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Author: Subject: Hydrogen from [bio]glycerine by electrolysis for fuel cells
deltaH
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smile.gif posted on 4-10-2013 at 14:10


@papaya

Yeah, I've been playing with deep eutectic solvents... used it for another innovation of mine, choline soap, but that's another story. I'll open a thread about that soon, it won't save the world but it's fun chemistry :)

As for what I intend to with this, I have been desperately trying to get some funding for things which as you pointed out, was too hard to do without any money (I am a unemployed chemical engineer and can't find work here, been looking now for over a year in SA, but let's not get into that politically loaded issue on SM).

Anyhow, so I've released this idea into the public domain in the hopes that since I cannot do anything with it (believe me I've been trying with this and many others for two years now and still trying) others should be given a chance to start experimenting with it. This is the idea about open innovation. Not everybody in the world is greedy and no, contrary to what Traveller said, nobody is giving me a couple millions lol

I've also entered it into a big local innovation competition (along with my other ideas) that just closed... if I'm lucky and win something there, then I can get started properly!

But I fear that initial skepticism this idea caused when posted here would not be atypical, so I don't know if I will ever have it looked into as it deserves any time soon. Even scientists are likely to have the same initial reaction!

Otherwise if all else fails, I will still try to fiddle with this as best I can manage in my backyard...

I am very resourceful to doing science for cents :)

I'm also hoping that maybe people here on SM might show interest in the idea and those who can, would also start experimenting with it and we could discuss issues and results here. I might not have the means at the moment, but I have a lot of knowledge (going to waste) and the will to make this thing work and solve it's problems (if it is a sound idea... proof of the pudding is in the eating!)

Surely someone here has access to a platinum foil/gauze/wire and can start experimenting with beaker electrolysis of this stuff? I think the secret is going to lie in getting the anodes right and THAT is one thing I know amateur science is DAMN good at.

Maybe what we should do next is get serious about discussing the way shape and form of a simple proof of concept for this, if only the first electrolysis half for starters and later the fuel cell whole system.

I just want it to start with beaker type experiments, no need to go huge, plus... one can buy small toy fuel cells that drive a little fan or such, these days these things sell for minimal amounts of money... some people on SM may even have these!

Anyway, very late here now, will come back and we can get into serious planning of how this principle can be tested in a simple proof of concept home experiment and maybe SM community may start playing around with it then.

Otherwise, start thinking about it if you're interested in the concept and maybe you can help with it's investigation?

Unfortunately, you won't be able to patent it because I've released it now, but you can have kudos for being instrumental in its development (if successful that is).

Anyhow, it's super late again, catch you guys tomorrow!!!

Cheers for now.:)




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[*] posted on 5-10-2013 at 04:36


Quote: Originally posted by deltaH  
But I fear that initial skepticism this idea caused when posted here would not be atypical, so I don't know if I will ever have it looked into as it deserves any time soon. Even scientists are likely to have the same initial reaction!



It's about 'selling' the idea: good presentation makes all the difference to a naturally sceptical audience. I think you made a bit of a pig's ear of your presentation initially here. It would be worth spending quite a bit of time developing the right angle for pitching the idea.

Stripped bare, it comes down to extracting hydrogen from a plentiful renewable (glycerol) for use in hydrogen fuel cells. Put concisely like that, I think some ears would prick up already.




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[*] posted on 5-10-2013 at 09:13


Quote: Originally posted by blogfast25  
Quote: Originally posted by deltaH  
But I fear that initial skepticism this idea caused when posted here would not be atypical, so I don't know if I will ever have it looked into as it deserves any time soon. Even scientists are likely to have the same initial reaction!



It's about 'selling' the idea: good presentation makes all the difference to a naturally sceptical audience. I think you made a bit of a pig's ear of your presentation initially here. It would be worth spending quite a bit of time developing the right angle for pitching the idea.

Stripped bare, it comes down to extracting hydrogen from a plentiful renewable (glycerol) for use in hydrogen fuel cells. Put concisely like that, I think some ears would prick up already.


Electricity in, hydrogen out; followed by hydrogen in, electricity out. If the amount of electricity coming out of this is greater than the amount of electricity going in, I'll eat the darn thing.

