Cristina L. Archer from the Department of Geological and Environmental Sciences, California State University and Ken Caldeira from the Department of Global Ecology, Carnegie Institution of Washington, Stanford have come up with research on the available wind power resources worldwide at altitudes between 500 and 12,000 miles above ground. Based on the geographical distributions and the persistent wind strengths at all altitudes, their reports identified New York, Tokyo, Sao Paulo, Seoul and Mexico City as having the highest high-altitude wind potential. These high-altitude winds are capable of meeting the world energy demands 100 times over. They re-analyzed 28 years of wind data from the National Centers for Environmental Prediction and the Department of Energy.
Meticulous details regarding wind power density and wind speed of the jet streams throughout the troposphere were amassed, thanks to some useful re-analysis of wind speed, temperature, pressure, and specific humidity from the National Centers for Environmental Prediction (NCEP) and the Department of Energy (DOE). Moreover, the analysis deals with geographical and statistical distributions including global vertical profiles, city vertical profiles, and the optimal heights from a specific location. Various factors such as the climatic conditions, the jet speeds and the intermittency factor were considered.
Major findings of the whole research:
Image Courtesy: Wind Powering America
I. The eastern coast of the United States, Japan, Eastern China, Southern Australia and northeastern Africa are the best-suited regions to exploit wind power.
II. The median values in these areas are greater than 10 kilowatts per square meter.
III. Tokyo, New York, Sao Paulo, Seoul and Mexico City are the most affected by the high-altitude jet streams.
IV. New York outclasses all the cities with a 16 kilowatts per square meter wind power density.
V. The East Asian jet stream empowers Tokyo and Seoul to flaunt high wind power density.
VI. The power-generation depends on the continual wind flow at high altitudes. Contrary to it, wind strength keeps on fluctuating and hence limits the power production on a large scale.
Possible ways to harness this form of electricity:
Mainly eying on the jet stream winds, the studies demand a greater insight into the electricity generation and associated costs. So what we are mainly concerned about is the electricity generation and the possible ways to do it.
The first possible way includes transmission of mechanical energy from altitude to the Earth’s surface, where generators would produce electricity at the ground. Dubbed as KiteGen, the device consists of tethered airfoils (kites) connected to a ground-based generator with two lines. A control unit keeps on pulling and releasing the airfoils where traction generates huge electricity. An array of several kites arranged around a circular rail could generate up to 100 MW of electricity. It’s more suited to the lower atmosphere.
The second approach suggests generating electricity in the air and then its transmission to the surface via a tether. Sky Windpower is one such design having four rotors mounted on an airframe. These rotors are further tethered to the ground via insulated aluminum conductors wound with Kevlar-type cords. The rotors are responsible for lift and these power electric generation as well. Current designs promise up to 40 megawatts of electricity.
Some obvious barriers:
Despite it being a feasible energy source, researchers and scientists need to deal with certain snags:
I. As this technology makes use of tethers, it’s hazardous to aircraft. On the contrary, you can’t compromise even on the tether’s thickness since density means more output.
II. Wind strength keeps on fluctuating depending on the weather conditions. Hence it adversely affects the constant power-generation.
III. At high altitudes, the amassed charge goes far beyond the wires’ potential. So, it might call for more expenses on electrical insulation around the wire to avoid energy loss.