Mary,

It breaks down like this: a vane driven wind generator creates power by redirecting / slowing down air as it passes through the vanes. It literally takes energy from the moving air and transfers it to mechanical motion and then generates electricity from it. Conservation of Energy (physics term) is a physical property of any closed loop energy system. It's just like pouring water between two buckets where you can't pour 1 gallon into the second bucket and get 2 gallons. You can only get 1 gallon in a perfect pour - you'll probably get a little less because of a drop or two spilled or evaporation.

If you divert X amount of energy from the moving air, you can only create "X-losses" amount of energy in electricity. The losses (which can be pretty signifiant) mechanical and mechanical/electrical energy leaks ... i.e. "spillage" that mostly comes from friction and is the energy lost by converting it to heat. The heat generated from the moving parts is energy lost from the vanes in the generator and the electrical energy that comes from the system is actually less than the energy being pulled from the moving air. There are other losses associated with the conversion of the mechanical motion to electrical energy.

Looking at the big picture of the closed system, in order for the blades to spin on a wind generator, they slow down the passing breeze by redirecting it's flow. There is a backwards push on the generator roughly equal to the amount of energy that it's extracting. This backwards push is creating drag on the car moving down the road that is at best, equal to the amount of energy being pulled from the moving air - the bucket thing again. If we could figure out how to extract MORE energy from the air than is lost in drag, you would have created the equivalent of a perpetual motion machine in that it actually has found a way to make 1+1 = 3. (which is thusfar proven impossible). Now that I made that really confusing...any questions?