A Cell Tower in the Swiss Alps Is Struck by Lightning More Than 100 Times a Year | Hacker News Reader

A Cell Tower in the Swiss Alps Is Struck by Lightning More Than 100 Times a Year

spectrum.ieee.org

62 pointsamynordrum33 comments

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.

And yes, it’s a beautiful hike this time of year!

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:

http://map.blitzortung.org/#4.88/43.72/-5.29

People say it isn’t practical because it isn’t, and that’s why we don’t do it. [1]

[1] https://www.independent.co.uk/news/science/why-cant-we-extra...

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 ...

If you could harvest it with 100% efficiency you'd still save less than $2000 in electricity (assuming 5e9 joules in a lightning bolt).

I bet cable maintenance in mountains costs more.

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.

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.

>> The savings just isn't even remotely worth it.

> 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."

Of course, it doesn't guarantee success.

It's a cell tower. It needs cables anyway.

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.)

Yup, the local WISP does the same thing. Relay high up on the mountains and ptp link back to the main office.

TIL. Wow!

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?

Is that $2000 figure for a single discharge or a yearly figure already multiplied by 100 (days)?

1kWh = 3.6e6 joules

1 lightning bolt = 5e9/3.6e6 = 1389 kWh

price of energy = 0.10 $/kWh

price of 1 lightning bolt = $138.90

I'll buy one

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.

https://hypertextbook.com/facts/1998/MathieuLo.shtml

Since the earth is acting like a giant capacitor before the lightning strike, it may be easier to siphon off the charge before hand?

Could they send the lightning into the ground and put capacitors at points in the ground where the potential difference is acceptable?

My EE degree is getting a bit dated, but I think that would work because you'd effectively be using the earth as a power resistor.

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?

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.

This one is 20kv: https://www.amazon.com/20000V-10000PF-Voltage-Ceramic-Capaci...

So I only need 5000 of them in a series.

The first N capacitors will fail catastrophically, leaving the circuit open. Blown caps are a very common cause of failure in power circuits.

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.

Maybe channel the energy to a huge bank of resistive material and use the heat in some way.

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.

[1] https://www.ge.com/reports/post/123663889550/power-trip-watc...

Say lightening hits the sensors at the next mountaintop instead!

Lightning strikes each of the three major skyscrapers in Chicago (Sears Tower, John Hancock, Trump Tower) anywhere from 50 to 100 times per year.

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