Airborne solar wind energy systems (ASWES)

Perhaps there are some possibilities to harness both solar and wind energy at high altitude, benefiting from both more powerful winds and more solar energy above clouds, by using the same ASWES. Some solar films could cover the balloon, being quite light although less powerful and still hazardous for the environment.

Aerospace products – Flisom :

  • Weight: commercial products as light as 80 g/m²
  • Flexibility: rollable down to 1cm diameter

Projects with balloons:

https://inhabitat.com/sunhope-solar-balloons/

The wind power part remains to be imagined.

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Not a bad start, there is research being done if to fluorescent to improve solar panels efficiency by Doppler shifting light. There is light filters used by stage companies that just to this by selecting wavelength of light. Then you also have prisms mirrors and light guides which are able to be employed. Many of the cheapest light filters I’ve seen a pretty simple coloured plastic. Others with fluorescent coatings. Robert Murray smith just covered this very topic recently. On how to improve solar panels. Down to the individual how its achieved? You seem to have the firs stage of a parabolic prism. That would only need a coating on one side to better select the em frequency. Rochester university’s did a study some years back on the use of light guides to improve solar panels. I’m also are you can trap light. Light can be let in but it can’t get back out due to certain applied coatings. So get stuck between the solar cell and outer membrane. Research in to the various eye in the natural world has helped advance the technology somewhat. With some animals abilities to see a broader spectrum of light.a demonstration showing it possible to covert larger rangers of light to electrical chemical impulses. I believe there are a few animals that can see both inferred and ultraviolet. It might be a octopus? Though can’t recall of the top of my head. Chlorophyll from plant tend to improve solar panels efficiency. When Robert Murray smith did it his range improved 4.8v - 6.8v. which was somewhat of 45% or so improvement on the voltage. Might not be worth my time some days but you miss the tip bits that help out somewhere else.

They could use the same fluorescent white powder inside fluorescent tubes to convert UV to visible light.

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I like this idea if the balloons were shaped more like air mattresses. More area facing the sun to mount the solar panels on. The kite function could help keep it aimed at the sun.

Some of the most expensive parts of solar installations these days is the support structure to hold the panels, so a giant air mattress might be cheaper. Add hydrogen for buoyancy, and stay out of the way when lightning strikes! What would the wind’s role be? Keeping it airborne instead of blowing it down, by producing some lift to keep it in place.

Airborne Wind Solar. AWS. Amazon Web Services. It would probably just be called Airborne Solar or AS. The wind part would be inside baseball that only techies would know about. “Say, did you know that those floating solar air-mattresses act like a kite when it gets windy, to help hold their position?”

And the solar panels would produce a similar amount of electricity as a wind turbine sweeping a similar area. They could fly one over my house in the hot desert in summer to keep the sun off my house so it stays cooler as Joe Faust used to advocate - kites providing shade.
OK I’m in on this idea! Let’s make some JUICE!!! :slight_smile:

I received some interesting remarks from Dave Santos in private mode, having put in bold the most realistic passage :

Flying is a difficult art while flying solar surfaces do not offer great advantage.
No one can say how to orient to the sun and wind optimally at the same time.
Solar power is roughly power-equivalent from the surface up to high altitudes.
Solar stops at night. Flying collectors and conductors become parasitic mass.
The best use of AWES flying mass is to extract superior Upper Wind energy.
Solar is most ideal for distributed generation on roof-tops, not for flying on kites.

What are your observations?

He makes good points too. I’m not so enthusiastic over solar on house roofs. The reason is every house roof is a little different, and their main job is protecting and waterproofing the house, and the solar panels get in the way of the roofing, and vice-versa. I’m sold on solar carports, or elevated shade panels for parking cars under. They have huge versions at schools and Walmarts, and everyone loves to park under them in the shade during summer. The house-roof mounting: yeah, obviously it can and does work, however, it seems like roofing and solar panels are two conflicting uses for a roof. If that is your only option, fine, but even a specially-fabricated awning shade structure across the back of a house that uses solar panels for not only blocking the sun and rain, but making power from the sun too, is a better idea than interrupting the integrity of the roof, when possible, in my opinion.

