I've made the simplest estimates of the energy efficiency of a windmill. Modern windmill weighs approximately 20 tonnes. Let's assume those 20 tonnes are just a big chunk of steel. To produce a tonne of steel one needs approximately 30GJ of energy. Let's assume winmill power is 2MW. Then in the best case a windmill produces 2*365*24=17.5 GJ per year. Therefore, just to get even a windmill must work for approximately 40 years uninterrupted. So where is energetical point of so called wind energy? Without abundant supply of fossil fuels to manufacture a mill wind energy is deadborn. It doesn't appear to be an energy "source". Am I wrong?