Changes

Wind turbine blades are used to extract the kinetic energy of wind and convert to mechanical energy. These blades are made up of fiber glass-reinforced polyester or wood-epoxy. Wind turbines have one or two or three or multiple blades based up on the construction. Most of the HAWT have three blades. These are connected to rotor hub. Multiple blade concept is used in earlier days for pumping water and grinding etc.

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| It reduces the cost and weight of the turbine. These are rarely used due to tower shadow effects, needs counter weights on the other side of the blade, less stability.

[[Image:single.jpeg|center|200px|thumb|Fig 9(a) [http://www.wind-energy-the-facts.org/en/part-i-technology/chapter-3-wind-turbine-technology/evolution-of-commercial-wind-turbine-technology/design-styles.html Single blade turbine]]]

| It requires more complex design due to sustain of wind shocks. It is also less stable. It saves the cost and weight of one rotor blade.

[[Image:two.jpeg|center|300px|thumb|Fig 9(b) [http://www.trendir.com/green/?start=15 Two blade turbine]]]

|Modern wind trubines uses three blade concept. Because this structure have hight strength to withstand heavy wind stroms. Less effect due to towe shadow. Produces high output

[[Image:three.jpeg|center| 200px|thumb|Fig 9(c) [http://www.china-windturbine.com/wind-turbines-blades.htm Three blade turbine]]]

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