So how do wind turbines make electricity?
- Wind turbines use wind to make electricity. It acts like a
fan, but instead of using electricity, it produces electricity
from a renewable resource, and that is wind. The wind turns the
two-bladed or three-bladed turbines, in which shaft also spins
in the process. The shaft is connected to a generator and
eventually the energy converts into the electricity people need
in society. Most utility-producing turbines range in size from
50 to 750 kilowatts. Single small turbines, below 50 kilowatts,
are used for homes, telecommunications dishes, or water pumping.
- More simply stated: the wind turns the rotor of the wind
turbine and the rotor will then turn a generator, which makes
electricity. The electricity travels through the tower by
conducting it through some very thick cables located inside the
tower. The electricity then passes through the transformer and
then to a household or building in need of electricity.
- Uneven heating of the Earth’s surface by the sun causes the
wind. The warmer air in some places rises. The resulting
low-pressure area draws in cooler air. Wind patterns are
affected by the spin of the planet, weather patterns, and
terrain. Wind energy potential increases very rapidly with
increasing wind speed. In fact, if wind speed doubles the energy
content goes up by a factor of eight.
Types of Windmills
The electricity from a wind turbine is sent through transmission
and distribution lines to homes, businesses, and schools.
There are two types of wind turbines:
- Three-bladed wind turbines are operated with the blades
facing into the wind when the wind blows. These types of
turbines works against the wind in the opposite direction.
- The two-bladed operates in a downwind turbine, and these
turbines works along with the wind in the same direction.
- Upwind machines have the rotor facing the wind. The vast
majority of wind turbines have this design because it is very
- On the other hand, there is also some wind shade in front of
the tower. For example, the wind will start bending away from
the tower before it reaches the tower itself, even if the tower
is round and smooth. Therefore, each time the rotor passes the
tower, the power from the wind turbine drops slightly.
- The basic drawback of upwind designs is that the rotor needs
to be made rather inflexible, and placed at some distance from
the tower. The upwind wind turbines need a yaw mechanism to keep
the rotor facing the wind.
- The greatest advantage of downwind turbines is that the
machine will bend the tower and rotor blades in the direction it
is blowing. Upwind machines must resist bending, although
downwind blades and towers can be allowed to bend. The blades
can also be made to further reduce bending loads.
- A hinged and controlled blade system allows the blades to
"flap" in the wind direction, causing the cone angle between the
blades to vary continuously with changing wind and rotational
speeds. This feature results in an enormous reduction of the
blade-root bending loads. Reducing these loads allows safety
with the wind turbines. This downwind system was a result of the
design of a 2-blade downwind turbine.
- They have the theoretical advantage that they may be built
without a yaw mechanism, if the rotor and nacelle have a
suitable design that makes the nacelle follow the wind
passively. A more important advantage is that the rotor could be
made more flexible. This is an advantage both in regard to
weight, and the structural dynamics of the machine, i.e. the
blades will bend at high wind speeds, thus taking part of the
load off the tower. The basic advantage of the downwind machine
is thus, that it may be built somewhat lighter than an upwind
- The basic drawback is the fluctuation in the wind power due
to the rotor passing through the wind shade of the tower. This
may give more fatigue loads on the turbine than with an upwind
Small vs. Large Wind Turbines
- Large wind turbines are used primarily in arrays, called
“wind farms.” These huge machines require high wind resources
because they must compete with conventional generation (coal,
natural gas, oil, and nuclear) at the wholesale level.
- Large wind systems cost less when it comes to costs and has a
tower height usually higher than 200 feet, with a rotor diameter
ranging from 60 to 80 meters.
- Small wind systems are used primarily for individual homes,
businesses, or facilities. Though they cost relatively more than
large turbines, small wind turbines can be used in areas with
modest wind resources because they compete at the retail level.
- Large wind turbines have gotten much bigger and much less
expensive in the last 15 years. They can already produce
electricity less expensively than power from coal or nuclear
- The costs of small wind turbines has not dropped very much in
the last 15 years, principally because small wind systems have
not been granted the subsidies that are available for large wind
turbines and solar modules.
- The cost of smaller wind turbines are less than large
turbines, operating costs 1 cent/kWh compared to the large wind
turbines which cost at 8 cents/kWh.
- Less land is used to support smaller wind turbines than large
Wind Turbine Terminology
Anemometer: This device measures the wind
Blades: Most turbines have either two or three
blades. Wind blowing over the blades causes the blades to "lift" and
Brake: A disc brake that is used to stop the
rotor in emergencies to ensure the safety of all wind turbines.
Controller: The controller starts up the
machine at set wind speeds and it will also stop the machine
generator when wind speeds are very high because the generator may
overheat in some cases due to high levels of friction.
Gearbox: Gears connect the low-speed shaft to
the high-speed shaft and increase the low rotational speeds to a
much higher rotation levels that is required by most generators to
produce electricity. The gearbox is considered a costly and rather
heavy part of the wind turbine.
Generator: A device that produces a 60-cycle AC
High-speed shaft: Drives the generator.
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 gearbox, high and low
speed shafts, generator, controller, and brake. Some nacelles are
large enough for a technician to stand inside while working. A cover
always protects the components inside the nacelle
Pitch: Blades are turned, out of the wind to
keep the rotor from winds that are too high or too low to produce
Rotor: The blades and the hub together are
called the rotor.
Tower: Towers are made often made from tubular
steel or steel lattice. Because wind speed increases with height,
taller towers enable turbines to capture more energy and generate
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
and 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, and the wind blows the rotor downwind.
Yaw motor: Powers the yaw drive.
The current must be fed into the electrical grid when the generator
makes electricity. The electricity is conducted through some very
The wind turbine controller is a computer, which checks that
everything works as it should. If a part breaks down, the controller
will call a computer at the wind turbine owner’s house to report the
Semi-Conclusion: The large downwind wind turbine is more
efficient when producing energy; therefore this design is most
suitable for Nose Hill Park.