Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Steve on 06/05/2008 08:59:52

Title: Why can't lightning strikes be bottled?
Post by: Steve on 06/05/2008 08:59:52

Steve asked the Naked Scientists:

Would it be feasible to bottle lightning strikes to collect or store the power they discharge?


What do you think?

Title: Why can't lightning strikes be bottled?
Post by: lyner on 06/05/2008 09:41:08

Lightning ( and sparks in general) are a plasma state, in which a lot of the atoms are ionised. There are a lot of ions and electrons buzzing round together. The total charge is zero (neutral charge). At atmospheric pressure, this involves high temperatures but, under reduced pressure (as in a fluorescent tube) it can all happen at room temperature.
The ions are continually recombining with electrons and emitting light etc., which means that energy is radiated away. The energy is supplied by the electric discharge from the clouds (or the mains supply, in the case of a flu tube). When the lightning or the stuff in the flu tube have lost energy, the spark dies.
If you put it in a bottle, the ions would interact with the sides of the container and the charges would dispell or, as the temperature fell, the ions would recombine, releasing light etc.
You can maintain a plasma for longer than normal by putting it in a 'magnetic  bottle' which is a fancy shaped magnetic field  (inside a doughnut shaped torus of coils) and it can't actually touch the sides but it still leaks away and the bottle needs a lot of power to keep it going.
Electricity is, essentially, a dynamic thing and can't be stored. Chemical cells (batteries) are not really storing electric energy - they are storing chemical energy. The charging process transfers the electrical energy to create new chemical compounds on the plates of the battery. When the battery is being used the compounds change back and electrical energy results.

Title: Why can't lightning strikes be bottled?
Post by: syhprum on 06/05/2008 15:08:02

I disagree electricity can be stored in a capacitor, the current in a lightning strike is of course oscillatory but the electromagnetic radiation from the the strike could be received on a suitable antenna, rectified and used to charge a capacitor (a very expensive way to obtain a small amount of power).

Title: Why can't lightning strikes be bottled?
Post by: lyner on 06/05/2008 20:07:19

Yes, you are right - but only in principle - capacitors are not really practical.
The problem with lightning is the short lived nature of it. Vast amounts of energy but frustratingly inaccessible.