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As it is well known, a vacuum balloon using the materials we have at our disposal is not possible, because of the sheer force they have to resist from the air outside.

I have an idea and I want to know if there is anything that makes it impossible.

1) Build a balloon out of graphene which is very light and it is conductive too. 2) Since graphene is not airtight, cover graphene (that is not yet inflated) with a good electrical insulator which is also airtight. 3) Now make the graphene store electric charge. 4) This would exert force from inside as the electric charges on the graphene repel each other. 5) This causes the balloon to inflate while having a vacuum inside.

Now my question is there any theoretical problems (not engineering problems) with this model?

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  • $\begingroup$ Funny and interesting idea - if your question would be closed, I suggest a retry on engineering.stackexchange.com . $\endgroup$
    – peterh
    Commented Apr 3, 2015 at 1:14

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First, it is not "well known, a vacuum balloon using the materials we have at our disposal is not possible, because of the sheer force they have to resist from the air outside." In our patent application (Akhmeteli, Gavrilin, Layered Shell Vacuum Balloons, you can find it at USPTO site or at http://akhmeteli.org/wp-content/uploads/2011/08/vacuum_balloons_cip.pdf ), we show that sandwich structures made of existing materials can be both strong enough to withstand atmospheric pressure and light enough to float in air, according to our finite element analysis. As for your idea, external charge can gather on the surface of your structure due to discharge in air, say, during thunder, and ruin your design.

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    $\begingroup$ Well, you can add another layer of graphene that is not charged on top of the insulator to create a Faraday shield from thunderstorm. Secondly, the strong insulator I mentioned is to prevent discharges. Let's not talk about longevity of such a design and the engineering problems like I mentioned in my question. Let's focus on whether theoretically it is possible. $\endgroup$
    – Moj
    Commented Apr 3, 2015 at 3:28
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    $\begingroup$ There are actually two un-issued patent applications from 2006 (App 11/127613) which was abandoned 10/2006 and 2007 (App 11/517915) which was abandoned 6/2013. There's prior art in Armstrong, US patent 1,390,745 from 1919. For those of you who'd like to explore this technology: patents.google.com/patent/US1390745 $\endgroup$
    – Bob Jacobsen
    Commented May 15, 2018 at 4:00
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Interesting idea! Let's check the numbers.

For this to work at Earth's surface, the electric force has to cancel $P = 10^5 N/m^2$.

The electric field $E = \sigma / \epsilon_0$ in the case (no field inside, all the field goes outside).

For an area $A$, the force on a conductor due to a field $E$ is $F = QE/2 = \sigma A E / 2$ so the force per unit area is

$P' = F/A = \sigma E / 2 = \epsilon_0 E^2$

where I've expressed it in terms of $E$ so we can solve for the electric field $E$ needed to set the electric "pressure" equal to atmospheric pressure (ideally, you'd want a bit more to keep things stable):

$ \epsilon_0 E^2 = 10^5$

$ E^2 = 10^5 / 9\times10^{-12} \sim 10^{16}$

So the electric field you need is about $10^8$ volts/meter. That's a lot. It's 3,000 times more than the 30kV/m breakdown voltage of air.

What does that mean? It means that the charge on your balloon is going to instantly spark off into the air and the balloon won't be held up against the atmosphere any more.

Note that insulating the balloon won't help. The electric field has to go off to infinity to hold up the balloon against pressure. If you add insulation against sparking, several things can happen:

  • That insulation will still have the electric field outside it, so where the insulation ends, the sparking starts, and the balloon ends up neutralized.

  • Or you make the insulation so thick, without adding weight, that the surface area of the ballon is much, much, much (3000X) times bigger than the balloon itself, spreading the field out and reducing it.

So it looks like this isn't going to work at Earth's surface. Bottom line, the atmosphere pushes too hard, electrostatic forces are too weak, and the atmosphere isn't a good enough insulator.

But it's still a cool idea.

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  • $\begingroup$ Is it possible to have two spheres, like a capacitor, on the inner one, have positive charge and on the outer one, negative charge and some insulation material in between and make this idea work? $\endgroup$
    – Moj
    Commented Sep 27, 2019 at 22:16
  • $\begingroup$ Two concentric spheres? You can build that, but since the force is all between them, it wouldn’t help. The e field is trying to crush the outer sphere, adds no to air pressure. If you could built those spheres as a stable object, the best value for the field would be zero. $\endgroup$
    – Bob Jacobsen
    Commented Sep 27, 2019 at 22:47
  • $\begingroup$ I was surprised at first that there was no scale dependency (it doesn't work, even for a microscopic balloon...). But then I guess since the atmospheric force in and the electric force out both go by $1/r^2$ the scale cancels out. $\endgroup$
    – Oscar Bravo
    Commented Oct 2, 2019 at 9:32

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