Re: Electricity again


"tadchem" <thomas.davidson@xxxxxxx> wrote in message
news:1155164237.258876.146800@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
|
| Sorcerer wrote:
|
| > It's all "amount, amount, amount". We have the technology to charge
| > a capacitor. Whilst I agree that it would be pointless, dangerous and
| > prohibitively expensive to capture Super Dooper Ultra High Voltage
| > for very little current, we regularly use much lower voltages at higher
| > current.
| > Power is measured in watt hours,
|
| No. That is *energy*. Power is in watts. The power of a lightning bolt
| is on the order of gigawatts, even if only for a fraction of a second.

Ok ;-)

One gigawatt for 1 microsecond is 1 kw/sec, which is 0.278 kWh.
I could run a 100 watt lighting bulb for 2.78 hours on the energy of
one lightning bolt. Not very useful.


|
| > submarine batteries of voltaic cells
| > would hold the same POWER as a lightning bolt.
|
| At 1.06 volts per voltaic cell
| http://www.fleetsubmarine.com/battery.html
| you would need about *5 Billion* cells wired *in series* to capture a 5
| gigavolt lightning bolt.

Connect them in parallel, then. I regularly recharge my beard trimmer
from a nominal 3V source, it's a "so-what" if it works and it has for 3
years.


| Each one would have to withstand the total current of the bolt (30,000
| to 300,000 amps) for a fraction of a second while the chemical
| reactions (slow, because they are diffusion-limited) convert the
| chemicals into a higher-energy form.


I'm not suggesting you charge batteries directly. I was comparing power,
read what I said.
On your guesstimates, 5 gigavolt * 300,000 amps for "fraction" of a
second (I've chosen 1 microsecond) is 5kV * 300,000 amps for one
second, or 1.5 MW per second, about that of a wind turbine generator.
I mention that because the air pressure pulse of a lightning crack is
essentially a short burst of wind that becomes thunder as it echoes
and lasts longer. Then there is the heating as the bolt boils the sap in
a tree to steam and splits the wood (faster than a chain saw but requires
the same energy, it is the same amount of work done).

[snip narrow-minded chemist's rant]

There is insufficient energy in a lightning bolt to be useful in a practical
sense, but we have the technology to capture it should we so choose.
Wind power is more reliable, the original poster was day-dreaming.

Androcles.





.

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