US researchers calculate that 20 times as much wind energy generation is possible worldwide than previously estimated -- much more than enough to satisfy the world's current electricity consumption. Stanford University researchers measured wind at 8000 points around the globe and determined that nearly 13% of the earth experiences "Class 3 winds" at a height of 80 metres -- an acceptable 6.4-7 m/s for generation using very tall wind turbines. About 72 terawatts of wind power are available worldwide, say the researchers, while the world's annual electricity usage is approximately 1.8 terawatts. In 2002, the American Department of Energy estimated world wind potential at 3.45 terawatts, significantly less than the Stanford study. Researchers Cristina Archer and Mark Jacobson say North America has the greatest potential, with some of the most consistent winds in the Great Lakes region and along the eastern, western and southern coasts. But strong winds were also measured along Europe's North Sea, the southern tip of South America and the Australian island of Tasmania. "The main implication of this study is that wind, for low-cost wind energy, is more widely available than was previously recognised," says Archer. Converting a mere 20% of that potential to electricity could satisfy all the world's energy demand. Considerable practical barriers remain to realising this potential. Foremost, researchers say, is creating and maintaining perhaps millions of turbines to produce an acceptable level of energy.