Question

Suggest why some of the kinetic energy of the air that passes through the circular area
swept out by the blades is not converted into electrical energy.

Answer 1

Answer:

If the wind imparted all its energy then the air would not travel past the propeller blades of the turbine. If it doesn't complete its path past the turbine, then the wind can't spin the turbine. So it cannot harvest all the energy.

Answer 2

Answer:

Speed of air not reduced to zero (in passing through turbine)

OR some air passes through the blade area without a change of speed OR

without hitting blades

OR not all k.e. of air transfers to blades

OR air retains some of its k.e.

OR friction in bearings of blades