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Photocatalyst Cracks Water with Sunlight

Posted by michael on from the catalytic-cracking dept.

lonenut writes: "With fuel cell laptop batteries in the news lately, I thought this article on water-cracking photocatalysts would be good reading. A bit short on details, but apparently Zhigang Zou of the NIAIST in Tsukuba, Japan is working on a promising catalyst which creates hydrogen and oxygen from water and sunlight. I look forward to someday watering my laptop just like the houseplants."

43 comments

  1. We know it works by adamy · · Score: 2, Interesting

    Look at all the biological systems on the planet that convert sunlight into energy. I guess it is no surprise that we can get this to work in the lab...

    Yeah, I know, we've been using solar panels for years.

    From what I've read, storing energy as hydrogen is one of the most effecient ways to do so. I wonder why all thos windmills on Route 580 out outside Pleasonton, CA don't use this as opposed to just turning off. I heard that it was because there was not effecient way to store the energy. Couldn't they just generate electriticiy, split water into it's componenets, and store the Hydrogen?

    Forget for laptops, I want this for my house...no more rolling blackouts. Course My h2o will be sky high.

    --
    Open Source Identity Management: FreeIPA.org
    1. Re:We know it works by Alpha+State · · Score: 2

      From what I've read, storing energy as hydrogen is one of the most effecient ways to do so. I wonder why all thos windmills on Route 580 out outside Pleasonton, CA don't use this as opposed to just turning off. I heard that it was because there was not effecient way to store the energy. Couldn't they just generate electriticiy, split water into it's componenets, and store the Hydrogen?

      Conversion between different forms of energy results in a low efficiency. Converting from electricity to hydrogen and back would have an efficiency of about 50% (at a guess), not including transport of the hydrogen. The electricity grid has an efficiency of about 75% (again an educated guess), and is very convenient.

      Of course, if you are going to generate hydrogen directly it would be great for transport use. this sounds like a great new form of solar power if it works well.

    2. Re:We know it works by Pogue+Mahone · · Score: 3, Informative
      Course My h2o will be sky high.


      Why? When you "burn" the hydrogen to recover the
      energy, guess what you get back?

      --
      Every bloody emperor has his hand up history's skirt [Peter Hammill/VdGG]
    3. Re:We know it works by hairyian · · Score: 3, Interesting

      Conversion between different forms of energy results in a low efficiency. Converting from electricity to hydrogen and back would have an efficiency of about 50% (at a guess), not including transport of the hydrogen. The electricity grid has an efficiency of about 75% (again an educated guess), and is very convenient.

      This is indeed true: the processes which convert energy from one form to another are rarely efficient. There is one thing which has struck me about this: we don't need to be efficient. What we need it lots of energy which we can waste.

      On a day to day basis we waste more energy than could be imagined. The great fiery fusion reactor in the sky emits it whether we use it or not. Lot's of it. More energy than even a Californian household could use! In a sense, sitting on a rock and collecting what comes out way isn't very efficient. I doubt we get more than a hundred billionth of the energy that we could get. It's just difficult to it!

      Imagine a process of generating hydrogen using sunlight which was commercially viable but was only 1% efficient. Is this a problem? Not if you can collect 100 times more of the free energy which is being lost from the great fusion reactor in the sky. To put it in context, use a reflector 10 times the size.

      This is entirely an engineering problem, and with current technology it's solvable but expensive. The end result though, is enough energy for rock and roll for as long as the fusion reactor in the sky is pumping it out. All we have to do is enough work to collect some of what's wasted!

      (yes, I know. Ultimately, you want an elipse with a collector at one focus and the sun at the other so we don't waste any of it. Dyson sphere anyone? ;)

      Ian Woods

    4. Re:We know it works by Anonymous Coward · · Score: 0

      hopefully there is some limiting factor
      to the catalyst to prevent an
      ICE9 type of chain reaction.
      Here is to even more unimaginable headlines.
      "In the news today, not only did the
      Hudson River catch on fire today after
      an enron hcatalyst spill, but it also
      blew up in a spectacular ignition of
      hydrogen gas bubbles"

    5. Re:We know it works by adamy · · Score: 1

      Ooops, should have been,

      My H2O Bill will be sky high.

