Google took the unprecedented step of talking about how much electricity it takes to power YouTube, Gmail, search and other services in the internet “cloud”.

“Google products for a month... our servers use less energy per user than a light left on for three hours,” senior vice president of technical infrastructure Urs Hoelzle said in a blog post. “And, because we’ve been a carbon-neutral company since 2007, even that small amount of energy is offset completely so the carbon footprint of your life on Google is zero,” he continued.

The global internet giant added “The Big Picture” section to its Google Green website to provide insights into its energy use and environment-friendly practices.

Handling 100 searches at Google data centres burns the same amount of power it takes to light a 60 watt bulb for 28 minutes, according to The Big Picture.

Three days of streaming YouTube video requires as much energy as making, packaging and delivering a DVD. A year of providing free Gmail email service to a user takes less energy than drinking a bottle of wine, stuffing a message in the empty vessel and tossing it in an ocean, according to Google.

“For the last decade, energy use has been an obsession,” Mr Hoelzle said.

“We’ve designed and built some of the most efficient servers and data centres in the world; using half the electricity of a typical data centre,” he added. Google uses renewable energy whenever possible and has a large solar panel installation at its headquarters in the California city of Mountain View, according to Mr Hoelzle. And by investing in renewable energy projects, Google is helping create 1.7 gigawatts of green power.

“That’s the same amount of energy used to power over 350,000 homes, and far more than what our operations consume,” Mr Hoelzle said. Google released the energy figures as it promoted software applications offered as services on the internet as saving energy as well as money.