As more U.S. companies commit to environmental responsibility, the U.S. Environmental Protection Agency (EPA) has named PepsiCo as the country's largest corporate buyer of renewable energy.

The company will buy more than 1.1 billion kilowatt-hours of renewable energy certificates over the next three years - enough, according to PepsiCo officials, to offset the electricity used at all of Pepsi's U.S. manufacturing facilities, distribution centers, headquarters, and regional offices. The EPA estimates that, based on national average emission rates, PepsiCo's purchase is the same amount of electricity needed to power 90,000 American homes annually.

Wells Fargo & Co. was second on the EPA list, with Whole Foods Market, the U.S. Air Force, and Johnson & Johnson coming in third, fourth, and fifth, respectively.