Web giant Google on Thursday revealed what had been one of its most closely guarded secrets: how much power it uses to fulfil its mission of organising the entire world’s information.

In a blog posting, Urz Hoelzle, the company’s senior vice-president of technical infrastructure, said that the company used 2.26 billion kilowatt hours of electricity in 2010 — the equivalent of some 200,000 U.S. homes. The company also emitted 1.46 million metric tons of carbon dioxide, equivalent to the yearly emissions of 70,000 Americans.

While this may seem like a lot, Google notes that its data centres actually use only about half as much energy as the industry average and that the total figure includes all the energy used by the company’s facilities and its 29,000 employees. The figure also encompasses the energy used for all Google services, including such relative energy hogs as YouTube.

“At Google, we’ve worked hard to minimise the environmental impact of our services,” the company said in a new website tracking its energy consumption. “In fact, to provide you with Google products for a month, our servers use less energy per user than leaving a light on for 3 hours. If you add in our renewable energy and offsets, our footprint is zero.”

Keywords: Google