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Electricity and Basic Electronics
Wind turbine locations
The amount of wind energy that is avail-
able for a given location changes with the
seasons and weather conditions. However,
there are certain areas in North America where
wind turbines are effectively used because the
average amount of wind is enough to power
them.
Many states now use wind turbines to sup-
ply part of their electricity. States where tur-
bines are found include California, Colorado,
Iowa, Minnesota, New Mexico, Oregon, Texas,
Washington, and Wyoming. You may see
a large number of wind turbines grouped
together in one location, Figure 24-19. Those
areas have the favorable wind conditions
needed to generate electricity. There are large
spaces between the wind turbines because
the rotating blades change the airfl ow to a
turbulent pattern for a short distance. If the
next turbine is too close, it will be less effec-
tive in generating electricity. Proper spacing
and distance between each unit is therefore
necessary to allow the wind to recover its nor-
mal pattern and for the turbine to be effec-
tive. These groups of wind turbines are called
wind farms or wind plants.
Wind turbine costs
The cost of the wind farms includes
acquiring the land, laying a foundation,
building the tower, assembling the parts, and
maintaining the equipment. Many times a
developer will buy or lease land from a farmer
or other landowner on which to build the
wind turbines. The landowner may receive
a one-time payment, a percentage based on
the wattage produced, or a fi xed amount per
year.
The electricity produced by wind turbines
is not usually fed directly into a home. DC is
produced as the blades turn. If a home is in a
remote area, its electricity may be produced
by a dc wind turbine. For most wind turbines,
however, dc is fed into an inverter and
converted to ac. The ac is then used on-site or
fed into the electrical grid. The landowners
158′. The total height of the structure is taller
than a thirty-story building. The towers are
tall because as altitude increases, wind speed
increases. Taller towers can capture the higher
wind speeds and generate more electricity.
The blades are connected to the gener-
ator by a gearbox and shaft. The generator is
usually mounted behind the area where the
blades meet, Figure 24-18. Recall that a gener-
ator turns mechanical energy into electrical
energy. The blades of the wind turbine turn
as the wind hits them, spinning the armature
inside the generator. Generators are most effi -
cient when the wind speeds are over 8 miles
per hour (mph).
More windy days and higher wind speeds
mean that more electricity can be generated.
However, at very high wind speeds (over
65 mph), the wind turbine must shut itself
down so it is not destroyed. Wind speed is
measured with an anemometer, which is
typically located above the generator. When
the speed gets too high, the control system
applies the brake. High wind speeds were a
problem with some of the early designs. In fact,
some towers were destroyed when the high
wind caused the blades to defl ect and actually
strike the tower supporting the system.
Figure 24-18. The generator sits behind the rotors.
Generator