Wind has been used to create energy for thousands of years. It can power boats and turn windmills. For much of the 20th century, however, wind power was replaced by coal, gas and oil. These days, wind is making a comeback. It is increasingly being used to produce electricity


In modern times, wind energy is produced with wind turbines. A wind turbine is a tall, tubelike tower with blades rotating at the top. When the wind turns the blades, the blades turn a generator. The generator then creates electricity. 


Horizontal-axis wind turbines (HAWTs) are the most common type of wind turbine. Most have three large blades. These spin parallel to their towers. The generator is located in the tower.


Most HAWTs are about 61 to 91 meters (200 to 300 feet) tall. Their blades rotate 10 to 20 times a minute.


A HAWT's enormous blades usually face the wind. A wind sensor first detects which way the wind is blowing. It then turns the turbine to face the wind.


Vertical-axis wind turbines (VAWTs) have blades that rotate in complete circles around their tower. The generator is located near the ground. VAWTs do not have to face the wind to create electricity. They can be much smaller than HAWTs. Often, they are installed on the roofs of buildings.


If winds are too strong, turbines can be damaged. Therefore, every turbine has a controller. The controller turns the turbine on when winds are blowing between 13 and 88 kilometers per hour (8 and 55 miles an hour). If the winds become stronger than that, it turns the turbine off.


Wind Farms

To generate a large amount of electricity, wind turbines are often placed in large groups. These clusters are called wind farms. They are made up of hundreds of turbines. The turbines can be spaced out over hundreds of acres.


Wind farms are often located on farmland. In the United States, many are found on farmland in Iowa, Nebraska and Kansas.


Wind farms can also be located offshore. These turbines use the stronger winds that develop above the ocean.


Wind is not steady or predictable. Both its speed and direction change often. So far, this has prevented wind power from becoming the main source of energy. However, it can be an excellent addition to traditional power sources. 


Windmills And The Evolution Of Wind Energy

Windmills are the ancestor of wind turbines. They have been around for almost 2,000 years.


Windmills work similarly to wind turbines. In fact, the only difference between windmills and wind turbines is what they are used for. Wind turbines generate electricity. Windmills were built to grind grain and pump water.


In windmills, a drive shaft connects the blades to two large wheels or millstones. These wheels are on the floor of the windmill. Wind rotates the blades. The blades then rotate the drive shaft, and the drive shaft rotates the millstones. Grain is poured into the hollow, rotating millstone. It is then crushed into flour as the wheels grind together. 


Water-pumping windmills operate similarly. These are known as wind pumps.


Wind pumps have as many as 12 rotating blades. Rotation of these blades causes a long rod to move up and down. The motion of the rod raises and lowers a cylinder. During the down stroke, the cylinder fills with water. During the up stroke, the water is raised to a pipe or well. Today, wind pumps are still being used all around the world.


Wind turbines that generated electricity were first developed in the late 1800s. They were used in both Europe and North America. 


However, wind energy fell out of favor in the 20th century. Fuels such as coal, oil and natural gas were seen as more reliable sources of electricity and energy. Such fuels create a great deal of pollution, though. By the 1970s, many people had become interested in finding less-polluting sources of energy. The world's first wind farm was set up during this time. It was built in New Hampshire.


Today, there are wind farms in many parts of the world. The largest one in the United States is the Alta Wind Energy Center in Kern County, California. It has more than 300 turbines.



There are many advantages to using the wind's energy to create electricity.

  • Wind cannot be used up.
  • Wind is a clean source of energy. Turbines do not pollute the air.
  • Wind energy is cheap! In the United States, it costs between 4 cents and 6 cents per kilowatt-hour. 
  • Wind is found all over the planet. Turbines can be put up almost everywhere. 


Wind energy also has many problems: 

  • Wind energy is cheap to produce once a wind farm has been built. However, the cost to build a wind farm is quite high. 
  • Wind farms need acres of land. In hilly areas, trees might need to be cut. Many kinds of birds and animals depend on trees. 
  • Wind turbines can kill bats and birds.
  • Offshore wind farms can damage the ocean. The seafloor has to be drilled into to keep turbines in place. 
  • Some people who live near wind farms complain about the noise. Others say the turbines are ugly. 
  • Locations that produce great amounts of wind energy are often far away from cities. Power lines have to be built to move the electricity long distances. This adds to the cost.

