How much electricity does sharing a photo on Facebook take? How much carbon does it put into the atmosphere?

Facebook doesn't reveal how much energy it uses. But overall, the vast computer farms that handle Internet data now use up 1.3 percent of the electricity generated globally. Facebook's energy use has been growing particularly fast. It processes more than 250 million photo uploads each day, and some two million "like"s and comments every minute.

Energy is foremost a competitive issue for Facebook. The computers, facilities, personnel, and electricity needed to keep your profile up to date, and available anywhere, are the company's largest single expense. That's one reason Facebook began to design and build more energy-efficient server farms from scratch. Its first data center, opened last April in Prineville, Oregon, uses 38 percent less energy than other facilities to do the same work, according to the company.