MINCO, Oklahoma (NYTIMES) - Last year, Google consumed as much energy as the city of San Francisco. Next year, it said, all of that energy will come from wind farms and solar panels.

The online giant said Tuesday (Dec 6) that all of its data centres around the world would be entirely powered with renewable energy sources sometime next year.

This is not to say that Google computers will consume nothing but wind and solar power. Like almost any company, Google gets power from a power company, which operates an energy grid typically supplied by a number of sources, including hydroelectric dams, natural gas, coal and wind power.

What Google has done over the past decade, with relatively little fanfare, is participate in a number of large-scale deals with renewable producers, typically guaranteeing to buy the energy they produce with their wind turbines and solar cells. With those guarantees, wind companies can obtain bank financing to build more turbines.

The power created by the renewables is plugged into the utility grid, so that Google's usage presents no net consumption of fossil fuels and the pool of electricity gets a relatively larger share of renewable sources.

"We are the largest corporate purchaser of renewable energy in the world," said Joe Kava, Google's senior vice president of technical infrastructure.

"It's good for the economy, good for business and good for our shareholders."

Whether Google is the largest buyer of renewables would be difficult to verify, as many industries do not release data on how much energy they consume.

There is no doubt, however, that Google's large computer complexes, along with similar global operations by Amazon and Microsoft, are among the world's fastest-growing new consumers of electricity.

Google hopes that success in working with large wind farms, like the 50,000-acre facility in Minco, Oklahoma, which supplies Google's large data centre in Pryor, Oklahoma, will spur development of the industry.

The 5.7 terawatt-hours of electricity Google consumed in 2015 "is equal to the output of two 500 megawatt coal plants," said Jonathan Koomey, a research fellow at Stanford University's Steyer-Taylor Center for Energy Policy and Finance. That is enough for two 140,000-person towns.

"For one company to be doing this is a very big deal. It means other companies of a similar scale will feel pressure to move."