The data you send through google spends very little time touching their own equipment, so the energy efficiency is of little , if any impact unless it can be spread to a majority of the providers whose equipment my data touches on its was to and from google.. A quick traceroute shows me that there ar 10 router hops in between my Laptop and www.gmail.com. If all the 10 devices are not 'green' , then what net impact does Google's data center being 'green' have?