The EPA wrote a report for the US Congress about it in 2006, and they estimated that servers and data centers represented about 1.5% of total electricity usage in the country for that year. That’s 61 billion (with a ‘b’) kilowatt-hours, and that’s for 2006, back when most people were just starting to discover Youtube. It’s probably more now.
virtual servers and website hosting called EC2 may be one solution.
virtual servers (one box with lots of memory, CPU and hard disk) let smaller websites that don’t need a whole computer get a “slice” of a computer. It operates just like a regular server to any given customer, but multiple customers can use a single box.
– from treehuggers
http://jagadees.wordpress.com/2008/06/04/us-servers-and-data-centers-gobbled-up-61-billion-kwh-in-2006