A wind turbine with a rotor diameter of 50 m is rated at 2500 kW at a hub height wind speed of 10 m/s. It has a cut-in wind speed of 4 m/s and a cut-out speed of 21 m/s. Assume that this machine is located at a site where the mean wind speed is 7 m/s and that a Weibull wind speed distribution can be used with a shape factor of 2.2.
a) Calculate the number of hours per year that the wind is below the cut-in speed.
b) Calculate the number of hours per year that the machine will be shut down due to wind speeds above the cut-out velocity.
c) Calculate the energy production (kWh/yr) when the wind turbine is running at rated power.