A sneak peek into Google’s servers and energy efficiency

A report from data center energy expert Jonathan Koomey, published on Monday morning, gave a rare glimpse into some educated estimates for how many servers and how much electricity Google uses, and how energy-efficient those custom servers are.

Koomey estimates Google had 900,000 servers in 2010, more than double the estimated amount it had in 2005 of 350,000. At the same time, Google used a total of 1.9 billion kilowatt-hours of electricity in 2010, from its combined servers, storage, communications, and infrastructure, up from .7 billion kilowatt-hours of electricity in 2005.

Google doesn’t commonly reveal the number of its servers or its total electricity use — for competitive reasons, it says — so the estimates are valuable figures to remember.

Koomey crunched the Google numbers because he was looking for the total amount of electricity consumption for data centers in 2010 and was using figures from IDC. However, because Google creates its own servers, its server numbers aren’t included in the IDC figures. So Koomey wanted to see how big of an omission it was to use the IDC figure and exclude Google. He based the estimates for Google on known electricity use he got from Google and data center floor space, as well as from media reports.

Yet despite that Google has so many servers, Koomey’s research helps to show how efficient Google’s custom-designed servers and data center designs are. According to Koomey, Google is responsible for less than 1 percent of the electricity used by the world’s data centers, but is responsible for 2.8 percent of the world’s volume of servers.

One aspect of Google’s server design is that each server uses an on-board, lead-acid battery to create a distributed backup power system. Usually, data centers use a centralized backup system — such as a room full of batteries, generators or flywheels — but Google found that having a backup power system for each server could lead to an energy-efficiency rating for the backup power supply system of over 99.9 percent. A lot of the efficiency has to do with the fact that the electricity doesn’t have to be converted between a central backup unit and the servers.

Google does lots of other energy-efficient things for its data centers, too: It attempts to eliminate chillers and cooling by using outside air when it’s available; it turns up the heat for its data centers to 80 degrees; and it installs all the low-hanging-fruit tech for data centers, like using hot and cold aisles. (More details on Google’s data center efficiency tech on GigaOM Pro, subscription required).

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