Wind,
in fact, is also a form of solar energy because winds
develop when the earth’s surface is heated up with the
solar radiation. To be more precise, the topography of
the earth’s surface that consist of plain land, high
hills, water bodies and the oceans receive and absorb
the rays of the Sun at different levels as a result of
which, the heated air above them behaves differently.
This disparity of warm air causes wind to flow, while
the gust of air so flowing is described as wind power or
wind energy. Wind energy was previously utilized by
sailing ships for faster transit through the high seas,
pumping water from the wells and for crushing corn,
while its contemporary use is directed to power
generation through wind turbines.
Simply
stating, a wind turbine acts more or less like an
electric fan, the only difference being its working
principle which is just the opposite of that of the
latter. In other words, while the electricity makes the
fan to turn its blades, the same is generated when wind
turns the turbine’s blades. What really happens is that,
when wind energy turns the blades of a wind turbine, it
turns a shaft attached to it which in turn, rotates the
wheel of a generator, producing electric
current.
Present
day wind turbines usually fall into two basic types –
the horizontal-axis type and the vertical-axis type of
which the former type is more in use for generation of
electricity. However, it would be easier to understand
how wind energy works if we take a look
at the working of the turbines and get acquainted with
its distinctive parts that are described here. The
entire assembly consist of (a) An Anemometer that
measures up the wind speed and transmits the same to the
controller; (b) a Controller that
starts up the turbine at wind speeds ranging from 9 to
18 mph (miles per hour) and shuts it off when it reaches
or goes beyond 55 mph as much higher speeds tend to
damage the system. Wind turbines are invariably provided
with Blades
(two or three for each turbine) that ‘lift’ and
rotate as the wind blows over them. Most turbines are
also provided with Brakes that can
be applied mechanically or hydraulically to stop the Rotor (the
blades and the hub) in emergencies. The Low-speed shaft
in turbine turns the rotor at revolutions varying
from 30 to 60 rpm while the High-speed shaft
drives the Generator which
actually is an off-the-shelf power generator that
produces a 60-cycle AC current.
Apart
from the components that have been described above, a
Wind Turbine also have a few other components that
consist of a Gear box
which
connects the low-speed shaft to the high-speed
shaft, thereby increasing its rotational speed to 1000 –
1800 rpm, which is the highest. There is a tendency now
towards eliminating this costly component, replacing the
system with ‘direct-drive’ generators that can operate
at lower rpm.
Also
included in the assembly is a Nacelle that
sits atop the Tower containing the gear box, controller,
both kinds of the shafts, brakes, etc which sometimes is
large enough for a helicopter to land on it. Besides,
the turbines are also provided with Pitch that can
control the blades by changing their slants while in
motion. And of course, there is the Tower that is
made from tubular steel, reinforced concrete or steel
lattice on top of which the whole contraption sits
smug.
Although
the basic description of how the wind energy
works through a wind turbine has been provided
here, several variations of this system are being worked
out at different parts of the country, some of which can
actually produce more electricity at a much lower rotor
rpm because of the ingenuity of their design structures.
But the fundamentals remain the same. But all said and
done, power generation through wind turbines still
depends on the whims of nature that can lower the volume
of wind all on a sudden or stop it temporarily for some
time.
