The Power of Wind

Wind turbines harness the wind—a clean, free, and widely available renewable energy source—to generate electric power. This page offers a text version of the interactive animation: How a Wind Turbine Works.

How a Wind Turbine Works

A wind turbine turns wind energy into electricity using the aerodynamic force from the rotor blades, which work like an airplane wing or helicopter rotor blade. When wind flows across the blade, the air pressure on one side of the blade decreases. The difference in air pressure across the two sides of the blade creates both lift and drag. The force of the lift is stronger than the drag and this causes the rotor to spin. The rotor connects to the generator, either directly (if it's a direct drive turbine) or through a shaft and a series of gears (a gearbox) that speed up the rotation and allow for a physically smaller generator. This translation of aerodynamic force to rotation of a generator creates electricity.

How a Wind Plant Works

Wind power plants produce electricity by having an array of wind turbines in the same location. The placement of a wind power plant is impacted by factors such as wind conditions, the surrounding terrain, access to electric transmission, and other siting considerations. In a utility-scale wind plant, each turbine generates electricity which runs to a substation where it then transfers to the grid where it powers our communities.

Screen capture of the wind plant view of the How Wind Turbines work animation.

Transmission

Transmission lines carry electricity at high voltages over long distances from wind turbines and other energy generators to areas where that energy is needed.

Still frame of an illustrated transmission tower highlighted in in an animation window.

Transformers

Transformers receive AC (alternating current) electricity at one voltage and increase or decrease the voltage to deliver the electricity as needed. A wind power plant will use a step-up transformer to increase the voltage (thus reducing the required current), which decreases the power losses that happen when transmitting large amounts of current over long distances with transmission lines. When electricity reaches a community, transformers reduce the voltage to make it safe and useable by buildings and homes in that community. 

Still frame of a wind power illustration in both land-based and offshore contexts with the transformers highlighted in an animation window.

Substation

A substation links the transmission system to the distribution system that delivers electricity to the community. Within the substation, transformers convert electricity from high voltages to lower voltages which can then be delivered safely to electricity consumers.

Still frame of an illustrated substation highlighted in an animation window.

Wind Turbine Tower

Made from tubular steel, the tower supports the structure of the turbine. Towers usually come in three sections and are assembled on-site. Because wind speed increases with height, taller towers enable turbines to capture more energy and generate more electricity. Winds at elevations of 30 meters (roughly 100 feet) or higher are also less turbulent.

Still frame of an illustrated turbine highlighting the turbine’s tower in an animation window.

Wind Direction

Determines the design of the turbine. Upwind turbines—like the one shown here—face into the wind while downwind turbines face away. Most utility-scale land-based wind turbines are upwind turbines.

Still frame of an illustrated wind turbine with a highlighted arrow showing wind direction in an animation window.

Wind Vane

The wind vane measures wind direction and communicates with the yaw drive to orient the turbine properly with respect to the wind.

 

 

 

Still frame of an illustrated turbine highlighting a wind vane in an animation window.

Anemometer

The anemometer measures wind speed and transmits wind speed data to the controller.

Still frame of an illustrated anemometer highlighted in an animation window.

Blades

Most turbines have three blades which are made mostly of fiberglass. Turbine blades vary in size, but a typical modern land-based wind turbine has blades of over 170 feet (52 meters). The largest turbine is GE's Haliade-X offshore wind turbine, with blades 351 feet long (107 meters) – about the same length as a football field. When wind flows across the blade, the air pressure on one side of the blade decreases. The difference in air pressure across the two sides of the blade creates both lift and drag. The force of the lift is stronger than the drag and this causes the rotor to spin.

Still frame of a wind turbine with the blades highlighted in an animation window.

Land-Based Gearbox Turbine

The drivetrain on a turbine with a gearbox is comprised of the rotor, main bearing, main shaft, gearbox, and generator. The drivetrain converts the low-speed, high-torque rotation of the turbine’s rotor (blades and hub assembly) into electrical energy. 

Still frame of an illustrated wind turbine nacelle with a gearbox in an animation wind.

Nacelle

The nacelle sits atop the tower and contains the gearbox, low- and high-speed shafts, generator, and brake. Some nacelles are larger than a house and for a 1.5 MW geared turbine, can weigh more than 4.5 tons.

Still frame of an illustrated wind turbine nacelle highlighted in an animation window.

Yaw System

The yaw drive rotates the nacelle on upwind turbines to keep them facing the wind when wind direction changes. The yaw motors power the yaw drive to make this happen.

Downwind turbines don’t require a yaw drive because the wind manually blows the rotor away from it.

Still frame of an illustrated wind turbine yaw system highlighted in an animation window.

Pitch System

The pitch system adjusts the angle of the wind turbine's blades with respect to the wind, controlling the rotor speed. By adjusting the angle of a turbine's blades, the pitch system controls how much energy the blades can extract. The pitch system can also "feather" the blades, adjusting their angle so they do not produce force that would cause the rotor to spin. Feathering the blades slows the turbine's rotor to prevent damage to the machine when wind speeds are too high for safe operation.

Still frame of an illustrated wind turbine pitch system on a wind turbine highlighted in an animation window.

Hub

Part of the turbine's drivetrain, turbine blades fit into the hub that is connected to the turbine's main shaft.  

Still frame of a wind turbine hub highlighted in an animation window.

Gearbox

The drivetrain is comprised of the rotor, main bearing, main shaft, gearbox, and generator. The drivetrain converts the low-speed, high-torque rotation of the turbine's rotor (blades and hub assembly) into electrical energy.

