Sun Catalytix

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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Carl White
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Sun Catalytix

Postby Carl White » Sat Mar 06, 2010 8:59 am

MIT chemist Dan Nocera has formed a startup company, Sun Catalytix, with the aim of applying home solar PV arrays (30 square meters) to the generation of a 30 KWh equivalent of hydrogen during four hours of sunlight. This is apparently done using a cobalt-phosphate catalyst to split water through "artificial photosynthesis".

More information at:

http://www.physorg.com/news187031401.html

http://www.suncatalytix.com/

Sounds like it could be integrated with a Bloom Box.

chrismb
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Postby chrismb » Sat Mar 06, 2010 9:32 am

The underlying theory appears to be summarised here;

http://web.mit.edu/chemistry/dgn/www/re ... pcet2.html

There are a few efforts around the world to "do" articifical photosynthesis and it really is one of the good ROI bets!

It seems so 'do-able'; the energy in a visible-wavelength photon is higher than that needed to liberate H from O in water that it strikes me as a problem waiting for some good chemistry/nano-technology to solve.

I'm against hydrogen as an energy vector due to the difficulties of handling, storage and the risk of unrecoverable atmospheric damage from industrial-scale leakage, but if artificial photosynthesis can be made to work [more efficiently than just growing-and-burning stuff!] then it will likely be worth the challenge of running a hydrogen infrastructure.

Skipjack
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Postby Skipjack » Sat Mar 06, 2010 9:43 am

What problems would leakage of hydrogen cause?
I would assume that it would just bind with an oxygen atom to form H20? Or maybe H2O2 under some circumstances?

chrismb
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Postby chrismb » Sat Mar 06, 2010 9:50 am

ozone depletion and earth and sea acidification.

There is around 500ppb elemental H in the atmosphere and there is almost no understanding of where it comes from and where it goes. Upset that balance [of something you just don't understand] and you'll get what you deserve!

Lots of CO2 has been seen before on earth, and life evolved from it. Lots of H2 has never been seen before - care to guess what'd happen, then, if you upset that balance?... 'cos it would be a guess....

MSimon
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Postby MSimon » Sat Mar 06, 2010 11:31 am

chrismb wrote:The underlying theory appears to be summarised here;

http://web.mit.edu/chemistry/dgn/www/re ... pcet2.html

There are a few efforts around the world to "do" articifical photosynthesis and it really is one of the good ROI bets!

It seems so 'do-able'; the energy in a visible-wavelength photon is higher than that needed to liberate H from O in water that it strikes me as a problem waiting for some good chemistry/nano-technology to solve.

I'm against hydrogen as an energy vector due to the difficulties of handling, storage and the risk of unrecoverable atmospheric damage from industrial-scale leakage, but if artificial photosynthesis can be made to work [more efficiently than just growing-and-burning stuff!] then it will likely be worth the challenge of running a hydrogen infrastructure.


I also like the idea of 24 hour electrical production from a few hours of sunlight. If safe residential storage can be done.
Engineering is the art of making what you want from what you can get at a profit.

Art Carlson
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Postby Art Carlson » Sat Mar 06, 2010 11:45 am

chrismb wrote:I'm against hydrogen as an energy vector due to ... the risk of unrecoverable atmospheric damage from industrial-scale leakage

Do you know more about atmospheric chemistry than I do? (It wouldn't be difficult!)
  1. H2 is not a greenhouse gas, is it? It doesn't have any bending modes, but I don't know if those are the ones responsible for the IR absorption in CO2 and CH4. The low mass should also push the vibrational frequencies up pretty high.
  2. Wouldn't the H2 quickly oxidize? The reaction might leave something like ozone or peroxide behind, the effects of which would depend a great deal on where the reactions occur.

P.S. Handling and storage are good reasons to be skeptical of hydrogen, especially for mobile applications. Furthermore, although it can be used directly or efficiently converted to electricity in fuel cells, the production by electrolysis is still (MSimon will correct me if I am not up-to-date) relatively inefficient and expensive.

MSimon
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Postby MSimon » Sat Mar 06, 2010 11:51 am

Skipjack wrote:What problems would leakage of hydrogen cause?
I would assume that it would just bind with an oxygen atom to form H20? Or maybe H2O2 under some circumstances?


It would be found by Post Normal Scientists to be an incredibly potent green house gas and there would be calls for restrictions and extreme regulation.

Or if an ice age scare is next up it would be proved to be an incredibly efficient conductor of heat or former of clouds.
Engineering is the art of making what you want from what you can get at a profit.

MSimon
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Postby MSimon » Sat Mar 06, 2010 12:07 pm

Art,

You are correct on both counts. When you ask the on site hydrogen generator mfgs what their energy efficiency is they clam up. The best number I ever got was in the range of 50%.

On top of that the safety rqmts for hydrogen are some of the most stringent. The ignition energy is very low. Sparks that would not ignite gasoline will set off hydrogen (if the concentration is right). I'd have to go back and look at the intrinsic safety charts to get numbers.

Now maybe a sealed system could work. Except that hydrogen is very hard to seal. It leaks through everything. Mechanical (bolting) joints esp. So you need a lot of monitoring. And regular inspections of the system.

The one thing it has going for it is that it dissipates rapidly (lighter than air) and doesn't pool.

And there is also the detonation velocity. Very high.

Oh. Yeah. Sufficiently high intensity UV can set it off.

Any way. We know what to do. Can it be done economically? Remains to be seen.
Engineering is the art of making what you want from what you can get at a profit.

taniwha
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Postby taniwha » Sat Mar 06, 2010 12:21 pm

And the "good former of clouds" would be very plausible: 2H2+O2->2H2O => clouds.

