Last year, Google used 5.7 terawatt-hours of electricity--enough to power the entire city of San Francisco, according to The New York Times. That would be one heck of a carbon footprint, to say the least.

But the Silicon Valley company says it plans to completely offset its environmental impact. Next year, Google says, it will reach 100 percent renewable energy for its data centers and offices around the world. Senior vice president Urs Hö?lzle made the announcement in a blog post on Tuesday.

Google has been making an active effort to buy renewable energy since 2007, when it publicly vowed to become carbon neutral by the end of the year. In 2010, the search giant agreed to buy all the energy from a wind farm in Iowa--enough to power several of its data centers. The company has 13 massive centers throughout the world, including locations in Oklahoma, Oregon, North Carolina, Belgium, and Finland. In 2015, Google covered about 44 percent of its power needs through renewable sources.

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Reaching the 100 percent figure doesn't mean that every Google office, server, and computer will be powered directly by renewable energy. Google gets its electricity from power companies, which get their energy from a variety of sources like coal, wind, gas, sunlight, and hydroelectric dams.

Through a variety of contracts with renewable energy companies, Google agrees ahead of time to buy amounts of green energy to offset its consumption. Next year, Google says its net consumption of fossil fuels will be zero.

Beyond good PR, there are business advantages to this move for Google. Wind energy prices remain constant, allowing Google to budget for its energy consumption more accurately. And in some cases, wind and solar power can be less expensive than fossil fuels. Because of advances in technology, solar energy prices have come down by 80 percent since 2010--a big reason why the industry has doubled in size during that time.

Wind prices have come down by 60 percent during the same period. The Times reports that 95 percent of Google's energy investments next year will come from wind turbines.

Other tech giants have made similar commitments to renewables. Amazon is the world's second-largest consumer of renewable energy, buying about half the amount of green energy annually that Google does. Facebook last year announced it was building a data center in Texas powered entirely by wind energy. And Microsoft hopes to have 50 percent of its energy usage come from renewables by 2018.

For all the energy Google consumes, the number has the potential to be even higher. The company says its data centers are 50 percent more efficient than the industrial average.