This aerial view of
a wind power plant shows how a group of wind turbines can
make electricity for the utility grid. The electricity is
sent through transmission and distribution lines to homes,
businesses, schools, and so on.
These three-bladed wind turbines are operated "upwind," with the
blades facing into the wind. The other common wind turbine type is
the two-bladed, downwind turbine.
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. Utility-scale turbines range in
size from 50 to 750 kilowatts. Single small turbines, below 50
kilowatts, are used for homes, telecommunications dishes, or water
pumping.
Look at the Wind Turbine Close Up
Wind Turbine Glossary
Anemometer: Measures the wind speed and
transmits wind speed data to the controller.
Blades: Most turbines have either two or
three blades. Wind blowing over the blades causes the blades to
"lift" and rotate.
Brake: A disc brake which can be applied
mechanically, electrically, or hydraulically to stop the rotor in
emergencies.
Controller: The controller starts up the
machine at wind speeds of about 8 to 16 miles per hour (mph) and
shuts off the machine at about 65 mph. Turbines cannot operate at
wind speeds above about 65 mph because their generators could
overheat.
Gear box: Gears connect the low-speed shaft
to the high-speed shaft and increase the rotational speeds from
about 30 to 60 rotations per minute (rpm) to about 1200 to 1500 rpm,
the rotational speed required by most generators to produce
electricity. The gear box is a costly (and heavy) part of the wind
turbine and engineers are exploring "direct-drive" generators that
operate at lower rotational speeds and don't need gear boxes.
Generator: Usually an off-the-shelf
induction generator that produces 60-cycle AC electricity.
Low-speed shaft: The rotor turns the
low-speed shaft at about 30 to 60 rotations per minute.
Nacelle: The rotor attaches to the nacelle,
which sits atop the tower and includes the gear box, low- and
high-speed shafts, generator, controller, and brake. A cover
protects the components inside the nacelle. Some nacelles are large
enough for a technician to stand inside while working.
Pitch: Blades are turned, or pitched, out of
the wind to keep the rotor from turning in winds that are too high
or too low to produce electricity.
Rotor: The blades and the hub together are
called the rotor.
Tower: Towers are made from tubular steel
(shown here) or steel lattice. Because wind speed increases with
height, taller towers enable turbines to capture more energy and
generate more electricity.
Wind direction: This is an "upwind" turbine,
so-called because it operates facing into the wind. Other turbines
are designed to run "downwind", facing away from the wind.
Wind vane: Measures wind direction and
communicates with the yaw drive to orient the turbine properly with
respect to the wind.
Yaw drive: Upwind turbines face into the
wind; the yaw drive is used to keep the rotor facing into the wind
as the wind direction changes. Downwind turbines don't require a yaw
drive, the wind blows the rotor downwind.
This aerial view of
a wind power plant shows how a group of wind turbines can
make electricity for the utility grid. The electricity is
sent through transmission and distribution lines to homes,
businesses, schools, and so on.
