Study suggests real-world generating capacity of wind farms at large scales has been overestimated

From Phys.Org: Study suggests real-world generating capacity of wind farms at large scales has been overestimated http://phys.org/news/2013-02-real-world-capacity-farms-large-scales.html ""People have often thought there's no upper bound for wind power—that it's one of the most scalable power sources," says Harvard applied physicist David Keith. After all, gusts and breezes don't seem likely to "run out" on a global scale in the way oil wells might run dry. Yet the latest research in mesoscale atmospheric modeling, published today in the journal Environmental Research Letters, suggests that the generating capacity of large-scale wind farms has been overestimated. Each wind turbine creates behind it a "wind shadow" in which the air has been slowed down by drag on the turbine's blades. The ideal wind farm strikes a balance, packing as many turbines onto the land as possible, while also spacing them enough to reduce the impact of these wind shadows. But as wind farms grow larger, they start to interact, and the regional-scale wind patterns matter more.
Keith's research has shown that the generating capacity of very large wind power installations (larger than 100 square kilometers) may peak at between 0.5 and 1 watts per square meter. Previous estimates, which ignored the turbines' slowing effect on the wind, had put that figure at between 2 and 7 watts per square meter. In short, we may not have access to as much wind power as scientists thought."