
A Cell Tower in the Swiss Alps Is Struck by Lightning More Than 100 Times a Year - amynordrum
https://spectrum.ieee.org/tech-talk/energy/environment/an-oftstruck-mountaintop-tower-gets-a-new-lightning-sensor
======
lukeqsee
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!

------
zeristor
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](http://map.blitzortung.org/#4.88/43.72/-5.29)

~~~
planteen
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](https://hypertextbook.com/facts/1998/MathieuLo.shtml)

~~~
DenisM
This one is 20kv: [https://www.amazon.com/20000V-10000PF-Voltage-Ceramic-
Capaci...](https://www.amazon.com/20000V-10000PF-Voltage-Ceramic-
Capacitors/dp/B01EXZVN2Q/)

So I only need 5000 of them in a series.

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

~~~
Dylan16807
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?)

~~~
robocat
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.

~~~
klyrs
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.

~~~
robocat
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.

------
Animats
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...](https://www.ge.com/reports/post/123663889550/power-trip-watch-these-
scientists-catch-lightning-2/)

------
Ericson2314
Say lightening hits the sensors at the next mountaintop instead!

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

