Fwd: More problems with hydrogen

Eugen Leitl eugen at leitl.org
Mon Dec 1 06:06:51 PST 2003


On Mon, Dec 01, 2003 at 01:33:51PM +0000, Russell Turpin wrote:

> Eugen Leitl:
> >This is not a good idea. Propane is a gas, not a liquid.

At normal conditions, I implied.
 
> Only if you have a leak in your propane system. All

When I drive up to refuel quickly, I'd rather not
have to establish a tight seal, which when broken results in
spraying of instantly evaporating liquid creating
denser-than-air explosive gas blankets. It is nasty to
handle diethyl ether near open flame/hot surfaces/sparks, precisely for
this reason. Switching over propane cylinders is
even more sucky.

It's simple engineering. If you want to refuel 
(on the run, in the hot desert, in the arctic sleet), you
don't want to shovel caustic hypergolic pellets (how do you charge?
by the pellet? weighing the car?), you don't want to handle
cryogenic liquids (want to pay for boiloff? run dry when
parked over a few days in the parking lot?), you
don't want to rip out and reinsert a quarter ton
of batteries: preferrably you pump high-vapor
pressure liquids.

In other words, just like a present diesel or gas pump.
It's a bitch you can't use a conventional pump with
an alcohol, as it corrosion profile is different from
hydrocarbons.

> the propane tanks you see, from the ones your
> neighbors use to BBQ to the large ones hauled down
> the highway, are carrying LIQUID propane.

I am very aware of that.
 
> Now yeah, if you let it escape, as you do just
> before burning, it gassifies. But cap it off, and
> it stays a liquid at room temperature. It's one of
> those substances whose boiling point at normal
> temperatures is below its vapor pressure. I don't

It is precisely why this is not a cryogenic fuel.

> know it's critical point, but it has to be well
> above 100*, since propane tanks work just fine in
> the tropics. I don't know its vapor pressure at
> room temperature, but I don't think it is that
> great. My impression of propane tanks is that the
> steel is more gauged for corrosion and to take the
> dents of handling, than what's required to hold the
> vapor pressure.

Propane is great, if you have it cheap from fossil sources.
You can't do that with methane, nor hydrogen.
Methanol is far less toxic then gasoline, and is just
a much nicer fuel to handle.
 
> Propane is a pretty nice fuel. Being a liquid, it
> is easily shipped, without any refridgeration.
> There is already a distribution system in place.
> It has about the same BTU per pound as gasoline.
> It burns cleanly and without any odor. There are a

To be clear, I think burning fuel to generate power
is an anachronism.

> broad variety of propane devices, from heaters to
> portable freezers. It's one drawback is that
> propane gas is heavier than air. A propane leak on
> a boat will turn your boat into a floating bomb.

Right. Ditto, methane. Given lousy engineering, I've
seen methane pipes running on the outside of buildings.
(Russians seem to be very fond of Brazilesque gargantuan
pipes snaking through the city, too).
 
> Besides, Hank sells it. ;-)
> 
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-- Eugen* Leitl <a href="http://leitl.org">leitl</a>
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