The simple answer is that there is not enough energy in lightning to be useful. As many people pointed out, there is also the little problem of harnessing it... but that is not as big a deal as most seem to think.
Lightning is a discharge of electrical charge stored between clouds and the earth. It can even be triggered on purpose with a metal wire shot into the cloud by a small rocket or by using an ionizing beam (UV laser will probably work). Once triggered, the current flowing through the discharge channel can, for instance, be converted into heat in a large resistor, which would then boil water, create steam and drive a turbine.
Many of the other answers you got seem to imply we have to store the electricity in a capacitor... we don't, we only have to store the energy in the lightning and release it more gradually. Steam will do this just fine.
But even if we wanted to store the electricity, the required capacitor would not be that awfully large. Something on the order of a freight container would probably be enough... see, there is really not that much energy in lightning and cabinet sized MJ capacitor banks are being used in many areas of physics and technology. Put a few of those in series and you are there.
If one did that, a very old circuit made of gas discharge and mechanical switches and these large capacitor banks could be used to get convert the large voltage/small charge into a much smaller voltage and larger charge of equal energy content, which could then be converted to AC by an electronic converter. The circuit is called a Marx-Generator and is usually used to "create lightning" rather than to catch it, but it is, in theory and with a little bit of though also in practice, reversible:
So why aren't we? Because there is not much energy in lightning. A single solar panel will produce more electricity between two storms than the most sophisticated "lightning catcher" could.
So why bother? Rube Goldberg came up with much more fun machines that make just as much sense as the lightning catcher.
PS: Somebody did the math and the results are really pathetic:
You really only get 1-10MJ out of the lightning bolt... which is pretty much what I had based my capacitor size on. In comparison: 1 gallon of gasoline = 100MJ! So one lightning hit into the lightning catcher and you get the equivalent of a cup full of gas. Is that worth a container sized machine costing millions of dollars? Probably not... at least not until gas prices are somewhere around $10000,- a gallon.
· 1 decade ago