What is wind power?Wind power captures the natural wind in our atmosphere and converts it into mechanical energy then electricity. People started using wind power centuries ago with windmills, which pumped water, ground grain, and did other work. Today's wind turbine is a highly evolved version of a windmill. Modern wind turbines harness wind's kinetic energy and convert it into electricity. Most wind turbines have three blades and sit atop a steel tubular tower, and they range in size from 80-foot-tall turbines that can power a single home to utility-scale turbines that are over 260 feet tall and power hundreds of homes. Learn more about thehistory of wind energy.Wind is a type of renewable energy, and there are three major types of wind power.The major types of wind power are: Utility-scale wind,wind turbines larger than 100 kilowatts are developed with electricity delivered to the power grid and distributed to the end user by electric utilities or power system operators; Distributed or "small" wind, which uses turbines of 100 kilowatts or smaller to directly power a home, farm or small business as it primary use; Offshore wind, which are wind turbines erected in bodies of water around the world, but not yet in the United States.Wind Energy and Wind PowerWind is a form ofsolar energy. Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and rotation of the earth. Wind flow patterns are modified by the earth's terrain, bodies of water, and vegetative cover. This wind flow, or motion energy, when "harvested" by modernwind turbines, can be used to generateelectricity.How Wind Power Is GeneratedThe terms "wind energy" or "wind power" describe the process by which the wind is used to generatemechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity to power homes, businesses, schools, and the like.Wind TurbinesWind turbines, like aircraft propeller blades, turn in the moving air and power anelectric generatorthat supplies an electric current. Simply stated, a wind turbine is the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity.Wind Turbine TypesModern wind turbines fall into two basic groups; thehorizontal-axisvariety, like the traditional farm windmills used for pumping water, and thevertical-axisdesign, like the eggbeater-style Darrieus model, named after its French inventor. Most large modern wind turbines are horizontal-axis turbines.Turbine ComponentsHorizontal turbine components include: bladeorrotor, which converts the energy in the wind to rotational shaft energy; adrive train, usually including a gearbox and a generator; atowerthat supports the rotor and drive train; and other equipment, including controls, electrical cables, ground support equipment, and interconnection equipment.Wind turbine diagram - click for enlarged image.

Turbine ConfigurationsWind turbines are often grouped together into a single wind power plant, also known as awind farm, and generate bulk electrical power. Electricity from these turbines is fed into a utility grid and distributed to customers, just as with conventional power plants.SeeWind Energy Photospage for wind farm photographs.Wind Turbine Size and Power RatingsWind turbines are available in a variety of sizes, and therefore power ratings. The largest machine has blades that span more than the length of a football field, stands 20 building stories high, and produces enough electricity to power 1,400 homes. A small home-sized wind machine has rotors between 8 and 25 feet in diameter and stands upwards of 30 feet and can supply the power needs of an all-electric home or small business.Utility-scale turbinesrange in size from 50 to 750 kilowatts. Single small turbines, below 50 kilowatts, are used for homes, telecommunications dishes, or water pumping.SeeWind Energy Photospage for wind turbine photographs.Wind Energy Resources in the United StatesWind energy is very abundant in many parts of the United States. Wind resources are characterized bywind-power density classes, ranging from class 1 (the lowest) to class 7 (the highest). Good wind resources (e.g., class 3 and above, which have an average annual wind speed of at least 13 miles per hour) are found in many locations (seeUnited States Wind Energy Resource Map). Wind speed is a critical feature of wind resources, because the energy in wind is proportional to thecubeof the wind speed. In other words, a stronger wind means a lot more power.Advantages and Disadvantages of Wind-Generated ElectricityA Renewable Non-Polluting ResourceWind energy is afree, renewable resource, so no matter how much is used today, there will still be the same supply in the future. Wind energy is also a source ofclean, non-polluting, electricity. Unlike conventional power plants, wind plants emit no air pollutants or greenhouse gases. According to the U.S. Department of Energy, in 1990, California's wind power plants offset the emission of more than 2.5 billion pounds of carbon dioxide, and 15 million pounds of other pollutants that would have otherwise been produced. It would take a forest of 90 million to 175 million trees to provide the same air quality.Cost IssuesEven though the cost of wind power has decreased dramatically in the past 10 years, the technology requires ahigher initial investmentthan fossil-fueled generators. Roughly 80% of the cost is the machinery, with the balance being site preparation and installation. If wind generating systems are compared with fossil-fueled systems on a "life-cycle" cost basis (counting fuel and operating expenses for the life of the generator), however, wind costs are much more competitive with other generating technologies because there is no fuel to purchase and minimal operating expenses.Environmental ConcernsAlthough wind power plants have relatively little impact on the environment compared to fossil fuel power plants, there is some concern over thenoiseproduced by the rotor blades,aesthetic (visual) impacts, and birds and bats having been killed (avian/bat mortality) by flying into the rotors. Most of these problems have been resolved or greatly reduced through technological development or by properly siting wind plants.Supply and Transport IssuesThe major challenge to using wind as a source of power is that it isintermittentand does not always blow when electricity is needed. Wind cannot be stored (although wind-generated electricity can be stored, if batteries are used), and not all winds can be harnessed to meet the timing of electricity demands. Further, good wind sites are often located inremote locationsfar from areas of electric power demand (such as cities). Finally, wind resource development may compete with other uses for the land, and thosealternative usesmay be more highly valued than electricity generation. However, wind turbines can be located on land that is also used for grazing or even farming.For More InformationMuch additional information on wind energy science and technology and wind energy development issues is available through the Web. Visit theWind Energy Linkspage to access sites with more information. In particular, theDOE Wind Energy Technologies pagehas good information on wind energy basics, and is the source for much of the information presented here. The American Wind Energy Association web site has an excellentFAQ pagewith information about wind technology, and theThe Danish Wind Industry Associationweb site has extensive information about wind energy and technology, including a 28-minute video introducing wind technology.Wind Energy and Wind PowerWind is a form ofsolar energy. Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and rotation of the earth. Wind flow patterns are modified by the earth's terrain, bodies of water, and vegetative cover. This wind flow, or motion energy, when "harvested" by modernwind turbines, can be used to generateelectricity.How Wind Power Is GeneratedThe terms "wind energy" or "wind power" describe the process by which the wind is used to generatemechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity to power homes, businesses, schools, and the like.Wind TurbinesWind turbines, like aircraft propeller blades, turn in the moving air and power anelectric generatorthat supplies an electric current. Simply stated, a wind turbine is the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity.Wind Turbine TypesModern wind turbines fall into two basic groups; thehorizontal-axisvariety, like the traditional farm windmills used for pumping water, and thevertical-axisdesign, like the eggbeater-style Darrieus model, named after its French inventor. Most large modern wind turbines are horizontal-axis turbines.Turbine ComponentsHorizontal turbine components include: bladeorrotor, which converts the energy in the wind to rotational shaft energy; adrive train, usually including a gearbox and a generator; atowerthat supports the rotor and drive train; and other equipment, including controls, electrical cables, ground support equipment, and interconnection equipment.Wind Turbine Size and Power RatingsWind turbines are available in a variety of sizes, and therefore power ratings. The largest machine has blades that span more than the length of a football field, stands 20 building stories high, and produces enough electricity to power 1,400 homes. A small home-sized wind machine has rotors between 8 and 25 feet in diameter and stands upwards of 30 feet and can supply the power needs of an all-electric home or small business.Utility-scale turbinesrange in size from 50 to 750 kilowatts. Single small turbines, below 50 kilowatts, are used for homes, telecommunications dishes, or water pumping.Wind Turbine

