Here are two maps summarizing the surface area of the earth that would be needed to generate all electricity from solar or offshore wind alone, useful to put the maximum scale into context.

 

http://www.treehugger.com/files/2009/09/surface-area-required-to-power-the-whole-world-with-solar-power-wind.php?dcitc=th_rss

 

Dr. Stephen R. Humphrey, Director,
School of Natural Resources and Environment,
Box 116455, 103 Black Hall, University of Florida
Gainesville, FL  32611-6455  USA
Tel. 352-392-9230, Fax 352-392-9748
http://snre.ufl.edu