ENERGY - How Wind Turbines Work
is a form of solar 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 vegetation. Humans
use this wind flow, or motion
energy, for many purposes: sailing,
flying a kite, and even generating
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.
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.
Take a look inside a wind turbine
to see the various parts. View
the wind turbine animation to
see how a wind turbine works.
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
|Types of Wind Turbines :
wind turbines fall into
two basic groups: the
as shown in the photo,
and the vertical-axis
design, like the eggbeater-style
Darrieus model, named
after its French inventor.
wind turbines typically
either have two or three
blades. These three-bladed
wind turbines are operated
with the blades facing
into the wind.
|Sizes of Wind Turbines :
turbines range in size
from 100 kilowatts to
as large as several megawatts.
Larger turbines are grouped
together into wind farms,
which provide bulk power
to the electrical grid.
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.
the Wind Turbine:
Measures the wind speed and transmits
wind speed data to the controller.
Most turbines have either two
or three blades. Wind blowing
over the blades causes the blades
to "lift" and rotate.
A disc brake, which can be applied
mechanically, electrically, or
hydraulically to stop the rotor
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 55 mph.
Turbines do not operate at wind
speeds above about 55 mph because
they might be damaged by the high
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 1000 to 1800 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
generators that operate at lower
rotational speeds and don't need
Usually an off-the-shelf induction
generator that produces 60-cycle
Drives the generator.
The rotor turns the low-speed
shaft at about 30 to 60 rotations
The nacelle sits atop the tower
and contains the gear box, low-
and high-speed shafts, generator,
controller, and brake. Some nacelles
are large enough for a helicopter
to land on.
Blades are turned, or pitched,
out of the wind to control the
rotor speed and keep the rotor
from turning in winds that are
too high or too low to produce
The blades and the hub together
are called the rotor.
Towers are made from tubular steel
(shown here), concrete, or steel
lattice. Because wind speed increases
with height, taller towers enable
turbines to capture more energy
and generate more electricity.
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.
Measures wind direction and communicates
with the yaw drive to orient the
turbine properly with respect
to the wind.
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
Powers the yaw drive.