Earth’s Future Electricity (page 46)

A paper from Harvard that looked at the global wind energy potential found that a network of land-based 2.5 MW turbines restricted to non-forested, ice-free, non-urban areas operating at only 20% capacity (compared to 40% for most new turbines) could supply more than 40 times the world’s current use of electricity, and more than 5 times the world’s total use of energy. In the United States, specifically in the central plain states, wind could supply 16 times the current use of electricity

Source: PNAS, April 2009