Ammonia fuel cells?
Andrew Usher
seems like a very simple reaction, and if possible, one could surely
reverse the process to produce ammonia from air and water. The
reaction I am speaking of would be:
2 N2 + 6 H2O <-> 4 NH3 + 3 O2
Perhaps we should be thinking of using NH3 rather than H2 for energy
storage. The advantages are obvious. I do not think safety issues
should be problematic; a small spill would quickly disperse (ammonia
is lighter than air), and the chemical is already handled by a huge
infrastructure.
Think of it: no carbon emission and no heavy, high-pressure fuel
tanks. No kooky chemistry either!
Andrew Usher
G. R. L. Cowan
It's chemistry; in what way does it seem non-kooky to you?
At http://www.eren.doe.gov/hydrogen/pdfs/32405b15.pdf
there is some discussion of ammonia as fuel
(although not of its anodic oxidation.
I don't know if anyone knows how to do that).
They say it's too hazardous, believably IMO,
and suggest the hazard can be reduced
by solidifying it with BH3.
Two very hazardous materials combine to give
one very much less hazardous one.
--- Graham Cowan
http://www.eagle.ca/~gcowan/boron_blast.html --
100 watt-hours in a baby's fist
Dr.Bob
"Andrew Usher" <k_over...@yahoo.com> wrote in message
news:6e197594.0301...@posting.google.com...
How do you propose to drive that equation to the right and remove the
ammonia? Unless I'm missing something, this is "Kooky chemistry." The normal
method of making ammonia is to catalytically react hydrogen with nitrogen
(air) at high temperature and high pressure. Of course the hydrogen comes
from reforming methane and you are right back where you started from,
releasing CO2. The real question is: Is ammonia a reasonable way to
transport hydrogen? I don't think so plus ammonia is a pretty dangerous
substance. However, an ammonia fuel cell should be possible and may already
exist. A friend of mine has a similar idea, also on the fringes of using
hydrazine as a fuel. I don't know about tanking up on unsymetrical dymethyl
hydrazine like the Titan missile once used as rocket fuel. Seems a bit
exotic and would probably give the hazmat guys fits.
Dr. Bob
Don Lancaster
Have you ever worked near a blueprint machine?
--
Many thanks,
Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: d...@tinaja.com fax 847-574-1462
Please visit my GURU's LAIR web site at http://www.tinaja.com
Michael Davis
> Are there any fuel cell designs that directly oxidise ammonia?
I have heard that ammonia can be used directly in SOFCs, though I
haven't seen any examples of it in use. Most applications that use
ammonia in fuel cells though employ a reformer to separate the
Hydrogen from the ammonia.
> This
> seems like a very simple reaction, and if possible, one could surely
> reverse the process to produce ammonia from air and water. The
> reaction I am speaking of would be:
>
> 2 N2 + 6 H2O <-> 4 NH3 + 3 O2
Um, you will find that reversing the reaction and making ammonia is
actually quite difficult. It takes high temperature and high pressures
(plus the use of exotic catalysts) to make ammonia. It is a very
energy intensive process.
>
> Perhaps we should be thinking of using NH3 rather than H2 for energy
> storage. The advantages are obvious. I do not think safety issues
> should be problematic;
You should think again. Ammonia is quite toxic. These quotes come from
the MSDS for anhydrous ammonia:
"Irritant and corrosive to skin, eye, respiratory tract and mucous
membranes. May cause severe burns, eye and lung injuries. Skin and
respiratory related diseases aggravated by exposure."
"EXPOSURE LIMITS:
50 ppm PEL - Federal OSHA
25 ppm TWA - NIOSH
35 ppm STEL - NIOSH
300 ppm IDLH - NIOSH"
http://www.wdserviceco.com/MSDSANHY.html
> a small spill would quickly disperse (ammonia
> is lighter than air),
Ammonia vapor also forms explosive mixtures with air. The vapor also
readily dissolves in water and a large spill will contaminate any
nearby bodies of water.
> and the chemical is already handled by a huge
> infrastructure.
>
> Think of it: no carbon emission
Well, not from the fuel cell, but what about the emissions from making
the ammonia in the first place? It is an energy intensive process, and
industrial scale ammonia production uses reformation of methane as
the source of the Hydrogen. There is lots of Carbon emission from
making ammonia.
> and no heavy, high-pressure fuel
> tanks. No kooky chemistry either!
Chemistry (properly done) is never kooky.
Ammonia for fuel cells may well work in a few niche applications, but
don't expect it to catch on big for general use. Too many problems and
not enough advantages.
