From what I have read, the rating of a windmill is about 3 times what you actually get. So you need 3 wind mills to do the job of what one is rated to do. Just right there that is an inefficiency in the system. One other that is often overlooked is that the wind comes and goes. Sometimes it is there, sometimes not. Wind is not a reliable source of energy. The reliable sources (coal, gas, diesel, hydro, nuclear) then have to be variable to make up for them, which is not what they are designed to do. Again, an inefficiency. All this inefficiency drives up cost too word
mspart