Is it a bird...is it a plane...nopes, it's a flying generator!

From kites that can power entire ships to kites floating far above the ground and powering cities. Wind power seems suddenly seems to be hot. One of the oldest forms of alternative energy is slowly focusing the world's energy on itself. Why? Perhaps because it's there in plenty and we just have to tap it.
With the same fervor, two Stanford University atmospheric scientists Cristina Archer and Mark Jacobson, did a study three years ago. They looked at the understood patterns of air circulation and did some number crunching. They reckoned only the energy that could be generated from winds blowing over land at an altitude of 80 meters which is the approximate height of a typical modern wind turbine. Under perfect conditions, the total would be close to 72 trillion watts. This is the potential that we could maximally tap from the ground.

To put this figure in perspective, in 2007 the entire electrical generating capacity of the United States was just a bit more than 1 trillion watts. But here is the clincher. Archer and Jacobson knew that wind speed rises with altitude, and available power rises at the cube of wind speed. So, technically if we go a few miles up we could have 250 times the energy of the same blade as from the ground. And this theoretically gives the power of the wind an entirely new dimension.

Now, innovators and scientists are looking at feasible ways to harvest this copious supply. One ingenious solution has come from Bryan Roberts, an engineering professor at the University of Technology in Sydney, Australia. Sky WindPower, a San Diego–based company is working on his designs based around kites. The kites are equipped with rotors that fly and hover to altitudes of a mile or more, where they can tap the strongest winds. Upon arrival, the rotors switch to generating mode, sending current down their tether cables, which might be many miles long. These aerial turbines feed electricity back to the ground like traditional wind turbines with their rotors rotated to the horizontal. When the winds shift, the platoon of kites (called flying electric generators, or FEGs)  pursues them.

These developmental models are all on the small scale working prototype stage. Questions of course have arisen over the feasibility of the concept especially related to safety. Will thunderstorms interfere with these aerial turbines? If lightning strikes the tethered cables could be the biggest lightning rods for miles around. What happens if one of these rotary turbines falls from the sky? What about planes running into them, or more likely, their tethers? Some solutions can be easily had like flying them in restricted air space and having multiple rotors and automated monitoring as anti-crash measures.

Objections aside, the crux lies in the concept and it’s potential. High altitude 'wind farms' could take the intermittent supply of wind out of the equation. Most wind farms on the ground only operate at their peak capacity 19-35% of the time. A distinct advantage could also come from portability and mobility. Turbines with a simple tether system could be used to power niche requirements akin to an off the grid power source. They could be moved around to locations that need them. Simpler and less costly solutions could be the solution for many Third World energy starved countries.

For now the benefits seem to suggest work on a fully practicable working device. If this comes about technologically, politically and financially we could soon see an entirely new reason to fly kites.

Source: Discover