      --
      Open Source Identity Management: FreeIPA.org
    6. Re:We know it works by InadequateCamel · · Score: 1

      One of my profs is interested in photochemistry and he gave our class a statistic: if you tally up all the energy humans use and produce in a year, you find that an equivalent amount of energy from sunlight strikes the surface of the earth in one hour.

      So if we have this much energy coming in, why bother converting to hydrogen at all? Inefficiency aside, you create the problem of storing a very large volume of highly explosive gas, when we could just be storing water.

      The nickel-indium tantalum oxide is probably not too cheap to prepare, but the costs are covered when you consider that you don't have to buy gas anymore. There was no note about the longevity of the catalyst, but time will tell I guess. It also precipitates a move to a nuclear-free world, but the process will have to be refined so it is much more efficient.

    7. Re:We know it works by hairyian · · Score: 1

      One of my profs is interested in photochemistry and he gave our class a statistic: if you tally up all the energy humans use and produce in a year, you find that an equivalent amount of energy from sunlight strikes the surface of the earth in one hour.

      Interesting. That's a hell of a lot of energy! Consider the amount of energy which doesn't strike the earth... staggering. Efficiency? What's that!

      So if we have this much energy coming in, why bother converting to hydrogen at all? Inefficiency aside, you create the problem of storing a very large volume of highly explosive gas, when we could just be storing water.

      You could easily make a distribution chain whereby electricity was produced by this process on a large scale either by cracking water onsite (the clever way) or getting it shipped in. Similarly, having cars running of hydrogen LPG is more feasible than running them from sunlight.

      The benefit of having a distribution chain is that the water cracking plants can be much less efficient than a process to drive a machine in situ because it is being produced in bulk. This is mostly because we know how to efficiently use combustible gasses and don't know effective ways of using sunlight.

      I don't see pressurised hydrogen gas as being any more or less dangerous than most hydrocarbon fuels swilling around the inside of billions of vehicles on the streets of the world.
      There are accidents, and there are explosions but they aren't a major risk (unless you're driving a Ford... ;)

      I just hope this happens instead of oil being the predominant source of energy.

      The only downside I can see is the number of Arabs and Texans who would find their market diminishing rapidly as companies and countries started making most of their energy from it's most abundant source - sunlight...

      Ian Woods

    8. Re:We know it works by Anonymous Coward · · Score: 0

      I don't see pressurised hydrogen gas as being any more or less dangerous than most hydrocarbon fuels swilling around the inside of billions of vehicles on the streets of the world. actually the petrol in car fuel tanks poses very little risk of explosion (despite what Hollywood may have us believe). The oxygen-fuel ratio in the average fuel tank is simply not high enough for combustion to occur.

  2. Just defers the problem... by Hard_Code · · Score: 2

    ..so now the problem becomes the laborious chore of mining finite resources out of the earth?

    What is wrong with a solar-powered electric generator used to split water? Is that not efficient enough? At least you wouldn't be lugging around all these minerals to replenish the water splitter.

    --

    It's 10 PM. Do you know if you're un-American?
    1. Re:Just defers the problem... by belg4mit · · Score: 3, Informative

      No it doesn't

      a) catalyssts are by definition resuable
      b) there are other source of minerals than just the Earth. (There aren't any other useful sources of hydrocarbons on the other hand).

      --
      Were that I say, pancakes?
    2. Re:Just defers the problem... by AntipodesTroll · · Score: 3, Interesting

      How do you convert the sunlight to electricity?

      Electricity producing silicon solar-cells actually take more energy and generate more pollution during manufacture, than they will ever generate. The uninformed non-tech green set never seems to understand this point.

      This leaves using an intermediary like water or sodium, to be heated by sunlight, and to generate electricity mechanically. This is highly inefficient, and/or dangerous.

