How much wind power is available way up high in the sky? Turns out a lot, according to new research from the Carnegie Institution for Science and California State University. Researchers there recently crunched 28 years worth of data and discovered not only that high altitude winds contain enough energy to meet the world’s global energy demand 100 times over, but they also determined that the best places to capture that wind are over population centers in East Asia and the eastern US. Which means New York City is a prime candidate for high altitude wind energy captured by tethered kite wind turbines.
Ken Caldeira of the Carnegie Institution’s Department of Global Ecology and Cristina Archer of California State University, Chico have created the first wind energy maps for high altitudes, and have assessed the potential wind energy density (kW/m²), which factors in both wind speed and air density. Their findings show that wind energy density is highest near populations centers, specifically over Japan and eastern China, the eastern coast of the United States, southern Australia, and north-eastern Africa. In those areas at high altitude, the average wind energy density is 10 kW/m² – compare that to the wind energy at ground level, which is, at best, 1 kW/m².
Ideally, the researchers say, “you would like to be up near the jet streams, around 30,000 feet,” where the “winds blow much more strongly and steadily than near-surface winds.” Jet streams winds are 10 times faster than surface winds making them that much steadier and reliable for renewable energy generation, despite their seasonal shift. A number of technologies have been proposed to capture this steady supply of wind, including tethered wind kites, which could generate up to 40 MW of power with current designs.
The Global Assessment of High-Altitude Wind Power also studied the wind resources of the world’s five largest cities – New York, Tokyo, Seoul, Sao Paulo and Mexico City. The cities located further north (New York, Tokyo, and Seoul) all had better high-altitude resources than Sao Paulo and Mexico City, which are located in tropical latitudes. The northernmost cities are all regularly affected by jet streams, and New York City has the highest wind energy density at 16 kW/m². Naturally though, the wind isn’t blowing constantly in the upper atmosphere and even in the best locations the wind doesn’t blow for 5% of the time. But even still, high-altitude winds could provide an amazing amount of power, if we can develop the wind turbine technology to capture it safely.
Lead image by Ben Shepard courtesy of Sky WindPower