Wind basics

Energy from moving air

Wind is caused by uneven heating of the earth's surface by the sun. Because the earth's surface is made up of different types of land and water, the earth absorbs the sun's heat at different rates. One example of this uneven heating is the daily wind cycle.

The daily wind cycle

During the day, air above land heats up faster than air above water. Warm air above land expands and rises, and heavier, cooler air rushes in to take its place, creating wind. At night, the winds are reversed because air cools more rapidly over land than it does over water.

In the same way, the atmospheric winds that circle the earth are created because the land near the earth's equator is hotter than the land near the North Pole and the South Pole.

Wind energy for electricity generation

Today, wind energy is mainly used to generate electricity. Water-pumping windmills were once used throughout the United States, and some still operate on farms and ranches, mainly to supply water for livestock.

Electricity generation from wind

How wind turbines work

Wind turbines use blades to collect the wind's kinetic energy. Wind flows over the blades creating lift (similar to the effect on airplane wings), which causes the blades to turn. The blades are connected to a drive shaft that turns an electric generator, which produces (generates) electricity.

Wind electricity generation has increased significantly

Wind electricity generation has grown significantly in the past 30 years. Advances in wind-energy technology have decreased the cost of wind electricity generation. Government requirements and financial incentives for renewable energy in the United States and in other countries have contributed to growth in wind power.

Total annual U.S. electricity generation from wind energy increased from about 6 billion kilowatthours (kWh) in 2000 to about 464 billion kWh in 2025. In 2025, wind turbines were the source of about 10.5% of total U.S. utility-scale electricity generation. Utility scale includes facilities with at least one megawatt (1,000 kilowatts) of electricity generation capacity.

Where wind is harnessed

Wind power plants require careful planning

Operating a wind power plant is more complex than simply erecting wind turbines in a windy area. Wind power plant owners carefully plan where to position wind turbines and consider how fast and how often the wind blows at the site.

Good places for wind turbines are where the annual average wind speed is at least 9 miles per hour (mph)—or 4.0 meters per second (m/s)—for small wind turbines and 13 mph (5.8 m/s) for utility-scale turbines. Favorable sites include the tops of smooth, rounded hills; open plains and water; and mountain gaps that funnel and intensify wind. Wind speeds are generally higher the greater the distance above the earth's surface. Large wind turbines are placed on towers that range from about 500 feet to as high as 900 feet tall.

Wind speeds vary hourly and seasonally

Wind speeds generally change throughout the day and from season to season. For example, in Tehachapi, California, where numerous wind turbines are located, the wind blows more frequently from April through October than it does in the winter months, and the wind is usually strongest in the afternoon. These fluctuations are a result of the extreme heat of the Mojave Desert during summer months. As the hot air over the desert rises, the cooler, denser air above the Pacific Ocean rushes through the Tehachapi mountain pass to take its place. In Montana, strong winter winds channeled through Rocky Mountain valleys create more intense winds during the winter.

Fortunately, the seasonal variations in wind speeds in California and Montana match the electricity demand of consumers in those states. In California, people use more electricity in the afternoon and during the summer. In Montana, people use more electricity, in general, during the winter.

Most U.S. wind electricity generation capacity is in the middle of the country

In 2025, about 10% (464 billion kilowatthours) of total U.S. utility-scale electricity generation was from wind energy projects in 43 states.¹ The five states with the most electricity generation from wind in 2025 were Texas, Iowa, Oklahoma, Kansas, and Illinois. These states combined produced about 52% of total U.S. wind electricity generation in 2025.²

Monthly and annual U.S. national and state electricity generation data are available in the Electricity Data Browser, and hourly generation data by energy source for the Lower 48 states by region are available in the Hourly Electric Grid Monitor.

U.S. offshore wind energy is expected to increase substantially

The waters off the coasts of the United States have significant potential for electricity generation from wind energy. At the end of 2024, the United States had two operating offshore wind energy project: the South Fork wind farm off the coast of New York, with 130 megawatts (MW) of electricity generation capacity, and the Vineyard Wind 1 project, with 174 MW of generation capacity. The U.S. Bureau of Ocean Energy Management has executed leases and grants for offshore wind energy development. Wind projects in state and federal waters off the U.S. East Coast are in various stages of planning and development. As of May 2026, wind project developers reported plans for about 5,089 MW of nameplate wind electricity generation capacity in waters off the coasts of New York, Rhode Island, and Virginia.³

European countries and China lead the world in offshore wind electricity generation capacity. Many other countries have and are developing offshore wind energy projects.

International wind power is growing

World wind electricity generation has also increased substantially in recent years. In 1990, 16 countries generated about 3.6 billion kWh of wind electricity.⁴ In 2010, 100 countries generated about 339 billion kWh, and in 2024, 135 countries (includes Puerto Rico) generated about 2,511 billion kWh of wind electricity.

The top five countries in wind electricity generation and their percentage shares of total world wind electricity generation in 2025 were:

• China–35%
• United States–20%
• Germany–6%
• Brazil–4%
• United Kingdom–3%

Types of wind turbines

There are two basic types of wind turbines:

• Horizontal-axis turbines
• Vertical-axis turbines

The size of wind turbines varies widely. The length of the blades is the biggest factor in determining the amount of electricity a wind turbine can generate. Small wind turbines that can power a single home may have an electricity generating capacity of 10 kilowatts (kW). The largest wind turbines in operation have electricity generating capacities of around 15,000 kW, and larger turbines are in development. Large turbines are often grouped together to create wind power plants, or wind farms, that provide power to electricity grids.

