How much energy does the internet really use?

A lot – although exactly how much is still not clear. The question is becoming a hot topic, not least thanks to a Guardian report in which senior officials voiced concerns over the growing financial and environmental cost of powering vast internet data centres as it expands.But the energy footprint of the entire internet is much more than data centres – it includes the devices we consume the internet on (computers, mobile phones, iPods and more) as well as the telephone exchanges that deliver information.
http://www.guardian.co.uk/technology/2009/may/14/internet-energy-savings