Of course, the biggest problem with wind energy is the wind itself. When the wind is not blowing, electricity cannot be generated.


Putting Wind to Work
Wind energy mechanisms, old and new.

Anemometers are machines that measure wind speed and direction. They are used to discover how much wind a site has on average. This helps people decide if the site is a good location for wind turbines.

In the past, most windmills were used to mill grain or pump water. Some were used for other purposes as well. They mixed paints or ground oil from things like peanuts or linseed.


land used for, or capable of, producing crops or raising livestock.


layers of gases surrounding a planet or other celestial body.


term for the rapidly developing economies of Brazil, Russia, India and China.


goods carried by a ship, plane, or other vehicle.


a barrier, usually a natural or artificial wall used to regulate water levels.

drive shaft

instrument or tool that transmits the movement of force (torque) to other pieces of connected machinery.


ability used by some animals to emit high-pitched sounds and determine an object's distance by the time it takes for those sounds to echo.


set of physical phenomena associated with the presence and flow of electric charge.


person who plans the building of things, such as structures (construction engineer) or substances (chemical engineer).


flat area alongside a stream or river that is subject to flooding.

fossil fuel

coal, oil, or natural gas. Fossil fuels formed from the remains of ancient plants and animals.


machine that converts one type of energy to another, such as mechanical energy to electricity.

grazing animal

animal that feeds on grasses, trees, and shrubs.

greenhouse gas

gas in the atmosphere, such as carbon dioxide, methane, water vapor, and ozone, that absorbs solar heat reflected by the surface of the Earth, warming the atmosphere.


environment where an organism lives throughout the year or for shorter periods of time.


part of a body of water deep enough for ships to dock.


(horizontal-axis wind turbine) type of windmill where the rotor is arranged horizontally, the main components are in the tower, and the blades rotate when the device faces the wind.


amount of water vapor in the air.

Industrial Revolution

change in economic and social activities, beginning in the 18th century, brought by the replacement of hand tools with machinery and mass production.


winds speeding through the upper atmosphere.

marine ecosystem

community of living and nonliving things in the ocean.


area of the United States consisting of the following states: Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin.


one of a pair of large, flat, circular stones between which grain or other substances are ground.


energy released by reactions among the nuclei of atoms.


land reclaimed from a body of water by dikes and dams, and used for agriculture, housing, or industry.

power grid

network of cables or other devices through which electricity is delivered to consumers. Also called an electrical grid.

Prairie Provinces

Canadian provinces of Alberta, Saskatchewan, and Manitoba. Also called the Prairies.

renewable resource

resource that can replenish itself at a similar rate to its use by people.


to turn around a center point or axis.


part of a machine that rotates around a fixed point (stator).

shipping route

path in a body of water used for trade.


radiation from the sun.


knowledgeable or complex.


level of Earth's atmosphere, extending from 10 kilometers (6 miles) to 50 kilometers (31 miles) above the surface of the Earth.


to increase or add to.


the science of using tools and complex machines to make human life easier or more profitable.


to tie or fasten an object to something else by a long rope (tether).

ultraviolet radiation

powerful light waves that are too short for humans to see, but can penetrate Earth's atmosphere. Ultraviolet is often shortened to UV.


(vertical-axis wind turbine) type of windmill where the rotor is arranged vertically, the main components are at the base, and the blades are parallel to the tower, rotating around it.


movement or circulation of fresh air in a closed environment. Also called air circulation.


movement of air (from a high pressure zone to a low pressure zone) caused by the uneven heating of the Earth by the sun.


kinetic energy produced by the movement of air, able to be converted to mechanical power.

wind farm

area with a large group of wind turbines, used to generate electric power.


instrument that generates power from the force of wind rotating large blades.


windmill used for pumping water from an aquifer or out of a flooded area.

wind turbine

machine that produces power using the motion of wind to turn blades.