Using Sun's Energy to Split Water Means Solar Power All Night 557
phorm writes "Reuters is carrying an article about a recent MIT development which may pave the way for solar-energy to be collected for use in low-input periods. According to Reuters, the discovery of the a new catalyst for separating hydrogen+oxygen from water requires only 10% of the electricity of current methods. This would allow storage-cells to function as a form of battery for other forms of energy-collection, such as solar panels. The new method is also much safer (and likely environmentally friendly) than current methods, which require the use of a dangerously caustic environment, and specialized storage containers." sanjosanjo points out coverage of the process at EE Times, which features the MIT group's press release.
Re:I have my doubts... but, (Score:2, Informative)
Re:I have my doubts... but, (Score:5, Informative)
Lets say your house needs 5000 W. To get through an 8 h dark period, you need 40 kWhr, or 136,000 BTU. That's roughly the energy in 2 lbs of hydrogen. To store that much hydrogen, you either need a balloon of 11 m^3 size, or you need a compressor that allows you to store the hydrogen as compressed gas (what costs energy to do) or to liquefy the hydrogen (what costs even more energy). Alternatively you can adsorb the hydrogen into certain alloys, but then you need to heat them to get the hydrogen back out, again ruining your energy balance, and driving up the cost.
This development can help with the development of a large scale hydrogen infrastructure, but there we're better of with natural gas (of which we're not running out anytime soon, and which has much less technological hurdles in storage).
Fly wheels are expensive too (Score:2, Informative)
Re:Benefits not just solar . . . (Score:3, Informative)
Not to mention, have you seen the waste products? I wouldn't call 'em "environmentally friendly"!
I have a toddler, trust me on this. ;)
self-repairing catalyst (Score:4, Informative)
If you read the actual article (you need to be a AAAS member or otherwise have access to Science), you would see that that these MIT guys are using a cobalt oxide catalyst which is created during the electrolysis of water. Yeah, it's really efficient, which is good (I don't know that I buy the green thing), but it's also self-repairing. Although it seems to be future work, they're envisioning tailoring the chemistry so that the activity of the catalyst is maintained by an equilibrium of dissolving and redeposition of the catalyst electrode. As a bonus, it looks really easy to make.
Re:If this is true... (Score:5, Informative)
My experience is that when you try to use electrolysis on salt water you get NaOH and chlorine.
Re:List of papers, but no online copies? (Score:3, Informative)
Since 1958? (Score:4, Informative)
50 years ago was 1958. Interestingly enough., that was the year the first solar panels went to space. Today, you can sit right there in your chair, do some googling, whip out your credit card and have dandy solar panels shipped right to your house at less than NASA cost plus pricing levels. That's pretty significant. A few years previous to that, some of the first ones were running $1,785 dollars per watt, and those are unadjusted dollars. Today you can look for deals and get them at around 5 bucks a watt. Not too shabby. And nanosolar started shipping this year, albeit all of it to Germany where demand is higher and they will pay a bit more now, because they know conventional will be going up fast later, so they did a whole nation push for it starting some years ago. That and it is cleaner.
here's the wiki ref for the figures, Solar timeline [wikipedia.org]
I bought mine at actually a little under 5 bucks a watt some years ago. silicon demand has been going more for throw away gadgets and so on in the meantime, but several new fabs go online this year and next year so prices will be dropping again.
Re:I have my doubts... but, (Score:2, Informative)
The whole point of this technology is to have it pre-electrolyzed. Electrolysis needs energy to be performed (the energy from the sun in that case) so you can get this energy (well, part of it) back when there is no sun.
The oxygen+hydrogen produced by the electrolysis would be the replacement for batteries.
Re:I have my doubts... but, (Score:3, Informative)
Huh?
Volume of a sphere: 4/3 * pi * r^3
d = 1.5.
-> r = 0.75
V = 4/3 * pi * 0.75^3 ~= 1,8 m^3
Your math is correct when we assume a sphere with a radius of 1.5 m (in that case V ~= 14.1 m^3), but that means we are talking about an orb with a 3 meter diameter, which is heigher than most ceilings (3 meters = 9.8 ft for the SI-impaired).
You still have to be careful (Score:5, Informative)
For one, professors have to get grants to do their research, so they are sometimes given to overstatement to that end. They are, after all, only human which means that not all of them are honest. Also, some are simply unrealistic. They think they can do something, so they announce it, even though they have no idea how to get there, and then maybe never end up doing so. Finally sometimes shit just ends up being impossible. It looks good, seems like things will work, however in the end you can't make it happen. That happens with research. You can spend millions only to realise you've been down a dead end and there's nothing to be done about it.
