energy saving

Google finally fesses up about energy use

Every time you click “Search”, Google’s data centres and servers use about the same amount of energy that your body burns in ten seconds. A useful fact, not really, but what is more interesting are the data released yesterday by the search giant about its overall energy use. Shy to reveal such data, Google has taken the historic step of publishing figures on its energy consumption: continuously enough energy to power 200,000 homes or about 0.01% of global electricity use.
Google finally fesses up about energy use

In a blog post yesterday, Urs Hölzle, Google’s Senior Vice President of Operations, explained that his company had taken the decision to publish details of its energy use to refute claims that a typical search uses "half the energy as boiling a kettle of water" and produces 7 grams of carbon dioxide. “We thought it would be helpful to explain why this number is many times too high,” said Hölzle, who went on to explain that each search uses about 0.0003 kWh of energy per search, or 1 kJ “together with other work performed before your search even starts (such as building the search index)”. For comparison, explained Hölzle, “the average adult needs about 8000 kJ a day of energy from food, so a Google search uses just about the same amount of energy that your body burns in ten seconds”.

In electricity terms, Hölzle explains that 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. This equates to about 180 watt-hours a month, or the equivalent of running a 60-watt light bulb for three hours.

Equivalent to doing dirty washing

In terms of greenhouse gases, Google estimates that one of its searches emits the equivalent of about 0.2 grammes of carbon dioxide. That means a typical individual's Google use for an entire year would produce about the same amount of carbon dioxide as just a single load of washing.

“The current EU standard for tailpipe emissions calls for 140 grams of CO2 per kilometre driven, but most cars don't reach that level yet. Thus, the average car driven for one kilometre produces as many greenhouse gases as a thousand Google searches,” says Hölzle.

While these figures are interesting, the headline figures published for the first time yesterday by Google are more revealing, especially given that the company has kept statistics about its energy use secret until now.

2,259 GW per annum

Google uses 2,259,998 MWh of electricity, about a quarter of the output of a nuclear power plant, and its operations produce 1,457,982 metric tonnes of carbon dioxide equivalent. The company reveals that the largest proportion of its electricity use comes from data centres, which produce (together with Google offices) 1,226,350 metric tonnes of carbon dioxide equivalent. “To give those big figures a bit of context, Googleland would rank as 132 largest country in terms of electricity usage - larger than 82 countries in the world – and its energy use is still growing fast,” explains Tom Dowdall, climate and energy campaigner at Greenpeace, who also blogged on Google’s figures yesterday.

Nonetheless, Google’s Hölzle argues that “the energy used per Google search is minimal” thanks to the “the most energy efficient data centres in the world”. Indeed his company asserts that the world is a greener place because people use less energy as a result of the billions of operations carried out in its data centres. Google says people should consider things like the amount of gasoline saved when someone conducts a Google search rather than, say, driving to the library.

In an article in the New York Times today, Noah Horowitz, senior scientist at the Natural Resources Defense Council in San Francisco, welcomed Google’s figures, but stressed that despite the advent of improvements in energy efficiency, electricity use at data centres was still rising because every major corporation now relied on them. He also warned that the data did not include the power drawn by the personal computers, tablets and iPhones that use information from Google. “When we hit the Google search button,” Mr. Horowitz said, “it’s not for free.”

25% renewables

That said, Greenpeace’s Dowdall does say there is a silver-lining to Google's energy figures. "The good news? Google used renewable power for 25 percent of its operations in 2010 and will increase this to 35 percent in 2012 through direct investment in renewable energy,” he says, adding that Greenpeace estimated Google’s data centres to be 36% renewable powered in its “How Dirty is Your Data?” report.

“Based on our estimates, only Yahoo! uses more clean energy at 55%. Google products such as Gmail and YouTube appear to have a relatively small footprint when measured on a per person basis. This is certainly due in part to its relatively high use of renewable energy and running efficient data centres, and also having a large user base it can spread this consumption across,” comments Dowdall, who mentions that Greenpeace has been pushing Google and all IT companies to be more transparent as part of its Cool IT leaderboard.

In its Dirty Data analysis of the power consumption and energy-source choices of data centres, Google scored “a big fat F for transparency”, although Dowdall says that if Greenpeace were giving out new grades based on Google’s figures, it would likely earn a low to middle “B”.

“We've made great strides to reduce the energy used by our data centres,” says Urs Hölzle, “but we still want clean and affordable sources of electricity for the power that we do use”. In 2008 the company’s philanthropic arm,, invested $45 million in breakthrough clean energy technologies. And last summer, it created an internal engineering group dedicated to exploring clean energy as part of its Renewable Energy Cheaper than Coal initiative (RE

“We're also working with other members of the IT community to improve efficiency on a broader scale. In 2007 we co-founded the Climate Savers Computing Initiative, a group which champions more efficient computing. This non-profit consortium is committed to cutting the energy consumed by computers in half by 2010 — reducing global CO2 emissions by 54 million tons per year. That's a lot of kettles of tea,” Hölzle ends.

Data centres demand 1.5% of global electricity

Growth in data centre electricity use 2005 to 2010 by Stanford consulting professor Jonathan Koomey describes trends in data centre electricity use since 2005. According to Koomey, electricity used in global data centres in 2010 likely accounted for between 1.1% and 1.5% of total electricity use, respectively. For the US that number was between 1.7 and 2.2%.

Koomey estimates that after rapid rates of growth in data centre electricity use between 2000 and 2005, power consumption slowed significantly from 2005 to 2010, yielding total electricity use by data centres in 2010 of about 1.3% of all electricity use for the world, and 2% of all electricity use for the US.

While Google is a high profile user of computer servers, less than 1% of electricity used by data centres worldwide was attributable to that company’s data centre operations. This makes Google responsible for about 0.01% of global electricity use.

“There is a lot of good info that Google has put out, including more detail on how it can claim to be ‘carbon neutral’, which we’ll have more to say on that later, but as a customer of Google and other ‘Cloud’ computing companies, we need to see others put their numbers and plans for clean energy on the table, both to help customers make more informed decision about the carbon impact of different online services, and hopefully to spur greater transparency and competition for improved performance that the IT sector is so known for,” Dowdall concludes.

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