How many windmills does it take to power the world?

My latest column on Scitizen entitled "How Many Windmills Does It Take to Power the World?" has now been posted. Here is the teaser:

Power densities are a measure of the land required for both energy sources and energy users. The current infrastructure matches the small footprint of energy sources against the large footprint of energy users. With the drive toward renewable energy sources, this relationship is about to be reversed with consequences few people understand.....Read more