OK so I know people say it isn't practical but perhaps with a bank of capacitors charging some lithium batteries this cell tower could be powed by lightning.
100 strikes a year, it depends though if these are in one season.
This website runs the data for citizen lightning detectors, but you have to be a member to access the data:
Well they asume the scenario to get all the land lightning strikes ... and say it is too expensive to build so many towers and not worth it. Surely true, but I thought the main reason is, that it is just too difficult. The lightning will just melt anything where you want to store it and probably take not the intented path to those capacitors or batteries and just burn something else.
And maybe with effort you could build something lightning proof, but the gain is probably way too low.
Still, if I would have the funds avaiable, it would be an awesome project ...
It's a cell tower. It needs cables anyway. And being a cell tower, it also likely needs to be fairly close to actual humans anyway, so the cables it needs likely aren't even that long.
Not to mention the one-off R&D investment you'd be making, along with all the specialty hardware (and its up-front costs), training, etc. involved in capturing lightning. The savings just isn't even remotely worth it.
Except it would be new technology, could be patented etc.
It's mostly in fiction that fixing X for one person or situation doesn't proliferate into a new way to handle X altogether, and that's done in fiction so the storyline can save the day and then keep pretending we totally live in the same universe as actual reality.
> Except it would be new technology, could be patented etc.
I don't think this works. New technology can only spread if it is worth it. Developing technology for the sake of having new technology is almost always worse than nothing; you would not expect it to proliferate into a new way to handle anything.
My point is "If you think of it as just a solution for this one cell tower, sure, it's not worth it. But if you think of it as new technology that will be used in many situations, then development costs can make sense."
I've seen plenty of remote communications towers that do not have cables. Solar powered with generator backup and microwave relays to the next hop. It's SOP in the railroad industry, and how Sprint got its first backbone. (The "SPR" in "Sprint" is Southern Pacific Railroad.)
Maybe, but lightning only occurs in warm months. If you are going off grid anyway, wouldn't you want something that works year round like wind or solar?
How many capacitors have you seen rated for over 100 MV (megavolts)? I think a dielectric that can survive a field with that much tension is called unobtanium. Lightning is causing dielectric breakdown of the air (a great insulator already) over thousands of meters.
Maybe not at a single fixed point on the strike zone, but what about a ring at surface level? or even an earth submerged hemispherical sphere? Shouldn't there be a zone at which the peak available materials are capable of harvesting energy safely in a hemispherical shape within the earth around the strike zone? Then the harvested energy would be effectively "whatever reaches that zone to be absorbed" with the rest of it being resisted by the earth, no? Which given the energy in a lightning bolt it's hard to imagine is not "a lot".
These ideas seem too obvious to think that somebody hasn't already tried them and ruled them out though.
Blown caps are common because they get overvolted or they wear out. Why would the first N capacitors fail when they're all splitting the voltage? (Assuming the string of caps is properly isolated from the outside world. Is parasitic capacitance unavoidably high?)
I presume that if you model a lightning pulse and treat the leading edge as a step function (ignoring leaders etc), then a tiny amount of inductance inside the capacitor will cause the voltage to transiently exceed the rating. Since the capacitors all start at 0 Volts, then the one connected to the lightening will fail explosively. I would expect all of them to fail like dominos since plasma is a good conductor and each failure would not significantly soften the rise-time.
Perhaps inductance is the answer? Connect your lightning rod to a beefy primary of a transformer, with lots of tiny secondaries; each sourcing a capacitor.
The primary would be a rod (zero turns). Or probably better a large circle of ribbons (current travels down surface of the circle because electrons repel each other). With independent current transformers around each ribbon.
I had also wondered about a multi-strand design with different lengths as a way to smear the initial step.
The real issue is that a strike is fast transient currents: I suspect that my normal calculations for voltage, current, transformers, inductance and capacitance don't hold. The amount of charge that travels through a lightning bolt is typically around 15 C, although for large bolts this can be up to 350 C.
The main problem with the whole idea is that the actual amount of kW is not that large. "a lightning bolt, which has over five billion Joules of energy, which could provide one household with all their energy needs for a month" which I presume is assuming 100% conversion and storage efficiency...