--
The Evil Michael Davis™
Ruler For Life of AAR
http://mdavis19.tripod.com
http://skepticult.org Member #264-70198-536
Member #33 1/3 of The "I Have Been Killfiled By Tommy" Club
"There's a sucker born every minute" - David Hannum (often erroneously
attributed to P. T. Barnum)
Justin R. Smith
>
>
> Andrew Usher wrote:
>>
>> Are there any fuel cell designs that directly oxidise ammonia? This
>> seems like a very simple reaction, and if possible, one could surely
>> reverse the process to produce ammonia from air and water. The
>> reaction I am speaking of would be:
>>
>> 2 N2 + 6 H2O <-> 4 NH3 + 3 O2
>>
This is how ammonia IS produced (industrially) for use in fertilizers,
etc. The process required enormous heat and pressure (as well as a
suitable catalyst).
G. R. L. Cowan
You seem to be replying to my article about ammonia-borane
(http://www.eren.doe.gov/hydrogen/pdfs/32405b15.pdf)
but in fact are not, and include none of it.
H2O is water. The Haber process uses hydrogen, H2, no O.
Don Lancaster
> Andrew Usher wrote:
> > a small spill would quickly disperse (ammonia
> > is lighter than air),
>
If you believe that hogwash, you are welcome to come along on our next
Ammonia hazmat call.
Ammonia is by far our most dreaded common incident here at TFD.
Tony Q King
Frankly, I'd rather take my chances with C02 pullution (and even the occasional
whiff of CO)
But, on a positive point - Just think of that glorious haze of ammonia products hanging
over our cities.
I wonder what colour the sunsets would be? Might actually be kind of beautiful, particularly
if enough N2O was produced a a sideproduct. We might not care a damn. (cough-cough)
I know- those nasty Nitrogen coumpunds would be 'sequestered' . But if you can do
it with Nitrogen, then why not do it with Carbon?
Andrew Usher
It is true that burning ammonia in air would produce oxides of
nitrogen, but I was proposing a fuel cell to oxidise NH3 without side
products. I now realise that it is probably impossible to reverse the
process; I doubt any electrochemical process could touch N2.
When I referenced 'kooky chemistry', I meant the use of chemistry to
support one's ideas without actual understanding of what is involved.
Certainly chemistry itself can not be 'kooky'.
I have yet to see a more efficient way of employing hydrogen as the
carrier of energy, than my proposal of converting to ammonia, which
can be liquified under pressure.
Andrew Usher
grumpy old man
wrote:
>
>H2O is water. The Haber process uses hydrogen, H2, no O.
>
>
Please forgive my ignorance - but - is hydrogen a monoatomic gas, ie
just H? Or is it a two atom element, H2?
G. R. L. Cowan
Two atoms. Oxygen is also diatomic.
The bonds between like atoms are strong,
but not quite as strong as H-O bonds.
TCS
H2
Only intert gasses are monoatomic.
Don Lancaster
Yes.
Under normal circumstances, monotomic hydrogen very quickly converts
into the diatomic form or quickly enters into other reactions.
Typically in milliseconds.
Duke McMullan N5GAX
news:slrnb1gn7v.cnj.The....@linux.adamf.dimensional.com...
> Only intert gasses are monoatomic.
At standard temperatures. At sufficiently elevated temps, all gases are
monatomic. At sufficiently elevated temps, all elements are monatomic,
ionized gases . . . well, plasmas, really.
Real relavant remark . . . . ;^)
d
--
<Bzzzz!> <Zap!> Wake up and smell the ozone! <Crackle!>
Duke McMullan n5gax nss13429rl(fe) (505)255-4642 mtm...@qwest.net
Duke McMullan N5GAX
news:6e197594.0301...@posting.google.com...
> Are there any fuel cell designs that directly oxidise ammonia? This
> seems like a very simple reaction, and if possible, one could surely
> reverse the process to produce ammonia from air and water. The
> reaction I am speaking of would be:
>
> 2 N2 + 6 H2O <-> 4 NH3 + 3 O2
That's the Haber-Bosch process. Hydrogen and nitrogen are combined, under
pressure and elevated temperature, and in the presence of a catalyst, to
make ammonia. I'm not aware of any fuel cells which can use ammonia, but
it's an interesting idea . . . academically, at least.
But: Guess where that hydrogen comes from.
> Perhaps we should be thinking of using NH3 rather than H2 for energy
> storage. The advantages are obvious.
The one obvious advantage is that it's a LOT easier to liquefy ammonia than
hydrogen. I fail to see any other advantages, obvious or not. There are
some obvious -- and severe -- DISadvantages.
> I do not think safety issues should be problematic;
I think you are just about 100% wrong there.
