deltaH
Dangerous source of unreferenced speculation
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Harvesting hydrogen from air... free energy with graphene?
I read this news article about harvesting hydrogen from air using graphene membrane technology. My knee-jerk reaction to the concept is one of
pseudoscience, but then I read that it was published as a Nature letter and that the study was led by Nobel Laureate, Sir Andre Geim?
The press reports:
http://edition.cnn.com/2014/12/23/tech/innovation/tomorrow-t...
and
http://www.hexapolis.com/2014/12/06/graphene-could-help-extr...
And the ?press release? from the University of Manchester:
http://www.manchester.ac.uk/discover/news/article/?id=13372
Will probably be going viral soon in the media as a 'free energy' story, while the term is of course not used anywhere, I think it's clear that this
is implied as they do say this harvested hydrogen could power fuel cells.
None of the stories link to the article itself, but I think they are referring to the Nature letter [1] referenced below.
Now a cursory search turned up that the hydrogen content in air is about 600 parts per billion [2], rather dilute.
I think there is a way to thermodynamically calculate the minimum work required to enrich a gas from one concentration to another, say from a partial
pressure of 0.6 mPa in air to 101325000 mPa or 1atm  I think comparing that to
the maximum thermodynamic work that could be derived from reacting the hydrogen with air would debunk this pretty quickly... or not.
Now the science behind the work and the discovery that protons diffuse through graphene while hydrogen does not, is very important and good, but I
have serious doubts about the harvesting hydrogen from air claims... sounds like the energy equivalent of harvesting gold from seawater.
I'd sooner harvest hydrogen from water 
BTW, is the diffusion of protons through graphene possibly a quantum tunneling effect?
Your thoughts?
References:
[1] S. Hu et al. (2014). Proton transport through one-atom-thick crystals [letter to the editor]. Nature 516, 227–230.
[2] E. Glueckauf and G. P. Kitt. (1957). The hydrogen content of atmospheric air at ground level. Quarterly Journal of the Royal Meteorological
Society 83 (358), 522–528.
[Edited on 24-12-2014 by deltaH]
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IrC
International Hazard
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Correct me if I'm wrong but I would think there is a greater chance of recovering Au in seawater than H2 at sea level.
"Science is the belief in the ignorance of the experts" Richard Feynman
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deltaH
Dangerous source of unreferenced speculation
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My thoughts exactly.
I have this little pet hate... when scientists put little asides to their research/articles, like "could one day be used for..." this or that, when
any scientist well knows it has no chance in hell of being used in that way, somehow inflating the potential importance of their research.
While this might be innocent at times, it's gotten out of hand, in fact so out of hand that people publish utter lies in this respect. Like in
energetics, when some insanely complex molecule gets synthesised with mediocre properties and then they say... could one day be used for propellants,
yeah right, like anyone wants to pay $10000 per bullet or $100000000000000000 for a rocket.
Anyway, this particular case about the... could one day be used to harvest hydrogen from air and solve all our energy needs is just so far off the
edge that it just proves how dangerous these claims are getting.
Anyhow, maybe I'm wrong and I'll stand corrected... wouldn't be the first or last time 
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gdflp
Super Moderator
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It might not necessarily be useful for pulling hydrogen out of the atmosphere, but it might be useful for other processes. For example, shifting an
equilibrium towards one side in cases such as splitting methane into it's constituent elements, as a lot of research is going into this topic
currently.
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forgottenpassword
Hazard to Others
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Quote: Originally posted by deltaH  | My thoughts exactly.
I have this little pet hate... when scientists put little asides to their research/articles, like "could one day be used for..." this or that, when
any scientist well knows it has no chance in hell of being used in that way, somehow inflating the potential importance of their research.
While this might be innocent at times, it's gotten out of hand, in fact so out of hand that people publish utter lies in this respect. Like in
energetics, when some insanely complex molecule gets synthesised with mediocre properties and then they say... could one day be used for propellants,
yeah right, like anyone wants to pay $10000 per bullet or $100000000000000000 for a rocket.
Anyway, this particular case about the... could one day be used to harvest hydrogen from air and solve all our energy needs is just so far off the
edge that it just proves how dangerous these claims are getting.
Anyhow, maybe I'm wrong and I'll stand corrected... wouldn't be the first or last time |
I thought that it was well understood that the only useful part of a journal article is the
experimental section?! The rest of the waffle is merely the authors trying to explain to themselves why they bother getting out of bed every morning
to mix chemicals together. 
Merry Christmas!
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