I agree an announcement from a major university is much more credible than some startup, but don't think things out of universities aren't overstated at times.
Re:Potential energy (Score:3, Informative)
What do you mean "would work"? It's been working for a long time. The British did this thirty years ago [wikipedia.org]. I'm sure there are other similar systems elsewhere in the world, too.
The two main problems with these schemes are that the capacity is quite limited - you run out of water in the high-altitude reservoir - and getting the response time down to small numbers of seconds requires energy input (you can't just let all the water in at once with the turbines stationary, since that would damage the bearings, so if you want fast response you have to spin the turbines up on compressed air).
Of course, such schemes won't work everywhere either. Countries like Holland don't have enough mountains for this to work well, and countries like the USA do have mountains, but the transmission losses between those and the centres of population are larger than is the case in a small country like the UK.
Re:I have my doubts... but, (Score:1, Informative)
Re:I have my doubts... but, (Score:5, Informative)
15 amps? 120 watts?
No, most houses have 100-200 amp service. At 120 volts. Which works out to 12000-24000 watts, peak. Average electricity consumption is right around 1 kilowatt, so the poster who said to divide by 5 was right.
Re:List of papers, but no online copies? (Score:3, Informative)
The paper is being published in a journal that comes out this week. It wouldn't make sense for him to post it to his website before it is even published (and would probably be a breach of contract).
Although MIT press releases are notoriously pie-in-the-sky, there probably are some real improvements here.
Of course it's ludicrous (Score:2, Informative)
Perhaps next time you see something "ludicrous" you might pause to consider that may be because you've badly fucked up the maths.
If something has decreased the amount of energy needed by 90% it has reduced the inefficiency (of that part of the problem) by 90%.
In your 20% efficiency example there is 80% inefficiency. Reducing that by 90% would leave you with 8% inefficiency, making your final efficiency 92%, not 200%.
Of course in the real world there are more sources of inefficiency in the overall process than just splitting the water, so a 90% improvement in that one part will have a lesser effect on the overall efficiency than above.
Re:I have my doubts... but, (Score:3, Informative)
Re:If this is true... (Score:2, Informative)
You need salt in the mix to get electrolysis to occur with any efficiency at all. It won't work with distilled water.
You need something to make the water conductive, but NaCl isn't a good choice. Usually, at least for demonstrations, sulfuric acid is used.
Re:Solar commuter cars won't work and here's the m (Score:4, Informative)
Re:I have my doubts... but, (Score:5, Informative)
Anyway, I guess where I was going with this is that this isn't some fuel pill, or Al Gore rambling on about things he doesn't understand. Nocera is to water splitting what Miyamoto is to video games, and if he says that he's done it, I'm sure he's done it.
Re:I have my doubts... but, (Score:3, Informative)
The smallest house service panel I have ever seen (by far) was a 50 amp one. 50 amps X 240 volts (U.S. uses split-phase) = 12,000 watt service.
Re:I have my doubts... but, (Score:5, Informative)
Indeed, Nocera has been working on this for what must be at least 15 years by now. I remember he had some catalysts four or five years ago that worked using only the ambient intensity of sunlight, but were far too expensive to be practical (so I heard).
I also work in catalysis, and one of my friends is doing water splitting, so I've read a few papers on the topic. The materials used don't surprise me, cobalt is approximately as good as you can find. Also, I would note that this catalyst (I downloaded the paper) is releasing oxygen and gradually producing HPO4, which can then later be oxidized to (presumably) release energy. I'm not familiar with using phosphoric acid as a fuel, but the paper sounds extremely plausible.
I would also suggest that, based on my reading of the paper, any real world applications would be 5-15 years away, depending on how well they're able to coat their electrodes.
Re:trade secret (Score:5, Informative)
The paper is published in a peer reviewed journal. It's patented, not secret.
They used ITO glass as an electrode with a neutral KPi electrolyte with 0.5mM Co^{2+} at 1.29V. They tried it with CoSO4, Co(NO3)2, and Co(OTf)2 as the cobalt source. It also works on FTO glass, as well as with a NaPi electrolyte.
The description of the processing method is extremely detailed. I would have little difficulty duplicating this experiment. (YIAAS)
Re:I have my doubts... but, (Score:2, Informative)
I know you edited that sentence below, but you might consider nuking it from orbit, instead. It really is quite an awkward sentence.
Comment removed (Score:5, Informative)
Re:Why oxygen? (Score:2, Informative)
Thanks! That link clarified matters considerably. To answer my own question, you have to extract the oxygen as well as the hydrogen or else the electrical circuit isn't complete. (Doh!)