There are no free lunches, at least not in this universe, anyways.
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[*] posted on 5-10-2013 at 10:27


Quote: Originally posted by Traveller  

Electricity in, hydrogen out; followed by hydrogen in, electricity out. If the amount of electricity coming out of this is greater than the amount of electricity going in, I'll eat the darn thing.

There are no free lunches, at least not in this universe, anyways.


The "electricity coming out won't be greater than the electricity going in", nor is it being claimed, nor does it have to be so to work.

If hydrogen can be extracted (by whatever means) from a renewable like glycerol, then it can be used to fuel hydrogen fuel cells. If the energy needed to extract that hydrogen is greater than the energy provided by the fuel cell then that difference plus the cost of the glycerol determines the running cost of the propulsion.

No free lunch is being chased here.

It's in essence no different from cracking water with cokes, producing water gas (CO + H2) and using that water gas as fuel. There's bills to be paid but your car runs.

The interest is in the fact that there's a lot of glycerol to be had and that it's carbon neutral.




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[*] posted on 5-10-2013 at 11:36


@blogfast26

I hear you and will try to do better in future

@traveller

Since my previous thermo calculation indicated that I only need 4.7% H2O2 to break even in the dG, I think WHEN you eat it, you may even find it quite palatable and sweet :P May even be an excellent tooth whitener lol.

@elementcollector1

Quote:
I see a major problem here.
If you use a 70% solution of H2SO4 with the balance being water, it's very true that the solution will now be very conductive. But now, the electrode potential will be much higher because - you guessed it! You are now electrolyzing sulfuric acid and water. So, any glycerine added will be both an insignificant source of hydrogen and an insignificant reactant to this mixture at the concentrations you're proposing.

You might want to read this - it might clear some things up. http://pubs.acs.org/doi/abs/10.1021/ie9016418
Sorry for the late commentary on this. You raised an interesting point here and believe me, I swore shortly after reading it and realising that the thread was temporarily closed, I didn't want to deal with it in my subsequent thread cause I didn't want to be accused of ignoring the closure. Instead I appealed it and thankfully the powers that be ruled in favour of unification.

Now I can come back and discuss this point. Firstly, this paper looks excellent (from the abstract). I cannot open it, so I will have to request it from whoever is kind enough to volunteer it. I believe there is a paper request option somewhere here... will look into that.

Now about your point that the solution would consist predominantly of H2SO4 and water and so this will be electrolysis of sulfuric acid or water (making either peroxydisulfuric acid or oxygen at the anode, respectively):

Consider the following oxidation half reactions (from wiki's table of standard electrode potentials):

2 SO4sup2- <=> S2O8sup2− + 2 e− E(std.) = -2.010V
2H2O <=> O2 + 4H+ + 4e- E(std.) = -1.229V

Now compare with that of formic acid (they didn't have glycerine, but you get the idea even with formic acid)

HCOOH(aq) <=> CO2(g) + 2H+ +2e- E(std.) = +0.11V

Now as you can see, the standard electrode potentials for either water oxidation or sulfuric acid oxidation are very unfavorable, while that of an oxidised simple organic is in fact favorable.

Now your argument is that dilution may alter this. It does slightly and we can use the Nernst equation to calculate by how much...

Let's say it was formic acid we were using at 0.1M and not 1M for which that standard potential is quoted at, we can use the Nernst equation to calculate the 'new' electrode potential under such dilution:

We need to flip the half reaction, so CO2(g) + 2H+ +2e- <=> HCOOH(aq) E(std.) = -0.11V

Then Eeff. = E(std.) - 0.05916V/z * log([HCOOH]actual) = -0.11V - 0.05916V/2 * log(0.1) = -0.08V

So you see the oxidation half reaction for formic acid only dropped it's electrode potential from +0.11V to +0.08V even when diluted to 0.1M

So as you can see, while dilution does change the half reaction potentials somewhat, the changes are small!

Now that said, thermodynamics is one thing, chemical kinetics are another.

If you have a completely catalytically inactive anode, say graphite or plain titanium, then you're glycerine cannot oxidise because you have a MASSIVE overpotential due to a large activation energy barrier. This WOULD make water electrolysis or even sulfuric acid favoured. In fact this is what @woelen refered to on the second page of this thread when he pointed out that when he tried to electrolyse ammonia with graphite anodes, he simply got water electrolysis and made oxygen at the anode!

