Land area needed by Solar Energy to Power the Entire World!

The entire population of the world uses 18 terawatts (18 trillion watts) of energy per year.  The image below shows the total amount of land area that would be required for the whole earth to rely exclusively on Solar Energy.  (The black dots represent the total land area needed).

http://physics.ucsd.edu/do-the-math/2011/09/dont-be-a-pv-efficiency-snob/