Can We Harvest Lightning for Energy?

[taylaron]

hey all,
has it ever been possible or even attempted to capture the vast amount of electricty there is in lightning?:rofl:
all that ground wire is in almost every non-stationairy device leads into the ground. (kind of waisting electricity in my opinion)
why can't we use all this energy going into the ground. espcially lightning because it is the process of a massive static discharge.
i asked around and i got the reply "nothing can hold that amount of energy for that long of a time. nothing could stand the temperature of lightning."
and i suppose they're right. lightning is somewhat "hotter" than the sun.
but why can we use water (a conductor) as the conductor.
i have no clue what on Earth could be charged by a lightning strike in about 1/1000'th of a seccond. charging at that speed i suppose would be very diffucult:grumpy:


im simply asking why we're not harnessing all of natures energy. or potential energy in some cases. lightning has a lot of electric potential to us i think.

 

[chroot]

From an electrical engineering perspective, the hardest part about capturing the energy in a lightning strike is indeed its very swiftness. You're probably aware that batteries must be charged very slowly; all batteries have some unavoidable series resistance, and trying to pump tens of thousands of amperes of current through even a tiny resistance will still generate an enormous amount of heat -- enough to essentially fry the battery.

If you really wanted to capture the energy in lightning, you wouldn't want wait until a bolt occurs -- that's just too much current in too short a period of time. Instead, you could conceivably build a tall vertical structure which is capable of continually neutralizing static charge between cloud and ground. This structure could move the same amount of charge as in a lightning bolt, but spread over a much longer period of time. A current of tens of hundreds of amperes is quite easy to deal with, and could be used to charge ultracapacitors, spin up flywheels, etc.

Building such a tower would be an engineering feat, however, and it's not clear to me (I'd need to do some calculations) that the economic value of the energy that could reasonably be captured this way would justify the cost of the structures.

- Warren

 

[taylaron]

thats very interesting. i actually thought of that but i failed to mension it in my post. i would greatly appreciate it if you did those calculations to see if it would be "worth it"
this lightning rod would have to be thousands of feet hight though. facinating idea though.

 

[chroot]

Wikipedia says:

An average bolt of negative lightning carries a current of 30-to-50 kiloamperes (kA), although some bolts can be up to 120kA, and transfers a charge of 5 coulombs and 500 megajoules (enough to light a 100 watt light bulb for 2 months).

I am no expert on lightning, so I don't know the veracity of this information. If it's correct, it means a single lightning bolt has very little energy indeed; it just looks spectacular because of its nearly instantaneous release.

- Warren

 

[es1]

Hmm...
i=Dq/Dt -> Dt=Dq/i=5C/30kA=160uS
Bigger currents just make Dt smaller.
The best games are ~100fps (right?) so ~10mS is fast for trained human eyes. Back the envelope sure, but ~200uS seems too fast to me.

Anyway, I agree with the conclusion, not much useful energy in lighting, but something seems weird in those wikipedia numbers.

University of Florida has it at 5 light blubs for month. They also address the original question in detail.
http://plaza.ufl.edu/rakov/FAQ.html

 

[es1]

Whoa it's surprisingly difficult to determine how long a strike lasts on average through cursory searches. My google searches found answers varying from 1uS to 100mS.

The guys who operate cameras seem to operate on the order of 10s of mS.

http://lightningtrigger.com/CameraCompatibility6/CameraCompatibility6.htm

But this was the most interesting.

http://www.srh.weather.gov/mlb/ltgcenter/whatis.html

It seems the forward path of lightning is a series of discrete jumps each lasting about 1uS over ~50m with the time to traverse the total path taking 10s of mS.

Also, according to the above link, the return does takes less than 100uS and has 5C of charge which does jive with the wikipedia article.

A stroke is one up down path of charge and a flash can (and often does) contain many strokes.

Amazing.

 

[Danger]

There's another possible approach that I just thought of. The practicality is pretty 'iffy', and it would entirely depend upon being able to direct where the lightning strikes.
I'm wondering if, given the intense temperature of a lightning bolt, it could be used to heat a large water reservoir. That could imply flash-boiling in order to run a turbine, although the explosion hazard seems rather high and steam regulation to get a smooth flow could be difficult. The hot water itself, however, could be used for other purposes. This would obviously have to be utilized in an area with a very high incidence of thunderstorms in order to be even marginally practical.
Any comments from resident experts about this?

