The online giant said on Tuesday that all of its data centers around the world will 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 last 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.