Airborne solar wind energy systems (ASWES)

Lounge
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From the illustration of CNRS and JFG’s solar balloon project I sketched (see below) a wind energy system (WES) part, including isotropic kites (to face any wind changes) and an airborne wind turbine.

As the initial balloon seems to be able to orient everywhere to face sun due to its apparent or supposed two axes of orientation, adding wind energy seems possible and would provide some additional and significant electricity production, as well as stabilization of the set in spite of strong winds.

I think adding the WES below the balloon looks to be easier, but above could perhaps be studied, by using the two horizontal axes on either side of the balloon.

That said such an installation raises challenges at the limit of what is possible. It is the reason why I suggested untethered solar thermic and photovoltaic systems (U-SES), for uses that are certainly more limited, although they can become more important, but whose implementation seems much easier and simpler.

cnrs_-ballon_solaire_04-_pixscience et éolienne aéroportée
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Suddenly I’m reminded of the perennial announcements of resurrecting the airship and blimp industry, by showing a rendering of some very large airship pr airship/blimp, filled with details of how fast it will go, how much cargo it will handle, how wonderful it will be, then it never happens. :slight_smile:

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Zéphyr©, photovoltaic balloon

Multidisciplinary team project : two Product Designers, Cédric Tomissi and Julie Dautel, and one Ingeneer, Karen Assaraf.

Some modifications for an AWE use: this balloon could be a kytoon although the kite part could make shadow on the photovoltaic balloon, or a Sharp rotor, both aerostats supplying aerodynamic lift from the kite part.

Then a classic wind turbine aloft would add additional power.

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Manufacturing of ASWES is favored by the progresses in photovoltaic film encapsulated in fabric supports, that are used for wings, sails, airships. Now large areas are suitable.

Although I mentioned balloons or airships, flexible kites are also quite adapted, and if flexible ASWES are also of type fly-gen, the electrified tether is already there, as for FlygenKite.

Some features are explained on https://heole.fr/en/opv/ :

Organic photovoltaic cell technology (OPV for Organic PhotoVoltaic) is the eco-responsible transformation of light energy into directly usable electricity. It is based on polymers from organic chemistry: semiconductor polymers sensitive to light.

Advantages

  • Flexible, fine and light:
    30 times lighter than a conventional solar panel, it fits on curved surfaces and can be rolled up: it can fit on previously unused supports
  • Semi-Transparent:
    it is made up of ultra-thin layers whose unit of measurement is the nanometer, which makes it possible to capture light energy on both sides
  • Efficient even in low light:
    It produces energy even on a cloudy day, from early morning to late at night!
  • Environmentally friendly:
    Low in energy to manufacture, it does not use rare materials and is easy to recycle
  • Low-carbon process:
    they are to date the only carbon-free photovoltaic solution

It is the dream technology to design the solar sail!

Perspectives

The energy conversion efficiencies of these organic semiconductor devices are in constant progress. The energy efficiency of OPVs has jumped from year to year.

This may become a turning point for the evolution of AWES into ASWES, when the efficiency, lightness and robustness of these complex films have progressed sufficiently.

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This seems at least to have some value catering to the traditional sailboat market

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As for all that contains large flexible surfaces, freeing up space on the ground for photovoltaic panels, in addition to the specific use (to supply the boat with electricity on board) of pleasure or regatta sails.

As this technology is quickly progressing, perhaps some light and efficient products will be available by soon.

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Something that might interest you and many on Awes

Apparently the uk government wishes to ban solar farms on farm land as it take up too much arable land. ASWES could fill the niche? Just thought I link in the vid with a barrister talking about it.

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An alternative and simpler configuration of Airborne Solar Wind Energy Systems (ASWES) would be using mainly high altitude wind energy as any static (or crosswind) AWES operating in yo-yo mode, with solar energy used only to heat the air in a suitable kite so that the kite can remain in the air most of the time, even without wind, including night. So there would be no need for a challenging electric tether, expensive photovoltaic film, or absolute constraint on altitude.

A sketch below about two sorts of solar kites:

Airborne Solar Wind Energy Systems
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A solar assisted Kitewinder system would be preferable. In the yo-yo system, retracting the LTA balloon kite may be problematic. The LTA force is vertical, so the solar assisted Kitewinder kite can provide more lifting force at higher tether angles.
A general advantage of airborne solar is the ability to supply warning lights on the device to comply with regulations.

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I already tested the turning of a solar balloon by a central rope: deflation was very fast, even with large volumes. So the reel-in phase would be facilitated. And a solar balloon heats up quickly, quickly reaching its limit, adding a bit of force during power reel-out phase.

The parachute on my sketch above is a little like the balloon I tested, comprising a large opening.

Here solar energy (by day) or infrared (by night) would allow the kite to stay in the air (avoiding some takeoff and landing operations), even when there is no wind. But the power / mass ratio has to be high: it is the reason why I thought about a yo-yo system with a flexible kite. Such a use would not be possible with a turbine (Kiwee or another) aloft adding weight, above all when scaling. Indeed heat generated by infrared is not high, but can be sufficient for a kite-balloon.

When there is sunshine. But when there is no sun or by night, the lifting force and the tether angle would be lesser, and perhaps the whole system would be too heavy to stay in the air. For a stationary device, too significant changes of tether angles may also result in the loss of the advantage of being stationary.

