from Official Google Blog: Powering a Google search: "Together with other work performed before your search even starts (such as building the search index) this amounts to 0.0003 kWh of energy per search, or 1 kJ. For comparison, the average adult needs about 8000 kJ a day of energy from food, so a Google search uses just about the same amount of energy that your body burns in ten seconds"
I do 30 - 40 google search per day. Sometimes less, and sometimes more.
That's say .... 30 * 1kJ... I spent 30kJ energy per day on google search ~.~"
BUT... the energies I spent on typing keywords, clicking links, etc ... are not counted =]
Perhaps ... I might spent 80kJ per day as a sum ~~ lol
I really like GOOG. It's really doing a good business!