How Does Windmill Power Work to Harness Energy?

Windmills have been used for various tasks for more than 1,000 years.

Windmills have been used for numerous tasks for more than a thousand years, but it wasn't until the late 19th century that they were used to produce electricity. Those early machines weren't cost effective compared to other forms of energy, but new advances in technology and changes in governmental policy have made wind energy a more economical power resource over the past few decades.

Wind Turbines

Wind turbines are mounted on towers to capture the most energy.

The windmills used to generate electricity in today's world are known as wind turbines. They are mounted on tall towers to capture the most energy, and have two to three blades on a shaft to form a rotor. The blades work in much the same way as an airplane wing does, with an air pocket pulling the blades, causing the rotor to turn. The blades are connected to a drive shaft that turns an electric generator, which in turn produces the electricity. Wires and cables then carry the electricity to a transmission line for immediate use or storage for future use.

Horizontal Axis Turbine

The horizontal axis wind turbine is the wind machine used today that most resembles windmills. They have blades like airplane propellers, some longer than a football field.

Vertical Axis Turbines

Vertical axis turbines resemble egg beaters and have blades that go from top to bottom. These turbines make up only a small share of wind turbines used today.

Wind Energy Use

According to the U.S. Department of Energy, wind machines produced about 1.8 percent of the total U.S. electricity generated in 2009. That is enough to power 6.4 million households, or the entire state of Wisconsin.

References

• U.S. Energy Information Administration: Energy Kids--Renewable Wind
• National Renewable Energy Laboratory: Wind Energy Basics
• "Power from Wind: A History of Windmill Technology"; Richard L. Hills; 1994