To supply warning lights is an obvious application. There are many possible applications for ASWES that I have initiated in this topic. I described some configurations with photovoltaic films for electricity generation, and just before some methods for thermal solar energy.

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Except warning lights mostly work at night, whereas solar works in daylight.

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Small batteries should not weigh too much

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After some preliminary rough calculations, I must admit that a ram kite would not be voluminous enough to fly by aerostatic lift with infrared (by night), or even thermal solar energy (by day). Perhaps a suitable parachute kite could do it, working a little like an open balloon. This would be a way to stay in the air even without wind.

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Another option from the modified drawing: the photovoltaic balloon becomes a kytoon in order to benefit from high winds, and above all solar energy is used only to produce hydrogen to inflate said kytoon, not to convey electricity through an electric cable.

On the one hand, it takes a lot of energy to produce hydrogen, and solar energy just allows provide it, on the other hand, it is necessary to isolate the kytoon as much as possible in the top of the installation, in order to avoid the propagation of a possible fire through the cable.

Other lifting kites and wind turbines are installed below as shown on the modified drawing. If a rope drive device like on Kiwee replaces wind turbines an electrical cable is not required. Other (crosswind or not) AWES such like fly-gen (with the requirement of the electrical cable), even perhaps some yo-yo systems (without electrical cable) could also replace wind turbines.

An example of solar panels producing hydrogen:

Examples of light flexible solar panels on sails or balloons:

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Not sure how relatable this is? With something I read this morning saying an isomer can store sunlight for 18 years. @PierreB , as you have interest in the field? I wondered if you had come across this? Or even consider it applications in AWES?

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Chapter

Full-text available

Aerostat for Solar Power Generation

PDF available on https://www.researchgate.net/publication/221907407_Aerostat_for_Solar_Power_Generation

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These two figures are extracted from the publication.

This could perhaps be an ASWES by modifying it, for example by implementing the second alternative version of the preprint (Preprint: Towards a gigantic Magnus balloon with motorized belts), sketch reproduced below:

Static lifter Magnus balloon with drop stitched discs for belts
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Aerostatic lift (hydrogen or helium rather than thermal solar which is insufficient to carry the wind turbines and solar films) combined with aerodynamic lift, and perhaps more scalability with external motorized belts.

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its upper surface, which is large, is ideal for power solar technology

ability to be operated as a tethered aerostat

I would add a possibility to add blades rotating around or with the central lenticular balloon, although it is not without difficulties.

Some experiments:

And also:

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L’épaisseur est de 65 microns pour un poids de 300 g au m². Il est intégrable sur des voiles en laminé ou ajustable sur des textiles tissés comme le dacron ou le taffetas.

Trois films PV de 25 W représentent une surface d’un m² soit 75 W de puissance. Le prix du m² de 588€ TTC.

Translation:

It is 65 microns thick and weighs 300 g/m². It can be integrated on laminated sails or adjusted on woven textiles such as dacron or taffeta.

Three 25 W PV films represent a surface area of one m², i.e. 75 W of power. The price per m² is €588 incl. VAT.

A part of this website in English:

Another company (website only in French), using flexible organic photovoltaic membranes and fabrics, with an excerpt just below:

Quelques chiffres :

Empreinte carbone : < 20gCO²/kWh
Cout prévisionnel à 10 ans : 10 €/m²
Rendement à 10 ans (Wc) : 15 à 20%
Poids : 200-500 g/m² selon application
Génération de l’électricité : par les 2 faces

Translation:

Key figures:

Carbon footprint: < 20gCO²/kWh

Estimated cost over 10 years: €10/m².

10-year yield (Wp): 15-20%

Weight: 200-500 g/m² depending on application

Electricity generation: from 2 sides

This can perhaps be a plus for large ASWES, kites or aerostats. For single skin kites, the generation from 2 sides can be specially interesting. A single skin FlygenKite would use electric cable to convey electricity from both wind generators aloft and photovoltaic fabrics.

Initially I conceived and experimented FlygenKite as a crosswind kite device. But it can be used as a static kite device: FlygenKite (video, static use for a few seconds).

Thus the secondary turbine(s) becomes the wind turbine.
This would produce several times less energy than in crosswind flight, but this would be partly compensated by a higher elevation angle and better winds, a more regular production, and less wear and overheating due to excessive rpm.

Thus we would then be much more close to what exists in current wind power. Control would then consist of avoiding collisions as much as possible (which would only concern the kite part) between units which could be very close to each other.

The two lines of FlygenKite were used for a manual control. But a wind turbine mounted through the single line (less drag) in Kiwee way and close to the control pod (with basic functions if only static) could be a possibility.

So go to a static FlygenKite with photovoltaic fabric.

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OK so a kite with a sail fabric weighing almost a pound per sq yard?
The entire misguided idea of providing an airborne “wind energy” system with photovoltaics for actual power production is just a desperate “last gasp” which translates to “We could never get an actual AWE system to effectively generate meaningful amounts of power.” The only “reason” for it would be to pretend your “AWE” system is functional, otherwise there is no good reason to locate a solar system, for powering things on the ground, in the air, when it can more easily just be located on the ground.

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The tone was different here:

And the initial post mentioned a device with only solar function in high altitude.

Putting the photovoltaic at altitude saves space on the ground, and saves on costs as you mentioned.