Google is the first web firm to reveal how much energy it consumes, this information will help researchers understand how the massive explosion of Internet consumption and cloud computing is contributing to global energy consumption.

Google consumes 260 million watts continuously across the world,the company reported on Wednesday. This is equivalent to the power used by all the houses in Richmond, Virginia, or Irvine, California (around 200,000 houses), and nearly a quarter of the output of a standard nuclear power plant.

Until now, the most of Google's energy use is tied up in its data storage centers, according to Jonathan Koomey who is a professor at Stanford University and a researcher who focuses on energy and IT. He says that nearly 220 million of these watts are used only by the company's data centers, based on figures Google showed him . Most of this energy is used in cooling data center systems. Google custom builds many data centers, for example a new one in Finland that uses a seawater cooling system, to cool the system.

This has made Google to be relatively energy efficient, says Koomey, who estimates that the company owns about 3 percent of servers worldwide and uses only 1 percent of electricity for data centers worldwide. "They're operating more efficiently than other data centers," he says.

In its report, Google compares the energy usage of companies' in-house computer systems to the energy used by its cloud servers. It estimates that running Gmail instead of an in-house e-mail system can be almost 80 times more efficient .Google says that 25 percent of its energy was generated by renewable fuels, from wind farm in 2011, and plan to increase that to 30 percent this year.

Sherif Akoush, a researcher at the University of Cambridge who studies IT energy consumption, indicates that Google could be even more energy efficient, and notes that the company's environmental works will continue to rise. "Google tackles this problem mainly by using power purchase agreements from green sources, which offset basically the emissions from its data centers," says Akoush. Instead, "it should just try to apply more radical solutions like green energy and be a zero-carbon company instead of pumping waste then trying to clean it up."

Bruce Nordman who is a researcher at the Lawrence Berkeley National Laboratory, notes that most IT-related energy usage occurs from homes and offices, and not major data centers.

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