, of course; they are harvesting wind energy and converting it into the electrical energy that helps keep our lights on.

Wind energy is one of the fastest growing energy industries. Wind farms are cropping up all around the world, including right here in Allen County! The largest wind farm in the world is in China. The second largest in India, and the largest in the United States is in California. You can see a wonderful map of wind farms in the United States on the U.S. Department of Geology’s U.S. Wind Turbine Database.

Wind energy is a clean source of energy which does not produce carbon dioxide, one of the prime contributors of global warming. Wind energy still only contributes less than 5% of the total energy production in the United States, but it is expected to grow to 20% by 2030.

Here in the US, Kansas is one of the top five states in producing electricity from wind along with Texas, Oklahoma, Iowa and California. In terms of its potential capacity of wind power, Kansas ranks second after Texas. In 2018, 36% of Kansas’s electricity generation came from wind.

Image courtesy of the U.S. Wind Turbine Database. The colored dots represent wind turbines installed in Kansas as of 2017.

Energy produced by objects in motion is called kinetic energy. Since the wind is blowing, it carries kinetic energy. Wind turbines convert kinetic energy from the wind to electrical energy. So how do turbines do this?

Simply stated, wind turbines work the opposite of a fan. Instead of using electricity to make wind like fans do, wind turbines use wind to make electricity. The wind turns the blades, which spins a generator to create electricity.

Graphic provided courtesy of the author.

When wind flows across the blade, the air pressure on one side of the blade decreases. The difference in air pressure across the two sides of the blade creates both lift and drag. The force of the lift is stronger than the drag, causing the rotor to spin. The rotor is connected to a generator, either directly (if it's a direct drive turbine) or through a shaft and a series of gears (a gearbox) that speed up the rotation and allow for a physically smaller generator. This translation of aerodynamic force to the rotation of a generator creates electricity.  

Windmill at Water Mill, New York

Harvesting wind energy to produce electricity might seem new and innovative, but it’s not. The turbines today are echoes of the past, new iterations of an ancient form of capturing energy. Centuries ago, windmills were used to mill grain and pump water. In fact, many of these windmills are still in use today, their designs and uses unchanged over the centuries.

It just goes to show: the more things change, the more they stay the same. 

 

 

 (Dr. Yadav Pandit is an experimental nuclear physicist currently working at Allen Community College as a physical science instructor. He writes a column of general interest in science for The Register.)

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