Every year lightning strikes cause a lot of damage — with the high-voltage discharges being a major risk to buildings, infrastructure, and the continued existence of squishy bags of mostly salty water. While some ways exist to reduce their impact such as lightning rods, these passive systems can only be deployed in select locations and cannot prevent the build-up of the charge that leads up to the plasma discharge event. But the drone-based system recently tested by Japan’s NTT, the world’s fourth largest telecommunications company, could provide a more proactive solution.
The idea is pretty simple: fly a drone that is protected by a specially designed metal cage close to a thundercloud with a conductive tether leading back to the ground. By providing a very short path to ground, the built-up charge in said cloud will readily discharge into this cage and from there back to the ground.
To test this idea, NTT researchers took commercial drones fitted with such a protective cage and exposed them to artificial lightning. The drones turned out to be fine up to 150 kA which is five times more than natural lightning. Afterwards the full system was tested with a real thunderstorm, during which the drone took a hit and kept flying, although the protective cage partially melted.
Expanding on this experiment, NTT imagines that a system like this could protect cities and sensitive areas, and possibly even use and store the thus captured energy rather than just leading it to ground. While this latter idea would need some seriously effective charging technologies, the idea of proactively discharging thunderclouds is perhaps not so crazy. We would need to see someone run the numbers on the potential effectiveness, of course, but we are all in favor of (safe) lightning experiments like this.
If you’re wondering why channeling lightning away from critical infrastructure is such a big deal, you may want to read up on Apollo 12.
That means natural lightning is 30kA. I always imagined it to be a lot more, for whatever reason. Something like hundreds of thousands of A
it’s the voltage the problem, not the current
I always thought it was the wattage. One point twenty-one gigawatts!!
Jiggawatts!
What? No!
You need both to be a problem.
It’s the difference between standing in lake Erie and standing under Niagara falls.
A natural lightning is 1.21GW according to a “documentary” on time travel I’ve watched on TV.
Great Scott!
That’s heavy, man.
From what I can recall from a very serious dive I did into the literature back into the 80s, the highest recorded discharge at that time was around 450kA. However the current was inferred from the residual magnetization created in samples placed adjacent to the engineered discharge path. I’m not sure if that measurement method has stood the test of time, as it’s basis always sounded a bit iffy to me.
Also I remember that one of the early ’70s ESA geomagnetic measurement satellites had to be hauled off the stack at Canaveral and de-gaussed yet again after the gantry took a lightning hit a few hours before launch, generating some inter-organizational friction in the process.
30,000 amps at that voltage is a cosmic amount of power. Taking 30 kiloamps and the average voltage of 300 million gives us 9e+12 Watts, which even to me seems like it’s probably too much and one of the figures is wrong
They’ve been doing it for decades with what are effectively model rockets. Kennedy Space Center had a program not only for mitigation, but a scientific study of lightning. There are also programs to use moderately powerful lasers to create an ion channel in the atmosphere in order to ground out charge potentials; creating artificial plasma streamers, precursors in the formation of a bolt of lightning.
Rockets are single use only (but pretty cheap, only some paper, propellant and cheap clay nozzle). This drone could survive many hits and can fly until the storm ends.
This makes me wonder about a helium balloon flying above the cloud layer so the balloon itself doesn’t have to withstand the strike. That probably doesn’t work where I live, because the thundercloud tops are in the 20,000 meter range, but in a lot of places the majority of the weather seems to happen within 8000 meters of ground level.
once the cable gets iced it will drop.
Run a current in the cable to keep it hot. Maybe even have some sort of super-capacitor bank to gather a small fraction of the energy when lightning does hit it, and then release this energy over time along a higher resistance wire (paralleled to the low resistance lightning conductor cable) to keep the thing above 0 celsius.
You have independently reinvented “barrage balloons” and all of the inherent hazards they cause for airplanes. https://en.wikipedia.org/wiki/Barrage_balloon
On the down side, their demo unit melted on the first try. And then you’re defenseless for the rest of the storm.
Disposable model rocket engines cost a few dollars each and won’t leave you stranded if the storm exceeds the drone’s EM defenses.
Would be interesting to see the engineering process which makes a drone which can fly for a full storm and not melt down or get battered to pieces by winds… Also whether there are environmental effects to consider when discharging all that energy from the troposphere down a wire in one spot instead of letting nature play out
Also: what gauge copper wire do you need to repeatedly withstand that amperage over that distance? Is the wire re-usable, or does it vaporize after each strike?
I remember an article posted here where some Russians were doing it with a kite.
They connected the ground end to the HV output of a small TV in order to attract the lightning, and that apparently works.
IIRC, they mentioned that the UV emitted at the ground point of the strike was strong enough to peel the paint off of some of their equipment.
UV strong enough to peel paint. That’s a little scary.
Attempting to capture the energy is futile; while the instantaneous power is very high, the length is very short and strikes are very infrequent, so the energy power strike and average energy over a long time (days to weeks) is very low.
Google says a strike can be between 0.2 and 7 GJ; the high end of that translates to 2MWh, which can power an average household for about 2 months. Realistically, only a small portion of that energy can be captured, and the device to do so would be extremely expensive, since only capacitors could possibly store that energy fast enough.
Putting down a few solar panels would be way cheaper for the same power output.
To be fair, solar panels don’t usually work well in a thunderstorm.
And, I suspect, super terrible at absorbing a lightning strike.
Your thinking is stuck inside the box. Why try to capture it electrically? As a plasma discharge, it is very hot. If that heat could be used to expand some fluid, and that expanding fluid could be channeled through one or more turbines, the energy could be extracted over a longer period of time (or over a much larger surface area) mechanically, then converted to electricity (or compressed air, or even back to heat, but at a lower temperature for a longer duration).
