Wind Turbine Blade Specifications

• Blades must meet certain requirements to be most effective. Richard Kolker/Photodisc/Getty Images

  Sitting atop the large towers stretched across open land in wind farms, rotor blades for wind turbines represent the signature feature of this alternative energy source. In order to maximize the potential for energy production, certain specifications have evolved for wind turbine blades.

Number of Blades

• The standard specification calls for three blades. Based upon research that determines the optimal number of blades, manufacturers agree that for large-scale industrial wind turbines, three blades produce the greatest wind power, or energy. The purpose of the blades is to turn the shaft that generates electricity, so three blades produce more energy than one or two blades. Research shows that a turbine with more than three blades does not add to energy production, so the industry standard is three blades.

Rotor Diameter

• Think of a circle with the ends of the blade touching the outside of the circle as they rotate. Rotor diameter is the same as the diameter of the circle the blades create as they spin. Longer blades create larger circles and thus more energy. Enercon blades are 44 meters, or 144.3 feet. The GE 2.5 MW wind turbine with its 100-meter, or 328-foot, blades are much larger and more powerful.

Swept Area

• This specification is based upon rotor diameter: the area the blades sweep, or cover. The longer blades cover more area, which explains why longer blades generate more electricity. Enercon lists 1,521 square meters, or 16,345 square feet. For the GE 2.5 MW turbine, 7,854 square meters translates to 84,453 square feet.

Material

• According to the specifications for the Enercon E-44 wind turbine, the blades are made from fiberglass with a coating of epoxy resin with lightning protection built in. The epoxy hardens the material so the blades can withstand the stress of many years in the wind.