Fwd: More problems with hydrogen

Eugen Leitl eugen at leitl.org
Mon Dec 1 02:54:22 PST 2003


On Sun, Nov 30, 2003 at 11:21:31PM +0100, Dr. Robert J. Harley wrote:
> >It is impractical to ship liquid hydrogen over any significant distance 
> >by pipeline [...]. Thus the hydrogen must be delivered to the 

Cryogenic hydrogen is a small niche. Pipelines are there for gas.
Diffusion loss is a red herring, if compared with high tension transport loss.
In situ generated hydrogen doesn't have to be shipped at all, or
only within residential network to equilibrate demand spikes.

Jesus lord.

> >station as a liquid, by a refrigerated tank truck. Such a truck is an 

Are you nuts? You can power a scramjet with hydrogen, or a very large
plane, or a large ship.

You might get away with powering a monster truck with it, but I honestly
doubt that one. The boiloff issue (dewars don't scale small due to
surface/volume) and large loss when fuelling up.

Why addressing this strawman, then?

> >immense bomb, much more dangerous than a tank truck of gasoline. [...]

Get your facts straight. You get two failure modes: rupture, diffusion, and
detonation from an ignition source. This is extremly fatal in confined spaces. You do
not get detonation in open space, because hydrogen is lighter than air and
rises immediately, so you don't have the lingering hydrocarbons effect.

If ruptured and ignited on impact you'll get a huge fireball _rising upward_. 
Unlike hydrocarbons it doesn't cling and burn, and it doesn't radiate
blackbody like soot particles in a hydrocarbon flame. So it's a very hot
ball, that doesn't radiate IR downward.

Look at the Hindenburg total body count, and how many of survivors were
there. Look at the image sequence in slow motion.

Have you ever seen what a liquid gas truck does when it blows up?
I won't get nearly that damage with hydrogen. It would be spectacular,
but you'd get less victims.

> >[etc. etc.]
> >This whole idea is so ludicrous that I cannot believe it is serious. 

If you wouldn't keep wresting wagonloads of strawmen, it wouldn't perhaps
seem as ludicrious.
 
> Uh... palladium?  Any fule knows it can absorb hydrogen at higher
> density than liquid, even at atmospheric conditions, and desorb it
> easily.

There are far cheaper metal hydrides, though you have to heat 
to unload, and power storage density/weight is not good.

Direct hydrocarbon fuel cells and onboard-reforming for hydrogen fuel cells are canonical
sources to generate mobile power. Pipeline and pressure storage
are for immibile appications.

Cryogenic fuel is for rockets and scramjets, and maybe planes and ships. 

-- Eugen* Leitl <a href="http://leitl.org">leitl</a>
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