Still frame of an illustrated wind turbine gearbox highlighted in an animation window.

Rotor

The blades and hub together form the turbine's rotor.

Still frame of an illustrated wind turbine rotor highlighted in an animation window.

Low-Speed Shaft

Part of the turbine's drivetrain, the low-speed shaft is connected to the rotor and spins between 8–20 rotations per minute.

Still frame of an illustrated wind turbine low-speed shaft highlighted in an animation window.

Main Shaft Bearing

Part of the turbine's drivetrain, the main bearing supports the rotating low-speed shaft and reduces friction between moving parts so that the forces from the rotor don't damage the shaft.

Still frame of an illustrated wind turbine main shaft bearing highlighted in an animation window.

High-Speed Shaft

Part of the turbine's drivetrain, the high-speed shaft connects to the gearbox and drives the generator.

Still frame of an illustrated wind turbine high-speed shaft highlighted in an animation window.

Generator

The generator is driven by the high-speed shaft. Copper windings turn through a magnetic field in the generator to produce electricity. Some generators are driven by gearboxes (shown here) and others are direct-drives where the rotor attaches directly to the generator.

Still frame of an illustrated wind turbine generator highlighted in an animation window.

Controller

The controller allows the machine to start at wind speeds of about 7–11 miles per hour (mph) and shuts off the machine when wind speeds exceed 55–65 mph. The controller turns off the turbine at higher wind speeds to avoid damage to different parts of the turbine. Think of the controller as the nervous system of the turbine.

Still frame of an illustrated wind turbine controller bearing highlighted in an animation window.

Brake

Turbine brakes are not like brakes in a car. A turbine brake keeps the rotor from turning after it's been shut down by the pitch system. Once the turbine blades are stopped by the controller, the brake keeps the turbine blades from moving, which is necessary for maintenance.

Still frame of an illustrated wind turbine brake highlighted in an animation window.

Direct-Drive Offshore Wind Turbine

Direct-drive turbines simplify nacelle systems and can increase efficiency and reliability by avoiding gearbox issues. They work by connecting the rotor directly to the generator to generate electricity.

Still frame of an offshore, illustrated direct-drive wind turbine.

Direct-Drive Offshore Wind Vane and Anemometer

The wind vane measures wind direction and communicates with the yaw drive to orient the turbine properly with respect to the wind.

The anemometer measures wind speed and transmits wind speed data to the controller.

Still frame of an illustrated wind vane and anemometer of a direct-drive wind turbine in an animation window.

Direct-Drive Yaw System

The yaw motors power the yaw drive, which rotates the nacelle on upwind turbines to keep them facing the wind when the wind direction changes.

Still frame of an illustrated direct-drive wind turbine anemometer and wind vane highlighted in an animation window.

Direct-Drive Generator Blades

Most turbines have three blades which are made mostly of fiberglass. When wind flows across the blade, the air pressure on one side of the blade decreases. The difference in air pressure across the two sides of the blade creates both lift and drag. The force of the lift is stronger than the drag and this causes the rotor to spin. Blades on GE's Haliade X turbine are 351 feet long (107 meters) – about the same length as a football field!

Still frame of an illustrated direct-drive wind generator blades highlighted in an animation window.

Direct-Drive Pitch System

The pitch system adjusts the angle of the wind turbine's blades with respect to the wind, controlling the rotor speed. By adjusting the angle of a turbine's blades, the pitch system controls how much energy the blades can extract. The pitch system can also "feather" the blades, adjusting their angle so they do not produce force that would cause the rotor to spin. Feathering the blades slows the turbine’s rotor to prevent damage to the machine when wind speeds are too high for safe operation.

Still frame of an illustrated direct-drive wind turbine pitch system highlighted in an animation window.

Direct-Drive Hub

Turbine blades fit into the hub that is connected to the turbine's generator.

Still frame of an illustrated direct-drive wind turbine direct-drive hub highlighted in an animation window.

Direct-Drive Rotor

The blades and hub together form the turbine's rotor.

Still frame of an illustrated direct-drive wind turbine rotor highlighted in an animation window.

Direct-Drive Generator

Direct-drive generators don't rely on a gearbox to generate electricity. They generate power using a giant ring of permanent magnets that spin with the rotor to produce electric current as they pass through stationary copper coils. The large diameter of the ring allows the generator to create a lot of power when turning at the same speed as the blades (8–20 rotations per minute), so it doesn't need a gearbox to speed it up to the thousands of rotations per minute other generators require.

Still frame of an illustrated direct-drive wind turbine generator highlighted in an animation window.

Direct-Drive Controller

The controller allows the machine to start at wind speeds of about 7–11 miles per hour (mph) and shuts off the machine when wind speeds exceed 55–65 mph. The controller turns off the turbine at higher wind speeds to avoid damage to different parts of the turbine. Think of the controller as the nervous system of the turbine.

Still frame of an illustrated direct-drive wind turbine controller highlighted in an animation window.

Direct-Drive Brake

Turbine brakes are not like brakes in a car. A turbine brake keeps the rotor from turning after it's been shut down by the pitch system. Once the turbine blades are stopped by the controller, the brake keeps the turbine blades from moving, which is necessary for maintenance.

Still frame of an illustrated direct-drive brake highlighted in an animation window.

Direct-Drive Rotor Bearing

The rotor bearing supports the main shaft and reduces friction between moving parts so that the forces from the rotor don't damage the shaft.

Still frame of an illustrated direct-drive wind turbine rotor bearing highlighted in an animation window.

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