Wind was used to create energy for thousands of years. It was used to power boats and turn windmills. It stopped being used for much of the 20th century. Now wind is making a comeback. Increasingly, it is being used to produce electricity.
Today, wind energy is produced with wind turbines. A wind turbine is a tall, tubelike tower. It has blades that rotate at the top. When the wind turns the blades, the blades turn a generator. The generator then creates electricity.
The Main Turbines
Horizontal-axis wind turbines (HAWTs) are the most common kind of wind turbine. Most have three large blades. These spin parallel to their towers. The generator is in the tower.
Most HAWTs are about 76 meters (250 feet) tall. Their blades rotate up to 20 times a minute.
A HAWT's huge blades 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) are the second kind of wind turbine. They have blades that rotate in complete circles around their tower. VAWTs do not have to face the wind. They can be much smaller than HAWTs. Often, they are put on the roofs of buildings.
To produce more electricity, wind turbines are often set up in large groups. These groups 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 placed on farmland. In the United States, they are common in the states of Iowa, Nebraska and Kansas.
Wind farms can also be set up offshore. These turbines use the ocean's strong winds.
Windmills And The History Of Wind Energy
Windmills are an early form of wind turbines. They have been around for almost 2,000 years.
Windmills work much like wind turbines. The main difference between the two is what they are used for. Wind turbines produce electricity. Windmills were built to grind grain and pump water.
Wind turbines were first developed in the late 1800s. They were used to make electricity in Europe and North America.
This did not last long, though. Wind is unpredictable. It comes and goes. Sometimes there is almost no wind at all. In the 1900s, wind power was replaced by coal, oil and gas. These fuels were seen as more dependable.
Such fuels cause pollution, though. By the 1970s, many people wanted cleaner ways to create 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. California's Alta Wind Energy Center is the largest in the United States. It has more than 300 turbines.
Wind energy has many advantages.
- Wind cannot be used up.
- Wind is a clean source of energy. Turbines do not pollute the air.
- Wind energy is very cheap.
- Wind is found all over the planet. Turbines can be put up almost everywhere.
Wind energy also has many problems:
- Wind energy is cheap once wind farms are running. However, wind farms are expensive to set up.
- 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 birds. They can also kill bats.
- Offshore wind farms can damage the ocean.
- Some people who live near wind farms complain about the noise. Others say turbines are ugly.
- Wind farms are often set up far away from cities. Power lines have to be built to move the electricity over long distances. This adds to the cost.
The biggest problem with wind energy is the wind itself. When the wind is not blowing, electricity cannot be produced.
In the past, most windmills were used to mill grain or pump water. Some were used for other purposes. A few mixed paints. Others ground oil from things like peanuts or linseed. They had many uses over the years.
Anemometers are machines that measure wind speed and direction. They show how much wind a place has on average. This helps people decide where to build wind turbines.
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.
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.
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.
animal that feeds on grasses, trees, and shrubs.
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.
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.
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.
network of cables or other devices through which electricity is delivered to consumers. Also called an electrical grid.
Canadian provinces of Alberta, Saskatchewan, and Manitoba. Also called the Prairies.
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).
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).
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.
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.
machine that produces power using the motion of wind to turn blades.