A
vertical wind power generator, also called
vertical-axis wind turbine (VAWT) is a type of turbine
whose axis of rotation is perpendicular to the wind flow
and the ground. The concept is as simple as that of a
water or hydro-turbine where a jet or cascade of water
hits the turbine directly, initiating the rotational
movement. Save and except that in the case of VAWT, the
wind flow does the trick, thereby generating
electricity. It does not have any propeller-like blade
as in a horizontal-axis wind turbine or
HAWT.
Vertical-axis
wind turbines usually fall into two categories: (a)
Darrieus Turbine and (b) Savonius Turbine, both of which
are no more used now-a-days. However, the Darrieus
Turbine that was designed by Georges Jean Marie
Darrieus, a French aeronautical engineer in 1932 consist
of a number of aerofoil that were vertically mounted on
a rotating shaft whose biggest snag was its unwieldy
structure. Also, it could not start on its own and
needed a ‘push’. Nevertheless, this was eventually
solved by connecting the contraption to the grid. In
fact, the grid power was made to act on the turbine’s
generator, turning into a motor which started the
rotational motion. However, no tower was needed for
installing these types of turbines as they were mostly
set in ground level.
The
Savonius Turbine, also a vertical-axis wind turbine
consisted of a pair of opposing concave vanes rotating
round a central vertical axis Customary Savonius rotors
were open in the center, permitting cross flow of air in
an S formation, passing the inner edges of the rotating
vanes. However, these also died a natural death, mostly
because of cumbersome design structures and unstable
installation process.
Although
horizontal-axis wind turbines (HAWT) now rule the
market, engineers do not consider the system to last
long because of several practical reasons. Moreover, the
ERDA-NASA design (devices that run through
propeller-like blades) may not eventually prove as cost
effective as originally conceived. It has also been
estimated that for generating enough power for an
average dwelling house (leaving aside push sale of small
rooftop models that are neither good for the roof nor
for generating adequate electricity) may need propellers
at least 25 feet in diameter. To achieve higher outputs,
larger diameter (125-200 feet) blades will be needed.
And as the range increases, the production, installation
and maintenance costs increase ten fold. On top of all
that, the ERDA-NASA units require supplementary control
mechanisms for keeping the unit perpetually turned to
the air current, feathering the
blades as well as provision for braking when wind
velocity exceeds the rated limit. Since these
controlling mechanisms also require power, the overall
output is likely to go down
substantially.
However
this is no reason for you to review your decision to opt
for wind energy. There are many other cheap wind power
systems that are working just fine – in fact, an ever
increasing number of people are today are going for wind
power across the world. Many countries have gone to the
extent of declaring their wind policy and their aim is
to rapidly replace fossil fuel generated power with this
safe and clean energy as soon as
possible.
And
there are many reasons for this. Do not forget – wind
power does not create any pollution, it is cheap and it
is hassle free as well. Plus, when you use wind power,
you can save a lot on your power bills and there is very
less maintenance cost as well. These are the main
advantages of wind power. So go ahead and read this
manual that teaches you where to set up the system in
your home for best results, how to do it, how to wire
the system, where to get the parts from cheaply and
lastly, the all important safety precautions that need
to be followed always.
