Google has for the first time released details about the energy consumption of its data centres
Google has revealed it used 2,259,998 MWh of electricity last year – enough to power 200,000 homes – but claims that many of its cloud-based services are up to 80 times more efficient than traditional alternatives.
The Internet search giant published its energy usage for the first time on Thursday, via a new web page called “The Big Picture” on it’s Google Green site. While admitting to be one of the largest users of data centres, Google claims that its facilities use only 50 percent of the energy of most other data centres.
“To provide you with Google products for a month – not just search, but Google+, Gmail, YouTube and everything else we have to offer – our servers use less energy per user than a light left on for three hours,” said Urs Hoelzle, Google’s senior vice president of technical infrastructure, in a blog post.
Less that a percent of data centre energy
The company cited an independent study by Jonathan Koomey of Stanford University, showing that the company as a whole uses less than one percent of the electricity used by data centres globally, and less than 0.01 percent of total worldwide electricity use.
“This result is in part a function of the higher infrastructure efficiency of Google’s facilities compared to in-house data centres, 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,” the report stated.
Google’s own figures show that its data centres have a 12-month average Power Usage Effectiveness (PUE) rating of 1.15, largely due to free cooling techniques such as evaporative cooling and sea-water cooling. The PUE score of a data centre is the energy delievered to it, divided by the energy which actually reaches the server racks.
“Our servers lose only a little over 15 percent of the electricity they pull from the wall during power conversion steps, less than half of what is lost in a typical server,” the company claimed. “Efficient power conversion pays real dividends: we estimate an annual savings of over 500 kWh per server over a typical system.”
Google emphasised that, despite producing 1.46 million metric tons of carbon dioxide in 2010, the company has been carbon-neutral since 2007. This is largely due to its use of renewable energy – including a large solar panel installation at its Mountain View campus, and two wind farms dedicated to providing power for Google’s data centres.
These projects have helped to generate over 1.7 GW of clean electricity – enough to power more than 350,000 homes. This is far more electricity than Google needs to run its own facilities, so any surplus power is pumped back into the grid, resulting in a reduction of carbon for the rest of the world.
“For the greenhouse gas emissions we can’t eliminate, we purchase high-quality carbon offsets,” added Hoelzle. This means investing in projects that reduce carbon emissions at another source outside of Google. For example, the company pays for reductions in emissions from a landfill near one of its data centres.
By investing in these projects, Google’s total climate impact ends up being zero, meaning that its cloud products and services are carbon neutral.
Is cloud computing green?
The statistics should add fuel to the debate over whether the cloud is inherently green. A report from analyst firm Forrester earlier this year found that the self-service and pay-as-you-go nature of cloud computing encourages users to consume only what they need, driving energy and resource efficiencies.
Meanwhile, consolidation and virtualisation – which are inherent to cloud data centre environments – help to reduce the total physical server footprint. Fewer servers mean that less electricity is consumed, and also cuts down on potential e-waste, as well as the embodied energy in the servers.
As cloud environments – whether private or public – tend to be shared between a number of users, economies of scale in energy use and infrastructure resources can also be achieved.
However, many cloud initiatives fail to maximise other green opportunities, including the use of renewable sources of energy, ‘design-for-environment’ policies – such as recyclability, reduction of toxic chemicals, reduction in packaging, and longevity – and environmentally-friendly disposal of e-waste, according to Forrester.