This wasn't because of dilution, it was because the graphite was completely catalytically inactive towards ammonia dissociation into hydrogen and nitrogen and so THAT process faced a massive activation energy barrier. Had he used a platinum anode, he would would probably have made nitrogen gas at the anode because of platinum's ability to catalyse the dissociation/decomposition of ammonia.

Once again, this issue elligantly illustrates the importance of differentiating between thermodynamic and chemical kinetic effects / issues.

Please do tell me if you agree with my reasoning here.


[Edited on 5-10-2013 by deltaH]




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[*] posted on 5-10-2013 at 12:59



Quote:

You might want to read this - it might clear some things up. http://pubs.acs.org/doi/abs/10.1021/ie9016418



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[*] posted on 5-10-2013 at 13:24


Thanks kmno4, I'm printing that attachment off.



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[*] posted on 5-10-2013 at 13:28


@kmno4 I second the thanks.



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[*] posted on 5-10-2013 at 13:55


Very interesting paper indeed... first time I hear of hydrothermal electrolysis (electrolysis at high pressure so that you can carry it out in water at very high temperatures). I would not want to do it this way... 10MPa electrolysers is not amateur science lol

Anyhow, these guys were trying to convert glycerine into partially oxidised products because they could possible be sold as more valuable chemicals. I actually think carrying out a partial oxidation by electrolysis is harder than a complete one because those products are easier to oxidise further than what the glycerine was in the first place.

Note they used non-catalytic titanium electrodes, but at 220C and 280C it appears catalysts are hardly necessary and since they didn't want to completely oxidise, it's hardly surprising either.

This gives me renewed confidence that electrocatalytic anodes such as platinum based ones could work at lower temperatures!

[Edited on 5-10-2013 by deltaH]




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[*] posted on 5-10-2013 at 14:06


@blogfast25

Quote:
The "electricity coming out won't be greater than the electricity going in", nor is it being claimed, nor does it have to be so to work.

If hydrogen can be extracted (by whatever means) from a renewable like glycerol, then it can be used to fuel hydrogen fuel cells. If the energy needed to extract that hydrogen is greater than the energy provided by the fuel cell then that difference plus the cost of the glycerol determines the running cost of the propulsion.

No free lunch is being chased here.

It's in essence no different from cracking water with cokes, producing water gas (CO + H2) and using that water gas as fuel. There's bills to be paid but your car runs.

The interest is in the fact that there's a lot of glycerol to be had and that it's carbon neutral.
Well said!

[Edited on 5-10-2013 by deltaH]




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[*] posted on 6-10-2013 at 06:02


deltaH:

I read the paper yesterday and for me the main relevant conclusion was that more hydrogen was being produced in the presence of glycerol than in its absence, showing a small degree of actual electrolytical decomposition of that substrate, in those specific conditions.

You're right that their goal is different: production of higher value, often shorter chain reaction products. Oxidising everything to CO2 and H2 would be counter productive to that goal.

There may be a wealth of information in some of the many papers referenced.

But I remain convinced that near-complete electrolysis of glycerol in the presence of an oxidiser in 'amateur science' attainable conditions is going to be a real hat trick. Maybe very specific, milder oxidisers should be looked at. But I'm just 'mouthing off' here because at present I've no idea what they could be...

[Edited on 6-10-2013 by blogfast25]




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[*] posted on 6-10-2013 at 06:30


Yeah it's going to be a real schlepp... SA speak for a pain in the... lol

Quote:
Maybe very specific, milder oxidisers should be looked at.
wow... THAT is a VERY interesting idea... I've been so focused on maximising energetic content that I've been concentrating my thoughts on super strong oxidisers (completely unwittingly). However, since we don't need much to 'fix' the dG, maybe there's leyway to play with gentler things.

In fact, in normal reforming/gasification, in many ways the water is the 'oxidant', okay granted, a very bad one, but between water and peroxide, maybe there's something in between... not as terrible as water, nor as aggressive as peroxide, but can provide both a source of oxygen and hydrogen so all the carbon in the glycerol can go to CO2.

What about hydroxylamine? The only problem is that it's not particularly green, but at least the glycerine is.

I'd need to work out how much hydroxylamine is needed to get a dGrx = 0.

The nice thing about hydroxyamine is that unlike glycerol peroxide mixtures, this should be stable indefinately without gas generation?

