Google says its data centers are the most efficient

Claims an average PUE of 1.21

Google's leadership on the Web stems partly from its powerful data centers, which allow it to provide lightning-fast search results while keeping energy costs to a minimum. The company has been mostly secretive about what goes on inside these giant computing factories, but on Wednesday it offered a peek at what it has been able to achieve -- on the energy side, at least.

Google has published results from internal studies showing that its data centers are "the most efficient in the world," according to a blog post from Urs Hölzle, its senior vice president of operations. Some of what Google does, like designing its own servers, isn't practical for most businesses, but other tricks could be replicated by other companies, albeit for an upfront capital cost.

This announcement coincides with a speech about energy that CEO Eric Schmidt gave Wednesday evening in San Francisco, in which he proposed a $4.4 trillion clean-energy plan.

In a report to the U.S. Congress in 2006, the Environmental Protection Agency estimated that the typical enterprise data center had a PUE of 2.0 or higher. The PUE -- or Power Usage Effectiveness -- scale measures the power devoted to IT equipment running applications; it doesn't factor in the power consumed by support functions such as cooling and power distribution. The EPA also forecast that by 2011, data centers employing "state-of-the-art" techniques such as liquid cooling could reduce their PUEs to 1.2.

Google said Wednesday that it has achieved an average PUE of 1.21; that's the average across all of its data centers. One of Google's data centers operates with a PUE of 1.13. "Today we are operating what we believe to be the world's most efficient data centers," Hölzle wrote.

That's no small claim, given that many of its competitors are also experimenting with data center designs to improve efficiency. Microsoft has been packing servers into shipping containers, creating a closed environment that allows it to manage cooling more efficiently. The company said recently it had achieved a PUE of 1.3 in one of these containers. They are not widely used yet, but Microsoft plans to put more than 200 of them at a new data center in Chicago.

Google starts its energy push by designing better servers, which typically waste one-third of the energy they consume before any of it reaches the components. The company uses highly efficient power supplies for the servers and efficient voltage regulators on the motherboards. It said it also strips out components that it doesn't need, like graphics chips, and designs computers and server racks to use as little fan power as possible.

The company says it saves $30 and 500 kilowatt-hours per year for each server, and puts 300kg less carbon dioxide into the atmosphere.

For its data centers, it focused on cooling, which can account for up to 70% of the overhead in energy use. It uses water evaporation to minimize the use of its chiller equipment, which is basically a large air conditioner for the data center. It showed a photograph of a large cooling tower in Oregon that it uses for water evaporation.

"With cooling towers, our data centers spend most of their time running in a mode called 'free cooling.' This means the chillers are off. Free cooling isn't technically free, but it is really inexpensive and really efficient," the company said.

Google is also using recycled water for its cooling to relieve the strain on the environment. A data center that it's building in Belgium will use only recycled water, pulled from a nearby canal and run through a filtration system. By 2010 it hopes that 80% of all the water it uses will be recycled.

"Sustainability is good for the environment, but it makes good business sense too," the company said. "Most of our work is focused on saving resources such as electricity and water, and more often than not, we find that these actions lead to reduced operating costs."

Copyright © 2008 IDG Communications, Inc.

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