Wind results from air in motion due to pressure gradient that is caused by the solar energy irradiating the earth. Wind possesses energy by virtue of its motion .Any device capable of slowing down the mass of moving air can extract part of the energy and convert into useful work.
Theoretically it is possible to get 100% efficiency by halting and preventing the passage of air through the rotor. However, a rotor is able to decelerate the air column only to one third of its free velocity.
Following factors control the output of wind energy converter : –
- The wind speed
- Cross-section of the wind swept by rotor
- Conversion efficiently of rotor
- Transmission system
A 100% efficient wind generator is able to convert maximum up to 60% of the available energy in wind into mechanical energy. In addition to this, losses incurred in the generator or pump decrease the overall efficiency of power generation to 35%.
Following factors are to be considered for selection of good site for wind power generation:-
- High annual wind speed.
- No tall obstructions for a radius of 3 Km.
- Open plain or open shore
- Top of a smooth, well rounded hill with gentle slopes
- Mountain gap which produces wind funneling.