Kytoons would be suitable for lift from both buoyancy and aerodynamic lift. With an elevation angle of 60 to 80 degrees, airborne solar collectors (ASC) or ASWES would occupy much less space than AWES, whose elevation angle is lowered by harnessing winds for energy generation. As a result, and unlike AWES, ASC could be installed virtually anywhere.

The gain of solar energy in altitude compared to the ground would perhaps not be enormous (but not negligible), but it would be constant whatever the season and the hour of the day, and this thanks to the possible orientation of the balloon, and the cloudy weather or not.

In a way the more constant and powerful high altitude winds are still used, but only to obtain more lift, and thus more carrying capacity of solar cells.

There alway inflatable wings with solar to consider? As @dougselsam mention the uv powers that covert more uv to visible light. I see no reason why that can’t be fixed into epoxy and turned into a prism. by casting into a mould. Depend how big you like a balloon wing to be? As that would give it general scaling potential. Almost calls for a blimp? Solar barrage balloons prehaps?

This is indeed one of the possible positive points of such a project. An achievement:

In altitude a lifter kite could be added.

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Nicely done, Pierre, and it only took you one day! :slight_smile:

Some explains of this balloon with flexible organic solar cells:

I think there are other possibilities in order to use the wind for additional (or main) lift with a kite or with a kytoon.

I like the idea of solar cells on the wings of a hang-glider, with a propeller powered by onboard batteries feeding an electric motor. I could take off from my backyard, go up, and then find thermals for normal daytime soaring flight, while having my batteries recharged by the sun, for that little extra bit of power when you need it.

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See the solar cell adhesive strips on this RC model:

And also, in flight:

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A solar panel generates 200 W per square meter. A rigid AWE kite maybe 8 kW (wild guess, probably quite conservative if AWE turns out to be feasible)

The solar panels would only make sense to power onboard electronics. But that would leave the kite to only have power during daytime.

You may use solar panels to charge onboard batteries, being cheaper than a moving solution [onboard turbine]. This one I would actually consider calculating on.

That being said, the panels must be robust wrt wear and tear. I expect protective covering of panels for a turbine blade could be difficult.

So all in all, I am not overly enthusiastic about these solar panels for AWE. It always seem simpler to me to put then on the ground or a roof, with cheap robust frames that may even be heavy…

Is there an opening for soft kites here? Maybe a single membrane kite could make use of solar panels. Though adding the solar panels does seem to defeat the purpose of going membrane kites to save weight in the first place. Also, textiles deform more I believe than would be allowable by solar panels. I honestly dont see this as a likely turn of events

Even if you did go there, the wing area of a crosswind kite is facing ideally vertically for zero elevation angle. And the azimuth may well be totally unaligned with the general direction if the sun.

For these reasons it seems more feasible to have a large mirror on the ground focusing sunlight to the bottom of the kite where the solar panels could be mounted. Mind you, this is where logic reasoning takes us. Further logic reasoning would probably also tell us this is a terrible idea

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Dave Santos made a similar remark:

When I started this topic I thought of combining solar and wind energy for electricity production.
Then I changed by thinking the high altitude winds would be used only to provide additional (or main) lift.

By this way, if a favorable combination kite-balloon-solar-film-cells is found, some solar energy could be transmitted, while the flying device could perhaps fly at a correct elevation angle, unlike crosswind and other AWES.

I think that trying to extract wind energy from high altitudes and convert it into electricity was a strategic mistake by the AWES projects. None of them showed the slightest ability to produce anything substantial over a long period of time. And the low elevation angle involved in harnessing high altitude winds destroys any real possibility beyond the technical problems encountered.

For this reason, I believe that the use of upper winds should only be allocated to lift, not to wind power generation. Even by harnessing powerful high altitude winds, the efficiency will remain far to that of current wind turbines harnessing lower winds.

