Why is not possible to store electric energy from a Lightning?

[Thalita Luna]

That question has been puzzling me recently. But I know there is a simple answer to it.

 

[Vanadium 50]

It is, c.f. Ben Franklin

 

[Nugatory]

That question has been puzzling me recently. But I know there is a simple answer to it.

It's possible, just not economically feasible. It's a combination of unpredictability (we can't put our lightning capture device where we need it when we don't know when and where the lightning) and the cost of building something that can handle a huge short-term energy spike without breaking.

 

[russ_watters]

Also, google tells me a lightning bolt dissipates about a billion joules (1,000,000,000)! (zeroes and emphasis added by google). That looks and sounds like a whole lot, but it's 280 kWh (a month of electricity for a house), which is....some. Google also tells me there are 40 million lighting strikes a year in the US. If all of the energy in all of them were captured, that would be 11,200 GWh, which is about 1.3 nuclear reactors or a third of a percent of US annual consumption.

 

[Baluncore]

"Why is not possible to store electric energy from a Lightning?"
That question has been puzzling me recently. But I know there is a simple answer to it.

You cannot do it all at once. But if you use a loop antenna at a distance, to capture part of the radiated magnetic pulse, you can charge a smaller capacitor or battery.

To store all the energy in a strike, while the lightning current flows, requires you maintain the voltage, which is already above the breakdown voltage of the atmospheric insulation. Your device will therefore need better insulation than air, but the strike will then avoid you, and hit your neighbour instead.

 

[berkeman]

but the strike will then avoid you, and hit your neighbour instead

https://ifunny.co/picture/you-dont-have-to-run-faster-than-the-bear-get-mqQ74yGt8

 

[Baluncore]

That is a bit off-topic but
You do not always have to run faster than the slowest guy next to you.
You only need to injure someone sufficiently, that they display a weakness.

 

[BWV]

Also, google tells me a lightning bolt dissipates about a billion joules (1,000,000,000)! (zeroes and emphasis added by google). That looks and sounds like a whole lot, but it's 280 kWh (a month of electricity for a house), which is....some.

280 kWh is also about the daily output of an acre of solar panels, another reason why no one cares about lightning

 

[PeroK]

It's possible, just not economically feasible. It's a combination of unpredictability (we can't put our lightning capture device where we need it when we don't know when and where the lightning) and the cost of building something that can handle a huge short-term energy spike without breaking.

That didn't stop Dr Frankenstein:

 

[Vanadium 50]

I'll raise...



Getting back on track, the earth's electric field is about 60 V/m. It is probably easier to extract this tiny bit of energy when it is not discharging - a little at a time. Instead of giant currents for fractions of a second every few weeks, use small currents most of the time.

It's still not a lot of energy.

 

[nightvidcole]

You could, but it wouldn't be cost-effective. If you built a giant, modified version of this setup, you could use lightning to split water into hydrogen and oxygen. But you'd be waiting a very, very long time for lightning to strike your metal rod.

 

[DaveC426913]

Agree with all. Is there some on-topic way to loop this back to the ravishing 30-year-old Teri Garr?

 

[Nik_2213]

Tangential: Back in the early days of fusion research, IIRC, an Italian team managed to collect interesting data on a shoe-string budget by linking a stormy Alpine mountain resort's summit lightning conductor to a 'zap chamber'.

As I understand it, each zap was a different length, shape and energy, so not 'reproducible'. However, their data set did 'explore the envelope', each spectacular storm generating many 'sampling points'. And, as they paid their own bar-bill, inexpensively, by side-stepping rival teams' costs of storage / discharge hardware and utility supply...

Upside, lots of fun data. Down-side, fusion initiation / sustaining demonstrated to be a hard problem...

Can any-one put detail to this tale, as I cannot find reference ??

 

[Vanadium 50]

I'd start with Martin Ulam's book Lightning.

 

[snorkack]

It is, c.f. Ben Franklin

Franklin captured energy from thunderstorm before actual breakdown (and was lucky not attract a lightning like Richmann).

You cannot do it all at once. But if you use a loop antenna at a distance, to capture part of the radiated magnetic pulse, you can charge a smaller capacitor or battery.

To store all the energy in a strike, while the lightning current flows, requires you maintain the voltage, which is already above the breakdown voltage of the atmospheric insulation. Your device will therefore need better insulation than air, but the strike will then avoid you, and hit your neighbour instead.

You don´t need to keep your "loop antenna" at a distance. You might actually coil your antenna around - but insulated from - the lightning path, i. e. a lightning rod. That is, use a lightning rod as one "coil" or a transformer and wind another coil of transformer around it.
But I suppose there are a lot of problems with it.
Another option might be concentrating lightning voltage by direct obstacles. The dielectric breakdown voltage of air is quoted as 3 MV/m. Copper of lightning rod is a conductor all the time. In contrast to air, "window glass" is quoted as 10...14 MV/m, "alumina" 13 MV/m, "borosilicate glass" 20...40 MV/m, "fused silica" 470...670 MV/m... Does bringing a lightning rod to ground even ground it? If you build your house upon a rock with the result that the lightning follows the rod but at the bottom of the rod meets solid and insulating rock, impassable for water or electricity?