 

[taylaron]

in my opinion, you would still have to use the long rod sticking up into the atmosphere to "direct" it to the ground where the water is underneith it. but using the static electricty that causes lightning. it would make much more sense to harness electricty for power, to me , would make much more sence. right?

good idea using water. one downside is that water is a conductor and if the water is in contact with a fraction of any piece of conductive material that leads into the ground. your hosed. in otherwords, it can't be grounded. right?

 

[taylaron]

i know lightning bolts; when they strike the sand, it melts the small section of sand into a "ball" or something like that. directing the current to some material in order to melt or use its conductivity in order to change some substance into another form.

this experiment would have to be taken place in a "bad-weather" location. eg.. a coastline because of all the evaporation by the clouds.
sigh...

 

[taylaron]

when lightning strikes water does it turn to steam/boil?i guess we sould ask ourselves that question first...

 

[schnitzer]

...

The only problem is in that energy storage device... I think that the temp. problem could be handled...
One of the profs. said once that a study proved that a single capture of a lightning could save up energy equal to a big country's 100 year supply of fuel...

lets try & capture one... anybody interested ??

 

[Danger]

We could take over the Empire State Building. Doesn't that thing get hit something like a couple of hundred times a year?

 

[tehno]

Wikipedia says:

/An average bolt of negative lightning carries a current of 30-to-50 kiloamperes (kA), although some bolts can be up to 120kA, and transfers a charge of 5 coulombs and 500 megajoules (enough to light a 100 watt light bulb for 2 months)./

I am no expert on lightning, so I don't know the veracity of this information. If it's correct, it means a single lightning bolt has very little energy indeed; it just looks spectacular because of its nearly instantaneous release.

- Warren

500 MJ is aproximately the explosive energy of 100 kg of TNT.
Is that much or very little? I would't know to say.
EDIT:I heard/read there are more than just one high current discharge in an individual lightning flash.Usually 3-5.Does that mean that total energy is 3-5 x higher than 500 MJ?

 

[Emicro]

Just a quick question, why dou you need a building? I would think that it would be way more cost effective to use a weather balloon on the end of a wire running into something like a Li ion bath. It would be like the mother of all batteries.

 

[taylaron]

i think it would vaporize the Li ion "bath" because it wouldent be able to abosrb all the energy quick enough. it would overheat quickly and "boom!" just like real battories when you crank a lot of voltage and current into them.. hee he..
good suggestion though.
i think using a building would be much easier than building just a baloon or building a giant vertical rod to capture this lightning because there would be a significant amount of structure benith the wire that extends FAR above the sky scraper to support it. this would be benificial to the structure and to the cost. a building is a good support for this wire, but it is still a problem with "stray" strands of lightning going away from the "guide wire" after it gets near the ground in order to be obsorbed in this massive Li ion pool.

the problem with a baloon ( think.. correct me if I am worong) is it would mealt the canavs that envelops the hydrogen. plus this thing would have to be HUGE! to carry a significant gague of wire from the Earth to our atmosphere. if it was a really small gague, than i think it would "guide" the lightning but all that electricity is being forced into that little space and would "fry" it almost instentaniously.
all that crap about ben frankeln catching a lightning bolt with a key on a string is crap if you had that on your mind.
i think temperature is our problem for baloons. for this reason, baloons would be (if not at all) 1 time use. because they would fall back to the Earth (if not vaporized first)
but you always hear about planes being struck by lightning and nothing damaged (but the electronics) because the lightning was simply "passing through" the plane. the plane wasent grounded to the ground. the same principle might work here. I am not sure.
good idea though. keep up the thinking.

correct me if I am wrong, but there would have to be some sort of "battorie" part to this Li ion "bath" the rods used for the + and - would have to be HUGE if not impossible to make/use. the lightning would also fry these on its way.
please feel free to correct me on anything i say. I am just basing this off my current knowledge

forgive my spelling as well...ugh...

 

[Danger]

im just basing this off my current knowledge

forgive my spelling as well...ugh...

I can forgive your spelling, but not that pun. :yuck:

 

[Arctic Fox]

Capturing lightning is easy...http://www.basestationzero.com/img/AFlarge.jpg

 

[Emicro]

I had not intended for the balloon to actually be struck by the lightning, the balloon would be above the weather. There are balloons that have been used to get into the jet-stream at 35,000 ft. and circumnavigate the globe, I'm sure that would work to keep the balloon above the lightning clouds. Also I was not intending for lightning to strike the wire at all, but going with chroot's suggestion of collecting energy all the time. The only real problem is the weight of conductor.

