Mar 242010

Wind Kites

“There is enough energy in high altitude winds to power civilization 100 times over; and sooner or later, we’re going to learn to tap into the power of winds and use it to run civilization.”

Says Ken Caldeira, Professor of Global Ecology at the Carnegie Institution for Science. (Discovery Channel, Project Earth, Infinite Winds episode)

At any moment, the winds in high-altitude jet streams hold roughly 100 times more energy than all the electricity being consumed on Earth, according to a study by Stanford environmental and climate scientists Cristina Archer and Ken Caldeira.

To capture that energy, designers are dreaming up models of wind-turbine kites that fly so high, cruising airliners would have to steer around them. The tethered kites would float high enough for powerful jet streams to flow through their turbines more than 10 times faster than winds would flow near the ground.

The spinning rotors of the kite turbines would convert the wind’s kinetic energy to electricity and send it back down the wire 30,000 feet to a distribution grid.

Harnessing these high-flying currents could open up an effectively unlimited source of electricity, the researchers say. Kites may have the potential to be cost competitive, Caldeira said, and the study shows that the wind resource is huge and relatively reliable.

The researchers reached this conclusion by analyzing 27 years of data from the National Center for Environmental Prediction and the European Centre for Medium-Range Weather Forecasts. By studying the distribution of wind power in the atmosphere, by location and time, they found that winds at altitudes around 32,000 feet have the highest wind power density. “The wind power density tells you how much wind energy would flow through a wind turbine,” Caldeira said.

The researchers used the data to compile the first global survey of high-altitude wind energy. Archer is an assistant professor at Stanford University and California State University-Chico and Caldeira is an associate professor at Stanford and a researcher at the Carnegie Institution of Washington. Their findings were published in the journal Energies last month.

High-altitude winds hold a huge energy potential waiting to be harnessed. “If you tapped into 1 percent of the power in high-altitude winds, that would be enough to continuously power all civilization,” Caldeira said. In comparison, similar solar cells would cover roughly 100 times more area than a high-altitude wind turbine, he said.

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