> a small spill would quickly disperse (ammonia is lighter than air),
Not quickly enough to prevent it from being VERY hazardous. A faceful of
hydrogen gas will not hurt you. A faceful of methane or other alkane gas
will not hurt you. A faceful of ammonia gas can damage you very badly,
even kill you _in_extremis_.
> and the chemical is already handled by a huge infrastructure.
Not as a consumer item, with the exception of a dilute aqueous solution,
"household ammonia". That's something you don't let little children play
with, for excellent reasons: it's NASTY.
Experiment 1: Open a bottle of household ammonia. Look into the bottle,
very closely, but don't let the rim of the bottle touch your eye. Make
certain you expose your eye to the ammonia vapors for a few seconds.
Experiment 2: Open a bottle of household ammonia. Place your nose very
close to, but not in contact with, the bottle rim. Inhale lightly.
These two experiments, with a very limited supply of ammonia gas, will
demonstrate why ammonia is considered VERY hazardous, and why a spill of a
few gallons of liquid ammonia (as contrasted with ammonia solution) -- and
that's a small spill, by most standards -- is an extremely dangerous
situation. If this spill, or leak, took place in an enclosed space, such
as a garage or perhaps an under-river tunnel, you probably have a disaster
of considerable scale.
Write this in your notebook in three-inch high letters, boldfaced and
underlined: Ammonia is NASTY!
> Think of it: no carbon emission . . .
As I said above, guess where that hydrogen comes from. Roughly half of the
hydrogen produced by industry goes for ammonia manufacture. The carbon
emission comes at the manufacturing plant.
> and no heavy, high-pressure fuel tanks. No kooky chemistry either!
Yep. You do have an easier storage/transport problem, as compared to
hydrogen. The remark about "kooky chemistry" is a non-sequitur, so I won't
bother addressing that.
d
--
"Hydrogen is the fuel of the future, and probably always will be."
-- Anyone know who said that?
G. R. L. Cowan
Duke McMullan N5GAX included:
>
> "Andrew Usher" <k_over...@yahoo.com> wrote in message
> news:6e197594.0301...@posting.google.com...
>
> > Are there any fuel cell designs that directly oxidise ammonia? This
> > seems like a very simple reaction, and if possible, one could surely
> > reverse the process to produce ammonia from air and water. The
> > reaction I am speaking of would be:
> >
> > 2 N2 + 6 H2O <-> 4 NH3 + 3 O2
>
> That's the Haber-Bosch process. ...
No it isn't, see comments elsewhere in thread ...
>
> Write this in your notebook in three-inch high letters, boldfaced and
> underlined: Ammonia is NASTY!
But see http://www.eren.doe.gov/hydrogen/pdfs/32405b15.pdf .
See ammonia at its keenest.
Duke McMullan N5GAX
news:3E188236...@eagle.ca...
>
>
> Duke McMullan N5GAX included:
> >
> > "Andrew Usher" <k_over...@yahoo.com> wrote in message
> > news:6e197594.0301...@posting.google.com...
> >
> > > Are there any fuel cell designs that directly oxidise ammonia? This
> > > seems like a very simple reaction, and if possible, one could surely
> > > reverse the process to produce ammonia from air and water. The
> > > reaction I am speaking of would be:
> > >
> > > 2 N2 + 6 H2O <-> 4 NH3 + 3 O2
> >
> > That's the Haber-Bosch process. ...
>
> No it isn't, see comments elsewhere in thread ...
Wups! You're right -- I was reading too fast.
The Haber-Bosch process is N_2 + 3 H_2 --> 2 NH_3, with an Al-Fe catalyst
and elevated pressure. H&B received the 1918 Dynamite Prize in chemistry
for this work, and it's arguably one of the most important chemistry
discoveries of the 20th century. Other catalysts are sometimes used
today -- I seem to recall something about Ruthenium micro- or
nano-particles scattered in a zeolite bed.
There also are some low-pressure syntheses, but I know nothing about them.
I'm not aware that the nitrogen-water reaction listed above is used for
ammonia synthesis. While an ammonia/oxygen fuel cell is theoretically
reversible, I doubt that it would be competitive with H/B.
> > Write this in your notebook in three-inch high letters, boldfaced and
> > underlined: Ammonia is NASTY!
>
> But see http://www.eren.doe.gov/hydrogen/pdfs/32405b15.pdf .
> See ammonia at its keenest.
