Based on the estimated electricity use of Google's data centers published by Jon Koomey, Data Center Knowledge believes that Google currently runs about 900,000 servers to power its empire.
Google representatives apparently told Koomey, who publishes an influential annual data center power consumption report for the New York Times, that Google's data centers consumed less than 1 percent of the world's combined data center electricity consumption of about 198.8 billion kWh in 2010. Google's computers could be using somewhere in the neighborhood of 220 MW, which would point about 900,000 servers, Koomey believes. The researcher also noted that Google provisions about 50 MW of available power for its largest data centers, which could indicate that Google is preparing for significant expansion in the future.
“Google’s data center electricity use is about 0.01% of total worldwide electricity use and less than 1% of global data center electricity use in 2010,” Koomey writes in his report. “This result is in part a function of the higher infrastructure efficiency of Google’s facilities compared to in-house data centers, which is consistent with efficiencies of other cloud computing installations, but it also reflects lower electricity use per server for Google’s highly optimized servers.”
Koomey noted that Google's data centers account for about 0.01 percent of total worldwide electricity use.