Agriculture Reference
In-Depth Information
•
It generates the energy used in its construction in just 3 months of operation, yet
its operational lifetime is about 20-25 years.
•
Greenhouse gas emissions and air pollution produced during its construction are
tiny and declining due to advancement of technology.
•
There are no emissions or pollution produced by its operation.
•
In substituting for base-load coal power, wind power produces a net decrease in
greenhouse gas emissions and air pollution, and a net increase in biodiversity.
•
Modern wind turbines are almost silent and rotate so slowly (in terms of
revolutions per minute) that they are rarely a hazard to birds.
There is still the problem of what to do when the wind isn't blowing. At those
times, other types of power plants must be used to make electricity.
13.5.6 Assessing Wind Energy Potential
The water output of a windmill pump is very sensitive to any variation in wind
speed. Wind speed at any location depends upon a variety of site specific factors.
Within a country or state, large variation in annual monthly mean wind speeds exists.
Therefore, analysis for the estimation of potential of windmill pumps for irrigation
water pumping should be carried out using data of small area, such as district or
other local unit. Other data such as surface water irrigation facility and depth to
groundwater table should be taken into account to estimate potential uses.
The wind speed at any location increases with an increase in height from the
ground level. In most of the prevailing windmill pump designs, rotor is fixed on
a tower at about 10 m height from the ground. From the available data on mea-
sured values of annual monthly mean wind speed at different locations, the annual
monthly mean wind speeds at the 10 m height from the ground level should be
estimated by using standard relationship. One of the forms of such relationship is
V
h
10
h
α
V
10
=
where
V
h
annual monthly mean wind speed measured at a reference height of
h
meters from the ground level
α
=
=
ground surface friction coefficient
The value of
varies from 0.1 to 0.5 depending upon the terrain of the location. For
crops and shrubs type terrain, a value of 0.2 is generally recommended. For water
or smooth flat ground,
α
α
is taken as 0.1.
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