Neither giants nor windmills: the kites that want to revolutionize wind power generation

• WILLIAM OF THE PALACE

• JUAN C. SANCHEZ

  @_JuanCsanchez_

  Graphics

Updated Thursday, May 5, 2022-01:32

• Share on Facebook

• Share on Twitter

• send by email

See 7 comments

Look, Your Grace," answered Sancho, "those that appear there are not giants, but windmills, and what seem to be arms in them are the blades, which, turned by the wind, make the millstone move.

Of all renewable energy sources, wind power is the one that has been implemented the longest on the entire planet, where windmills have been

for centuries .

Its most modern versions, which generate electricity, cover the fields of Spain and begin their assault on its seas.

However, the Quixotes of the coming decades could also find an ancient opponent that is beginning to be used as a green source: kites.

generation systems

, or AWE for its acronym in English [Airborne Wind Energy], are machines that use aircraft such as flexible kites or rigid wings to generate wind power," summarizes

, professor at Carlos III University Madrid specialized in these systems.

Although it is a considerably mature technology and there are already commercial solutions (they are used in Mauritania and Aruba, for example), it is still a few years away from being viable on a large scale.

According to industry estimates, it could become more efficient and cheaper than traditional wind power.

The operation is simple: the ships are linked to the ground by a cable connected to a generator that takes advantage of the 'pulls' of the wind to produce energy.

To do this, during the so-called release phase -which constitutes most of the so-called yo-yo cycle- the aircraft performs some flights in which it describes a kind of horizontal eight or infinity symbol, which produces a very high tensile force on the wire.

"This force is used to generate electrical energy with a generator located in the ground station of the machine", points out Arriaga.

There are also in-flight generation systems that "have wind turbines on board and the energy is transmitted to the ground through the same cable, which in this case must be a conductor."

At the moment there are no commercial solutions deployed with this technology.

"Currently it is not clear which architecture is the most favorable and there are very different concepts," he contextualizes.

The cable has a double function, since it also serves to 'recover' the kite and return it to the starting point of this cycle.

"When the cable is retracted, the aircraft is positioned

to produce a small tension in the cable", while in the generation phase "large angles of attack are used to increase the tension in the cable and maximize power generation", points out the expert.

In other words, it is done efficiently so that it consumes as little energy as possible while increasing production.

Once installed, the ship flies autonomously, which also represents "a very important challenge from the point of view of dynamics and control", since it is a changing environment.

If it ends up being imposed, the occupation of the air space or the noise, which can affect the neighbors, would also have to be taken into account.

truck power

The system has several advantages.

From a purely energetic point of view, the fact of using kites instead of windmills makes it possible to access

, more intense and less intermittent winds.

"With wind from 6 meters per second they can fly," explains

, secretary general of Airborne Wind Europe.

From there, no problem up to almost hurricane speeds.

However, with storms at the moment not many tests have been done: "There is a lack of experience to know how it performs in the most difficult conditions."

"Right now the costs are higher than those of conventional wind," Petrick details.

Thus,

, while the current costs in wind turbines are between five and seven.

"We think that if the market and the regulation go well and there is investment, we could drop quickly and in the long term also be below the conventional one", highlights the manager.

Right now, the savings in material and the fact that they can produce for more hours throughout the year and with stronger winds "could allow us to be very cost competitive."

At the moment, those 20 cents per kilowatt hour are already below the costs of generation with diesel that is used, for example, in the Canary Islands.

All this could also make airborne wind power

, for example.

It just needs to be close by and then a truck can easily transport it to any area as it is the size of a container.

The ease of installation could also help in the event that it is developed as an alternative -or complement- to offshore wind, especially the more complicated floating one.

kite fields

Lastly, there is a perhaps more subjective argument, but one that AWE is also studying:

.

If they are not running, they are practically invisible.

And already underway, unlike the huge fields of mills that extend through rural areas, the kites do not generate so much rejection, although the organization recognizes that it is something that still has to be studied.

"We're very aware of this acceptance issue," Petrick acknowledges.

"We are studying what the impact is for the population and how they perceive it," she adds, because what they seek is "to limit all the problems arising from conventional wind power and not fall into the same trap, basically."

"To do this,

," he explains.

In any case, he believes that they are still far from this point "because there are few systems and they would be very specific cases."

"We are facing the valley of death", illustrates the general secretary of AWE.

This means that right now the technology is about to face the moment in which it must demonstrate that it is viable, efficient and economical.

Many companies have developments and proofs of concept, but it is not yet a reality.

At the moment, there are few systems available, but several firms consider that within two to four years they will be able to commercialize their products.

And later, energy production could be multiplied by ten and go from 100 kilowatts to megawatts.

The airborne is even considered as an energy source -alternative, not the main one- that helps to decarbonise marine transport, since large ships could carry these containers.

Both Petrick and Arriaga agree that a collaboration between companies and the State would help to accelerate the development of these energy kites.

In Spain, where some studies have been carried out, there is a certain delay compared to other countries, although the professor celebrates "a growing interest, especially during the last year. "If a good public-private collaboration is established, I think we can recover ground quickly lost and for a Spanish company to develop its own machine in a short period of time," he argues. At that point, Don Quixote will be able to add kites -perhaps dragons- to his cast of enemies.

Conforms to The Trust Project criteria

Know more

• Environment