Wow, getting a drone to survive the massive electromagnetic fields (and plasma!) around lightning strikes is quite an accomplishment. Prior art in the area used rockets trailing a similar light wire to trigger lightning - used by Dr Uman's team at University of Florida (https://ufdc.ufl.edu/UFE0047331/00001).
Aren’t lighting strikes on aircraft a pretty common occurrence and even without that the charge on the skin of an aircraft flying through the air is quite substantial.
Rockets triggering lighting with wire has been since the late 50's (M. M. Newman), what's cool about the drone is you can send back data before the strike. Obviously a kite or aerostat would work as well.
I'm sure someone in the 90's was using rockets without wires, the exhaust from the rocket made the trail. I cannot source it.
These guys charging cars shows they are not really serious, but a lot of forest fires are lightning, it's a worthy thing to control if possible.
This is really cool, but I'm super skeptical of their proposed use case for protecting cities.
Aren't lightning conditions often preceded by strong winds and poor weather conditions? Not a great time to be flying drones. And the approach seems more complicated than simply installing lightning rods.
I'd sooner envision people using the technique to get a kick out of throwing lightning around like they're Zeus.
> Aren't lightning conditions often preceded by strong winds and poor weather conditions? Not a great time to be flying drones.
Well, the drone would be tethered by the ground attached wire, so it might not need to be that controllable. Elevation is the main concern, so as long as it can reach the right altitude, the tether could keep it reasonably in the right area.
I've flown my Mavics in rain and strong wind before - certainly stronger than anything I'd associate with lightning. Most of the lightning storms I've seen haven't been especially windy, but it might vary elsewhere. And that's a consumer drone with negligible weatherproofing.
I assume if there's a business case, they'll eventually automate this with drone swarms that wait in cabinets on building rooftops.
FWIW, where I live there are often intense thunderstorms during the spring and summer, and they are usually accompanied by windstorms, sometimes generating tornadoes.
I've been in Tokyo in some massive storms (NTT is a Japanese company), the wind and rain is absolutely insane sometimes. Kind of like a 30 minute hurricane.
> Traditionally, lightning protection has relied heavily on lightning rods. However, their protective range is limited, and in some cases—such as wind turbines or outdoor event venues—it may not be feasible to install them. At NTT, we are exploring the use of rapidly advancing drone technology to create a new approach: "drone-triggered lightning"2.
I can't believe that's a practical solution. Surely just installing more lighting road is simpler et more effective. They just want to do something cool and try to justify it sideways.
> flying drones into optimal positions beneath thunderclouds to actively trigger lightning strikes, and then guiding the discharge safely away from vulnerable areas
From a military standpoint, I wonder what it would take to discharge into a vulnerable area...
You could put the wire in the vulnerable area - perhaps using the same drone? But I don't think it would be any use. A lightning strike releases about 1 GJ of energy, mostly into the sky. So the effect at the target would probably be no more than a few kg of explosives which you could have delivered using the wire anyway.
> Future efforts will focus on developing technologies for capturing and storing lightning energy for potential use (Figure 7).
According to a quick search, a typical lightning strike carries about 1-5 billion joules of energy, equivalent to roughly 250-1500kWh; enough energy to power a typical home for 10-60 days. But larger bolts of lightning can have up to 8000kWh, almost a year's supply of electricity for a home in a single bolt!
Kuala Lumpur gets (generous assumption) about 100 lightning strikes per square kilometer per year [0].
If a single drone could service a lot of square km, then it could conceivably collect a lot of electricity. E.g. if it could service 20 square km: 20 * 100 * 8mWh = 16gWh per year. Not bad, but an upper bound, and it hinges a lot on that first parameter (service area).
Based on this and other comments in this HN thread, harnessing the lightning energy for potential use wouldn't be a replacement for a power plant. However, if the resources for the lightning energy capture are/become too cheap, this could be a replacement for solar panels. Instead of replacing the power plant, it would replace/complement electricity production of a single home/building. Maybe with big enough batteries that can capture this energy, it could become a viable solution?
> Maybe with big enough batteries that can capture this energy, it could become a viable solution?
No, it could not. The problem is that lighning strikes are so short, that their middling amount of energy still results in an insane amount of electrical power (for a very short time). And electrical power is the primary driver of cost in most components here.