As for other chemistry: I can't comment on probabilities of various reactions, but I wouldn't worry about a major hydrogen leek depleting atmospheric oxygen because it would be taking out oxygen that we put there in the obtaining of the hydrogen. O2 neutral, in theory.

Hmm, I just realized that along with CO2, we've been putting a lot of H2O into the atmosphere as well. For methane, it's twice as much H20 as CO2 (molar, not mass).

chrismb
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Postby chrismb » Sat Mar 06, 2010 2:17 pm

Art Carlson wrote:Do you know more about atmospheric chemistry than I do? (It wouldn't be difficult!)

No. But a chap called John Eiler at Caltech knows more than both of us. This issue dawned on me some years ago and when I researched it this chap was the only other I found in the world who had just started considering the issue similarly and publishing on it. We corresponded briefly. This was several years ago and he had some PhDs looking into elemental hydrogen flows in the atmosphere.

I tried to raise it with the UK and European governments, but they were wholly uninterested. One chap from the health and safety executive responded with a vaild point that hydrogen infrastructures have been run before, in a manner of speaking. Coal gas, that was the main 'energy' gas before off-sea fossil methane was extracted, is around 40% H2, and there didn't appear to be any issues then. But, there again, it would be interesting if the pre-coal-gas era atmosphere was 50ppb and after that period it had become 500ppb and stuck there - but no-one knows.

This 'not knowing' is the issue. We know what happened when there is 7000ppm CO2 in the atmosphere; live evoloved!! We know what happened when there was 2000ppm; mammals evolved! So if mammals evolved when there was 2000ppm CO2 then does this not means mammalian life is more suited to 2000ppm CO2 levels?

Whereas we have no idea if life is even survivable with >500ppb elemental H2. It is not the *risk* that is very high, but it is the severity that could be high. It is the not knowing that, to my mind, makes atmospheric hydrogen indefinitely worse than CO2 could ever be.

Skipjack
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Postby Skipjack » Sat Mar 06, 2010 3:21 pm

Hmm, my guess would be that at least some of atomic hydrogen in the atmosphere is emitted from the sun? I know that the sun emitts so many hydrogen atoms that they have a notable effect on the planets venus and mercury (recent probes were seeing those in surprisingly high concentration on the sun facing surfaces of both planets, IIRC).
I have to look this up again, it has been a while since I read that and my memory is not as good anymore since my heart attack.

In any case the concentration of hydrogen in the atmosphere is pretty low at the moment (0.000055%) Even lower than CO2 or even Helium, which is at ten times the concentration. Methane, which is a very strong greenhouse gas is 3 times as concentrated in the atmosphere.

Btw, I do agree with the sentiment that hydrogen is rather impractical as a wide spread solution for whatever problems we supposedly do, or do not have. It might be useful in big facilities with lots of control mechanisms (with limitations), I do see it as rather problematic for consumers though.

Tom Ligon
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Postby Tom Ligon » Sat Mar 06, 2010 5:40 pm

I would like to think we could produce enough hydrogen with rooftop photocells to be an environmental problem! As pollutants go, it is pretty innocuous, and I don't expect it to last long in the atmosphere. If leaks occur, they will be a small portion of production ... we won't want to waste all that fuel.

No fuel is cleaner. It can be used for combustion or more likely in fuel cells, where it is the ideal fuel.

People like to bring up the Hindenberg and cite hydrogen's explosive nature, but live with natural gas and gasoline as if they were safe or something.

Hydrogen is not the most convenient motor vehicle fuel, but a few outfits have been working on storage tanks for the purpose, and it can be done. Lack of an economical source of hydrogen has been the limiting economic incentive.

The earliest I read about photocatalysis of water to hydrogen was circa 1975, a paper on the use of photon-excited titanium dioxide simiconductors to dramatically reduce the energy required to perform electrolysis.

chrismb
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Postby chrismb » Sat Mar 06, 2010 6:05 pm

Tom Ligon wrote:As pollutants go, it is pretty innocuous, and I don't expect it to last long in the atmosphere.

That's most people's reaction.

But it'd hardly be of much benefit in 50 years time if I say "hey, Tom, everyone is dying from UV, the crops are failing, life in the sea is all but dies out, and all because we thought that stratospheric elemental hydrogen was innocuous.". It's not like I would feel good about it, or anything!?

Probability of a problem from H2 - virtually zero; consequence - planetary death. The severity/occurence calculation should demand more than just a comment that it is thought to be innocuous, don't you think?

MSimon
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Postby MSimon » Sat Mar 06, 2010 6:23 pm

chrismb wrote:
Tom Ligon wrote:As pollutants go, it is pretty innocuous, and I don't expect it to last long in the atmosphere.

That's most people's reaction.

But it'd hardly be of much benefit in 50 years time if I say "hey, Tom, everyone is dying from UV, the crops are failing, life in the sea is all but dies out, and all because we thought that stratospheric elemental hydrogen was innocuous.". It's not like I would feel good about it, or anything!?

Probability of a problem from H2 - virtually zero; consequence - planetary death. The severity/occurence calculation should demand more than just a comment that it is thought to be innocuous, don't you think?


Then why aren't you on about large meteor strikes?
Engineering is the art of making what you want from what you can get at a profit.

chrismb
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Postby chrismb » Sat Mar 06, 2010 6:47 pm

MSimon wrote:Then why aren't you on about large meteor strikes?

I do. Just not here as it is well served by others. I only wonder if the next one will hit N America and induce a double-caldera eruption to boot. It'd probably happen during a solar storm whilst the magnetic fields are reversing and as salination inclines change and arrest normal oceanic currents.

Those who have spent their careers worrying over the minutiae of a few extra 100ppm of CO2 will, presumably, feel "a bit small".

Why d'you think I go to bed with a dust-bin lid on my head and a paper bag nearby?


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