Re: How does a windmill make energy?

       Dear Joe:
Early windmills used the energy of the wind to drive grist mills or water 
pumps. Windmill pumps are still a common way of filling stock watering tanks in 
remote locations. A modern electrical windmill "makes" energy by using 
the energy in the wind to push coils in a generator through magnetic fields - 
this is very hard work as you might discover from riding a push bike with an 
electric generator!
The way a modern windmill works is very subtle.  You might notice that the
direction the blades travel is ACCROSS the wind direction and not
downwind as you would be blown along the road!
Moveover, everyone asks why there are only 2 or three blades and they
seem to be running so slowly.  Surely the wind would go between the
blades!
The answer is that the blades actually go a lot faster than the wind -
about 7 times - and the shape of the blade in cross section is very
complicated so as to produce force in the direction around the path,
rather than just down wind. 
I recommend that you go and stand right underneath the machine when it is
running and watch very closely!
Regards,
Kali