Fwd: More problems with hydrogen

Eugen Leitl eugen at leitl.org
Mon Dec 1 03:47:01 PST 2003


On Sun, Nov 30, 2003 at 12:29:09PM -0800, Joseph S. Barrera III wrote:
> 1. I didn't realize spin mattered that much at the macroscopic level

This is something chemists learn as undergrads. As effective catalysts
are available and cryogenic gases are a mature industry you can assume
ortho/para isomery is not a practical problem today.

Cryogenic hydrogen is an extreme niche as fuel. It might have lower
power density than liquid oxygen/kerosene, but it has higher exhaust
velocity and is a much cleaner fuel for launches (though people using
ammonium perchlorate/alumin/resin boosters don't give a flying fuck
about environment anyway).

> 2. I like the idea at the end about using propane as a fuel, created
>    from hydrogen and atmospheric CO2, for no net CO2 increase.

This is not a good idea. Propane is a gas, not a liquid. Methanol
is easier to synthesize, and has a far better conversion rate in 
fuel reforming (and can be processed as is in direct methanol fuel
cells, which will dominate the marketplace). Propane makes sense
if you already have it from a fossil source, and can use it in 
high-temp oxide fuel cells, or in ICUs.

You have to use the right fuel for reforming, otherwise it
will soot up your catalyst.

> 3. Original source appears to be item 8 on
> http://www.sepp.org/weekwas/2003/Nov29.htm
> 
> Interesting item from Fred Singer's newsletter.
> -----------------------------------------------------------------------
> 
> More problems with hydrogen
> Phil Chapman reports:
> 
> Hydrogen exists in two forms, called ortho- and para- (in one, the spins 
> of the 2 hydrogen nuclei (protons) in the molecule are parallel, and 
> anti-parallel in the other). At room temperature, 75% of H2 molecules 
> are ortho, and 25% are para. At the boiling point, however (-253 C), the 
> equilibrium is 0.3% ortho and 99.7% para. If you simply liquefy 
> hydrogen, the liquid is unstable, as the 75% ortho converts to para. 
> This is an exothermic process, releasing 50% more heat per mole than the 
> heat of vaporization. In other words, the liquid boils, without any 
> external heat input. The tank will explode, or vent, both of which are 
> disasters.

Straw man. This hypothetical scenario would emerge if no one would
use a catalyst in the liquification plant. What's the ratio of ortho/para
in electrolysis hydrogen, and don't you think it's trivial to use
the catalyst at fabrication stage?

Who on earth would want to use cryogenic fuel, but a rocket scientist? Oh,
wait... 
 
> To prevent this happening, it is essential to convert the ortho hydrogen 
> to the para form during liquefaction. Various catalysts can be used for 
> this purpose, but it complicates the process. We are not going to see 

Look at a liquification plant layout. It's an infitesimal increase.
Which is irrelevant: it is being done already. Otherwise, you wouldn't
be able to ship.

> hydrogen liquefied at your friendly local gas station, whether it is 

Idiot. Gas liquification doesn't scale to small installations.
No one in his right frame of mind would be thinking about fuelling up
cars with a cryogenic fluid.

> produced locally by electrolysis or arrives as a gas by pipeline, 

If you produce hydrogen by electrolysis, it is using by juice from
the roof solar, which stays in the pressure tank to cover night use.

If hydrogen arrives by the pipeline, it is consumed immediately
in the home.

> because the equipment is too expensive and requires too much care and 
> because the process is too dangerous.

Nice strawmen he's producing. One could almost think this is 1970 all over
again. Each time people start from scratch, regurgitating the same tired
crap all over again.

The pathetic thing about this is that people will still listen to "experts"
with a pensive eye, and nod sagely. If anything, the general public
has now less basic science knowledge that a generation before.
 
> It is impractical to ship liquid hydrogen over any significant distance 
> by pipeline (the insulation requirement is prohibitive, because of the 

Patient: "Doctor, it hurts if I poke a screwdriver in my eye!"
Doctor: "Why do you keep doing it then, you silly git?".

> surface area of the pipe). Thus the hydrogen must be delivered to the 
> station as a liquid, by a refrigerated tank truck. Such a truck is an 
> immense bomb, much more dangerous than a tank truck of gasoline. NIMBY, 

Actually, it far less dangerous than liquid gas trucks rolling daily
through your streets. 

But: just don't poke the screwdriver into your eye.

> guys, NIMBY.
> 
> Hydrogen is not a liquid above its critical temperature, which is -240 
> C, no matter what the pressure (that's what critical temperature means). 
> An automobile using it thus requires a very well insulated tank, or 
> perhaps a cryogenic refrigerator on board. If you don't have a 
> refrigerator, you can't park your car in your garage, because any heat 
> making it through the
> insulation will cause boil-off. The gas is explosive in air in all 
> concentrations from 5% to 95% by volume. Goodbye, house.

