How Do Wind Turbines Work?
How wind turbines convert wind power into clean, usable electricity.
For millennia, humans have harnessed the power of wind. Wind fueled the boats of the Egyptians, the irrigation of the Babylonians, and the grain-grinding windmills of the Persians. Today, modern wind turbines have amped up wind’s potential even more. Now, wind power can be directly converted into clean, usable electricity for our cities and homes.
Where does wind come from? As the sun beams solar radiation toward the Earth, different areas warm up at different rates. In the areas that absorb more heat, hot air begins to rise. This creates a gap of lower pressure, which cooler air quickly rushes in to fill. That’s wind!
Once gusts reach about seven to eleven mph, the rotor of a wind turbine can capture the wind’s kinetic energy. A rotor usually has three massive blades, each on average about as long as the width of a U.S. football field. Rather than being pushed like sails, wind turbine blades act more like airplane wings. They’re shaped so that wind flows at different speeds above and below them. As a result, there’s a pressure difference on each side, which “lifts” the blades toward the low-pressure area and makes the rotor begin spinning.
Kinetic energy has been transformed into mechanical energy. But one more conversion is needed. How do you change the mechanical energy into electric energy, a.k.a. electricity?
The key is a generator, which uses the properties of electromagnetic induction. In wind turbines, the rotor is connected to a shaft, which in turn enters an electrical generator made out of an assembly of magnets and a coil of wire.
When the rotor spins the shaft, the shaft then spins the assembly of magnets. This generates a voltage in the coil of wire. Voltage, a difference in electrical charge, drives a current. As a result, electrical current comes out from the generator. Then, the electricity can be funneled through power lines for distribution.
With turbines both on land and in the sea, wind energy is now the largest source of renewable energy in the United States. It’s only poised to grow more: as long as the sun shines, wind will blow, and we can continue to power the grid.