Palo Alto, CA — Imagine the New York sky filled with giant kites - like a bigger, better version of the famous Kabul festival.
New York - not Chicago - has been identified as the US's prime location for exploiting high-altitude winds, which globally contain enough energy to meet world demand 100 times over.
Using 28 years of data from the National Center for Environmental Prediction and the Department of Energy, Ken Caldeira of the Carnegie Institution's Department of Global Ecology and Cristina Archer of California State University, Chico, compiled the first-ever global survey of wind energy available at high altitudes. The researchers assessed potential for wind power in terms of wind power density, which takes into account both wind speed and air density at different altitudes.
"There is a huge amount of energy available in high altitude winds," said Caldeira. "These winds blow much more strongly and steadily than near-surface winds, but you need to go get up miles to get a big advantage. Ideally, you would like to be up near the jet streams, around 30,000 feet."
Jet stream winds are generally steadier and 10 times faster than winds near the ground, making them a potentially vast and dependable source of energy. Several schemes have been proposed to harvest this energy, including tethered, kite-like wind turbines transmitting energy to the ground via the tether.
"We found the highest wind power densities over Japan and eastern China, the eastern coast of the United States, southern Australia, and north-eastern Africa," said Archer. "The median values in these areas are greater than 10 kilowatts per square meter. This is unthinkable near the ground, where even the best locations have usually less than one kilowatt per square meter." He added that New York has an average wind power density of up to 16 kilowatts per square meter.
"While there is enough power in these high altitude winds to power all of modern civilization, at any specific location there are still times when the winds do not blow," said Caldeira. "This means that you either need back-up power, massive amounts of energy storage, or a continental or even global scale electricity grid to assure power availability. So, while high-altitude wind may ultimately prove to be a major energy source, it requires substantial infrastructure."