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 electricity.
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.
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.
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.
wind farms have sprung up in the Midwest in recent years,
generating power for utilities. Farmers benefit by receiving
land lease payments from wind energy project developers.
wind turbines fall into two basic groups: the horizontal-axis
variety, as shown in the photo, and the vertical-axis design,
like the eggbeater-style Darrieus model, named after its French
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 Energy's 3.6 megawatt wind turbine is one of the largest
prototypes ever erected. Larger wind turbines are more efficient
and cost effective.
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 speed and transmits wind speed data to the controller.
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 in emergencies.
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 winds.
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 exploring "direct-drive" generators that
operate at lower rotational speeds and don't need gear boxes.
an off-the-shelf induction generator that produces 60-cycle
rotor turns the low-speed shaft at about 30 to 60 rotations
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
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 electricity.
blades and the hub together are called the rotor.
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
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 direction and communicates with the yaw drive to orient
the turbine properly with respect to the wind.
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.
the yaw drive.