harnessing lightning, or not
in [Design]
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From: Paul Keinanen on 13 Jun 2010 04:29 On Sat, 12 Jun 2010 11:20:05 -0700, Archimedes' Lever <OneBigLever(a)InfiniteSeries.Org> wrote: >On Sat, 12 Jun 2010 10:58:49 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>> >>> My cap would flash over as well, but more would remain stored than in >>>any of the scenarios discussed here thus far. >> >>I doubt that. Show us some numbers. Like Win did. > > > If lightning comes down here from a half mile up, it can certainly span >the distance between the nodes of any cap you can name, unless it gets >made as I described, with its nodes parted by vast distances. Again, no >friggin numbers needed. > > And I did mention numbers. 6MV and up. Duration doesn't matter. What >matters is that the cap's insulative layer survives the charge event >without a plate to plate breach. > > A huge, flat, encapsulated charge plate, placed flat against the Earth >plate will charge up, and hold charge, even after some flash over. > > The closer the charge plate can be placed to the Earth plate, the >higher the final charge will be, IF and AS LONG AS there is ZERO punch >through on the insulator. > > Since glass is the best, a thin glass plane mated to the charge plate, >and then encapsulated except for an in/out node is all that is needed. >The other plate is tied to Earth. The math is the plate area, and the >plate separation. The same math used for capacitance calculation the >whole time. If we can get the plate closer without a breach, the >capacitance of the assembly will grow. If you manage to make some huge capacitor on the ground and connect to an lightning arrester on top of a say 300 m isolated antenna tower, the capacitor will sooner or later charge to the potential of the air at 300 m (assuming lower leakage in the capacitor and feed line than through the surrounding air). The lightning arrestor tip potential would finally be about the same potential as the surrounding air at 300 m, thus, reducing the likelihood to that electrode, compared to grounded 300 m arrestor. Thus you may have to wait for the hit quite a long time. If the lightning hits after all and the capacitor is charged, but there is some flash over between the plates (perhaps only weak point), the arc will burn as long as there is sufficient power to maintain the ionization in the arc. With a large capacitor with a large charge, there is going to be a large current maintaining the arc, hence dropping the voltage across the plates. When the voltage has dropped sufficiently, the current is no longer capable of maintaining the arc and it will blow out. However, the remaining capacitor voltage is now much less than the initial flash over voltage, so very little energy can be recovered (energy proportional to the square of capacitor voltage). Why wait for the lightning strike ? There is a quite a steep (20-200 kV/m) voltage gradient in the air during a thunderstorm that could be utilized. Benjamin Franklin essentially tried this. Using a balloon, lift a string of series connected capacitors into the cloud and let those capacitors be charged. To collect enough charge, 2-3 balloons may be needed to suspend a "collector" net between them. When the capacitors have been charged, disconnect the "collector" from the capacitors and lower the balloons. On the other hand, if there are high towers, in which the lightning arrestor is frequently hit, why not put a current transformer at the lower end of the grounded arrestor to capture some of the energy ?
From: Archimedes' Lever on 13 Jun 2010 05:12
On Sun, 13 Jun 2010 11:29:03 +0300, Paul Keinanen <keinanen(a)sci.fi> wrote: > will sooner or later charge to the potential of the air >at 300 m So you think air has a gradient voltage that is tied to altitude? Where did you learn that at? The node could be a ball at the center of the cap lid. It does not have to be a tower. If charged clouds are passing over a 300 foot or 2000 foot diameter insulator down on the ground and a single node is at the center, it will find it to be a nice attractor, and it will strike it. a one inch spike would do it. No tower needed since there is no nearby 'competition' as an 'attractor'. Any pointyness at all will make for a huge gradient compared to anywhere else within quite a distance. Granted, a tower would be nice, but should not be needed to grab the attention of a charged cloud. |