Thanks, Graham! I was unaware of any of this work.
d
--
Not that anyone cares, but I am:
Dean Hoffman
6e197594.0301...@posting.google.com, "Andrew Usher"
<k_over...@yahoo.com> wrote:
Farmers use a lot of NH3 for corn fertilizer. It takes about 1# of N
for each bushel of corn. The U.S. produces about 9 billion bushels of corn
per year. There are other sources for the N but that might give a rough
idea of the upper limit of the farm use.
Storage facilities for NH3 are being moved out of the towns. It's
probably due to safety reasons. It's wicked stuff. A shot of NH3 will burn
skin and eyes. A little bit of NH3 will absorb a lot of water. That's what
leads to the tissue damage. There's a water tank mounted on every 1000
gallon trailer the farmers use to haul it. Breathe it in and it will kill.
I vaguely remember an accident involving a rail car. A dozen or so people
were killed in a nearby small town as a result of the accident.
NH3 is stored in the same type of tanks as propane. It's stored under
pressure just like propane. Imagine what happens when a hose breaks. It's
not uncommon to see tank pressure over 100 psi in the summer. Rubber gloves
and safety goggles are the minimum for safe handling. Farmers get burned
every once in awhile. I have a tough time picturing NH3 as a replacement
for gasoline. Look at the people at a gas station fueling their vehicles
sometime. Would you want them close to you with a NH3 hose in their hands?
Part of my job involved repairing fertilizer monitors at one time. Even a
little whiff of NH3 will make you want to stop breathing and your eyes
water.
Nothing in life is risk free of course. Surely something safer than NH3
could be used for fuel.
Question: What about compressed natural gas? Isn't most NH3 made from
natural gas in the first place? CNG doesn't sound good either for a
consumer fuel.
Dean
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 80,000 Newsgroups - 16 Different Servers! =-----
Duke McMullan N5GAX
news:BA4F8318.251AA%dh0...@inebraskaINVALID.com...
<Description of ammonia hazards deleted.>
> Question: What about compressed natural gas? Isn't most NH3 made
from
> natural gas in the first place? CNG doesn't sound good either for a
> consumer fuel.
Ammonia is made from hydrogen and nitrogen under pressure, and perhaps
nudged along with a catalyst. The nitrogen is taken from the air, and the
hydrogen is made by "reforming" methane with water, a two-stage process
whose one-step equation is 2H_2O + CH_4 --> 4H_2 + CO_2.
Compressed methane is used here and there, but it remains experimental, and
probably won't become mainstream, due to the very high pressure needed with
methane. Liquefied Petroleum Gas (LPG), which is propane or butane
(depending on climate and time of year) has seen some usage, but it wasn't
the Big Improvement Over Gasoline it was supposed to be, was rather
expensive (limited infrastructure and tricky to handle) and MUCH more
dangerous in an accident, so it also continues to be an also-ran, although
it's much more commonly used than methane.
Ammonia isn't a very efficient fuel, due to 1) cost of manufacture and 2)
low yield of energy per unit weight. It's also extremely nasty to handle,
and would be absolutely horrible in an accident: very dangerous to
spectators as well as to participants. It's also somewhat flammable, but
chemical toxicity and its contact corrosive properties pretty much take
center stage for reasons NOT to use it. You gave a good review of those
difficulties.
d
--
"Cynicism is a virtue, especially for engineers."
-- David Weinberger
Dean Hoffman
McMullan N5GAX" <mtm...@qwest.net> wrote:
> "Dean Hoffman" <dh0...@inebraskaINVALID.com> wrote in message
> news:BA4F8318.251AA%dh0...@inebraskaINVALID.com...
>
> <Description of ammonia hazards deleted.>
>
>> Question: What about compressed natural gas? Isn't most NH3 made
> from
>> natural gas in the first place? CNG doesn't sound good either for a
>> consumer fuel.
>
> Ammonia is made from hydrogen and nitrogen under pressure, and perhaps
> nudged along with a catalyst. The nitrogen is taken from the air, and the
> hydrogen is made by "reforming" methane with water, a two-stage process
> whose one-step equation is 2H_2O + CH_4 --> 4H_2 + CO_2.
How is the natural gas used in the process? This isn't a scientific
source but this article talks about using natural gas to make NH3. I
remember the price of NH3 fertilizer took a big jump years ago. The cost
increase was blamed on the increased cost of the natural gas.
"Here's the logic. Almost all nitrogen fertilizer is made from anhydrous
ammonia (NH3). Urea and UAN solutions, the fastest growing form of nitrogen,
are on that list. Natural gas is the major ingredient in NH3 -- it takes
about 34 million BTU to make 1 ton of NH3. Do the math. When natural gas is
at $4.25 per million BTU, its cost in a ton of NH3 is $145. With gas prices
at $9, the cost is $307 per ton without any labor, transportation or return
on investment to a $400 million production plant. A return to the troubling
days of $400-a-ton NH3 may be upon us."
