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Wind Energy
Wind results as Sun hits the oceans and the surface of the Earth
and causes differential heating of these surfaces. Warmer air rises and
blows over the surface as wind.
Wind Energy is the energy due to wind motion (i.e. kinetic energy).
This energy can be harnessed to provide mechanical energy for driving
mechanical systems and for providing electricity. The amount of available
wind energy increases with the speed of wind. Wind speed, on the other
hand, is determined by:
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Density of the air,
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Temperature of the air,
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Barometric pressure, and
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Altitude.
Temperature decreases with height, while pressure increases. Wind effects
are more pronounced at high altitudes.
Wind energy is a renewable
resource. A renewable resource is a resource that is able to be replaced
or replenished, either by the earth's natural processes or by human
action. Wind energy is available at varying proportions almost everywhere
on earth. It cannot be depleted unlike the conventional fossil fuel based
energy resources.
Wind energy is a
“clean” energy resource. It does not involve the emission of Green House
Gases (GHGs) that are believed to be responsible for the worsening global
warming of our planet, Earth. It is believed that each megawatt-hour of
electricity that is generated by wind energy helps to reduce the 0.8 to
0.9 tonnes of greenhouse gas emissions that are produced by coal or diesel
fuel generation each year.
It provides a
suitable energy alternative to the traditional fossil fuel energy sources
that are currently widely in use.
Previous and currently applications of wind energy includes:
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Windmills - used to grind grains
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Wind Turbines – to generate electricity
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Wind Pumps – water pumping
The current extensive use of wind energy is in wind turbines. Wind
turbines transform energy from wind into electricity. Wind turbines
perform optimally when placed at very windy locations and at high
altitudes because available wind energy increases with speed and altitude.
Wind
turbines are
designed to
start
generating electricity when wind speeds reach 4 metres a second. They cut
out when the wind speed
exceeds
25
metres a second to avoid damaging the turbine.
There are various sizes of wind turbines for the different levels of
needs: Large (over 300 Kilowatts (KW)) Medium (30 to 300 KW) and small
(below 30 KW) sizes. Large wind turbines can be used to supplement
national electricity supply by combining the turbines to the national
grid. Small scale uses like supply to homes and farms can be met with
smaller turbines either connected to electricity grid or powered locally.
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