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Wind turbines convert the kinetic energy in the wind into mechanical energy. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity. Most turbines have three aerodynamically designed blades. The energy in the wind turns two or three propeller-like blades around a rotor that is connected to the main shaft, which spins a generator to create electricity. Wind turbines are mounted on a tower to capture the most energy. At 100 feet (30 meters) or more above ground, they can take advantage of faster and less turbulent wind.
Three main variables determine how much electricity a turbine can produce:
1. Wind speed- stronger winds produce more energy. Wind turbine generates energy at a speed of 4-25 metres per second
2. Blade radius- the larger the radius of blades, the more the energy produced. Doubling the blade radius can result in four times more power.
3. Air density- Heavier air exerts more lift on a rotor. Air density is a function of altitude, temperature and pressure. High altitude locations have low air pressure and lighter air so they are less productive turbine locations. The dense heavy air near sea level drives rotors faster and thus relatively more effectively.