I know hydroxylamine can decompose energetically, but it only seems to be possible at very high concentrations and I don't think we would be anywhere near that.

Ok so lets say we go ape with this and use 50% hydroxyamine solution in water mixed with the appropriate amount of glycerine. Should make the dG of the reaction negative (will confirm shortly).

The electrolysis then yields:

C3H8O3(l) + NH2OH(l) + 2H2O(l) => 3CO2(g) + 1/2N2(g) + 7.5H2(g)

WOW Blogfast25... I think I like it a lot... you're a genius!

The hydrogen mass content of such a liquid mixture is 9.3% to boot! OMG

Okay... need to check the dG of that reaction...







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[*] posted on 6-10-2013 at 06:48


Okay before I get crucified by the pure chemists for referring to hydroxylamine as an 'oxidant' of sorts, I am well aware that it is a reducing agent, I simply need it as an inorganic source of oxygen for the carbon in glycerine.

The fact that it contributes hydrogens as well is a bonus :)

There is a problem though, peroxide would quickly form peroxysulfuric acid when mixed with strong H2SO4 electrolytes and so I don't have much doubt this would be attracted to the anode where we need it.

But wouldn't hydroxylamine simply form hydroxyammonium cations or could enough hydroxylamine-O-sulfonic acid form in sufficient amounts when the hydroxylamine hits the strong sulfuric acid solution? Can hydroxylamine-O-sulfonic acid even form in any amounts between strong H2SO4 and hydroxyamine? Fortunately the acid will be in excess here so that acts in its favour.




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[*] posted on 6-10-2013 at 09:23


Is there a particular reason for using sulphuric acid? Why do you think it's better than alkali? Personally I don't have the foggiest idea...

Rather than being a genius, I confess to being totally in the dark here. I'd really have to read up on much of the prior art first before being able to meaningfully contribute.

[Edited on 6-10-2013 by blogfast25]




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[*] posted on 6-10-2013 at 10:57


@blogfast

No its great and thanks for your thoughts, they are helping me a lot! The reason I would prefer acidic media is so that CO2 gas is produced at the anode, otherwise in caustic media carbonates would be formed... and then what. There are technologies for converting the carbonate to CO2 gas in a second step, but that's just too complicated for my liking.

There is, however, the big problem that for some reason, from what I've read in the literature... they never seem to get the acid version of organic electrolysis to work properly. This is puzzling to me and admittedly I need to dig deeper in the literature.

I don't think they are using concentrated enough acids though... let me explain my thinking here, I think for the organic molecule to be oxidised, it should be converted to an anion so that it can concentrate on the anode where oxidation is taking place. This is easy to do in basic media, so for example, formic acid forms formate anions that are drawn to the anode. Even anhydrous ammonia can have some sodium amide dissolved into it and you can carry out ammonia electrolysis with the amide ions being drawn to the anode.

Now as for acids, I think the mistake most researchers might have made was to not use sufficiently concentrated acids. For example, lets say you want to electrolyse methanol. You need methanol anions pulled to the anode but in acidic media?! This can only happen if the methanol forms an ester with sulfuric acid so you make methylsulfuric acid. If there is sufficient water present then you will have lots of methysufate anions and H3O+ present and the methylsufate anion can be pulled to the anode for oxidation and the H3O+ to the cathode for reduction.

The problem, come to think of it, is that not only do you need fairly concentrated acids to convert the organic molecule into an anion that can be drawn to the anode, but you also need your oxygen source to be converted to an anion in the acidic environment at the anode and I think this is why the conventional electrolysis of organic molecules in acid media haven't yielded good results. In the case people were carrying it out, using just acids in water, how was the water supposed to be anionically attracted to the anode under strongly acidic conditions, most of the water would be in the H3O+ form?!

This is were my idea for peroxide could make a big difference, because peroxide can form persulfuric acid and be pulled to the anode to act as my oxygen donor (in the form of persulfate anions) to the glycerol molecules (as glycerylsulfate anion esters).

In fact, I can form my first hypothesis to test this theory:

First hypothesis
The complete oxidation of glycerol to form carbon dioxide gas at the anode and hydrogen gas at the cathode in acidic sulfuric acid electrolyte requires an oxygen source that like the glycerol can also be esterified by the acid and drawn to the anode.

