I’m still (ha! always?) catching up with old New Yorkers, so forgive me that this statistic is from the Dec 20/27 2010 issue: prediction—by 2014, the computer network in the USA will require the amount of energy used by the whole country of Australia (now? author David Owen isn’t clear) to power it.
Add to that the power it takes the rechargers, and, whew, how efficient Wal-Mart makes its buildings and delivery trucks pales.
The article is called “The Efficiency Dilemma,” and starts here. Owen gets the statistic from Stan Cox, I think from his book Losing Our Cool.