Solar is one of the possibilities. On the other hand I find the project of balloons carrying solar panels interesting, although not sufficiently worked out, in first because the lift by kite with high altitude winds is not used.

A recent French study:

Pourquoi ne pas couvrir massivement toits, parkings ou zones polluées de panneaux solaires ? Le gouvernement, avide d’économies, soutient plutôt le photovoltaïque au sol — qui grignote les terres. Enquête [2/4].

Cela devrait tomber sous le sens. Il faut mettre en priorité les panneaux solaires sur les zones déjà artificialisées : parkings, zones polluées et surtout, toitures. Coup de chance, selon une étude européenne parue en 2019 dans la revue Nature, l’Europe de l’Ouest est une zone à fort potentiel photovoltaïque (notamment autour de la Méditerranée) et dotée d’une solide capacité d’investissement. « Si tous les toits de l’Union européenne adaptés étaient équipés de systèmes photovoltaïques, 680 térawattheures (TWh) d’énergie solaire pourraient être produits. Cela représenterait 24,4 % de la consommation actuelle d’électricité des États membres de l’Union européenne », lit-on. Il faudrait amorcer la pompe : comme le montre une autre étude parue dans Energy policy, les panneaux photovoltaïques sur les toits des particuliers créent un effet de contagion spatiale (« spatial spillover ») auprès des voisins, en rendant la technologie plus familière.

Alors, pourquoi ne pas couvrir massivement nos toits de panneaux ? Si aujourd’hui les puissances installées en solaire se répartissent à cinquante-cinquante au sol et sur du bâti, la dynamique est clairement en faveur des installations à terre. D’abord parce qu’installer sur une construction existante coûte paradoxalement encore trop cher [1], ou dégage une rentabilité moindre qu’au sol. Dans une étude publiée en 2020 sur les « coûts des énergies renouvelables et de récupération », l’Agence de la transition écologique (Ademe) estime que le coût d’une installation résidentielle intégrée au bâti se situe entre 154 et 184 euros par mégawattheure (MWh) dans la zone sud la plus ensoleillée, tout juste au niveau du tarif d’achat actuel. Elle ne devient intéressante économiquement que sur des toitures moyennes ou grandes.

Translation:

Why not massively cover roofs, parking lots or polluted areas with solar panels? The government, eager to save money, supports instead the ground photovoltaic - which nibbles the land. Survey [2/4].

This should be obvious. Solar panels should be placed in priority on already artificialized areas: parking lots, polluted areas and, above all, roofs. Luckily, according to a European study published in 2019 in the journal Nature, Western Europe is an area with high photovoltaic potential (especially around the Mediterranean) and with a solid investment capacity. “If all suitable EU rooftops were equipped with photovoltaic systems, 680 terawatt hours (TWh) of solar energy could be produced. This would represent 24.4% of the current electricity consumption of the EU member states,” it reads. The pump should be primed: as another study published in Energy policy shows, photovoltaic panels on private roofs create a spatial spillover effect among neighbors, making the technology more familiar.

So why not cover our roofs massively with panels? If today the installed solar power is divided fifty-fifty between ground and building, the dynamic is clearly in favor of land-based installations. Firstly, because installing on an existing building is paradoxically still too expensive [1], or less profitable than on the ground. In a study published in 2020 on the “costs of renewable energy and recovery”, the French Agency for Ecological Transition (Ademe) estimates that the cost of a residential building-integrated installation is between 154 and 184 euros per megawatt-hour (MWh) in the sunniest southern zone, just at the level of the current feed-in tariff. It only becomes economically attractive on medium to large roofs.

This may be a justification for the Solar Energy Aims for the Sky project mentioned in the initial post, in addition to a higher expected annual production (the author mentioning 5x due to the higher radiation power at altitude and especially the higher number of sunshine hours).

Indeed, despite its undeniable advantages, solar panels occupy a rather limited space both on the ground (which is normal) and on the roofs (because of the costs).