The above paragraph came from here:
http://www.agriculture.com/sfonline/sf/2001/mid-february/0103production.html
Thanks,
Duke McMullan N5GAX
> How is the natural gas used in the process?
I know no details concerning reactor construction, but methane and water
are reacted in the presence of a nickle catalyst at 1k deg. Celcius:
CH_4 + H_2O --- 1000C Ni ----> CO + 3H_2
I don't know if the hydrogen is removed at this point or not. In any
event, the carbon monoxide is mixed with another mole of water at 350
Celcius in the presence of an iron oxide catalyst:
CO + H_2O --- 350C FeO ----> 4H_2 + CO_2
or Fe2O3
or Fe3O4
Overall:
2 H_2O + CH_4 -------------> 4H_2 + CO_2
Again, I don't know process details, but I suspect bubbling the gas through
pressurized water, or spraying a mist of water through the gas (again, the
gas is under pressure) would dissolve the carbon dioxide quite efficiently.
The resulting hydrogen is mixed three volumes to one volume with dry
nitrogen, and raised to a rather high pressure (a few hundred atmospheres,
if I recall correctly) and a catalyst may be used to speed things up.
Reaction:
3H_2 + N_2 ----> 2 NH_3
That's four moles of gas becoming two moles of gas, which means the
pressure drops considerably. The high pressure causes the reaction to
become thermodynamically favorable. This is arguably one of the great
discoveries of twentieth-century chemistry. Basically, it enabled the
agricultural revolution.
> This isn't a scientific
> source but this article talks about using natural gas to make NH3. I
> remember the price of NH3 fertilizer took a big jump years ago. The cost
> increase was blamed on the increased cost of the natural gas.
> "Here's the logic. Almost all nitrogen fertilizer is made from
anhydrous
> ammonia (NH3). Urea and UAN solutions, the fastest growing form of
nitrogen,
> are on that list. Natural gas is the major ingredient in NH3
Not an ingredient, exactly, but it's one of the two main feedstocks from
which the hydrogen is made, and that hydrogen IS an ingredient in the
ammonia.
<Begin Noo Yawk Accent> "It's in there."<End Noo Yawk Accent>
> -- it takes
> about 34 million BTU to make 1 ton of NH3. Do the math. When natural gas
is
> at $4.25 per million BTU, its cost in a ton of NH3 is $145. With gas
prices
> at $9, the cost is $307 per ton without any labor, transportation or
return
> on investment to a $400 million production plant. A return to the
troubling
> days of $400-a-ton NH3 may be upon us."
>
> The above paragraph came from here:
>
>
>
http://www.agriculture.com/sfonline/sf/2001/mid-february/0103production.htm
l
All these things, and many more, are irrevocably coupled together. Trying
to "power" our world with hydrogen is going to make almost everything more
expensive. We really do need to find new ways of powering our vehicular
infrastructure, but hydrogen sure appears to me to be a wrong number,
excepting certain niche applications.
Which is too bad, but you really CAN'T get out of the game. :-(
d
PS -- And, in any event, hydrogen is NOT a power source.
--
Shouldn't that be spelled "fonetyk"?
Harry Conover
> On 1/18/03 11:38 PM, in article mRqW9.98$tJ6....@news.uswest.net, "Duke
> McMullan N5GAX" <mtm...@qwest.net> wrote:
>
> > "Dean Hoffman" <dh0...@inebraskaINVALID.com> wrote in message
> > news:BA4F8318.251AA%dh0...@inebraskaINVALID.com...
> >
> > <Description of ammonia hazards deleted.>
> >
> >> Question: What about compressed natural gas? Isn't most NH3 made
> from
> >> natural gas in the first place? CNG doesn't sound good either for a
> >> consumer fuel.
> >
> > Ammonia is made from hydrogen and nitrogen under pressure, and perhaps
> > nudged along with a catalyst. The nitrogen is taken from the air, and the
> > hydrogen is made by "reforming" methane with water, a two-stage process
> > whose one-step equation is 2H_2O + CH_4 --> 4H_2 + CO_2.
>
>
> How is the natural gas used in the process?
Just a stab in the dark on my part, but given that natural gas is
primarily composed of methane, I'd tend to believe it's the source of
the methane for the above reaction.
Also, if the 2H2O + CH4 reaction is endothermal, I'd also be tempted
to guess that natural gas combustion is also the source of energy
required to power the reaction. Still, don't bet a weeks pay on this.
Harry C.