HOW A WIND TURBINE WORKS?
From massive wind farms generating power to small turbines powering a single home, wind turbines around the globe generate clean electricity for a variety of power needs.
WHAT IS A WIND TURBINE?
The concept of harnessing wind energy to generate mechanical power goes back for millennia. As early as 5000 B.C., Egyptians used wind energy to propel boats along the Nile River. American colonists relied on windmills to grind grain, pump water and cut wood at sawmills. Today’s wind turbines are the windmill’s modern equivalent — converting the kinetic energy in wind into clean, renewable electricity.
HOW DOES A WIND TURBINE WORK?
The majority of wind turbines consist of three blades mounted to a tower made from tubular steel. There are less common varieties with two blades, or with concrete or steel lattice towers. At 100 feet or more above the ground, the tower allows the turbine to take advantage of faster wind speeds found at higher altitudes.
Turbines catch the wind’s energy with their propeller-like blades, which act much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on one side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is much stronger than the wind’s force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller.
A series of gears increase the rotation of the rotor from about 18 revolutions a minute to roughly 1,800 revolutions per minute — a speed that allows the turbine’s generator to produce AC electricity.
A streamlined enclosure called a nacelle houses key turbine components — usually including the gears, rotor and generator — are found within a housing called the nacelle. Sitting atop the turbine tower, some nacelles are large enough for a helicopter to land on.
Another key component is the turbine’s controller, that keeps the rotor speeds from exceeding 55 mph to avoid damage by high winds. An anemometer continuously measures wind speed and transmits the data to the controller. A brake, also housed in the nacelle, stops the rotor mechanically, electrically or hydraulically in emergencies. Explore the interactive graphic above to learn more about the mechanics of wind turbines.
TYPES OF WIND TURBINES.
There are two basic types of wind turbines:
(those with a horizontal axis, and those with a a vertical axis) .
The majority of wind turbines have a horizontal axis: a propeller-style design with blades that rotate around a horizontal axis. Horizontal axis turbines are either upwind (the wind hits the blades before the tower) or downwind (the wind hits the tower before the blades). Upwind turbines also include a yaw drive and motor — components that turns the nacelle to keep the rotor facing the wind when its direction changes.
While there are several manufacturers of vertical axis wind turbines, they have not penetrated the utility scale market (100 kW capacity and larger) to the same degree as horizontal access turbines.
Vertical axis turbines fall into two main designs:
▪️ Drag-based, or Savonius, turbines generally have rotors with solid vanes that rotate about a vertical axis.
▪️Lift-based, or Darrieus, turbines have a tall, vertical airfoil style (some appear to have an eggbeater shape). The Windspire is a type of lift-based turbine that is undergoing independent.
WIND TURBINE APPLICATIONS.
Wind Turbines are used in a variety of applications – from harnessing offshore wind resources to generating electricity for a single home:
▪️Large wind turbines, most often used by utilities to provide power to a grid, range from 100 kilowatts to several megawatts. These utility-scale turbines are often grouped together in wind farms to produce large amounts of electricity. Wind farms can consist of a few or hundreds of turbines, providing enough power for tens of thousands of homes.
▪️ Small wind turbines, up to 100 kilowatts, are typically close to where the generated electricity will be used, for example, near homes, telecommunications dishes or water pumping stations. Small turbines are sometimes connected to 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.
▪️ Offshore wind turbines are used in many countries to harness the energy of strong, consistent winds found off of coastlines.
How a Wind Turbine Works”, www.energy.gov