Horizontal-axis turbines are similar to propeller airplane engines

Horizontal-axis turbines have blades like airplane propellers, and they commonly have three blades. The largest horizontal-axis turbines are as tall as 20-story buildings and have blades more than 100 feet long. Taller turbines with longer blades generate more electricity. Nearly all of the wind turbines currently in use are horizontal-axis turbines.

Vertical-axis turbines look like egg beaters

Vertical-axis turbines have blades that are attached to the top and the bottom of a vertical rotor. The most common type of vertical-axis turbine—the Darrieus wind turbine, named after the French engineer Georges Darrieus who patented the design in 1931—looks like a giant, two-bladed egg beater. Some versions of the vertical-axis turbine are 100 feet tall and 50 feet wide. Very few vertical-axis wind turbines are in use today because they do not perform as well as horizontal-axis turbines.

Wind power plants, or wind farms, produce electricity

Wind power plants, or wind farms, are clusters of wind turbines that produce large amounts of electricity. A wind farm usually has many turbines scattered over a large area. One of the United States' largest wind farms is the Horse Hollow Wind Energy Center in Texas, which at the end of 2021, had 422 wind turbines spread over about 47,000 acres. The project has a combined electricity generating capacity of about 735 megawatts (or 735,000 kilowatts).

History of wind power

People have been using wind energy for thousands of years

People used wind energy to propel boats along the Nile River as early as 5,000 BC. By 200 BC, simple wind-powered water pumps were used in China, and windmills with woven-reed blades were grinding grain in Persia and the Middle East.

New ways to use wind energy eventually spread around the world. By the 11^th century, people in the Middle East were using wind pumps and windmills extensively for food production. Merchants and the Crusaders brought wind technology to Europe. The Dutch developed large windpumps to drain lakes and marshes in the Rhine River Delta. Immigrants from Europe eventually took wind energy technology to the Western Hemisphere.

American colonists used windmills to grind grain, pump water, and cut wood at sawmills. Homesteaders and ranchers installed thousands of wind pumps as they settled the western United States. In the late 1800s and early 1900s, small wind-electric generators (wind turbines) were also widely used.

The number of wind pumps and wind turbines declined as rural electrification programs in the 1930s extended power lines to most farms and ranches across the country. However, some ranches still use wind pumps to supply water for livestock. Small wind turbines are becoming more common again, mainly to supply electricity in remote and rural areas.

Wind energy use expanded in the wake of oil shortages and environmental concerns

The oil shortages of the 1970s changed the energy environment for the United States and the world. The oil shortages created an interest in developing ways to use alternative energy sources, such as wind energy, to generate electricity. The U.S. federal government supported research and development of large wind turbines. In the early 1980s, thousands of wind turbines were installed in California, largely because of federal and state policies that encouraged the use of renewable energy sources.

Beginning in the 1990s and continuing today, the U.S. federal government and state governments have established financial incentives and requirements to use renewable energy sources. The federal government has also provided research and development funding to help reduce the cost of wind turbines and offers tax and investment incentives for wind power projects. In addition, state governments have established minimum requirements for electricity generation from renewable sources, and electric power marketers and utilities may offer electricity generated from wind and other renewable energy sources (sometimes called green power) to their customers. These policies and programs have resulted in more wind turbines and more electricity generated from wind energy.

The share of U.S. electricity generation from wind energy has grown from less than 1% in 1990 to about 10.5% in 2025. Financial and other incentives for wind energy in Europe have resulted in a large expansion of wind energy use there. China has invested heavily in wind energy and is now the world's largest wind electricity generator. In 1990, 16 countries generated a total of about 3.6 billion kWh of wind electricity. In 2024, at least 135 countries (including Puerto Rico) generated about 2,511 billion kWh of wind electricity.

Wind energy & the environment

Wind is an emissions-free source of energy

Wind is a renewable energy source. Overall, using wind to produce energy has fewer effects on the environment than many other energy sources. Wind turbines do not release emissions that can pollute the air or water (with rare exceptions), and they do not require water for cooling. Wind turbines may also reduce the amount of electricity generation from fossil fuels, which results in lower total air pollution and carbon dioxide emissions.

An individual wind turbine has a relatively small physical footprint. Groups of wind turbines, sometimes called wind farms, are located on open land, on mountain ridges, or offshore in lakes or the ocean.

Wind turbines can affect the environment

Modern wind turbines are very large machines. Wind turbine blades are noisy when they turn in the wind, and some people do not like the sound. Birds and bats are at risk of injury or death if they fly into turbine blades. The wind energy industry and the U.S. government are researching ways to reduce the effect of wind turbines on birds and bats.

A small number of wind turbines have caught fire, and some have leaked lubricating fluids, but these occurrences are rare. Producing the metals and other materials used to make wind turbine components can also affect the environment, and fossil fuels may be used to produce those components. Although most materials used to make wind turbines can be reused or recycled, turbine blades, as currently constructed, cannot be recycled. Researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) established an approach to manufacturing wind turbine blades using a thermoplastic resin system. These thermoplastic resins allow wind turbine blades to be recycled and reduce the energy required to manufacture blades.