Of course, I'd always assumed you had to extract both (although I'd never thought about why exactly) but the original article confused me by saying that platinum was efficient for the extraction of hydrogen but not for the extraction of oxygen - it wasn't obvious to me that what they really meant was that platinum was efficient at the cathode (where the hydrogen is produced) but not at the anode (where the oxygen is produced).
Re:I have my doubts... but, (Score:1, Informative)
Can you ride 30 miles to work in Texas without smelling so much like ass that you boss has to ask you to go home?
Perhaps you missed the /. article about a wonderful new invention, it's called a "shower" and uses to miracle of running water to produce cleanliness! I used to run 5km to work every day and used this fabulous invention daily, but then I'm not the type whose sweat smells like ass. Perhaps you might want to re-evaluate your diet.
Re:I have my doubts... but, (Score:4, Informative)
I don't remember using KVA for any calculations in building houses, but here's what a typical house may have. (I'm like 15 years out of the business, so this is from rusty memory.)
My own house:
Outlets - generally 4-5 per circuit, about 8 sets.
8x20A circuits
Oh, plus 2 more for furnace and washer.
That's 10 20 amp circuits.
Then I have a range, dryer, an air conditioner and a heat pump with electric backup. That's a double pole 20, 3 30's, and a 40, all double pole for 240 volts.
That completely maxes out all the available slots in a 200 amp square-d main breaker box.
So while the actual use never meets the full potential, it has to be sized that way due to engineering and saftey codes.
Re:Good solution but wrong problem. (Score:3, Informative)
The price of their cells continues to drop, they're light, can discharge safely down to low temps (20 F and lower), and last 1,000s of cycles: [particular example of a currently available cell deleted]
In fact the lifetime of lithium ion batteries is mainly determined by the oxidation of one of the electrodes. It is a very close approximation to a clock that starts when they're assembled and runs out after a certain number of years, regardless of the number of cycles (though there is a slight effect from state-of-charge, lasting longest at 40% or so, and the capacity drops as they age).
Some newer models have much longer lifetimes - comparable to the life of a "buy it new and drive it until it falls apart" car.
Some newer models (not sure if there's an overlap with the above) can be charged or discharged 80% of their capacity in a matter of a couple minutes. This is suitable for directly powering a motor, and even regenerative braking, without the aid of a supercapacitor buffer. It's also an indication of extreme efficiency: Only a tiny bit of that capacity is lost at heat (or it would be slag...)
Re:You still have to be careful (Score:2, Informative)
Dropping Inefficiency by 90% (Score:3, Informative)
The Reuters article claims the new catalyst drops the conversion inefficiency by about 90% compared to platinum. Since platinum efficiency is about 50-70%, that means that the new efficiency is about 95-97.5%.
This is an incredible advance, if it's true. Even though it increases the efficiency of only the oxygen generation, leaving hydrogen still generated by a platinum catalyst at the old efficiency. Even if the efficiency has jumped only from 50-70% to about 70-85%, that's still a big jump. And it shows that there's a lot of reachable gains left to get, and not necessarily in the distant future.
Re:Gimme a break (Score:4, Informative)
The Cobasys example is bullshit. I admire your integrity in agreeing that it's a bullshit example, by citing the fact that they are used in hybrids (although you also lie about them only being in RAV4 EVs), but am puzzled at your inability to reconcile that fact with your lie about it being supressed. So they don't want to sell piddly quantities to shadetree mechanics. So what. They ARE selling to automakers, while you claim they aren't.
Try again.
Re:I have my doubts... but, (Score:3, Informative)
Just dam up a valley [dom.com], and there you go [wikipedia.org]!
I toured this facility a long time ago back before the days of evil terrorists - it's pretty impressive! It actually helps the local ecosystem.
Re:I have my doubts... but, (Score:5, Informative)
But these claims really aren't as extraordinary as you might think. They've found a new catalyst that reduces the amount of energy required to split water. That's what catalysts do--they reduce the activation energy of a reaction. Life would not function without catalysts. Every enzyme in your body (there are thousands of them) is a catalyst designed to make some reaction run efficiently at body temperature.
Every few years a breakthrough catalyst is discovered that makes new reactions feasible. See for example the Grubbs' catalyst [wikipedia.org] which when discovered had almost magical properties compared to the state of the art. Grubbs recently won a Nobel prize for this work.
Currently, platinum is a catalyst on the cathode, for generating hydrogen. This works well and has been known for a long time. This new research has found a useful catalyst for the anode, which generates the oxygen.
While this might be a major breakthrough, I don't find it to be extraordinary, at least in the same sense that a self-sustained cold fusion reaction is extraordinary. These results should be easy to duplicate in other labs as the materials are straightforward.