A 100 percent energy efficient machine would change all the energy put into the machine into useful energy. It would not waste any energy. Wind machines are just as efficient as coal plants. Wind plants convert 30 percent of the wind's kinetic energy into electricity. It is the capacity factor of wind plants that puts them a step behind other power plants.
Capacity factor refers to the capability of a plant to produce energy.
A plant with a 100 percent capacity rating would run all day, every day at full power. There would be no down time for repairs or refueling, an impossible dream for any plant. Wind plants have about a 25 percent capacity rating because wind machines only run when the wind is blowing around nine mph or more. In comparison, coal plants typically have a 75 percent capacity rating since they can run day or night, during any season of the year. That is enough electricity for about 50 homes per year.