Re: Solar-hydrogen home power system?
From: Gymmy Bob (nospamming_at_bite.me)
Date: 10/27/04
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Date: Wed, 27 Oct 2004 17:54:16 -0400
As I said "A hydrogen bomb waiting to happen"
"K. Jones" <shadetree1999@hotmailNODAMNSPAM.com> wrote in message
news:PuTfd.11562$Qs6.1195376@news20.bellglobal.com...
>
> "George William Herbert" <gherbert@retro.com> wrote in message
> news:417dd701$0$71140$c0de7616@newsreader.dsl.net...
> > Don Lancaster <don@tinaja.com> wrote:
> > >George William Herbert wrote:
> > >> Don Lancaster <don@tinaja.com> wrote:
> > >> > [...]
> > >> >A common misconception.
> > >> >The latest of modern multicycle power plants with bottom cycling
> > >> >routinely approach 60 percent thermal efficiency.
> > >>
> > >> Still 10% lower than SFOC fuel cells.
> > >
> > >You are confusing the theoretical lab efficiency with the fully
burdened
> > >amortization efficiency.
> > >
> > >The latter is NEGATIVE for SFOC fuel cells today.
> >
> > And the fully burdened amortization efficiency of growing
> > plants, burying them under silt for tens of millions of
> > years of process time, and then having to dig them up is?
> > Do you have any concept of what a hundred and eighty
> > million years of internal rate of return does to your
> > amortization calculations? You're killing accountants
> > just posing the problem.
> >
> > The interesting comparisons are what cycles can we do
> > when (a) the petroleum eventually runs out or
> > (b) we finally stop using (or at least, releasing)
> > fossil carbon fuels.
> >
> > Your analysis is not more insightful. You are merely
> > using a different boundary condition, and cheating on
> > how you describe the problem to puff yourself up.
> >
> > I am not rabidly enthusiastic about hydrogen vehicles
> > in any sense. My personal favorite renewable fuels
> > are either (methanol/ethanol) or thermally depolymerized
> > plant materials turned into diesel fuel. Those are a
> > lot easier to handle and probably cheaper cycles to set
> > up and use.
> >
> > But unlike you, I have worked with hydrogen, and I have
> > paid enough attention to what it really can and can't do,
> > and I don't think you have any sort of vaguely useful
> > approach to criticizing it at all.
> >
> > I frankly cannot respect anyone who spends their time
> > changing boundary conditions to make fraudulent debating
> > points and who is so afraid of liquid hydrogen and the
> > safety concerns of hydrogen fuels.
>
> I have used hydrogen daily in a previous job.
> A tube-trailer a day of it.
> I've also worked, daily, with liquid hydrogen.
> I'm also a hazmat specialist, and have responded to hydrogen incidents.
> IMHO, Don shows due dilligence and respect for the stuff, which helps to
> keep oneself alive when dealing with it in the manner to which he would,
as
> a hazmat professional. Do not confuse a "healthy respect" for being "so
> afraid".
> Note thus far, he is not one of the many response personelle who die evey
> year simply from lack of knowledge, or lack of "healthy respect".
>
> > In the San Francisco / San Jose area (SF Bay Area) you see
> > just about as many tanker trucks full of LH2 (about ten
> > cubic meters per trailer) as you do propane out on the
> > freeways. Hydrogen is used in bulk in semiconductor
> > processing. I can't recall hearing of any accidents with
> > hydrogen tankers. Several propane tankers have blown up
> > for one reason or another in the last 20 years. Hell, we
> > had a gasoline tanker explode in one of the bores of the
> > Caldecott Tunnel a couple of decades ago, killing a couple
> > of dozen people if I recall right.
>
> Not sure the reason for this paragraph....What are you suggesting, that
> nothing bad ever happens with hydrogen, or what?
> Wanna trade ancedotes?
> Or how about verifiable, comparable data, instead?
>
> > I know a bunch of fire personnel and hazmat team people.
> That makes at least three of us that know "a bunch" then.
> At least two of us work side-by-side with "bunches" of them every day.
>
> > None of them are more afraid of liquid hydrogen than
> > they are of gasoline or propane. None.
>
> Anyone who says they don't "pucker up" when dealing with anything that can
> kill you in a heart beat or less, is either very stupid, or lying.
> Well trained hazmat folks have an adage "If you don't know, you don't go",
> pick whatever nasty you want. The concern isn't so much for
> professional responders who have good training, "if they don't know, they
> won't go". The educated, experienced concern, is for the public at large.
>
> > They are frankly
> > more afraid of LOX, which also is transported in large
> > quantities. Or large quantities of fluorine compounds.
> >
> > Spilling hydrogen causes a flammability hazard and
> > possibly a low energy fuel-air explosion. The low
> > density of LH liquid and low boiling temp makes it
> > boil off rapidly, and the gas dissipates rapidly
> > and effectively.
>
> I'd say there is a little more to it than that.
