[rescue] SCRAPPLE

[James Lockwood]

On Tue, 13 Nov 2001, Kurt Huhn wrote:

> I recall a program on TLC or DSC about a fuel cell (?) car that produced
> steam and water as exhaust - the down side was that it was fueled by bottles
> of hydrogen and oxygen.  Talk about an impressive car wreck!

Hydrogen has a _lousy_ energy density.  I'd be far more worried with a
tank of acetylene, or even gasoline on board.  Hydrogen is actually safer
in some ways because if you avoid immediate ignition, if the tank is
breached it will all go up rather than pool near the ground.

The O2 tank is far, far more worrisome.

The chief problem with using hydrogen as your evergy source is the
density.  You need a huge high pressure tank to come close to the energy
that can be liberated from a few gallons of gasoline.  It doesn't liquify
under convenient conditions.

> That goes back a few years - and I'm sure that technology has advanced to
> where pure hydrogen and oxygen isn't necessary...

Oxygen can be used from air, with minor efficiency losses.  Hydrogen is
produced by catalytically reforming LP gas or similar (though this in
itself consumes some energy).  Catalyst poisoning is the big problem with
this, if the guts of a fuel cell see anything other than hydrogen they
stop working very rapidly.  Fuel cell tech is over 100 years old, Edison
made quite a name for himself working with them.

-James