 

[Darryl]

has anyone seen those researchers who fire model rockets up into storm clouds, trailing a fine wire, they measure the electrostatic field levels, and when the get high enough, they fire the model rocket, ALOT of the time, very soon after they get a stike on the launch platform, where the wire is connect to ground, they use this rig to measure the lightnings parameters.

i remeber years ago, when i was working in radio comms, working at a transmitter station with 3 600 foot towers, when a electrical storm was approaching, we would drive out to the base of the towers, and with any lighting close by, the lightning arresters "spark gaps" would have a continuous arc across it, we'll before the storm was overhead and before the towers had receive any direct hits.

(we were out of there by them, its a scary sight very loud and violent).

i don't know how much power is in lightning, but i once saw a strike, when i was driving in a very bad storm, i heard the explosion and the light at the same instant (it was really close).
this lightniting strike, actually ignited the tree, and split in or snaped off a branch. the tree burst into flames in the poring rail. quite a sight to see, but scary :)

 

[tehno]

has anyone seen those researchers who fire model rockets up into storm clouds, trailing a fine wire, they measure the electrostatic field levels, and when the get high enough, they fire the model rocket, ALOT of the time, very soon after they get a stike on the launch platform, where the wire is connect to ground, they use this rig to measure the lightnings parameters.

http://www.lightning.ece.ufl.edu/

 

[taylaron]

i think you would want to use a building because it would be more cost-effictive in the long run

 

[Panda]

It just so happens that I have STANAG 4236 on my desk that is the NATO definition of lightning. I can't find a free download on the Internet, my copy comes from a subscription site. Alternatively look for work carried out by Cianos and Pierce, they seem to be the most quoted experts in the field.

A standard Negative strike comprises an Initial return stroke followed by a series of Restrikes between half and quarter of the peak current. Each stroke peaks at between 1.2 and 1.8uS, half current pulse width 45 to 170uS with a duration of 60 to 320ms between strokes. A Strike on average has 3 strokes but can be over 11 strokes. The peak current average is 20kA up to severe 200kA. There is a constant current period giving 140-500A for 0.16-0.5 seconds that may be easier to handle. In total the charge in a strike varies between 15C average to 200C severe.

So in general there is lots of current arriving in a very short time. If I had to store that sort of energy I would try and dump it into a massive ceramic capacitor bank. The problem would be preventing flash over on the capacitors. Commercial Ceramic caps can withstand up to around 50kV but the very high slew rates will easily create much higher potential differences. From experience charging to much more than 20% over rated voltage results in the ceramic explosively failing.

The best I have generated in artificial lightning tests is 1m arcs in non-ionised air and they are really hard to control because everything in the vicinity coroners and flashes over. So an umpteen mile long lightning strike would be a nightmare to store.

 

[tehno]

hey all,
has it ever been possible or even attempted to capture the vast amount of electricty there is in lightning?:rofl:
all that ground wire is in almost every non-stationairy device leads into the ground. (kind of waisting electricity in my opinion)
why can't we use all this energy going into the ground. espcially lightning because it is the process of a massive static discharge.
i asked around and i got the reply "nothing can hold that amount of energy for that long of a time. nothing could stand the temperature of lightning."
and i suppose they're right. lightning is somewhat "hotter" than the sun.
but why can we use water (a conductor) as the conductor.
i have no clue what on Earth could be charged by a lightning strike in about 1/1000'th of a seccond. charging at that speed i suppose would be very diffucult:grumpy:


im simply asking why we're not harnessing all of natures energy. or potential energy in some cases. lightning has a lot of electric potential to us i think.

I found posts on this forum relating this subject:
https://www.physicsforums.com/showthread.php?t=15163&highlight=lightning

I hope it helps to see how difficult is to capture (part) of a lightning energy!

 

[Ivan Seeking]

[copied from another thread]

Here is some information from The Feynman Lectures on Physics; Vol II, Chap 9, pp 2,3,11

The total power available worldwide is about 720 MW; having a typical average worldwide current of 1800 amps at 400,000 volts.

The current in a lighting strike is about 10,000 amperes at the peak, and carries about 20 coulombs of charge.

A typical strike can consist of 1, 2, 5, 10, or as many as 42 separate strikes.

