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My dad asked me the oh-so-famous question yesterday:

Why can't we harness the electricity from lighting?

After explaining to him the impracticalities of this as far as the amount of energy in lightning and how hard it is to get the same thing striked more than a few times in a year, I began to ponder another critical issue...

How big of a transformer would it take to get the theoretical 100,000,000 volts down to a level that could be stored in capacitors? From my understanding right now, this is a HUGE transformer! I don't know the math and EE involving fast transformers though.

When I talk big, I mean size. Like building big? Truck big?

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Maybe a Tesla coil style transformer can be much smaller in this scenario? – sharptooth Jun 9 '12 at 6:38
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Perhaps by the time it is 'lightning' it is too late. The voltage (charge?) differential is already in the atmosphere... try snagging it before it discharges. – Tony Ennis Dec 31 '12 at 17:18
Good Question. I would suspect that you would want to charge a cap with the lightning, and then discharge the cap through some sort of SMPS. It would be interesting to experiment with capturing an ESD pulse and powering an LED with it. I might have to do that when I go back to the lab after the holidays. – David Kessner Jan 1 at 1:47

3 Answers

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According to the Wikipedia article on lightning, a typical lightning bolt has enough energy to light a 100 watt bulb for 5.5 hours. This is not anywhere near enough energy to make it economically worthwhile to harness that energy. Especially since the location of a bolt cannot be known before it strikes and since successive strikes will be at different locations. Also, a transformer will not work since a lightning bolt is basically DC based as it is a discharge of electricity from one point (typically a cloud) to another (typically the earth) that only moves in one direction.

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It is a pulse, so maybe a transformer would be able to work. I mean it would have to work similar to the flyback transformer in a TV or a monitor. Still, 550Wh is too little energy - the batteries in my UPS contain about the same. – Pentium100 Jun 9 '12 at 5:01
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Oh it's not a question of the feasibility. It's a question of what size the transformer would be to even do that! – Kyle Jun 9 '12 at 13:50
@Kyle A really insulated one? Go convert volts to newton-metres per coulomb (hint) and hazard a guess at what weight or wire gauge is required. – Kenny Robinson Jun 9 '12 at 14:32
up vote 0 down vote

you cant charge a battery because it is a pulse
and a battery can't be charged with a huge pule / peek current

but there are super gold capacitors they have a capacity of 400 F and more
but a voltage of 2.7 V max

a pulse transformer to convert the voltage to a low, with a high current, a couple of 100 to 1000 of these capacitors. And you can store the energy;

The transformer needs to be very large due to high voltage, it can be that the spark from the lightning breaks true the transformer.

the huge current drawn by the capacitor is just a peek, so the wires on the secondary side doesn't have to be that thick 2 to 5 mm²

the transformer should have a size of minimum a house or even better.
the capacitor array is an other house big;

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You can heat (or vaporizesome) any conductive materials using lightning. For example you can heat water in a basin (or in bath tub) using energy of lightning.

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Interesting. Basically convert the energy into heat and store that. Doesn't sound very efficient, but might be easier to accomplish from a practical perspective. – David Kessner Jan 1 at 1:50

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