The question then becomes how to get that plasma discharges heat to your turbine effectively, you would need to be in the ‘eye’ of the storm so to speak to get the max effect on the turbine. If you could aly out where the storms go on a regular basis, then you could build facilities in those areas but that’s alot of if’s and but’s to overcome.
Problems I see:
1. If it is still a plasma discharge, then it is vaporizing some part of the apparatus and thus the thing isn’t reusable. Otherwise it would be current.
2. How do you efficiently transfer heat from a plasma discharge into a liquid if it is a mile long and nearly vertical? That’s going to be a difficult water jacket to design, or else it’s only going to capture a teeny tiny fraction of the heat
This assumes you’re capturing lightning strikes. If your system is up there in the cloud before the voltage rises high enough to exceed the breakdown voltage of air, it could run off the lower voltage difference over a longer time: maybe a very large number of cloud to cloud discharges rather than one big cloud to ground strike.
All the research I’ve seen on this previously has been on initiating single cloud to ground strikes, but the reasoning behind sharp lightning rods on buildings was that they were dissipative to prevent the strike ever happening in the first place, and that might be a more useful way to try to harvest power.
Or put a generator on the pendulum of a Franklin’s Bells setup! (j/k I’ve built these and unless you had thousands of them you’re not going to get anything usable. But there is a significant amount of electron flow.)
I do not think so:
“a lightning bolt is typically around 15 C, although for large bolts this can be up to 350 C” – https://en.wikipedia.org/wiki/Coulomb#In_everyday_terms
The number of electrons in a lightening strike is much less than the typical alkaline AA battery from being fully charged to discharged (5000 C ≈ 1400 mA⋅h). The big difference between a battery and a lightening strike is the potential energy released from traveling high up in the atmosphere to ground and we have no way to capture that.
This also assumes the voltage differential is between the cloud and the ground. The differential goes all the way up to space. Most of lightning is above the cloud. In some theories, the cloud is kind of like a huge version this drone in that it is giving that voltage differential a low-resistance path to ground.
Hey! This article needs to cite the OG lighting catcher Ben Franklin! (https://en.wikipedia.org/wiki/Kite_experiment)
Could you send those Gigajoules into a big water tank and then heat your house for a couple weeks off the hot water?
Only if you could prevent those joules from radiating away over however many thousands of meters it travels before it gets to ground, blasting out heat and light and sound before it even reaches the drone. But even the bit that reaches the ground is enough to fuse a fairly impressive amount of sand into glass, so it might heat water up for a while. Not a couple weeks worth.
And the short time over which the energy is applied is a problem. It’s kind of why pulsed lasers are useful. If you pour that much energy into water that fast, it is likely to ablate away a tiny amount of the top layer and all your energy disappears in an explosion of steam, leaving very little which actually soaks into the bulk mass and warms it up.
“although the protective cage partially melted.”
Sounds like they should be using a titanium alloy because they are light weight and all have an absurdly high melting point.
“…and possibly even use and store the thus captured energy rather than just leading it to ground.”
Nikola Tesla had wanted to do this with a long antenna and a switch periodically turned on by a wind turbine and crank shaft. Although, that one just relied on atmospheric potential so I don’t know if he was really thinking about storms.
I’m surprised the wire leading from the drone to the ground was not also damaged like the cage. At least I didn’t see any mention of it.
I was wondering that too. I see no mention of it, but I haven’t searched very hard. I would assume that the wire was sacrificial and blew out like a fuse after each strike… If it is beefy enough to transmit more than a gigawatt without turning into a rapidly-expanding cloud of charged particles, surely it is too heavy for a solitary drone to lift hundreds of meters of it into the air.
At least that would be my armchair assumption. After all, even the cage melted, and that’s only a very short section of the circuit and doubtlessly thicker than the wire.
Time to repeat the experiment with a Chinook and a spool of massive cable. If the wire is single-use and the cage melts (and surely the drone will fail too after a few runs) I do not see the advantage of this over a very cheap small sounding rocket
Just thinking out loud here:
since the distance between drone and clouds is (how?) much closer the potential difference required for a strike shrinks accordingly.
-> the voltage diff of any strike is smaller.
could part of that energy be stored in a giant capacitor?
I’m thinking of a lake in an isolating geological formation. (does something like this even exist?)
pre-lightning it would have the same potential as the earth/ground around it (so it would still count as ground for the lightning).
post-strike maybe one could harvest that stored energy (and get the lake back on “ground” potential)?
Buildings and infrastructure are one thing, but if this could prevent wildfires that’d be huge.
Haha oh man. This kind of thinking is exactly why we should have a very strict taboo against letting engineers try to “save the world.”
Imagine what happens after we have an effective way to prevent random lightning strikes over vast amounts of wilderness for several decades, and then for whatever reason that ability atrophies, or its budget is cut, or there’s a war or political shift–anything. What is the next lightning strike gonna do?
If it has been happening for billions of years and life has adapted to it, the safest bet is to allow it to keep happening. Chesterton’s fence. Maybe using it to protect a couple specific areas is kosher, or in certain regions during severe wind storms to prevent a city from burning down (cough L.A.) but then you have to actually go and burn out all that brush that the lightning would have naturally taken care of and has been taking care of for eons. You could say “of course we have to do that!” …But thus far we haven’t been doing that.
There was a test in the Swiss mountains to do it with lasers :
https://actu.epfl.ch/news/deflecting-lightning-with-a-laser-lightning-rod-2/