Going by some seat of the pants calcs: if we assume 20 coulombs at 400,000 volts as an upper limit for energy delivered per strike, then we get something like 8 MJ of energy [again as an ideal upper limit]. A typical storm may deliver 100 strikes but over a large area. Even if we could capture all of this energy, then assuming that each strike is really an average of 5 individual events, we get about 4000 MJ of energy; this gives us 1 MW of power for about 1 hour. Not enough to be worth the trouble it would seem. Note that for any real system, if one could be designed and built, we would likely find the efficiencies very low - yielding perhaps 1-5 minutes worth of power in practice [as an example].

The other problem is that if we really somehow tapped this system, we would likely find many unexpected consequences in nature. Lighting is part of a worldwide charging and discharging system that may be an integral aspect of the biology of the planet.

 

[tehno]

Ivan:
It's not 400,000 volts (It's much higher when it comes to lightning).
400,000 volts Feynman talks about is probably the Fair weather potential difference between Earth and Ionosphere.

 

[Ivan Seeking]

That is the worldwide potential. It accounts for all of the energy available.

If you want to multiply by 10, make that an hour's worth of power in the example given.

Another way to look at it: A gallon of diesel fuel has about 100 MJ of energy. [edit]

 

[tehno]

I was talking about this part of your post:

Going by some seat of the pants calcs: if we assume 20 coulombs at 400,000 volts as an upper limit for energy delivered per strike, then we get something like 8 MJ of energy [again as an ideal upper limit]. A typical storm may deliver 100 strikes but over a large area. Even if we could capture all of this energy, then assuming that each strike is really an average of 5 individual events, we get about 4000 MJ of energy.

These 20 coulombs you cannot associate with the worldwide potential of 400,000 V just like that.
Total energy corresponding to an average single lightning stroke must be about two orders of magnitude higher.
OTOH, a continious total worldwide power due to atmospheric electricity you can relate to the mentioned 400,000 V.
Knowing worldwide total current 1800 A -->P=400000×1800=720MW.
That part of the post seems ok.

 

[Ivan Seeking]

I realize what your objection was. The point is that even on a global basis, the energy return doesn't even come close to justifying the investment.

If you want to multiply by one-hundred for any individual event, we still have nothing of significance. But you also must consider that at 10 million volts or so, that is the maximum potential. It does not represent the average potential during a discharge. Once the ionized path is established, a much lower potential can spark the gap.

Also, how much energy is lost to heat and thunder? I would bet that a good percentage of the total energy is used up in creating the ionized path.

 

[tehno]

What is a voltage drop per meter of length of a steady state nitrogen arc passing current 1800 A?

 

[Ivan Seeking]

I don't know what the minimum required potential would be over an established path.

Even at 500 MJ per event as was cited earlier, that is worth about five gallons of diesel.

 

[tehno]

Just a wild guess:Do 1000 A steady state arc with 1000 V/m voltage drop seem acceptable?
Than 4 to 5 km long lightning path should require at least 4 to 5 MV.

 

[Ivan Seeking]

I don't know; and I don't know if this could even be calculated.

I once built a system that used 20KV [maybe it was 50KV?] to establish an ionized path, then this path was used to conduct a large current [several thousand amps] at 1KV, but we never did see what the minimum required potential was to keep the path ionized. The thing is, an established ionized path is nearly as good as a wire.

But you do see that as the best case equivalent of ~five gallons of diesel per event, it is hardly worth trying to catch lighting for power, right?

 

[tehno]

But you do see that as the best case equivalent of ~five gallons of diesel per event, it is hardly worth trying to catch lighting for power, right?

Yes,not worth a try .
Fair weather electrical power of 720 MW is equivavalent to the capability of a pretty decent electric power plant.
Unfortunately, this energy is ,as you indicate ,spread all over the globe and impossible to tap I think.
On the other hand,the electrical energy of a single continental storm (which is a local event) exceeds 1 GW!That's what I have read.
Also,I don't have idea how to extract that power from the cloud cell.
And ,at last ,the power of wind of such storm exceeds many times electrical power of it and is much easier to tap.
And again nobody tries to do capture it becouse storms can not be directed and controled.
People are using the wind of fair weather,and solar energy.That's what has been done.

 

[krazyboi]

what happens when there's a lighting storm over the oceans? do a whole bunch of fish go belly up? and are they well done?

 

[taylaron]

im no expert but wouldent the energy in the lightning just travel straight down and out because water is a conductor. since the ground is -ground-
its reached where its trying to reach basically.
right??
if it did do something to a fish, (however) the fish probably would not exist any more.