Capturing lighning is like building literally a hundred electrical substations just to run them for 50 microseconds a day, 10 days per year. Our planet simply does not have the lighning density for this to ever work out.
All that (very expensive!) capture infrastructure would basically sit uselessly for almost all the time (even in the middle of a lightning storm!).
This [1] article claims that the electricity from 115 strikes could power the entire US grid for a year, but it's surely napkin math. Awesome tech, though!
Apparently a single lightning strike contains the equivalent of about 40 gallons of gasoline. It’s very powerful but not that significant on the scale of a whole city.
In fact a quick back of the napkin math suggests it would only power a city of a million people for half a second.
This comment made me wonder about the idea of harvesting lightning as a power source. Obviously it’s incredibly challenging, but I wondered if we had magic sci-fi technology that allowed it, how useful would it be?
Back of the napkin math suggests that even with theoretically perfect prediction, capture, storage and distribution you’d still get at best ~1% of the US’ energy through lightning capture.
I wonder what the average property damage is per strike. And if forcing lightning reduces or changes storm power. Maybe for preventative reasons you put them outside of towns and such.
Secondary school physics teacher here: The article is conflating power (watt or joule per second) and energy (joule or kilowatt-hour), so any claim they make is nonsense and the article shouldn't be taken seriously. My students make the same mistake all the time but they don't get to publish it :-)
Power is energy per time unit (thus: energy = power x time), so while the power of a lightning strike is very high (~10GW), the overall energy isn't because it only lasts for a very short duration (apparently the duration of a lightning event is hard to define, [1] says about 0,5 seconds, other places mention much shorter durations, ~10us). So if that 10GW lasts for 0,5 seconds, the total energy is 1,4MWh, which is 1/6 to 1/10 of the electrical energy an average American household consumes in a year[2].
Right at the bottom under Frequently Asked Questions:
How much lightning would we need to capture to power the entire U.S. electricity grid?
Merely capturing the energy from 115 lightning strikes would supply all of the U.S.'s annual electricity needs.
I wonder if we managed to harness and store this electricity from the lightning into some kind of large battery. If a drone can successfully fly and connect with the lighting, this seems like a possibility.
Edit: I read past the line where they mentioned this was in the plans.
The lightning "strike" mentioned in the article was probably not a direct hit. Nothing can really survive >30kA of current. I recall concerns from Boeing engineers when they switched to carbon fiber fuselages, that a strike would be far more serious than before, with Aluminum fuselages.
> I recall concerns from Boeing engineers when they switched to carbon fiber fuselages, that a strike would be far more serious than before, with Aluminum fuselages.
It's a serious problem for carbon-fiber wind turbine blades. Fiberglas is an insulator, and doesn't have lighting problems. Aluminum is a good conductor, and doesn't have lighting problems as long as there's a good a path to ground through the hub. But carbon fiber is a resistor, so conducting a lightning strike generates heat. Some copper or aluminum wire has to go into the turbine blades to bypass this.
I believe Boeing puts a conductive mesh into the carbon fiber fuselages, but there is still a trade between conductive capacity and weight. Guess which one wins?
There's 2 kinds of CG and there's long-line-induced EM.
Ordinary -CG is 30 kA / 30 C / energy of 1 t of TNT. +CG is 10x that.
Direct hits are survived all
the time by lightning rods for the past 275 years.
Long, unshielded lines of any sort can induce massive transient voltage transients (low current) that need to be protected with appropriate TVS circuits that will wear more in storm-prone areas. EMI from nearby lightning in unshielded computing systems with antennas or even without antennas can also be a factor.
A lightning rod is copper the thickness of your thumb. Anything thinner would melt. Lightning rods are expensive because thick pieces of copper cost a lot.
That is impressive, specially the drone surviving! I expect something along the lines of disposable drones, which would like still be cost effective at saving 100-200b yen a year!
It’ll be fascinating seeing this deployed!
Apparently they already have the ability to create lightning bolts in the lab for testing. Maybe they can license that.
> we conducted artificial lightning tests on drones equipped with the lightning protection cage. The results showed that the system withstood artificial strikes of up to 150 kA—five times greater than the average natural lightning strike—without any malfunction or damage, covering over 98% of naturally occurring lightning conditions.