Edit: and this really screws with any possible design: "Occasionally a lightning stroke will travel from the positive charge region in the top of the thunderstorm cloud to ground. This type of lightning is called positive lightning and accounts for about 5% of all cloud-to-ground lightning strikes. Positive lightning is powerful and typically carries more current than normal cloud-to-ground lightning". The diagram showed normal lightning bolts at about 30kA, and the rarer positive lightning bolts (electrons go from ground to cloud) at 100 to 200kA.
Energy from single lightening strike is something in the order of 5 billion joules or 1.500 kWh. The device should be relatively cheap to be worth of the cost.
Lightning strikes at the Empire State Building have been studied since the 1940s.[1] General Electric used to do this. They had cameras at 500 Fifth Avenue to photograph the lightning strikes.
I live not far from here. I recently hiked up and down to the peak (Säntis) mentioned, and wondered about lightning strikes and their frequency. The tower adds a good 20-30m to the peak, which is the highest for many kilometers around. They have a pretty large number of massive cables in and around the peak and tower to handle the current from strikes.
33 comments
[ 4.4 ms ] story [ 101 ms ] thread100 strikes a year, it depends though if these are in one season.
This website runs the data for citizen lightning detectors, but you have to be a member to access the data:
http://map.blitzortung.org/#4.88/43.72/-5.29
[1] https://www.independent.co.uk/news/science/why-cant-we-extra...
And maybe with effort you could build something lightning proof, but the gain is probably way too low. Still, if I would have the funds avaiable, it would be an awesome project ...
Not to mention the one-off R&D investment you'd be making, along with all the specialty hardware (and its up-front costs), training, etc. involved in capturing lightning. The savings just isn't even remotely worth it.
Except it would be new technology, could be patented etc.
It's mostly in fiction that fixing X for one person or situation doesn't proliferate into a new way to handle X altogether, and that's done in fiction so the storyline can save the day and then keep pretending we totally live in the same universe as actual reality.
> Except it would be new technology, could be patented etc.
I don't think this works. New technology can only spread if it is worth it. Developing technology for the sake of having new technology is almost always worse than nothing; you would not expect it to proliferate into a new way to handle anything.
Of course, it doesn't guarantee success.
I've seen plenty of remote communications towers that do not have cables. Solar powered with generator backup and microwave relays to the next hop. It's SOP in the railroad industry, and how Sprint got its first backbone. (The "SPR" in "Sprint" is Southern Pacific Railroad.)
1 lightning bolt = 5e9/3.6e6 = 1389 kWh
price of energy = 0.10 $/kWh
price of 1 lightning bolt = $138.90
https://hypertextbook.com/facts/1998/MathieuLo.shtml
But by the time you've dropped the voltage potential of the strike, is it worth it for the smaller amount of energy you'd recover?
These ideas seem too obvious to think that somebody hasn't already tried them and ruled them out though.
So I only need 5000 of them in a series.
I had also wondered about a multi-strand design with different lengths as a way to smear the initial step.
The real issue is that a strike is fast transient currents: I suspect that my normal calculations for voltage, current, transformers, inductance and capacitance don't hold. The amount of charge that travels through a lightning bolt is typically around 15 C, although for large bolts this can be up to 350 C.
The main problem with the whole idea is that the actual amount of kW is not that large. "a lightning bolt, which has over five billion Joules of energy, which could provide one household with all their energy needs for a month" which I presume is assuming 100% conversion and storage efficiency...
Edit: and this really screws with any possible design: "Occasionally a lightning stroke will travel from the positive charge region in the top of the thunderstorm cloud to ground. This type of lightning is called positive lightning and accounts for about 5% of all cloud-to-ground lightning strikes. Positive lightning is powerful and typically carries more current than normal cloud-to-ground lightning". The diagram showed normal lightning bolts at about 30kA, and the rarer positive lightning bolts (electrons go from ground to cloud) at 100 to 200kA.
[1] https://www.ge.com/reports/post/123663889550/power-trip-watc...
And yes, it’s a beautiful hike this time of year!