Read other letters about this article
then windpower would be producing all electrical energy in about just over 12 years (Google for "(log(100/1.5) /log(1.41)) years" -- it's 1.41 because overall annual energy growth in the world is "about" 2%).
Exponential growth is great... the question is how long you can keep it up. At a certain point, scale factors start to come into play as you use up the good places to put your fans.