Sadly this would mean that just adding the minimum H2O2 required to break even on dG wouldn't be good enough, you would need stoichiometric amounts for the reaction, i.e.

2C3H8O3(l) + 3H2O2(l) => 6CO2 + 11H2

I don't like this large amounts of peroxide, this is maybe where hydroxylamine would maybe fair better:

C3H8O3(l) + 3NH2OH(l) => 3CO2 + 1.5N2 + 8.5H2

Anyhow, these are my thoughts on this point for now. I don't like the implications of having to use such concentrated mixtures... but how to make the water into an anionic intermediate to transport it to the anode under the acidic conditions?

I'll try to think up some possibilities...







[Edited on 6-10-2013 by deltaH]

[Edited on 6-10-2013 by deltaH]




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[*] posted on 6-10-2013 at 13:05


deltaH, I think your idea became your obsession and leads directly to madness.
Do you know any premise that such a (quantitative) electrolityc glycerin decomposition (to H2 and CO2) is practically possible ?????
There is no analogy between NH3 and glycerin. These are completely different compounds.
Also formic acid is "special" case:
HCOOH→CO2+H2 , ΔH is >0 (but not very high) ΔG is <0.
With Rh catalysts reaction goes smoothly, without any additional reagents.
In glycerin case you must use some odditional oxidant, it is of course.
Electrochemical reduction/oxidation of glycerin must be very complicated and multi step reaction. You want only H2 and CO2 - wishful thinking.
You plan to add some unstable compounds (H2O2, NH2OH, who knows what else) to improve effect.
To one complicated reaction mechanism you add another reactant and you still want only CO2 and H2 (+N2 or whatewer you wish) - (wishful thinking)<sup>2</sup>
Have you made any estimation of cost of your H2 production ?
Have you done anything but pure chemical speculations ?
Do you realise, that low cost of glycerin is caused by governments forced production of "biofuels" ?

The best you can do is making glycerin-driven motor.
Overall reaction:
C3H8O3 + air →CO2 + H2O
Without electrolysers, precious electrodes, hydrogen cells... and dreams

Bonus: H2 from NH3




[Edited on 6-10-2013 by kmno4]

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[*] posted on 6-10-2013 at 13:13


Can't really find fault with that. I certainly hadn't thought of the formation of carbonates. But think of it as a form of carbon sequestration! ;) I mean, who really needs gaseous CO2: carbonates are more useful.

And in alkaline media, alcohols tend also to form anions: alkoxides (RO-). Hydrogen peroxide does too (it's a very weak acid). So still speaking mostly from darkness maybe don't exclude alkaline conditions just yet. There must be a pathway that explains part electrolysis of glycerol and H2 formation in kmno4's study.


[Edited on 6-10-2013 by blogfast25]




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[*] posted on 6-10-2013 at 14:31


Quote: Originally posted by deltaH  
@blogfast25

Quote:
The "electricity coming out won't be greater than the electricity going in", nor is it being claimed, nor does it have to be so to work.

If hydrogen can be extracted (by whatever means) from a renewable like glycerol, then it can be used to fuel hydrogen fuel cells. If the energy needed to extract that hydrogen is greater than the energy provided by the fuel cell then that difference plus the cost of the glycerol determines the running cost of the propulsion.

No free lunch is being chased here.

It's in essence no different from cracking water with cokes, producing water gas (CO + H2) and using that water gas as fuel. There's bills to be paid but your car runs.

The interest is in the fact that there's a lot of glycerol to be had and that it's carbon neutral.
Well said!

[Edited on 5-10-2013 by deltaH]


Yes, yes, lots of glycerol to be had (grows on trees, right?) and it is carbon neutral, of course. In actuality, coal is carbon neutral, if you don't mind being on a million year cycle.

I put these notions right up there with the pipe dreams from the proponents of the "hydrogen economy". It takes 1.2 times as much energy to dissociate water into hydrogen and oxygen than you could ever hope to recover IF your conversion of H2 and O2 back to water was 100% efficient which, we all know, is impossible; at least in this universe, anyways.

And when those of the "hydrogen economy" are asked where all the energy to dissociate water (or make glycerol) will come from, we are given a Utopian view of a world covered in windmills, solar panels and tidal generators.