      The fact is, sunlight is too diffuse to be a practical large-scale energy supply without a hell of a lot of energy being put into it, by traditional means. Unless you count photosynthesis, which I give more creedence to than solar cells, the energy is just in a completely different form.

      The nice thing about conversion directly to hydrogen, is that it is definetly an easier way to concentrate the energy.

      --
      Anyone who considers arithmetical methods of producing random numbers is, of course, in a state of sin.-John von Neumann
    3. Re:Just defers the problem... by stevelinton · · Score: 3, Informative
      Electricity producing silicon solar-cells actually take more energy and generate more pollution during manufacture, than they will ever generate. The
      uninformed non-tech green set never seems to understand this point.


      I believe that this is no longer true. The latest generations of cells are much thinner and lighter (less silicon to refine and melt so less energy) and more efficient than earlier generations.
    4. Re:Just defers the problem... by Mandelbrute · · Score: 2
      Electricity producing silicon solar-cells actually take more energy and generate more pollution during manufacture, than they will ever generate.
      Some numbers to back this up would be nice - I hope it's not the trick of paying for the entire factory (which will outlive individual cells) plus all of the vehicles used to transport the products (which are also used for other things).

      Most people seem to forget that the oil they use doesn't grow in the pump, and the coal has to be dug up - getting those energy sources takes energy too.

      Anyway, the argument is fairly pointless, since the solar cells are used in applications where it is impractical to use power from the grid (eg. boats, pumps, telecommunication towers, navigation lights or hand held calculators)

      This leaves using an intermediary like water or sodium, to be heated by sunlight, and to generate electricity mechanically. This is highly inefficient, and/or dangerous.
      Why is it dangerous? Dangerous relative to what? More dangerous than the Hydrofluoric Acid used in oil refining (which of course is only nasty if it gets out)? Your garage is probably full of much more dangerous chemicals than small amounts of hydrogen.
      The fact is, sunlight is too diffuse to be a practical large-scale energy supply
      KiloWatts per square metre sound like serious amounts of energy to me. Even if you can only get 5 percent of that you are still getting a fair bit of energy.
    5. Re:Just defers the problem... by InadequateCamel · · Score: 1

      Just because it is called a catalyst does not mean that it has an infinite lifetime. A catalyst, by definition, helps a reaction along (be that making a slow reaction fast or an "impossible" or improbable reaction less so). The problem will be the amount you need, and last I checked, tantalum mines are not a common site of employment.

    6. Re:Just defers the problem... by belg4mit · · Score: 1

      Correct, it may not have an infinite usable lifetime. It will probably become poisoned eventually and require reprocessing. However a catalyst *cannot* be consumed, only reagents are consumed. As for quantities required, yes that could be a problem, but the more meaningufl limit as they themselves have addressed is simple throughput. As for tantalum, the composition of the catalyst is unknown and therefore speculation considering supply is just that.

      --
      Were that I say, pancakes?
  3. nice technology.. by zcat_NZ · · Score: 1
    Efficient hydrogen-based fuel cells have been around for a while now. Just recently there was a story on slashdot about using a sunlight-pumped orbiting laser (I'm not going to dig for the link..) which would presumably let you send the collected energy down to earth with minimal atmospheric loss. So I've been wondering for a while if there was a better way to split water; electrolysis is hopelessly inefficient.

    --
    455fe10422ca29c4933f95052b792ab2
  4. The problem is efficiency. by Bob_Robertson · · Score: 3, Informative

    Building the solar pannel requiers more energy than you get out of it. Same as a battery. It's only "efficient" for the end user.

    Petrolium is efficient because we are just harvesting millions of years of sunlight-and-plant stored energy. In real terms, it's not efficient at all. Ethanol is more efficient, brewing burnable liquid fuel out of sugar, or using lye and methanol to crack vegetable oil into "diesel" fuel. Or just burn the veggie oil directly, like Heir Diesel did in his original engines.

    All of these convert sunlight into fuel, with various efficiencies and usefulness. I think the direct use of veggie oil to be the best myself, but one still has to press the oil out!