Lightning is ~5GJ per strike. That means you'd need ~4 lighning strikes per hour just to keep up with a single large offshore wind turbine (15MW with 40% capacity factor).
There is also no realistic way to scale the whole thing up to significant levels of power; with the wind turbines, you just build several hundred to get into the GW range. There's simply not enough lighning to achieve that.
And the whole power buffering infrastructure that you would need would be an underutilized waste of (expensive) components.
There's never been any serious attempt at harvesting lightning at scale because a single glance at the numbers reveals how (economically) pointless an exercise it is.
Yes, thanks for repeating the content from the article.
"In addition, we aim to not only trigger and control lightning, but also to harness its energy. Future efforts will focus on developing technologies for capturing and storing lightning energy for potential use (Figure 7)."
I'm sorry but Figure 1 Lightning Protection Drone....all I see when I look at that is a abomination of antenna....like 5 or 6 roof antennas crammed into a single point in space time.
Not that it don't look super cook in its own way. But I just reminds me of antennas
Wow, getting a drone to survive the massive electromagnetic fields (and plasma!) around lightning strikes is quite an accomplishment. Prior art in the area used rockets trailing a similar light wire to trigger lightning - used by Dr Uman's team at University of Florida (https://ufdc.ufl.edu/UFE0047331/00001).
Aren’t lighting strikes on aircraft a pretty common occurrence and even without that the charge on the skin of an aircraft flying through the air is quite substantial.
And the prior art before that involved a kite and a key
Rockets triggering lighting with wire has been since the late 50's (M. M. Newman), what's cool about the drone is you can send back data before the strike. Obviously a kite or aerostat would work as well.
I'm sure someone in the 90's was using rockets without wires, the exhaust from the rocket made the trail. I cannot source it.
These guys charging cars shows they are not really serious, but a lot of forest fires are lightning, it's a worthy thing to control if possible.
This is really cool, but I'm super skeptical of their proposed use case for protecting cities.
Aren't lightning conditions often preceded by strong winds and poor weather conditions? Not a great time to be flying drones. And the approach seems more complicated than simply installing lightning rods.
I'd sooner envision people using the technique to get a kick out of throwing lightning around like they're Zeus.
My scepticism was more like “don’t cities already have lightning rods?”
> Aren't lightning conditions often preceded by strong winds and poor weather conditions? Not a great time to be flying drones.
Well, the drone would be tethered by the ground attached wire, so it might not need to be that controllable. Elevation is the main concern, so as long as it can reach the right altitude, the tether could keep it reasonably in the right area.
I've flown my Mavics in rain and strong wind before - certainly stronger than anything I'd associate with lightning. Most of the lightning storms I've seen haven't been especially windy, but it might vary elsewhere. And that's a consumer drone with negligible weatherproofing.
I assume if there's a business case, they'll eventually automate this with drone swarms that wait in cabinets on building rooftops.
FWIW, where I live there are often intense thunderstorms during the spring and summer, and they are usually accompanied by windstorms, sometimes generating tornadoes.
I've been in Tokyo in some massive storms (NTT is a Japanese company), the wind and rain is absolutely insane sometimes. Kind of like a 30 minute hurricane.
I'm pretty sure it'll be used as a weapon.
AFAIK the electric buildup starts even before the meteorological shenanigans.
> Traditionally, lightning protection has relied heavily on lightning rods. However, their protective range is limited, and in some cases—such as wind turbines or outdoor event venues—it may not be feasible to install them. At NTT, we are exploring the use of rapidly advancing drone technology to create a new approach: "drone-triggered lightning"2.
I can't believe that's a practical solution. Surely just installing more lighting road is simpler et more effective. They just want to do something cool and try to justify it sideways.
The expensive bit isn't the lightning rod itself, but the conductive path all the way to ground that has to handle 10^5 amps.
This probably has more value as a bizarre form of weapon than anything else.
Load up a bunch of B-52 bombers with giant Van de Graaff generators to fly over the target and then send the drone down.
I'd be shocked if that worked.
Codename Zeus.
> flying drones into optimal positions beneath thunderclouds to actively trigger lightning strikes, and then guiding the discharge safely away from vulnerable areas
From a military standpoint, I wonder what it would take to discharge into a vulnerable area...
You could put the wire in the vulnerable area - perhaps using the same drone? But I don't think it would be any use. A lightning strike releases about 1 GJ of energy, mostly into the sky. So the effect at the target would probably be no more than a few kg of explosives which you could have delivered using the wire anyway.
