Wind

“The analysis indicates that a network of land-based 2.5-megawatt (MW) turbines restricted to nonforested, ice-free, nonurban areas operating at as little as 20% of their rated capacity could supply >40 times current worldwide consumption of electricity, >5 times total global use of energy in all forms. Resources in the contiguous United States, specifically in the central plain states, could accommodate as much as 16 times total current demand for electricity in the United States.”  Read the entire article “Global potential for wind-generated electricity.”  http://www.pnas.org/content/106/27/10933.full?sid=155cea58-cfc5-47f9-a8af-a45bcacfce71

Notice that world energy is pretty different from world electricity and we always have to pay attention to which is being discussed.  We could infer from this article that electrical energy is something like 1/8 of total energy.