The latest assessment by the National Renewable Energy Laboratory more than tripled the wind energy potential of the United States. Why?

As I reported at Wired Science, wind speed generally increases with height, and most wind turbines are taller than they used to be, standing at about 250 feet (80 meters) instead of 165 feet (50 meters). Turbines are now larger, more powerful and better than the old designs that were used to calculate previous estimates.

“Now we can develop areas that in [previous decades] wouldn’t have been deemed developable,” Michael Brower, chief technology offier with AWS Truewind, which carried out the assessment, told me. “It’s like oil reserves. They tend to go up not because there is more oil in the ground but because the technology for accessing the oil gets better.”