    The answer, I believe, is to use them all. Bio-diesel, veggie oil, ethanol, hydrogen, tide and wave forces, wind, sunlight, petrolium.

    The "scarce resource" idea is a myth. 150 years ago, whale oil was an important strategic national resource. Silica is as common as sand, and more valuable than gold when formed into a computer chip.

    Bob-

    --
    The Ludwig von Mises Institute. The reasoning individuals economics
    1. Re:The problem is efficiency. by Mr.+Slippery · · Score: 1
      Building the solar pannel requiers more energy than you get out of it.

      No. It doesn't. Please check your facts and stop spewing photovoltaic FUD. Modern photovoltaic panels have a lifetime return of several times the energy required to build them

      --
      Tom Swiss | the infamous tms | my blog
      You cannot wash away blood with blood
    2. Re:The problem is efficiency. by Bob_Robertson · · Score: 1

      How very interesting. I'm glad to know that.

      Could you please send a note to Home Power magazine, then? I'm sure they'd like to update their statistics.

      Careful with the name calling, buster. Leave that to Microsoft.

      Bob-

      --
      The Ludwig von Mises Institute. The reasoning individuals economics
    3. Re:The problem is efficiency. by Mr.+Slippery · · Score: 1
      Could you please send a note to Home Power magazine, then? I'm sure they'd like to update their statistics.

      If they can't be bothered to do their own research - like, say, five minutes with Google to find this, or this, or this - why should I do it for them?

      But then, the last link I give above says "...a recent, very detailed study about solar panel energy payback time in the January 2001 issue of Home Power magazine...finds payback time for a standard module to be about 3.3 years, and 1.8 years on a thin-film panel." So maybe they are doing their research and you're reading back issues from the 1970s?

      --
      Tom Swiss | the infamous tms | my blog
      You cannot wash away blood with blood
  5. change? by smashin234 · · Score: 1

    It doesn't seem to me that this changes anything. You still need to recharge your laptop with Hydrogen, and it will polute just as much as batteries do today(very little). This seems to have more implications with automobiles and such since we will run out of oil before any other natural resource.

    1. Re:change? by hairyian · · Score: 2, Informative

      You still need to recharge your laptop with Hydrogen, and it will polute just as much as batteries do today(very little)

      There is a funamental difference between the use of hydrogen for power in a fuel cell and the use of a normal cell.

      You 'make' a cell. It's made of some pretty nasty things. There are around 70 million mobile phones in the UK, each of which has around 100 grammes of heavy metal in their rechargable (but not infinitely so) cells. In a few years each of these cells will need to be replaced. By my calculation that's 7 million kilogrammes, or 7000 tonnes of heavy metals that needs to be processed and/or recycled (or, thrown away). That's a hell of a lot of material for a place the size of the UK.

      A hydrogen fuel cell does not contain such nastiness and, baring wear and tear and failure, would last at least as long. Additionally, the oxidation of hydrogen (which is ultimately where the energy comes from) produces water. Not slightly nasty water, but pure water. The kind of thing which tastes awful ;)

      I think you'd find that a hydrogen fuel cell industry would be far better for the environment and cheaper to do (lower displosal, recycling, replacement cost) than any other chemical storage power supply.

      The part of the equation which is missing is an efficient (read, cheap) way of producing hydrogen. Sunlight is clean and free - if we don't use it then it's wasted. The sun emits quite a lot of it continuously. Using a million times more of it than we necessarilly need is still a hell of a lot cheaper and better than drilling for crushed and fermented vegetation below rock strata. If it can be made commercially viable, I for one am all for the use of H2 for power. The advantages are clear: the only thing missing is a cheap and plentiful supply of H2.

      Ian Woods

    2. Re:change? by Sir+Holo · · Score: 1

      > You still need to recharge your laptop with Hydrogen, and it will polute just as
      >much as batteries do today(very little).

      To get the electricity to recharge your laptop's batteries, someone, somewhere, is burning coal or oil. Dirty, dirty, dirty.

