Rotor blades

Modern wind turbine rotor blades can rotate at verifying speeds, because of the design of the wind turbine generator. Due to the use of aluminum and composite materials in the blade construction, modern rotor blades’ rotational inertia is low, which makes it possible for the modern wind turbines to quickly accelerate, when the wind picks up. The low rotational inertia results in the tip speed ratio being at an almost constant, which means that the wind turbine can improve the energy capture from gusts of wind.

The older wind turbines designed with the much heavier steel blades, resulted in a higher rotational inertia, and their rotation speed was governed by the power lines’ AC frequency.  

Today most rotor blades are made from glass fibre reinforced plastics. Carbon and aramid can also be used as reinforced materials, but these are uneconomic when used for larger wind turbines.