"Dreamer....you know you are a dreamer...."
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[*] posted on 6-10-2013 at 22:49


@ traveller
Quote:
And when those of the "hydrogen economy" are asked where all the energy to dissociate water (or make glycerol) will come from, we are given a Utopian view of a world covered in windmills, solar panels and tidal generators.
I must admit that I am myself sceptical of the hydrogen economy. However, I am a big fan of the biomass economy. Forget solar panels, plants do a most excellent job of converting solar energy into chemical potential energy. So for example, we already have a thriving biodiesel industry (with much debate about running cars on food), but nevertheless, it's there already and as a result there's lot's of glycerine. On the other hand we also already have hydrogen fuel cell powered cars, so really what I'm proposing is the last link in already well established technologies.

I will be frank, while I know that what I am proposing can work... I've PROVEN the overall thermodynamics already on this thread, it's not going to be easy to get it to work in terms of getting the kinetics to behave and finding all the right conditions to get this to tick over in a practical way.

Time will tell if it's feasible, I'm waiting on some bits and pieces to start experimenting... for now and until then, I need to focus on designing this system as best I can and try to wrap my mind around many chemistry issues that I do not understand. As this is electrochemistry... there is A LOT I don't understand!




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[*] posted on 6-10-2013 at 23:30


@kmno4

Obsession... science madness? Maybe... guess I'm at the right place then :P

Quote:
Do you know any premise that such a (quantitative) electrolityc glycerin decomposition (to H2 and CO2) is practically possible ?????


Maybe this paper might, I don't have access to it myself but the abstract sounds promising, can you help out again please?

http://pubs.rsc.org/en/content/articlelanding/2013/cp/c3cp50...

What sounded very interesting from the abstract of this was:

"We propose that active oxygenated species are gradually formed on the glassy carbon by potential cycling (up to the saturation of the carbon area) and these oxygenated species are additional oxygen suppliers for the oxidation of glycerol residues adsorbed on the Au particles..."

First time I see some evidence that to have 'active oxygenated species' on the anode may be helpful... while these guys seem to be generating it in situ, adding it stoichiometrically by way of H2O2 might thus not be a bad idea?




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froot
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[*] posted on 7-10-2013 at 03:28


Ha! Another Safrican! :cool:

DeltaH I briefly skimmed over this topic and think I get the gist of your idea so what I say might not be of much use, but..
Let's say you've now got your hydrogen from your glycerol. If it's intended for fuel cells then wouln't simply feeding vaporized glycerol into a MCFC save you a lot of snot and trane?

That been said it seems to me that extracting hydrogen from organics comes down to catalyst efficiency. Keep going.




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deltaH
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[*] posted on 7-10-2013 at 03:56


Howzat froot/boet :cool:

Yeah it basically comes down to whether breaking a process into two potentially more optimisable steps results in sufficient an efficiency gain in each so that it beats the efficiency of existing one step versions, such as a MCFC.

At least I'll be making the local PGM guys happy!

Thanks for your support and encouragement!









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watson.fawkes
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[*] posted on 7-10-2013 at 04:15


Quote: Originally posted by deltaH  
I've PROVEN the overall thermodynamics already on this thread
No you haven't. You've presented a number of theoretical calculations with not even a nod to real-world inefficiencies of actual apparatus. Hint: Go learn what the third law of thermodynamics is about.
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blogfast25
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[*] posted on 7-10-2013 at 04:48


Quote: Originally posted by Traveller  
[
And when those of the "hydrogen economy" are asked where all the energy to dissociate water (or make glycerol) will come from, we are given a Utopian view of a world covered in windmills, solar panels and tidal generators.

"Dreamer....you know you are a dreamer...."


Keep your political views out of it.

Nothing wrong with dreaming either.

You're still babbling as if this is water to hydrogen to water. It's not.

Glycerol? There's plenty of it.

[Edited on 7-10-2013 by blogfast25]




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[*] posted on 7-10-2013 at 04:57


Quote: Originally posted by watson.fawkes  
Hint: Go learn what the third law of thermodynamics is about.


Why don't you explain it here? Because I don't get what it's to do with this either.

If hydrogen could be extracted from glycerol why couldn't it be used as fuel for hydrogen cells? Of course it may prove to be impractically expensive or even technically undoable but right now we don't know this for sure.

Cryptic (and somewhat snobbish) remarks like yours don't really help, I feel.




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