Use the Joule effect of the generators to heat a balloon or kytoon in addition to generate electricity

Part of the output of a generator producing electricity is lost due to the Joule effect. This could be used to obtain aerostatic thrust from an aerostat. If it is possible and really effective, several configurations can be studied.

Joule Effect | Electricity :

In the vast majority of applications, however, it is an undesired effect and the reason why electrical and electronic devices need heatsinks, apart from one or more fans that scare away the heat generated and thus avoid excessive heating of the different components and / or devices. In these cases, heat is lost energy and therefore a decrease in efficiency.

Instead of losing this heat while generating electricity, is it not possible to recover and direct it to heat, even slightly for a very large balloon, a closed envelope?

That said the same website mentions also:

For example, in electric motors where electrical energy is transformed into mechanical energy, an efficiency can be defined as the ratio between electric power (Joule I · V law) and mechanical power, even if currently the most efficient electric motors they do not exceed 50% efficiency due to the electrical resistance of copper, the best existing conductor, the possibility of greater efficiency has been demonstrated with motors with superconducting windings. Therefore, it is possible to conceive a reversible transformation in which all electrical energy is transformed into mechanical energy.

An example of a study of a superconducting wind turbine generator:

The cost can be high, and perhaps usual generators making loss by Joule effect can be more suitable for the described use.

Maybe you can do some calculations of heat loss from a sample generator and from a (steam) aerostat, weight, lifting capacity, and so on and compare that to using, say, a hydrogen aerostat where you include the cost of buying “green” hydrogen.

I still like my idea, or perhaps combined heating and electrity generation, better, but then on the ground.

I was thinking of a way to recover the heat which is wasted by almost all wind turbine generators anyway. We therefore have a combination of an aerostat including a turbine aloft (like the Altaeros balloon, the hot air from the generator replacing the helium although it is much less lifting).

The Joule effect lost depends on the generator used and its age. Certainly @dougselsam knows how a generator heats up.

If the Joule loss is 1/5, for a 5 MW generator, we have 1 MW Joule effect (heat). A 120 m diameter spherical aerostat made of double-layered ETFE film, U-value of 2.6 (W/m²/K) (see the linked document ), area of 45,216 m², volume of 904,320 m³, will have 33 tons of lift (less its weight and the weight of the equipment), for a temperature rise of only 8.5 °C from 10 °C, 0.0365 kg/m³, assuming I am not wrong.

A smaller balloon with a smaller area will be heated to a higher temperature with the same power of 1 MW: use the U-value of 2.6 (W/m²/K) for a double-layered ETFE film.

Now it would also be possible to heat the aerostat without using a generator, so in a cheaper way (but without producing electricity by this mean) by using some ideas presented on Methods to use kinetic energy for useful work without a generator? And methods to use kinetic energy to heat water directly? (link on the message above), by producing friction with a brake, as shown on Heat your House with a Mechanical Windmill - LOW-TECH MAGAZINE.

As there would be no generators or electric cables, the multiplication of small brake wind turbines would perhaps pose fewer problem.

What’s the efficiency of the generator of a large wind turbine? 80 percent seems low. And how heavy is it?

I don’t think a steam or hot air aerostat is possible. Because of the wind loading you have to inflate it to higher than atmospheric pressure, and with that you’ve lost all your lift, and it’ll fail because of the hoop pressure. Only possibility I can think of is perhaps if you construct an inflatable double-walled shell around it, but that’s also a much poorer solution than any other to lift things. Or perhaps not one single balloon but many closely stacked together, or as a multilayered shell, keeping the warmth in, but then envelope weight multiplies.

Edit, I see the above is wrong:

I provided an example, not assuming it can really work (too large), just to show what is possible to do with Joule loss.The efficiency can be higher, leading to lesser Joule loss. But if the generator is not very efficient or is old, higher Joule loss can occur. And if we do not want produce electricity, heating directly with a brake is a theoretical possibility. For AWES I do not still know how or even if that can work.

A generator of a large wind turbine is too heavy for any AWES. I think about high rpm and density generators like
High Speed Motors, Electric Generators, Permanent Magnet Motor Generator, Magnetic Permanent, High-Speed Motor, High Performance Motors, Permanent Magnet Bearings, Magnaforce | Calnetix Technologies :

Electric machines can be much smaller and have better efficiency when they can operate at a higher speed than the 3,600 rpm limit imposed by 60 Hz power systems.

An example of a power dense machine that we have designed and manufactured is rated at 100 kW and weighs 7.7 kg in a 2.3-liter volume, which is equivalent to a machine power density of 13 kW/kg and 43 kW/liter.

I don’t know the efficiency and the percentage of Joule loss for these generators.
A very high rpm is possible by using a sort of rim drive transmission, or/and by using small wind turbines aloft (Makani style) for a crosswind device flying fast.

On the sketch below:
Fuselage balloon 10 m in diameter, diameter 78.5 m²; with blades of 2.5 m wingspan, 15 m in diameter, diameter 176.625 m². Surface swept by the blades of 2.5 m, 98,125 m². Assuming that the fuselage balloon (3) is 30 m long, for an area of ​​approximately 710 m², a mass of 141 kg with an envelope of 0.2 kg / m², and approximately 500 kg for a double envelope (double layered ETFE film) of 0.7 kg / m², volume about 1000 m³ and U value of 2.6, a power of 182 kW makes it possible to raise the temperature by 100° and to save about 0.33 kg / m³, so 330 kg / 1000 m³, for a mass of 500 kg of double envelope, 500 kg of generators, and 500 kg of wings. If the balloon has a shape comprising a cylinder 40 m long for a total length of 65 m, the surface would be approximately 2130 m², and the volume 4000 m³. A power of 546 kW would be required in order to raise the temperature of 100° and gain 1320 kg, for a mass of 1500 kg of double envelope, 500 kg of generators, and 500 kg of wings, which amounts to roughly the same . With a double envelope of 0.35 kg / m², and a U value assumed to be a little higher, i.e. 2.7, we would have respectively a required power of 189 kW and 567 kW, for masses of the double envelope of 250 kg and 750 kg for the same respective gains of 330 kg and 1320 kg: we gain more with the longest envelope (leading also to more heating power required), in gain of 570 kg against 80 kg. These figures are a rough approximation.

In short, aerostatic thrust will not be enough to lift the assembly but will lighten it by 1/3 or less. That can be interesting to obtain a low cut-in wind speed.

The balloon gives the possibility of implementing the rim drive transmission allowing the use of small generators rotating at high rpm. In this 5 MW (wind speed 12 m/s) example, the diameter of the balloon fuselage is 10 m, the diameter with 2.5 m span blades is 15 m. The two soft wings have a total area of 2000 m². Expected lift-to-drag ratio of 5 without the turbine.

The wind turbine (aloft) surrounding the balloon: