Re: the hydrogen dream

Frank Logullo wrote:
>
> "jim beam" <nospam@xxxxxxxxxxx> wrote in message
> news:jPSdnZNUM9lA10TfRVn-jQ@xxxxxxxxxxxxxxxx
> > Uncle Al wrote:
> > > jim beam wrote:
> > >
> >
> >>http://news.com.com/Start-up+coins+new+way+to+harvest+hydrogen/2100-7337_3
> -5783870.html?tag=nefd.top
> > >>
> > >>i love the way the sodium procurement question is so glibly
> side-stepped.
> > >
> > >
> > > Or the caustic waste disposal, ah, challenge.
> > >
> > > When somebody comes up with a denser hydrogen storage modality -
> > > atoms/liter - than an open bucket of diesel, Uncle Al will retract his
> > > middle finger. BTW... you get to burn the carbon in diesel, too.
> > >
> > > Diesel with a density of 0.84 g/cm^3 and nominal CH2 formula has 59.9
> > > moles of H/liter. The only hydrogen storage modality of any kind -
> > > including armored walls, super insulation, nanotube adsorption, and
> > > HYSTOR chemisorption - that is within a factor of two is gasoline.
> > > Diesel or gasoline, a cheap plastic tank at ambient temperature and
> > > pressure will do the job with a huge *proven* safety margin. National
> > > distribution networks for both are already in place.
> > >
> > what i'd /really/ like to know is, where these guys get the chutzpah to
> > try this stuff. and what kind of individual is happy to help them try.
> >
> I don't even want to be driving next to the GM concept car. You know that
> thing must have a tank pressurized to maybe 10,000 psi - or enough to take
> out the block if it goes ;)

An open bucket of diesel less the carbon holds 59.9 moles of hydrogen
atoms/liter. To duplicate the hydrogen in a liter of diesel, a liter
of hydrogen gas must be pressurized to

(22.4)(59.9/2)(295/273) = 725 atm or 10,700 psi.

Do the van der Waals equation if you want decimal trim. That won't
give you nearly the mileage of the diesel, of course, for want of 29.5
moles of carbon to burn. Even worse, you need

(710.2)(101.325) = 72,000 Joules/liter

to compress the hydrogen, and more for mechanical losses and
compressional heating, that is non-recoverable.
One presumes an initial heavily armored steel (DOT, OSHA, EPA,
Homeland Severity) pressure tank will instead be fiber-resin to save
hundreds of pounds of weight (and still leave about 100 lbs extra).
Vibration during driving, temperature from parking in the sun, grease
and oil splatter, fatigue from constant pressure cycling... no
problem. And the fittings will never leak, ditto the elastomer
seals. Hydrogen won't diffuse through orgnics, much, liek the resin
for instance. KA-FUCKING-BOOM!

Have you ever watched SCUBA tanks being filled? It's done in a vat of
cold water. /_\P/_\V = 101.325 J/liter-atm. Pressure fill, physisorb,
or chemsisorb hydrogen and you have incredible heat dumping problems
at the storage tank. The more efficient the fill, moles H2
contained/liter, the bigger the exotherm.

The obvious solution is liquid hydrogen at 20.4 K, although air
freezes solid around 60K. A housewife filling 'er up with liquid H2
ought to be interesting before, during, and after. Boil-off while
parked in a closed garage is a fun thought, as is a traffic accident
that ruptures the cryogenic tank. Liquid H2 has has a density of 0.07
g/cm^3, about 1/12 that of diesel. Your 12 gallon diesel gank would
be a 550 liter liquid hydrogen armored dewar (and you wouldn't get the
mileage from burning carbon in diesel). You didn't want a trunk
anway.

But wait! There's more! Merely liquefying hydrogen gives you a
mixture of ortho- (electron and proton spins parallel) and
para-hydrogen. At 20 K it reverts to all para with an exotherm and
substantial boil-off. You can filter the liquid through iron-doped
activated carbon to equilibrate the spin population and you still get
the boil-off, though on the spot. So liquefaction costs much more
than the glib numbers say, so what? /_\H(combustion) para-hydrogen
is smaller than for the spin-equilibrated gas, but what the heck. You
are already a bleeding sucker to the left of the decimal.

The E*L*E*C*T*R*I*C car was merely a violation of thermodynamics and
engineering. The H*Y*D*R*O*G*E*N car is awful beyond imagination -
corrupt, impossible, and offensive. Plus the hydrogen distribution
system. Let's put a hydrogen liquefier at every gas station. It's
only a one time cost, absorbable into teh product price, plsu
operating and maintenance expenses and liablity insurance. Man, is
that last one gonna csot or what? KA-FUCKING-BOOM!

Finally, we all know how utterly successful cars and buses powered by
liquefied propane or compressed natural gas are. Their initial cost
is not even double that of gasoline and diesel equivalents, and they
rarely run more than three times initially estimated bloated costs
thereafter. The H*Y*D*R*O*G*E*N car will be even better.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
.