Kinetic energy is the energy associated with motion. All moving objects have kinetic energy. The turning generator creates a field that forces electrons to move through the power line. Moving electrons form an electric current. Thus, a windmill transforms the kinetic energy of air into electric current.
Potential energy is stored energy.
Batteries, food, and water behind a dam are examples of potential energy. To answer this question, we must first calculate kinetic energy of the wind. In order to calculate the kinetic energy of the air moving a windmill blade, we first must calculate the mass of the air. This is not the problem that it appears. Thus it will be easier to calculate power than to calculate kinetic energy.