Therefore, a multiyear monitoring program is the only reliable method to determine the true wind speed at a location. In physics, energy is defined as the ability to do work. While this definition is technically correct, it is not very meaningful in this form. These are really the same question. It is useful to differentiate between kinetic energy and potential energy.
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.