TYPES OF WIND TURBINES

Modern wind turbines fall into two basic groups: the horizontal-axis variety, as shown in the photo to the far right, and the vertical-axis design, like the eggbeater-style Darrieus model pictured to the immediate right, named after its French inventor. Horizontal-axis wind turbines typically either have two or three blades. These three-bladed wind turbines are operated "upwind," with the blades facing into the wind.Wind turbines can be built on land or offshore in large bodies of water like oceans and lakes. Though the United States does not currently have any offshore wind turbines, the Department of Energy isfunding effortsthat will make this technology available in U.S. waters.SIZES OF WIND TURBINES

Utility-scale turbines range in size from 100 kilowatts to as large as several megawatts. Larger wind turbines are more cost effective and are grouped together intowind farms, which provide bulk power to the electrical grid. In recent years, there has been an increase in largeoffshore wind installationsin orderto harness the huge potential that wind energy offers off the coasts of the U.S.Single small turbines, below 100 kilowatts, are used for homes, telecommunications dishes, or water pumping. Small turbines are sometimes used in connection with diesel generators, batteries, and photovoltaic systems. These systems are called hybrid wind systems and are typically used in remote, off-grid locations, where a connection to the utility grid is not available.Learn more about what the Wind Program is doing to support the deployment ofsmall and mid-sized turbinesfor homes, businesses, farms, and community wind projects.ENERGY 101: WIND TURBINES VIDEOThis video explains the basics of how wind turbines operate to produce clean power from an abundant, renewable resourcethe wind.So how do wind turbines make electricity? Simply stated, a wind turbine works the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity. View thewind turbine animationto see how a wind turbine works ortake a look inside.Wind is a form of solar energy and is a result of the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and the rotation of the earth.Wind flow patterns and speeds vary greatly across the United Statesand are modified by bodies of water, vegetation, and differences in terrain. Humans use this wind flow, or motion energy, for many purposes: sailing, flying a kite, and even generating electricity.The terms wind energy or wind power describe the process by which the wind is used to generate mechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity.The U.S. Department of Energy (DOE) leads a large network of researchers and other partners to deliver innovative solar photovoltaic and concentrating solar power technologies that will make solar energy cost competitive with traditional sources of energy.From 1975 to 2008, more solar energy patents were linked to DOE than to any other organization in the world. Since President Obama took office, the amount of solar power installed in the U.S. has increased over thirteen fold from 1.2 gigawatts (GW) in 2008 to an estimated 15.9 GW today. Thats enough to power the equivalent of 3.2 million average American homes.SOLAR ENERGY TECHNOLOGIES OFFICEThe Solar Energy Technologies Office works to accelerate the market competitiveness of solar energy by targeting cost reductions and supporting increased solar deployment. Through itsSunShot Initiative, DOE supports efforts by private companies, universities, and national laboratories to drive down the cost solar electricity. TheSolar Powering Americawebsite makes it simple for communities, businesses, organizations and state and local governments to both learn about and commit to choosing solar.