Plausible deniability?
People tend to get mad when you bomb them, but if no one noticed the drone in the storm it's just a natural strike...
Fire it at a transformer, take out power in an entire region and blame God. A perfect tool for the CIA.
> I wonder what it would take to discharge into a vulnerable area
HAARP /s
> Future efforts will focus on developing technologies for capturing and storing lightning energy for potential use (Figure 7).
According to a quick search, a typical lightning strike carries about 1-5 billion joules of energy, equivalent to roughly 250-1500kWh; enough energy to power a typical home for 10-60 days. But larger bolts of lightning can have up to 8000kWh, almost a year's supply of electricity for a home in a single bolt!
8MWh is equivalent to a few hours of electricity generation of a wind turbine.
Kuala Lumpur gets (generous assumption) about 100 lightning strikes per square kilometer per year [0].
If a single drone could service a lot of square km, then it could conceivably collect a lot of electricity. E.g. if it could service 20 square km: 20 * 100 * 8mWh = 16gWh per year. Not bad, but an upper bound, and it hinges a lot on that first parameter (service area).
[0] https://forum.lowyat.net/topic/5376210/all
4 replies →
I thought it was muuuuuch more than that! I've learned something otday!
Based on this and other comments in this HN thread, harnessing the lightning energy for potential use wouldn't be a replacement for a power plant. However, if the resources for the lightning energy capture are/become too cheap, this could be a replacement for solar panels. Instead of replacing the power plant, it would replace/complement electricity production of a single home/building. Maybe with big enough batteries that can capture this energy, it could become a viable solution?
> Maybe with big enough batteries that can capture this energy, it could become a viable solution?
No, it could not. The problem is that lighning strikes are so short, that their middling amount of energy still results in an insane amount of electrical power (for a very short time). And electrical power is the primary driver of cost in most components here.
Capturing lighning is like building literally a hundred electrical substations just to run them for 50 microseconds a day, 10 days per year. Our planet simply does not have the lighning density for this to ever work out.
All that (very expensive!) capture infrastructure would basically sit uselessly for almost all the time (even in the middle of a lightning storm!).
This [1] article claims that the electricity from 115 strikes could power the entire US grid for a year, but it's surely napkin math. Awesome tech, though!
[1] https://www.treehugger.com/how-much-energy-is-in-lightning-8...
Apparently a single lightning strike contains the equivalent of about 40 gallons of gasoline. It’s very powerful but not that significant on the scale of a whole city.
In fact a quick back of the napkin math suggests it would only power a city of a million people for half a second.
https://en.m.wikipedia.org/wiki/Harvesting_lightning_energy
This comment made me wonder about the idea of harvesting lightning as a power source. Obviously it’s incredibly challenging, but I wondered if we had magic sci-fi technology that allowed it, how useful would it be?
Back of the napkin math suggests that even with theoretically perfect prediction, capture, storage and distribution you’d still get at best ~1% of the US’ energy through lightning capture.
I wonder what the average property damage is per strike. And if forcing lightning reduces or changes storm power. Maybe for preventative reasons you put them outside of towns and such.
Secondary school physics teacher here: The article is conflating power (watt or joule per second) and energy (joule or kilowatt-hour), so any claim they make is nonsense and the article shouldn't be taken seriously. My students make the same mistake all the time but they don't get to publish it :-)
Power is energy per time unit (thus: energy = power x time), so while the power of a lightning strike is very high (~10GW), the overall energy isn't because it only lasts for a very short duration (apparently the duration of a lightning event is hard to define, [1] says about 0,5 seconds, other places mention much shorter durations, ~10us). So if that 10GW lasts for 0,5 seconds, the total energy is 1,4MWh, which is 1/6 to 1/10 of the electrical energy an average American household consumes in a year[2].
[1] https://amt.copernicus.org/articles/16/547/2023/ [2] https://www.eia.gov/energyexplained/use-of-energy/electricit...
That article seems very very wrong. I think they missed the difference between GW and GWh.
https://www.youtube.com/watch?v=fs28lEq9smw
Hah quite the oversight! To put a spin on an old saying, a little math is a dangerous thing.
