My understanding is that it takes a few years of operation of the turbine in order to make up for the fuel, materials and pollution due to its manufacturing. After that it starts to show a positive benefit. I don't know what that time frame is. A problem they do have is disposal of worn out blades. The materials they are made of are not readily, if at all, recyclable. It may be a toss up as to what's worse, the turbine itself or the pollution they prevent from happening during their lifetime. To me, the holy grail of energy production would be fusion energy ("star in a jar"). If that can ever be mastered on a commercial scale, our energy problems would be over.