If one streak of lightening has enough energy to power a small town and there are billions of lightening strikes a year, why is it that a man can land on the moon but cannot capture a bolt of lightening?
Here is my answer. 1) We can easily cause lightening strikes. We do it with model rockets and lengths of wire.. we launch them into thunder storms. That's how we study them. 2) Lightening is caused by a potential difference between clouds and other objects (sometimes even other clouds). Once this potential difference is zero (voltage drops to zero), the bolt is done. You cannot really "trap" electicity. It's created when there is a voltage difference and it must flow. I guess the best thing one can do is create a bigass capacitor to harnes this difference... However take what I say with a grain of salt. I haven't taken physics in 3 years. But I am not really sure what you mean by "capture a bolt of lightening." Store it in a jar for later use? I guess that would be a capacitor. But why? We need a continuous voltage difference to keep the flow of electricity. I don't recall capacitors being able to do that.. they aren't like batteries.
Hi Andrew, Welcome to SciForums. Absane is right, we can capture bolts of lightning by launching rockets with wires up into the cloud. It turns out that the amount of energy in a typical lightning bolt is actually relatively small. They typically have a very high voltage, but a very low current. Many people have survived a direct hit by a lightning bolt, the amount of energy to power a small town would be more than enough to boil 100kg of water so nobody would survive a hit, therefore the amount of energy in a lightning bolt is not enough to power a small town. -Dale
Well it is... just not for very long Please Register or Log in to view the hidden image! Up to a minute for a town of 20,000, by a rough calculation (longer than I would have guessed).
you can capture all the energy of the bolt... but you will need a massive hyvoltage capacitor bank... and since we cant call on the bolts whwenever we want them... the costs of building the caps, wont ever equal the amount of energy we could collect... thus.. it is not worth it. -MT
You are better at physics than I am... how was my explaination? I keep meaning to pick up my old physics books and study up again.
Actually, the current is pretty high as well. It's just that the stokes don't last very long. The voltage is in the tens to hundreds of MV, and the peak current is in the 10's of kA, giving a peak power well into the GW range. But since each stroke only lasts a few microseconds, the energy transferred is still in the range of hundreds or thousands of Joules. This is enough to power a light bulb for 10 seconds or so. There may be 3-5 strokes ina strike, but it's still not much energy. Even if you could get lightning to strike in one place repeatedly, you'd need to use capacitors and electrical parts capable of handling very large peak powers. This is very expensive; the resulting electricity would probably be orders of magnitude more expensive than generating electricity using conventional means.
Like I said, it's been done and happens all the time. http://skydiary.com/gallery/chase2002/2002lightmovie.html (this one has a video Please Register or Log in to view the hidden image!) http://www.space.com/businesstechnology/technology/rocket_lightning_030130.html It is even being worked to be trigger with LASERs: http://www.spie.org/web/oer/july/jul99/laserlight.html But as I have read, they do it with copper wires and the when the strike happens, the wire vaporizes.
Pete is about correct concerning the amount of energy in a lightning strike. Each flash contains about a billion Joules (or a thousand million for some of you Europeans), according to the Univ. Of Florida's Lightning Research Group. They are funded through many government grants, including NASA. The Space shuttle launches from FL and lightning strikes are a concern. In their FAQ section, they state each flash contains the equivalent energy required to light five 100-watt lightbulbs continuously for a month. A link if anyone would like to read more: http://www.lightning.ece.ufl.edu/