There may be a small possibility with ASWES that would add the energy of the high winds but only to increase the lift of the integrated kite.

For example, if we make a version of Kiwee (kite area about 4 m²) with solar panels in flexible film on 1 m², we will have a power equivalent to that of the about 1 m² original turbine, for a similar additional weight (about 10 N (mass 1 kg)). On the other hand, if we consider a wind of 10 m/s, which is common at altitude, the device with the solar panels will not undergo the additional drag of about 60 N caused by the production of energy converted into electricity from the propeller. We can therefore expect higher solar panel capacities for the same static kite, or/and flying at a higher elevation angle.

For this you now face the minmax problem of kites. A large stationary kite will be very difficult to handle in high winds while still being able to fly in high winds.

This all reminds me of a solution looking for a problem. Why do the solar panels have to fly anyway? We already heard that solar power density is not radically different at lower altitudes. For higher altitudes one must consider also the weight of the conductive cable. It seems like an «impossible mission» to me

Single kite and kite train already flew at high altitude, respectively 4422 m in 2000 and 9740 m in 1919.

And also the Zhonglu High Altitude Wind Power Technology - 中路高空风力发电技术 projects has at least demonstrated that it was possible to add one aerostat to the kite train.

According to the author:

The main problem with photovoltaic energy is that sunlight can be obscured by clouds, which makes electrical production intermittent and uncertain. But above the cloud cover, the sun shines all day, every day. Anywhere above the planet, there are very few clouds at an altitude of 6 km—and none at all at 20 km. At those heights, the light comes directly from the Sun, as there are no shadows and hardly any diffusion by the atmosphere. As the sky loses its blue color, direct illumination becomes more intense: the concentration of solar energy results in more effective conversion, and hence higher yields.1

Under these conditions, the energy source is five times more abundant than on the ground,2 and production is entirely predictable. So why not send solar cells up above the clouds,

Five times in average power (far more time of sunlight as already mentioned), this is not negligible. Sure this involves to very long tethers, a little like some AWE projects like Sky Windpower for which I have never heard of any impossibility from AWE players, but only from Mike Barnard.

But if we want avoid these very long tethers, lower altitudes would allow to keep another advantage (losing 5x advantage) which is avoiding saturation of solar panels on the ground, and the high cost on roofs that leads to the preference of solar installations on the ground (see above).

The major advantage with flying solar panels in regard to current ground-based solar installations, is the possibility to increase the total of solar panel area.

The major advantage with flying solar panels in regard to current testing high altitude wind for electricity production, is avoiding the drag which is inherent to electricity generation by wind, and which lowers the elevation angle.

This is all the problem with AWE and likely the main reason why it don’t succeed.
The energy is maximum in the horizontal: the more we go up, the more powerful the winds are, but the more we lose in efficiency, first by cosine loss³.

With stationary flying devices equipped with solar panels, there is no cosine loss since only the lift force of the high winds is used, by Bernouilli’s principle. The benefit of higher and higher winds is a net benefit, apart from the total mass and drag (less for a static aircraft) of tether.

I think these arguments must carefully be studied in a AWE world which persists in denying the problems of land and space use due to a low elevation angle and which would lead to an impossibility for massive marketing, in the unlikely event of efficient working in the time.

That is because you seem to still be locked into the initial stories of high altitude winds and not «pivoting» to something that makes physical sense.

The premise if AWE or even all wind energy is the difference in speed ground vs airflow. This difference must be maintained by some connecting force, eg a tower or a tether. The amount of tension vs downwind tether pull is determined by the cosine of the elevation angle for tethers. So anything >30 deg elevation makes less sense to me, because the tether must be really thick to soak up the tension, driving mass/weight at scale.

If you look back to kiting sessions on single line kites, which I believe @PierreB that you have accumulates quite a few, having super long tethers does bot feel that great. Slack tethers, tether lying on the ground, difficulties getting the kite down etc. I think you can not just say «this is fine». These are real problems, that could not be easily overcome. And these problems get more severe with scale