Arkansas-based Wal-Mart has an eco-store in the suburbs of Denver that is powered by wind turbines and solar power, has sidewalks made of recycled airport runways; dirty cooking oil from the deli and used motor oil from the lube department are recycled to heat the store; spoiled food is turned into fertilizer and resold; its jewelry cases are made of renewable bamboo; it stocks tuna certified by the Marine Stewardship Council and coffee endorsed by the Rainforest Alliance. It is one of two experimental stores built by Wal-Mart to test ways to cut energy and reduce waste, according to the July 31 2006 edition of Fortune Magazine.