1 reply →
that article does not make that claim
I think it does:
Right at the bottom under Frequently Asked Questions:
[dead]
I wonder if we managed to harness and store this electricity from the lightning into some kind of large battery. If a drone can successfully fly and connect with the lighting, this seems like a possibility.
Edit: I read past the line where they mentioned this was in the plans.
Protecting cities from lightning damage? This is a weapon and you all know it.
We've come a long way from Benjamin Franklin flying a kite into lightning. https://en.wikipedia.org/wiki/Kite_experiment
Whosoever is worthy of this drone shall wield the power of Thor.
The lightning "strike" mentioned in the article was probably not a direct hit. Nothing can really survive >30kA of current. I recall concerns from Boeing engineers when they switched to carbon fiber fuselages, that a strike would be far more serious than before, with Aluminum fuselages.
https://www.weather.gov/safety/lightning-power
https://aviation.stackexchange.com/questions/35493/are-carbo...
> I recall concerns from Boeing engineers when they switched to carbon fiber fuselages, that a strike would be far more serious than before, with Aluminum fuselages.
It's a serious problem for carbon-fiber wind turbine blades. Fiberglas is an insulator, and doesn't have lighting problems. Aluminum is a good conductor, and doesn't have lighting problems as long as there's a good a path to ground through the hub. But carbon fiber is a resistor, so conducting a lightning strike generates heat. Some copper or aluminum wire has to go into the turbine blades to bypass this.
I believe Boeing puts a conductive mesh into the carbon fiber fuselages, but there is still a trade between conductive capacity and weight. Guess which one wins?
There's 2 kinds of CG and there's long-line-induced EM.
Ordinary -CG is 30 kA / 30 C / energy of 1 t of TNT. +CG is 10x that.
Direct hits are survived all the time by lightning rods for the past 275 years.
Long, unshielded lines of any sort can induce massive transient voltage transients (low current) that need to be protected with appropriate TVS circuits that will wear more in storm-prone areas. EMI from nearby lightning in unshielded computing systems with antennas or even without antennas can also be a factor.
A lightning rod is copper the thickness of your thumb. Anything thinner would melt. Lightning rods are expensive because thick pieces of copper cost a lot.
That is impressive, specially the drone surviving! I expect something along the lines of disposable drones, which would like still be cost effective at saving 100-200b yen a year! It’ll be fascinating seeing this deployed!
That's a freefly Alta X in the photos which is a $20k drone commonly used in cinematography.
So.. how long do we have before situational personal lightning bolt is a thing?
Apparently they already have the ability to create lightning bolts in the lab for testing. Maybe they can license that.
> we conducted artificial lightning tests on drones equipped with the lightning protection cage. The results showed that the system withstood artificial strikes of up to 150 kA—five times greater than the average natural lightning strike—without any malfunction or damage, covering over 98% of naturally occurring lightning conditions.
The future is now: Check out Lightning On Demand, https://lod.org/ (Tesla tower approach & scientific motivations) & https://youtu.be/lix-vr_AF38?si=w78LyF9tlxGJB8Ay (capacitor driven Lorentz plasma cannon demo)
https://youtu.be/D6_ZC6BywXs
“Remember who the real enemy is!”
Next step, use the energy?
This is never going to be economical.
Lightning is ~5GJ per strike. That means you'd need ~4 lighning strikes per hour just to keep up with a single large offshore wind turbine (15MW with 40% capacity factor).
There is also no realistic way to scale the whole thing up to significant levels of power; with the wind turbines, you just build several hundred to get into the GW range. There's simply not enough lighning to achieve that.
And the whole power buffering infrastructure that you would need would be an underutilized waste of (expensive) components.
There's never been any serious attempt at harvesting lightning at scale because a single glance at the numbers reveals how (economically) pointless an exercise it is.
Yes, thanks for repeating the content from the article.
"In addition, we aim to not only trigger and control lightning, but also to harness its energy. Future efforts will focus on developing technologies for capturing and storing lightning energy for potential use (Figure 7)."
isn't conventional wisdom that this is "impossible" because you cannot charge batteries that fast?
4 replies →
I'm sorry but Figure 1 Lightning Protection Drone....all I see when I look at that is a abomination of antenna....like 5 or 6 roof antennas crammed into a single point in space time.
Not that it don't look super cook in its own way. But I just reminds me of antennas