From: Simon Stapleton (simon_at_tufty.co.uk)
Date: Wed Sep 08 2004 - 00:34:40 PDT
On 7 Sep 2004, at 21:39, karel Jansens <kareljansens_at_tiscalinet.be>
wrote:
> AFAIK, most of the "portable" fuel cells in development use (m)ethanol
> as fuel.
Methanol, if I'm not very much mistaken.
> Not inflammable, obviously, but a lot less finnicky than
> hydrogen.
Not inflammable? Shome mishtake, shurely. I run my pulsejets on
methanol, and the burns I have sustained in so doing can vouch for the
fact that methanol is _highly_ flammable. Ethanol is somewhat less
flammable. The lower and upper explosive limits (the lowest and
highest percentages by volume in air) at which they will burn are given
below.
Ethanol - LEL 3.3% UEL 19%
Methanol - LEL 6.7% UEL 36%
Hydrogen - LEL 0% UEL 100%
As can be seen, ethanol will burn at a lower by volume percentage, but
methanol has a wider range at which it will burn. That's why I use
methanol, not ethanol. Makes it less easy to overfuel the jet, you
see. Of course, Hydrogen is a rather more - how should I put this -
'tolerant' fuel. Maybe I should try some...
I must admit, though, that I personally would rather have a methanol
fuel cell than a hydrogen one. The thought of having a mini-hindenerg
in my laptop gives me the heebie-jeebies. A 'hydrogen battery
malfunction' could make a disk crash seem like a birthday present.
> All of them should be easily refillable, which is basically
> the point of a fuel cell.
Yes, but getting hold of 99% pure or better methanol is currently
bloody difficult (read - expensive). Admittedly, one could make a
refluxing still and distill on'e own from wood alcohol, but one had
better be bloody careful with the vapours. You'd better keep the
refill bottle sealed, as well, as methanol's hygroscopic (hence it's
difficult to get better than 99%). Mind you, if methanol fuel cells
become prevalent, I can see 'lighter refill' type pressurised
containers being developed, which should be no more dangerous than a
propane gas canister.
> For my Newtons, I'm basically holding out until the ultra-compact
> antimatter cells become more widespread. :)
Heh. I want the 'Mr Fusion' Newton add-on. Maybe if Einstein catches
on and we get some new hardware developed...
Simon
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