# Wind Power

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## Wind Power

Wind is caused by the uneven heating of the atmosphere by the sun, variations in the earth's surface, and rotation of the earth. Mountains, bodies of water, and vegetation all influence wind flow patterns[1]. Wind energy (or wind power) describes the process by which wind is used to generate electricity. Wind turbines convert the energy in wind to electricity by rotating propeller-like blades around a rotor. The rotor turns the drive shaft, which turns an electric generator.[1] Three key factors affect the amount of energy a turbine can harness from the wind: wind speed, air density, and swept area.[2] Mechanical power can also be utilized directly for specific tasks such as pumping water.

## Wind Energy Stakeholder Engagement & Outreach Portal

The U.S. Department of Energy hosts the following stakeholder engagement and outreach resources on OpenEI:

Also on OpenEI, you can find more information about the following topics:

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## Equation for Wind Power

$P = {1\over2} \rho A V^3$
• Wind speed
The amount of energy in the wind varies with the cube of the wind speed; in other words, if the wind speed doubles, there is eight times more energy in the wind ($2^3 = 2 x 2 x 2 = 8$). Small changes in wind speed have a large impact on the amount of power available in the wind.[3]
• Air density
The more dense the air, the more energy received by the turbine. Air density varies with elevation and temperature. Air is less dense at higher elevations than at sea level, and warm air is less dense than cold air. All else being equal, turbines will produce more power at lower elevations and in locations with cooler average temperatures.[3]
• Swept area of the turbine
The larger the swept area (the size of the area through which the rotor spins), the more power the turbine can capture from the wind. Since swept area is $A = pi r^2$, where r = radius of the rotor, a small increase in blade length results in a larger increase in the power available to the turbine.[4]

## Map of Wind Farms

OpenEI has a Map of Wind Farms, which displays a comprehensive list of wind farms, seeded with United States data with plans to expand internationally.

### References

1. Gipe, Paul. (2009).Wind Energy Basics. Chelsea Green Publishing Company. ISBN 978-1-60358-030-4