By Massimo Ippolito, August 8, 2009 3:14 pm

Why you, KiteGen, developed such ambitious energy technology, when wind turbines and Photovoltaics are already available and mature?

We suggest to read this extensive article:


KiteGen  produced energy and connected to the grid yet.

Yes KiteGen produced energy, for almost 1000h in several sessions during the validation of the concept, dissipating it on resistors connected in over-voltage condition to the servo DC bus.  To date the KiteGen different prototypes were never connected to the grid, due to  the provisional or mobile installations.

The peak power ever recorded  with a sport kite was 130 kW for few seconds, in a good 350 agl wind allowing more than 20m/s of rope reel-out, but suddenly followed by the sport kite overload and breakage. This early trial was for us the most decisive and motivating to proceed in KiteGen technology development despite such failure.

The  small and early research prototypes designed for 40kW already produced energy at about 0.9 €/kWh including the CAPEX mortgage and the fabric kites maintenance and substitution, at the moment no national institutions offered to KiteGen Feed in Tariff or subsidies  in order to pave the way to the technological and economical learning curve, starting from such research small machines and such costs,  so KiteGen is obliged to start to deliver industrial machines only when already competitive in the current electrical markets, and this is precisely the strategy we adopted with the design and manufacturing of the huge composite power wing and its manipulating robot.

How large is a KiteGen power plant and could be installed offshore?

It depends of the configuration. A wind farm of 9 KiteGen Stem, with a total nominal power of 27 MW, has a total footprint of 1000 square meters, it require an area of 9 ha and a reserved area of 1 square km of land free from infrastructures, woods, pasturage or agricultural field are suitable. In the Carousel configuration the generator ring of a 1 GW power plant has a diameter of 1,800 m.

the 5 GW Carousel is a double ring of 4km of diameter with a flying height of 4000m, the rope full extension could reach 7km intercepting a wind front of 20 square km, the installation site could be deep offshore and must provide a specific natural wind power of almost 250W/sqm corresponding to a mean wind speed of 4 m/s @ 50m AGL.

How much energy does a KiteGen power plant produce?

It is estimated that a 100 MW power plant composed by 33 KiteGen Stem and limited at 1500 of altitude AGL can produce approx. 680 GWh yearly.

in other words the capacity factor is 6800h, when limited at 1500m AGL in most of the world potential sites,

What is the cost of the energy produced by a KiteGen power plant?

The GW class  Carousel power plants are estimated to deliver energy for less than 0.003 Euro per kWh, some IEEE scientific papers on KiteGen arguments this forecast.

The Stem configuration powered by the composite and high efficiency KiteGen power wings,  shows a cost (LCOE) is around 0.02 € per kWh, this figure is highly reliable because the pre-production machines at industrial scale including the power wing are done, validated and analyzed in detail.

The small and early research prototypes of 40kW already produced energy at 0.9 €/kWh including the CAPEX mortgage and the fabric kites maintenance and substitution, at the moment no national institutions offered to KiteGen Feed in Tariff or subsidies  in order to pave the way to the technological and economical learning curve starting from such research small machines,  so KiteGen is obliged to start deliver industrial machines only when already competitive in the current electrical markets.

How does wind power change with altitude?

As altitude increases, average wind speed increases (and remember that wind power grows with the cube of wind speed) and air density decreases. Wind power decreases linearly with air density, but even at 1000 m air density is reduced by only about 10%. Wind power therefore always tends to grow from ground up to approx. 10,000 m of altitude, see Wind data page.

What is the risk of collision with airplanes?

A KiteGen power plant must obtain permission from the competent authorities (usually the national administration for civil aviation) for the needed flight restrictions on the airspace above, where airplanes and any other kind of airborne vehicles should not be allowed to enter. Such restricted areas are subject to international agreements and are already granted for other kinds of civil installations (for example nuclear power plants, oil refineries, explosive or chemical facilities). A typical P (Prohibited) Area, where no flight is allowed and the risk tends to zero, has an altitude above the ground of 5,000 ft (equal to 1,524 m) and a radius of at least 1 nautical mile (equal to 1,852 m); thus the resulting cylinder has a volume of 16.4 km³ (equal to approx. 579 billion cubic feet).

How can power kites pull their steering units along a circular path in the Carousel configuration?

Power kites fly in the wind maximizing lift and performing an alternate and transverse navigation. For this reason they can be faster than the wind and are able to sail against it, not only succeeding in pulling the steering units along circular paths but also maintaining almost all the time an effective tangential traction.

A video on youtube  could offer the precise elements  to better understand the KiteGen Carousel dynamic, the video initially shows the Carousel offshore, an animation of the concept  and then enter in a simulator page that follows and autopilot one single kite of the Carousel with the display of all the real time parameters.


How can power kites produce energy when cables reach the maximum lenght in the Stem configuration?

When the cables are completely winded the production phase ends, the wing is positioned in a condition of minimum resistance to the wind and the cables are rewinded, with a minor energy consumption, for the lenght necessary to start another production phase. The cycle then repeats (“yo-yo” cycle).

Indeed your composite semi-rigid and huge wing is the component suitable to harness effectively the wind power, but it seems too new, technologically extreme and ambitious, wasn’t easier to progressively scale up the existing fabric kites?

We made several tentative, almost one year of activity, to scale up the kites adopting different textiles including Dacron, but the most important wing parameters for our application are the aerodynamic efficiency and the strength resistance. The trials with such kites weren’t satisfactory because inefficiency, short life and cost. This video show a 50 sq m. wing in nylon in the takeoff phase, when the wing start to develop some lift the textile suddenly snatch due overload.   Finally our decision to proceed trough the design and the manufacturing of the wing suitable for energy production was satisfactory and successful.     

Is there a lighting risk?

Regarding the ground generator risk, is the same of any other steel structure, a good ground connection  avoid harmful consequences, during thunderstorms we occasionally experienced data link devices and camera damages but never involving servo drives and alternators.

The flying wing and cables instead are insulating devices, being made of composites and polymeric fibers, they doesn’t offer any preferential path to the discharging current, moreover  the high difference of potential of the different atmosphere layers aren’t short circuited or ignited by such ropes.

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