http://www.labnol.org/internet/search/google-query-uses-1000-machines/7433/

 this is quite an incredible amount of power for one search

Google disputes it and says its not that much, but its still all incredible numbers when thinking of the totally daily searches that google processes. 

the energy usage is probably much higher with the explosion of streaming music on Pandora, last.fm, and thesixtyone.  but probably video streaming in hd uses even more energy.

but I don't really know how this works but I think we need to find out