      The "recharge" of energy provided by sunlight-cracked water would not produce any pollution. Squeaky clean.

  6. your sig by Anonymous Coward · · Score: 0

    sad. but true.

  7. Does this mean... by delorean · · Score: 1
    1) that I'll be killing my laptop often,

    or, 2) that I'll remember to water my plants?

    I just don't know.

    --
    "You may all go to hell and I will go to Texas"
     Sen. Davy Crocket to US Congress, Nov. 1, 1835
  8. I'm not clear on this... by kippy · · Score: 1

    does this mean that you put a plate of this materal into a tub of water and it will produce hydrogen as long as there is water?

    or is it the less attractive option: you put a plate of the materal in water and when it dissolves or doesn't produce any more hydrogen, you need to replace it.

    help me out here.

    --
    Blaze a trail to the New World
    1. Re:I'm not clear on this... by Sylver+Dragon · · Score: 1

      does this mean that you put a plate of this materal into a tub of water and it will produce hydrogen as long as there is water?

      Of the two options, this is the more correct. According to the article, which was light on details, the alloy is a catalyst which, defined loosly, causes a reaction to take place but is itself not changed in the reaction. As such, in an ideal situation, you could put a lump of this stuff in a bucket of water, and assuming that you had any other nessecarry components (heat, light, electtricity, etc.) your bucket of water would eventually become a bucket of hydrogen and water, and the lump could be reused indefinatly. Though if there are other such considerations, the article did not say, it just said water, lump and light, they might limit the reaction. Anybody got a link to more info on this stuff?

      --
      Necessity is the mother of invention.
      Laziness is the father.
    2. Re:I'm not clear on this... by kippy · · Score: 1

      i found this and it's a little bit more detailed. What I want to know now is how much some of this stuff will cost and how do we sort out which little bubbles are O2 and H. wouldn't the whole thing just start fizzing like an alka-seltzer when you drop it in?

      --
      Blaze a trail to the New World
  9. A far simpler use.... by freerangegeek · · Score: 1

    Catalytic hydrogen crackers powering vessels at sea. Skip fossil fuel, instead your floating on your gas tank. Of course, you'd have to store the hydrogen for 'cloudy/stormy days'.

    I wonder how large an array you'd need to power a container ship.

    1. Re:A far simpler use.... by Anonymous Coward · · Score: 0

      Why are we taking the time to waste so much power on transportation? We should take these billions of dollars of research and aim them at teleporters. Even if teleporters aren't safe for humans, it could still transmit material goods. Imagine if the space station didn't have to have supplies rocketed up to it, or if we had a moon base...

      And we could accomplish this using that Bose-Einstein Compensate that was in the news awhile ago, creating a laser-type beam out of matter instead of light (radiation for you purists).

  10. Let's clear this up... by Sir+Holo · · Score: 1


    A catalyst is something that lowers the energy barrier for a chemical reaction. It "helps it along" without being consumed in the process. It is not used up.

    The article described a catalyst that would help sunlight to break H2O apart into H2 and O2, a chemical reaction.
    (specifically, 2 H2O => 2 H2 + O2). The catalyst would help some of the radiant energy in the sunlight to be converted to chemical energy. Plants do this all the time.

    In other words, it would not be a perpetual motion machine.

  11. "Payback" by Bob_Robertson · · Score: 1

    What is the definition of "payback"?

    ($Cost of purchase)-($Assumed Cost of electricity not purchased from the electric company)?

    Or as you imply, ($Cost of Manufacture)-($Assumed Cost of electricity not purchased from electric company)?

    Maybe you're not finding the answer to the question your asking. Or maybe you are. I can't make that judgement, not knowing you, a lacking on my part you do not seem to share.

    Bob-

    --
    The Ludwig von Mises Institute. The reasoning individuals economics
    1. Re:"Payback" by Mr.+Slippery · · Score: 1
      What is the definition of "payback"?

      We're talking - or at least we were talking - about energy payoff (the myth that solar panels take more energy to create than they ever return), not cash payoff. There is no energy cost to purchase. Maybe a small one to transport and install. But that doesn't change the fact that more energy is produced then required for creation and setup.

