Link: https://en.wikipedia.org/wiki/Harvesting_lightning_energy

Since the late 1980s, there have been several attempts to investigate the possibility of harvesting lightning energy. A single bolt of lightning carries a relatively large amount of energy (approximately 5 gigajoules[1] or about the energy stored in 38 Imperial gallons or 172 litres of gasoline). However, this energy is concentrated in a small location and is passed during an extremely short period of time (microseconds[2]); therefore, extremely high electrical power is involved.[3] It has been proposed that the energy contained in lightning be used to generate hydrogen from water, to harness the energy from rapid heating of water due to lightning,[4] or to use a group of lightning arresters to harness a strike, either directly or by converting it to heat or mechanical energy,[citation needed] or to use inductors spaced far enough away so that a safe fraction of the energy might be captured.[5]

What about a really big capacitor? Could someone do the math on that?

I did this in fulgora

I did the maths on this a good while back, and worked out that an average lightning bolt contained around 50 UK pounds worth of electricity, maybe 70 US Dollars. (Thats at the price as purchased by a householder, not wholesale). The cost of storing that, and collecting it, combined with the unpredicitability of the strikes, makes the whole scheme a non-starter. Sorry.

Set up some lightning rods around Lake Cabo Venezueala, more nights than not they have so much lightning they can read a newspaper at night to it. Hook up massive precious metal coated wires (they don't burn up as easy as copper, high voltages travel on outside so you could do big copper then platinum and silver on the outside or something maybe,) and lead them to an aluminum smelter. Which requires a lot of energy.

The biggest smelter as is last I heard is in Iceland using geothermal heat.