Wind energy is soaring in the U.S.; the nation’s renewable energy capacity has more than tripled in the past nine years, and wind and solar power are largely responsible. Now businesses want to harness even more wind energy, at a cheaper price—and one of the best ways to lower cost is to build bigger turbines. That’s why an alliance of six institutions led by researchers at the University of Virginia are designing the world’s largest wind turbine at 500 meters tall—almost a third of a mile high, and about 57 meters taller than the Empire State Building.

Turbines are already noticeably larger than they were 15 or 20 years ago. Size varies, but today’s typical wind farm towers stand around 70 meters tall, with blades about 50 meters long. Their power output depends on size and height, but it generally ranges between one and five megawatts—on the upper end, that’s enough to power about 1,100 homes. “There's this motivation to go to larger wind turbines, and the reason is pretty much economics,” explains John Hall, an assistant professor of mechanical and aerospace engineering at the University at Buffalo, S.U.N.Y. One reason giant turbines are more cost-effective is that wind blows stronger and more steadily at greater altitudes.