Wow, this guy is really an idiot. I guess it tells us something:
if NASA comes to solve your problems: run away. Fast. 
 
> It is very difficult to prevent hydrogen leaks, and they are very 

No, it is not. Hydrogen pipelines are in operation. You might have
to design for it, vs. methane.

> explosive, so I for one would not go anywhere near a gas station where 

Methane is very explosive, and sometimes it blows up houses. Nevertheless,
it is a widely used technology.

> consumers or ordinary gas jockeys were transferring the liquid into 
> cars. Goodbye, gas station.

Sure, if our cars ran on tetronitromethane, and we'd be juggling lit
dynamite sticks when refuelling, it could be pretty dangerous.

So: don't.
 
> The density of liquid H2 is only about 0.07 gm/cc (depending somewhat on 

The density of methanol is pretty close to water (it mixes freely with water,
and is instantly biodegradable by common soil bacteria), and it has about
half the energy density of liquid hydrocarbon.

If one would be stupid enough to burn it, electrochemical fuel sources
are non-Carnot, and have synergies allowing you to get an order of magnitude
more mileage than ICUs without even trying hard.

> the temperature), 10 times less than gasoline, but burning a kilo of H2 
> produces about 25% more energy than burning a kilo of gasoline. This 
> means that, everything else being equal (engine efficiency, etc), the 
> volume of the fuel tank on a hydrogen-powered car will have to be about 
> 8 times that of the tank on gasoline-powered car, for the same range. 
> Goodbye, trunk.

Please don't post this drivel. It hurts my brain just reading it.
 
> If the giant LH2 tank in your car is ruptured in a collision, the result 
> will be a shockwave and fireball that could destroy everything within 

No, this is simply wrong. This guy was an astronaut?!

> hundreds of meters. I suppose this means that we can save on ambulance 
> and funeral expenses, since there will be nothing left of the people 
> involved.
> 
> This whole idea is so ludicrous that I cannot believe it is serious. 

How come technically illiterate people are allowed on board of national
spacecraft?

> Could the hydrogen-powered car, like global warming, be just one more 
> attempt to solve a non-problem by imposing costs on the US economy (so 
> as to make capitalism less conspicuously successful, compared to 
> socialist disasters around the world)?
> 
> If we want to free ourselves from dependence on foreign oil, we can 
> drill in ANWR.  If we don't want to do that, we can convert cars quite 
> easily to natural gas, of which we and Canada have copious supplies. If 
> we want to avoid nitrogen oxides and other pollutants, we can 
> manufacture saturated hydrocarbons such as methane (CH4) or (better) 
> propane (C3H8) from natural gas, from coal, or from CO2 and hydrogen. 
> Propane is storable as a liquid at room temp, as for a gas barbeque. Its 
> density is 0.53 gm/cc, about 2/3 that of gasoline, so it needs a tank 
> about 50% larger (for the same range).

Just use biomass to make synfuel methanol, and your pain will end.
 
> Burning saturated hydrocarbons makes water and CO2, which in my opinion 

Fuel cells output destilled water, several/l day for household use. This 
is a big plus in the third world.

> is a Good Thing. There is no evidence that global warming exists; if it 
> does, it will improve the world climate, making northern winters more 
> tolerable, freeing lots of arable land in Canada and Siberia (as the 
> permafrost retreats), and delaying the inevitable reversion to the next 
> Ice Age. There is no evidence, however, that anthropogenic CO2 makes any 
> significant difference to climate trends, but increased CO2 is 
> unequivocally good for agriculture and the greening of the planet. CO2 
> is not a pollutant; it is plant food, as essential as oxygen to all life.
> 
> If however we worry about the greenhouse, we can make propane from 
> hydrogen and atmospheric or anthropogenic CO2. In that case, powering 
> cars with propane would produce no net releases of CO2.  The power 
> needed to make these fuels can come from nuclear power plants or solar 
> power.

Look at the carbon sources we burn or dump into the landfills. 
There are interesting new processes to hydrogenate cellulose and 
produce synfuel from random organics in general.

Looking at atmosphere and soil for CO2 sources is only an option
when you're sitting in a spacecraft on Mars. Oh, wait...

> ------------------------------------
> 
> Dr. Phil Chapman is a former NASA scientist-astronaut and a systems 
> engineer with extensive experience in many areas of research and 
> technical management. He was awarded the British Polar Medal for 
> services in Antarctica.

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