Fwd: More problems with hydrogen

Joseph S. Barrera III joe at barrera.org
Sun Nov 30 12:29:09 PST 2003


1. I didn't realize spin mattered that much at the macroscopic level
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.
3. Original source appears to be item 8 on
http://www.sepp.org/weekwas/2003/Nov29.htm


- Joe

-------- Original Message --------
Subject: 	[cdn-nucl-l] Go hydrogen?
Date: 	Thu, 27 Nov 2003 19:05:51 -0500
From: 	Jerry Cuttler <jerrycuttler at rogers.com>
Reply-To: 	Jerry Cuttler <jerrycuttler at rogers.com>
To: 	cdn-nucl-l (E-mail) <cdn-nucl-l at informer2.cis.McMaster.CA>



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.

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 
hydrogen liquefied at your friendly local gas station, whether it is 
produced locally by electrolysis or arrives as a gas by pipeline, 
because the equipment is too expensive and requires too much care and 
because the process is too dangerous.

It is impractical to ship liquid hydrogen over any significant distance 
by pipeline (the insulation requirement is prohibitive, because of the 
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, 
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.

It is very difficult to prevent hydrogen leaks, and they are very 
explosive, so I for one would not go anywhere near a gas station where 
consumers or ordinary gas jockeys were transferring the liquid into 
cars. Goodbye, gas station.

The density of liquid H2 is only about 0.07 gm/cc (depending somewhat on 
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.

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 
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. 
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).

Burning saturated hydrocarbons makes water and CO2, which in my opinion 
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.
------------------------------------

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.

 


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