Starbucks said the move, using power from around 11 large-scale windmills, would shave two per cent off its annual carbon dioxide emissions.
"Starbucks is mindful of the long-term implications that climate change has on the environment," said Sandra Taylor, company senior vice president of corporate social responsibility.
"Because the energy used at our retail stores makes up nearly 50 percent of our total greenhouse gas emissions, this is a natural starting point for us. By supporting renewable energy sources we believe we are taking a step in the right direction and encourage other businesses to do the same," she said.
Taylor added that Starbucks realised it was part of a global food economy and that climate change may hit its coffee growers in developing countries, not only harming their quality of life but also harming business.
The group's announcement follows efforts to promote its corporate social responsibility over the last few years.
The firm recently announced all its company-owned stores in the US would use partially recycled paper cups, and last autumn pledged to pay its coffee suppliers more money to encourage them to minimise their environmental impact.
Starbucks' new policy will not cover any of its franchised or overseas stores for now, yet its announcement is significant in the US after the Bush administration refused to sign the Kyoto Protocol setting out new global targets for reducing emissions.
Kyoto kicked in at the start of this year yet the absence of the US, as the world's largest polluter, was a major blow to the treaty's viability. Under it, industrialised nations must first cut CO2 emissions to about five per cent below 1990 levels by the period 2008-12.
The move by Starbuck's will already put the firm inside the top 25 US buyers of renewable energy.
And although the firm will only buy five per cent of it energy needs from wind farms, the move highlights how US food and drink firms could help to put climate change and carbon emissions on the radar even without initial government support.
Some analysts believe the US will eventually set emissions reduction targets anyway and that companies should be prepared to cut down.
Starbuck's said it had set an emissions reduction target for 2005 and had joined with World Resources Institute's Green Power Market Development Group.
"Starbucks is to be congratulated for taking a leadership stance on climate change. It is critical that US businesses aggressively take action if the most serious effects of climate change are to be averted," said Institute president Jonathan Lash.
However, Starbucks did not release details about the costs of using more renewable energy and price may remain a sticking point for many firms until new methods and resources are put forward to make such energy more widely available.