I am not convinced, yet.

“As the data center industry grows increasingly obsessed with energy efficiency, cloud computing presents a compelling opportunity to reduce data center power bills, according to a leading expert on IT power issues. 

‘There are powerful economic factors pushing us towards cloud computing,’ said Jonathan Koomey , a researcher who has studied data center energy use at Stanford and Lawrence Berkeley National Labs. ‘One of the major reasons is the more efficient use of power by cloud computing providers.’”

Link here.