James

Energy from water

Thursday, March 27, 2008 6:09:09 PM

Conspiracy theories about the petroleum companies are abundant. I can believe some of them, but not all of them. Just the same, if oil were an unlimited resource, it makes more sense to phase it out than to keep using it. Current alternatives either are too inefficient or too problematic. That begs the question of what to do.

Three research groups, two at Caltech and one at MIT, have just made some big strides towards answering that. They found a way to split water molecules using sunlight and not much else.

The full explanation is a little bit involved. In sum the system traps water molecules, then it absorbs light to split them. It expels oxygen gas and hydrogen gas separately. These two materials can then be used as fuel to release energy and (abracadabra!) water as exhaust.

They're still a long ways from producing a working model for consumers, but they've made it work. And that's the hardest part of all.

Pretty cool, huh?

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Comments

Peter Battypjbatty # Thursday, March 27, 2008 7:18:12 PM

Some minor saftey problems with the oxygen and hydrogen floating around, but anything's possible!

I honestly think the only way to solve the world's energy problems is by reducing the demand, either through massive efficiency gains, population control or pressure from environmental causes. Essentially, once oil runs out, which will happen sooner rather than later since demand is increasing, we will be forced into alternatives.

Jamesunlisted # Thursday, March 27, 2008 7:36:18 PM

I'm with you on both points, Peter, especially the second one.

We just have too many people in the world. From what I can tell, though, even Third World countries are pursuing family planning and conservation. Now if the First World countries could just ease up on their, er, OUR consumption...

hungryghost # Saturday, March 29, 2008 8:23:54 PM

Pretty interesting...would be curious to know what catalyst they're using, whether it's a transition metal based type or whether it's biological...that said...what could one do with all the H₂? Hmmmmmmm....maybe trap and run buses etc with H₂ fuel cells thereby regenerating the water again?

Jamesunlisted # Saturday, March 29, 2008 9:39:14 PM

While based on biological principles, the catalyst is not biologically derived. Rather it's a porphyrin ligand that's relatively easy to synthesize (if you're into that sort of thing...), quite stable, and a readily reactive catalyst.

The molecule's geometry acts as a cleft for electron donors/receivers. By balancing acid base activities in the substituent groups, a redox reaction can be highly localized. In this way, the device breaks water into its atomic substituents via catalyzed photolysis.

The resultant molecualar gases, H₂ and O₂, are combusted to release chemical energy and water vapor ("vapoUr" outside the US) as exhaust. This open-circuit style of reconsumption in situ can waylay the proliferation of the gases, thereby increasing system safety.

hungryghost # Sunday, March 30, 2008 12:47:48 AM

oh loverly porphyrins...I never quite worked with them, my specialty was sulfoxide complexes of Ru, but had friends who worked with Porphs - I saw their NMR spectra so many times during group meetings that I could probably still recognise them with my eyes closed

Jamesunlisted # Sunday, March 30, 2008 6:51:14 AM

Well, Ghost, I shan't hold the NMR thang against you.

Now, if you were a mass-spec guy... well, I could accept that.

Maybe.

hungryghost # Sunday, March 30, 2008 4:57:40 PM

LOL...I'm probably treading ragged edge of disaster here, but MS was a pivotal part of confirming the compounds in my thesis

I was a synthetic chemist - NMR, MS, X-Ray Crystallography - but these days, I'm a tumour biologist

so what do you do? You're in the sciences too I believe..

Jamesunlisted # Monday, March 31, 2008 4:29:40 AM

I have an edjumucation in the sciences. After completing all the work for a Ph.D. in physical chemistry, I figured out that life in the lab wasn't nearly as much fun to me as plunking away on the computer.

So now I'm writing my thesis (sporadically) in evaluation and optimization of electro-optic devices. Meanwhile, I'm working (steadily) as a dbase analyst.

I'd never have planned on doing, but it's a lot more enjoyable than any other job I've had.

hungryghost # Monday, March 31, 2008 4:40:21 AM

Yikes Physical Chem! The most difficult branch of chemistry!

Gibb's Law. Entropy. Yah. That's all I remember now.

Peter Battypjbatty # Wednesday, April 2, 2008 8:12:46 PM

Hoorah for sporadic thesis writing!

I always thought Chemistry more complex than Physics. It always seemed to me to be Physics + an extra few layers of complexity with extra long terminology to remember. Having said that, particle physics goes out of its way to confuse...

hungryghost # Wednesday, April 2, 2008 9:14:25 PM

Yes! And in chemistry, everything changed with the state of the matter - solid, liquid or gaseous.

But it's all good stuff. I have no regrets being a chemistry geek

Jamesunlisted # Wednesday, April 2, 2008 9:20:05 PM

Nerd Joke:

Q: What does a physicist call a diatomic molecule?

A: One atom too many!

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Yes, I think that physics is easier than chemistry in some ways because it (usually) operates at the fundamental level. Getting too basic, though, causes problems. That's why statistical mechanics is limited to producing exact answers for more than a handful of problems.

The terminology is a bit intimidating at first. Then you speak it all time, and it's easy.

I hear you, Peter, on the particle physics front. I used to be a nuclear chemist and went with physical chemistry because it's easier.

Peter Battypjbatty # Thursday, April 3, 2008 4:13:24 PM

Particle Physicists inhabit a different realm to the rest of us. It really does test one's patience with names like gluon, muon, neutrino and a particle nobody's even detected yet, the Higgs. They'll be up a creek if they don't find it on the LHC soon. Either it'll mean it doesn't exist and the Standard Model will need drastic revision, or it exists at higher energy, with the same outcome.

Jamesunlisted # Thursday, April 3, 2008 5:11:34 PM

Too true, my friend. I just messaged you a commentary on particle physics. A lot of physics' explanations, even now, are just mathematical expressions to accommodate explanations, e.g., fields cannot be measured directly. In a sense, they really don't exist in nature. Then there are simple sounding problems with nearly insoluble solutions: three body problem, sonoluminescence, etc.