Electric power from tethered balloons
June 4, 2008 at 4:15 pm #569
It’s little known that electric potential varies with altitude very quickly. The atmosphere has a steep electrical gradient, and your head is at roughly 160 volts from your feet when you’re standing up in the open air. The gradient can reach 300 V per m in winter. This permanent and pervasive electrical gradient has been harnessed for power generation in the 20s by Dr Plauson using a tethered balloon with conducting wire. The principle is very easy to understand: let the balloon rise to a couple kilometers altitude, and the wire will be charged at a few hundred thousand volts. You can draw that by connecting that wire at one end of a circuit and grounding the other end: this will lower the electric potential of the wire until the wire reaches an equilibirum where as many particles of air are ionized by the electrical potential difference up there as there are electrons leaving through the wire. Plauson was able to draw 3.4 KW from a 300 m altitude balloon this way. It is extremely cheap, simple, elegant, and pervasive.June 4, 2008 at 6:49 pm #2959
Sounds awesome, but do you know why it’s not used? Wikipedia says “it is thought to be too costly”, which is hard to believe when just a wire and a balloon would do.June 4, 2008 at 7:43 pm #2961
It’s not used because it’s very experimental, and because over land the tether would be a hazard to air transport, I think. Any industrial scale use would require special air trafic lanes redefining, which is more red tape heavy lifting than any interested party would be eager to try their hands at. However, on the ocean, there’s no such thing. I wonder if a boat or airship could be made to use this as a source of power…June 4, 2008 at 8:08 pm #2963
Well it would be worth a try i guess. But how come you don’t notice the 170V on your body? You wouldn’t need a huge cable, a cable from the top of the spar to the sea would be enough.June 4, 2008 at 8:29 pm #2967
Because voltage is a potential charge. Ampherage is what you’d notice passing through you, voltage itself goes nowhere, so to speak. Though I am still skeptical of the body having 120v from head to toe. uv maybe.June 4, 2008 at 8:47 pm #2970
I guess if everyone did it we would be sharing the potential with our neighbors. And all the lines would get tangled eventually. Could work on the sea though, if the payoff is big enough. 3,4kW doesn´t go that far after all.June 5, 2008 at 6:45 am #2988
What I said above might be misunderstood, as I had a poor choice of words: your head itself is not charged at a different potential than your feet because your body equalizes the potential by being somewhat conductive, but the air around you is. The potential builds up with altitude and reaches its maximum at the ionosphere, where the solar wind rips electrons off the molecules. Basically, the atmosphere works a lot like a spherical capacitor in this regard. Potential also builds up high there with frictional charging from cloud formation and winds (cloudstorms), to the point where the potential difference between the ground and cloud triggers a “capacitor failure” in the form of lightning.
The link says Oleg Jefimenko was able recently to power a LED with just a 5 meter antenna: because the current you get is sized after the resistance of your conductor and its capacity to ionize air (it goes higher when you use finer wire because then the gradient in the air close to the wire is steeper), you’d need more than just a wire to get any decent power.
Theoretically, you could power things off the potential difference between the ground and the air around your head, by using your body as antenna, but it would involve capaciting soles on your shoes, and the amperage would be minuscule.June 19, 2008 at 12:07 pm #3267
Actually, the reserve of potential is shared across the whole planet because of top atmosphere being conductive (low pressure gas). So wherever you put two balloons, they are feeding on the same capacity. Paulson used two balloons at once to reach 3.4 KW, so more balloons mean more juice.
I’ve set up a page dedicated to this power generation here on the wiki.
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Written by Jesrad