>
> INEEL/EXT-99-00522
> Safety Issues with Hydrogen as a VehicleFuel
> Lee C. Cadwallader
> J. Stephen Herring
> Published September 1999
> Idaho National Engineering and Environmental Laboratory
> Lockheed Martin Idaho Technologies Company
> Idaho Falls, Idaho 83415-3860
> Prepared for the
> U.S. Department of Energy
> Office of Energy Research
> Under DOE Idaho Operations Office
> Contract DE-AC07-94ID13223
> Table 1-1. Preliminary hazards list for hydrogen
>
> Table 1-1. Preliminary hazards list for hydrogen
> Form Hazard type Description of hazard
> Gaseous hydrogen Physical properties
> leading to safety
> concerns
> .Lighter than air
> .Highly diffusive
> .Flow-induced static charge generation
> .Low viscosity (leaks easily)
> .Odorless, colorless gas
> Pressure .High pressure storage (2000 psig or
> more) can result in pressure rupture,
> flying debris
> .Pipe whip concern with leak events
> .Oxygen displacement in confined spaces
> .Gas jet impingement damage is possible
> .Gas jet impingement on personnel is also
> a hazard, high pressure can cut bare skin
> Chemical .Flammable, with nonluminous flame, no
> toxic combustion products
> .Explosive, 4% to 74% by volume
> Can deflagrate (typically only a modest
> overpressure, ~a few psi in open areas)
> Can also detonate (high overpressure
> shock wave, ~ several atmospheres)
> .Low ignition energy, 0.02 mJ to 1 mJ
> spark to ignite a deflagration
> .Modest autoignition temperature, 574°C
> Temperature .Could be stored at room temperature, not
> an issue
> Materials issues .Embrittlement of metal
> .Embrittlement of plastics
> Toxicological .Asphyxiation in confined spaces
> .No other toxic concerns
>
> Table 1-1. Preliminary hazards list for hydrogen (continued)
> Form Hazard type Description of hazard
> Liquid hydrogen Physical properties
> leading to safety concerns
> .Boiloff gas quickly warms and then is
> lighter than air
> .Boiloff gas is highly diffusive
> .Flow-induced static charge generation
> .Boiloff vent rate from storage tanks/fuel
> tanks is typical to maintain cold
> temperature in tank
> .Liquid quickly, easily boils by heat
> transfer into the 20 K liquid
> .Rapid phase transition from liquid to gas
> can cause pressure explosions
> .Liquid quickly contaminates itself by
> condensing gases from air contact
> .Odorless, colorless, cannot easily be
> odorized since odorants will freeze out at
> cryogenic temperatures
> Pressure .Stored under modest pressure to suppress
> boiling (perhaps 200 psig)
> Chemical .Evolved gas is cold, otherwise the same
> concerns as gaseous hydrogen
> Temperature .Cryogenic burns, especially eyes
> .Lung damage by cold vapor inhalation
> .Possible hypothermia working near these
> systems
> .Condensation of air near LH2 systems if
> insulation allows heat leak paths; can
> lead to oxygen rich zones near systems
> Materials issues .Embrittlement of metal
> .Mechanical stresses generated by
> thermal contraction
> .Mild steels susceptible to cracking at
> cryogenic temperatures
> .Materials have low specific heats at
> cryogenic temperatures, easy heat
> transfer
> Toxicological .Asphyxiation in confined spaces
> .Frostbite from acute exposure
> .Hypothermia possible from long
> exposure
> .No other toxic concerns
>
> > Spilling LOX causes an equal or worse flammability
> > hazard and can lead to substances as inert as asphalt
> > and rubber tires out and out detonating, not just
> > deflagrating. It boils much more slowly and the
> > vapors typically stay near the ground, in clouds
> > of high oxygen concentration that will burn organics
> > and vehicles and buildings to ash and rust in
> > short order if there's an ignition source nearby,
> > such as a vehicle motor running.
>
> I don't remember anyone advocating a "LOX" economy?
>
> You are aware, of course, that hydrogen can transition from deflagrating
to
> detonation, all by it's little lonesome, without an initiator.
> From the same report:
>
> Table 2-2. Hydrogen gas combustion properties in air at one atmosphere
and
> 25°C
> Combustion property Hydrogen deflagration Hydrogen detonation Units
> Heat of reaction, high 142.5 142.5 MJ/kg
> Lower flammable limit in air 4.1 (a) or 3.6 g/m3 of air 8.3 or 16.1 g/m3
of
> air
> Volume % Upper flammable limit in air 74.0 or 67 g/m3 of air 59.0 or 51.8
> g/m3 of air
> Volume % Optimum detonation 29.53 Volume % mixture ratio in air
> (stoichiometric ratio)
> Detonation maximum 1.46 MPa overpressure in air
> Auto-ignition 574 574 °C temperature
> Minimum ignition energy 0.02 at 29.53 % (b)= 107 (c) mJ
> Maximum flame 2318 2318 K temperature in air
> Explosion energy 2.02 (kg TNT per m3 of NTP gas)
> d Laminar burning velocity in air, varies 102 to 325 (cm/s) with H2 % in
air
> Detonation velocity in 1.48 to 2.15 (km/s) air
> Maximum overpressure 8 : 1 14.5 : 1 ratio
> (a) For upward flame propagation; downward flame propagation is 9%
(Coward,
> 1952).
> (b) Hydrogen spark ignition energy varies between 1 mJ at the ends of the
> flammable range
> down to 0.02 mJ at the stoichiometric concentration (Bowen, 1976).
> (c) To initiate a prompt detonation in a gas-air mixture, the minimum
> ignition energy must
> be on the order of 104 to 106 Joules (AIChE, 1994). Under some
> circumstances, a hydrogen
> deflagration explosion can also "run up", or transition, to a detonation
> explosion.
> (d) Theoretical maximum at stoichiometric conditions, actual value is
> approximately 10%
> of the theoretical maximum (Winter, 1988).
> Sources: (Thomson, 1987), (Lewis, 1961), (Winter, 1988), (Glassman, 1987)
>
> Note the 2.02 kg TNT per m3 NTP gas equivilent.
> You are also aware, I assume, that with cyrogenic H2 leaks, that there
tends
> to be a significantly higher oxygen content in the vacinity of the leak as
> it condenses from the air.
>
> > You need perspective. Spend time where LH2 is
> > handled routinely and actually get to know what
> > its risks and hazards are.
>
> Indeed. Sound advice.
>
> K. Jones
>
> >
> > -george william herbert
> > gherbert@retro.com
> >
>
>
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- In reply to: K. Jones: "Re: Solar-hydrogen home power system?"
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