Yes, not only gray :-)
Seriously, we commissioned a study to see what the impact of cloud computing is not only to efficiency but the the environment. Can you save CO2 by moving to the cloud? I think its something we do not look at often enough. As pictures say more than 1000 words, here you see the overview of the results:
This is fairly significant. The whole study can be found here: Is cloud computing also "greener" computing?
Roger