 

[Nik_2213]

Modern 'code' differs, so take heed, but a cousin used to install lightning rods, cross-wires etc, had some 'fun' tales. IIRC, 'Grounding' is as important as 'catcher' size, positioning and down-feed. As with Radio Hams' antennae, the grounding arrangements must convey even worst-case mega-strikes to an appropriate 'pit'. This may be much more complex than a mere driven-metre of 'house' or similar electrical grounding rod.

To paraphrase my cousin, you could not permit any ambiguity in the disposal path. He mentioned having to test ground conductivity between the proposed 'pit' location and surroundings. The lightning strike must be led away safely, harmlessly dissipated, not allowed to ground-arc, ignite tree roots, jump to utilities, hand-rails or street furniture, form fulgurites etc etc...

Note that if you try inductively coupling to lightning conductor, you risk raising that conductor's 'impulse impedance', almost 'tempting' the strike to find another route or routes...
'Due Care, Please' ??

Added: Remembered this, which I'd sent to cousin...
https://www.volcanocafe.org/the-mystery-eruption-of-tor-zawar/

 

[Baluncore]

You don´t need to keep your "loop antenna" at a distance. You might actually coil your antenna around - but insulated from - the lightning path, i. e. a lightning rod.

I tried that about 35 years ago, when sensing the corona discharge through a lightning conductor to a ground mat. I used a toroid as the current transformer. Real lightning simply jumped through the air, around the outside of the toroid.

Does bringing a lightning rod to ground even ground it?

Yes, because that is a truism.

But not if you insulate the lightning conductor wire, or introduce an impedance. Then the velocity factor is too slow, so the fast lightning rise-time, goes around the outside, over the insulation.

Yes, when you bury a copper ground mat in damp soil, near the surface. I used 18 radial wires, each 250 metres long. A polygon of copper wire linked all radials at a radius of 150 metre. Back then, that was what I called a ground.

 

[snorkack]

Yes, because that is a truism.

But not if you insulate the lightning conductor wire, or introduce an impedance. Then the velocity factor is too slow, so the fast lightning rise-time, goes around the outside, over the insulation.

Yes, when you bury a copper ground mat in damp soil, near the surface.

Just because you build on "ground", i. e. "solid or pile or solids naturally piled on earth", does not mean that it is "ground" as in "low resistance conductor connected to the large capacitance of whole earth". And aiming to bury a copper ground mat "in a damp soil, near the surface", might be a contradictory goal if soil near surface is dry and insulating of electricity and groundwater and damp soil are far from the surface or absent. Or as I guessed, soil might be rock insulating of both water and electricity.

Tor Zawar... A conductive lightning rod (steel tower and steel supporting cables) grounded on ground that was poorly grounded because of high ground resistance? Causing the energy of lightning to concentrate near the grounding point, melting tons of rock that flowed for days?

Why doesn´t it happen all the time with lightning rods?

 

[berkeman]

I tried that about 35 years ago, when sensing the corona discharge through a lightning conductor to a ground mat. I used a toroid as the current transformer. Real lightning simply jumped through the air, around the outside of the toroid.

"I got this! I got this! ... I don't got this..."

 

[Baluncore]

Why doesn´t it happen all the time with lightning rods?

Because a lightning rod has a ground mat that is designed and engineered, to be a good conductor, to distribute lightning current radially and gradually deeper, onto the more conductive surface of the Earth. The radial wires spread out from a point on the surface, which results in a very low inductance. The circumference of the ground mat places the impedance of the radials in parallel with each other.

The lightning current initially flows through the ground wires, in the surface of the ground, between the air and the water table. Dry soil is a dielectric insulation, about the ground wire, Er = 2, so a velocity factor of 1/√2 = 70% of the speed of light. Where the moisture increases, the current departs the wire, to spread horizontally through the damp soil. The strike cannot immediately penetrate deep into the water table because at RF, water has an Er of 80, so a vf of 1/√80 = 11%, which is too slow. The lightning initially gets ahead by spreading through the intermediate moisture zone. The path taken to escape from the copper ground mat wires, to the Earth, will change during the seasons as the soil moisture changes. The lightning strikes that initiate the melting of rock, can only do so in very dry rock, rock that is also thermally insulated. It is so rare that it is an anomalous behaviour, occurring only where a vertical ground wire leads a strike into very dry resistive rock, possibly with carbon content. Without the transmission tower and lines, lightning would not have struck there.

The lightning strike jumps the insulators through the deliberate over-voltage path provided to protect the insulators from lightning, that punctures the ground resistance, then the capacitance of the distributed transmission line is discharges to follow the strike into the rock. The ground fault detection circuit is so far away, that energy from the transmission line can melt the rock by following the lightning underground. If the breakdown point on the line is remote, then the line-ground-fault current can continue to flow for a few seconds.

Therein lies the explanation for the small volcanic examples, the furnace is operated by energy from the power company, not from the precursor lightning. Once the line to a poor-ground connection is made, the transmission line can continue to operate since the 3PH lines are a closely coupled transformer that, in dry rock terrain, includes the grounded 'sky' wire. In the end, the asymmetry of the ground fault, seen from the alternator, must drop the line.

How I believe the miniature local volcanoes are created, is a very special case of the above, when more than one strike happens, to break down different lines of the same 3PH system. Those faults appear as load on the line, not as ground faults. The transmission line may then continue to function for several days, operating self-limiting rock furnace(s) along the route. I would be interested to know the carbon content of the dry rocks in the vicinity of the 'volcanic flows'.