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Friday, November 23, 2012

How Much Energy is Consumed by a Google Search?

Times Online ran an article citing several studies about Internet use and the consumption of energy. Information used for this report suggested that Google searches are responsible for a large amount of CO2 emissions.  The article reads:
While millions of people tap into Google without considering the environment, a typical search generates about 7g of CO2 Boiling a kettle generates about 15g. “Google operates huge data centres around the world that consume a great deal of power,” said Alex Wissner-Gross, a Harvard University physicist whose research on the environmental impact of computing is due out soon. “A Google search has a definite environmental impact.”
Google is secretive about its energy consumption and carbon footprint. It also refuses to divulge the locations of its data centres. However, with more than 200m internet searches estimated globally daily, the electricity consumption and greenhouse gas emissions caused by computers and the internet is provoking concern. A recent report by Gartner, the industry analysts, said the global IT industry generated as much greenhouse gas as the world’s airlines – about 2% of global CO2 emissions. “Data centres are among the most energy-intensive facilities imaginable,” said Evan Mills, a scientist at the Lawrence Berkeley National Laboratory in California. Banks of servers storing billions of web pages require power.
In what appears to be a response to this article, Urs Hölzle, Senior Vice President, Operations at Google, has put up a post on the Official Google Blog. Hölzle says:
But as computers become a bigger part of more people’s lives, information technology consumes an increasing amount of energy, and Google takes this impact seriously. That’s why we have designed and built the most energy efficient data centers in the world, which means the energy used per Google search is minimal. In fact, in the time it takes to do a Google search, your own personal computer will use more energy than Google uses to answer your query…
We’ve made great strides to reduce the energy used by our data centers, but we still want clean and affordable sources of electricity for the power that we do use. In 2008 our philanthropic arm, Google.org, invested $45 million in breakthrough clean energy technologies. And last summer, as part of our Renewable Energy Cheaper than Coal initiative (RE

Electricity Use
Between those paragraphs, Hölzle explains why the estimates made in the article about Google’s energy consumption are too high, which also cites Second Life and Twitter as potential energy problems. I must admit that energy consumption is not something I often think about when using any of these sites, and even if the article is off in it’s numbers, the issue discussed is still an interesting one to consider.

A single Google query consumes as much energy as an 11-watt light bulb does in one hour

A single Google query consumes as much energy as an 11-watt light bulb does in one hour





Light Bulb
Photo by Knut
This article from tagesschau.de (German) claims that a single Google search query (taking less than a second) consumes as much energy as an 11-watt light bulb does in one hour. This number is based on the total number of servers Google is running, the total energy consumption of those servers, and the total number of search queries processed.
Rolf Kersten estimates that running a single Google query releases 6.8 grams of CO2 and consumes a bit less—2 to 8 watt-hours of energy.
(Thanks to Mareen for combing the German language publications.)