We have been harnessing the wind’s energy for hundreds of years. From the picturesque windmills of Holland to farms in the United States, windmills have been used for pumping water and grinding grain for centuries. Today, the windmill’s modern equivalent – a wind turbine – can use the wind’s energy to generate electricity.
Wind turbines, are mounted on a tower at 100 feet or more above ground, where they can take advantage of the faster and less turbulent winds. Turbines catch the wind with their propeller-like blades, which is usually comprised of two or three blades mounted on a shaft forming a rotor.
A blade acts much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on the downwind side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is actually much stronger than the wind’s force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller, and the turning shaft spins a generator to make electricity.
Wind turbines can be used as stand-alone applications, connected to a utility power grid or even combined with a photovoltaic (solar) system. For utility-scale sources of wind energy, a large number of wind turbines are usually built close together to form a wind plant. Several electricity providers today use wind plants to supply power to their customers.
Stand-alone wind turbines are typically used for water pumping or communications. However, homeowners, farmers, and ranchers in windy areas can also use wind turbines as a way to cut their electric bills. Small wind systems also have potential as distributed energy resources.