|The Kite Generator: a Breakthrough in Wind Energy?|
|Scritto da Ugo Bardi|
|Martedì 16 Agosto 2005 08:55|
Wind energy is free and abundant, but we continue to have problems harnessing it efficiently. The present generation of wind power plants are still plagued by the limited availability of windy sites and by the intermittency of the wind. In addition, many people don't like to see giant turbines appearing on hills and ridges.
Ideally, we could solve the problems of intermittency and lack of sites if we could place the turbines higher up in the sky, where the winds are stronger and more constant. But with the present technology, the supporting towers have already reached their limits. Structures higher than the present ones (a hundred meters or so) would have to be too bulky and expensive to be practical, to say nothing of the aesthetic problem.
A possible way to overcome the height problem would be to get rid of the tower altogether and use aerodynamic lift to position the wind collecting unit high in the sky. In other words, to use kites. This idea has been already proposed in various forms, but recently Massimo Ippolito of Sequoia Automation S.p.a. has developed a simple and elegant concept that promises abundant energy at rock bottom costs: the kite wind generator (KiteGen).
To understand how the KiteGen works, think of the ancient way of pumping water from a well, where a donkey, walking in a circle, pulled a wooden bar which, in turn, acted on the pump. Think of building something like that, but very large. Think of a whole carousel of steel bars coupled to an electrical generator. To each bar, you attach the cables of an array of kites: that is the KiteGen.
In the KiteGen, the kites reach an altitude of one thousand meters or more. They act very much like the sails of a ship, orienting themselves in order to optimize the pull on the bars as the carousel turns. Just as the sails of a ship, the kites of the kitegen can "tack" against the wind and keeppulling for nearly three quarters of a complete turn of the bar. Of course,in the kitegen there are no sailors pulling the ropes of the sails, thekites are controlled by a sophisticated system of 3D positioning sensors developed by Sequoia Automation.
The advantage of using high flying kites is that it is possible to tap the energy of the strong - and relatively constant - winds of these heights. Simulations can be used to estimate how much power a KiteGen can provide and at what costs. The results depend on size and we can seethat a large scale kitegen could produce one to a few gigawatts of power, the same as a nuclear plant, but at a much lower cost. Electrical power from a kitegen could cost, perhaps, fifty times less than power produced by presently existing technologiesy.
These low costs, are derived from the essence of the concept: the KiteGen is asimple machine, all its sophistication is in the control software. If you own a game console you know that sophisticated software doesn't have to be expensive to manufacture, once it has been designed. The KiteGen is also safe: the kites are light sails which would do no damage if they were to fall on the ground. It has a low visual impact, as the kites are invisible from the ground and the carousel is low on the horizon. The footprint of the carousel itself occupies a very small area: the area over which kites fly can still be used for agriculture or as wilderness. Or, the KiteGen can be built offshore, consuming no land area at all.
One feature of the KiteGen is that the kites occupy a relatively large 'bubble' of air space. This bubble would not disturb airliners, which fly at much higher heights. It might interfere, however, with the flight of small planes and helicopters. A way to keep this airspace as a no fly zone would need to be implemented, but this is not a major problem. The kites also fly much higher than birds and the slowly moving cables don't present a threat larger than that of the already common cables for power transmission and telephony.
There should be no need to remark how important the KiteGen could be in the present situation, where the dwindling supply of fossil fuels is causing all kinds of problems, from high prices of everything to resource wars. If KiteGens can perform as the simulations indicate, we could invert these trends and have energy that is clean, abundant and for free, an energy that, more over, can be produced almost anywhere. The old promise (never fulfilled) that nuclear plants could give us electricity "toocheap to meter" could become a reality with the kitegen.
But, as always, we should avoid to be carried away by too much enthusiasm and keep a cool head. First, wind energy, though abundant, is not infinite. No technology can provide us with infinite energy. The KiteGen is no exception: if a really large number of plants were to be built, the effects on the atmospheric wind circulation could be negative, causing local climate changes, drought or similar bad effects. To avoid this, we could use the cheap electric power produced by the KiteGen to manufacture solar photovoltaic cells at low cost, which in turn could provide energy without affecting the atmospheric wind circulation.
Another reason to keep a cool head is that, at present, the kitegen exists only as a set of simulations in the computers of Sequoia Automation. We can do a lot with simulations but, still, technologies have to be tested as actual prototypes and, in a later phase, as industrial products, which must compete in a real market. We know that, in moving from an idea to a product, plenty of things can go wrong and many a beautiful theoretical concept has been slaughtered by an ugly reality.
The KiteGen must pass this reality test. It is an enormous challenge, but it offers also a huge promise. If the test is passed, we face a true breakthrough in energy generation, something that could lead us to a new era, away from pollution, climate change, and resource wars.
Further information about the KiteGen can be found at
|Ultimo aggiornamento Mercoledì 17 Agosto 2005 03:31|