      If you want to talk cash payoff, it's cost of purchase and installtion. But in comparing on-the-grid to a complete PV system, 1) you have to include the cost of connecting to the grid - it can be very expensive to run copper to a house, and 2) you should include the externalized costs of both options - the pollution, the consumption of irreplacable resources, the social costs of centralized energy production versus distributed sytems, etcetera.

      Taking 1) into account, my understanding is that photovoltaic will definitely pay off in cold hard cash if you're more than a certain distance from the grid - I think it's on the order of hundreds of meters. Also, for some large buildings (which can take advantage of economies of scale) with rooftop PV systems that are connected to the grid, there is a payoff in savings plus "running the meter backwards".

      --
      Tom Swiss | the infamous tms | my blog
      You cannot wash away blood with blood
    2. Re:"Payback" by Bob_Robertson · · Score: 1

      Good. I'm glad to know the technology has surpassed these solar voltaic pannels being just expensive batteries.

      I really like the idea of running the meter backwards. Too bad the electric companies tend to get unduely hostile about it...

      Bob-

      --
      The Ludwig von Mises Institute. The reasoning individuals economics
  12. And Enron's just gone bust? by Anonymous Coward · · Score: 0

    Fuel cell stories on /.; Enron goes broke - a new manifestation of the /. effect???

    - Bernard

  13. Economic payback isn't hell by Spamalamadingdong · · Score: 2
    Electricity producing silicon solar-cells actually take more energy and generate more pollution during manufacture, than they will ever generate.
    The figures I read say that the panels pay back their energy of construction in 2-4 years. Lifetime of a typical panel is at least 20 years, possibly upwards of 30 years.
    The nice thing about conversion directly to hydrogen, is that it is definetly an easier way to concentrate the energy.
    Conversion directly to hydrogen eliminates a bunch of intermediate steps. If you're making hydrogen from sunlight anyway, you might as well do it in the way which is simplest and cheapest.

    I personally think that hydrogen isn't as easily transported as e.g. aluminum metal (you won't have any NOx emissions from aluminum-air batteries, and the fuel doesn't leak either), but the popular consciousness among the ecology-minded doesn't seem to be able to grasp conservation of energy, let alone economic payback and leveraging techniques.

    --
    Scientists restrict study to entire physical universe; creationist
    1. Re:Economic payback isn't hell by global_diffusion · · Score: 1

      test post (my apologies)...

  14. Water and light in, gas mix and heat out by Spamalamadingdong · · Score: 2
    You get a mixture of hydrogen and oxygen out of such a beast. You can separate them using well-understood techniques, such as allowing the hydrogen to diffuse through palladium leaving the oxygen behind. I seem to recall that there are cells which can use an H2/O2 mix directly, but I'd be leery about having very much of such a gas mix in any one place.

    The idea which occurs to me about this is that a collector could perhaps be used to harvest part of the energy as H2/O2 and the remainder as heat. If you did this with distilled water and catalyst, and allowed the mix to heat up until you had low-pressure steam with "contaminants" (diluted with water vapor to below the flammability limit), you could harvest energy in two useful forms and make productive use of the waste heat from the catalytic decomposition process.

    --
    Scientists restrict study to entire physical universe; creationist
  15. No Ice9 (runaway environmental catastrophy) by n9hmg · · Score: 1

    This would run away for the same reason Ice9 couldn't happen - Thermodynamics. Greasing a slide won't let you slide UP, and a catalyst won't reverse entropy.

    If you dumped a ton of this catalyst into the ocean, it would be diluted into the depths where there's no sunlight to drive the reaction. If it would float and self-segregate, it would cool the surface and bring rain. It would also surely degrade over time.

    When this was brought up a few weeks ago, it was noted that the project was to be used with orbital mirrors to focus the light on the reactor vessel, anchored south of Okinawa, so it looks lke it requires high intensity, maybe even in a high-pressure water vapor environment?