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 ;-) You were the one mentioning power, we do not store power, we
store energy.

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.

That is a "so-what".
I'm not suggesting you charge batteries directly. I was comparing power,
which YOU raised, read what I said, not what you think I said.
We do not store power, we store energy.
On your guesstimates, 5 gigavolt * 300,000 amps for "fraction" of a
second (I've chosen 1 microsecond and your upper value) 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 trunk (faster than a chain saw
or a man with an axe, 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 any
practical
sense, but we have the technology to capture it should we so choose.
Wind energy is more reliable, the original poster was day-dreaming.

Androcles.






.

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