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Power Hardware Science

Self-Sustaining Solar Reactor Creates Clean Hydrogen 406

Posted by samzenpus
from the power-up dept.
An anonymous reader writes "A mechanical engineer working out of the University of Delaware has come up with a way to produce hydrogen without any undesirable emissions such as carbon dioxide. The solar reactor is capable of using sunlight to increase the heat inside its cylindrical structure above 3,000 degrees Fahrenheit. Zinc oxide powder is then gravity fed through 15 hoppers into the ceramic interior where it converts to a zinc vapor. At that point the vapor is reacted with water separately, which in turn produces hydrogen. If the prototype gets through 6 weeks of testing at the Swiss Federal Institute of Technology located in Zurich, we could see it scaled up to industrial size, producing emission-free hydrogen."
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Self-Sustaining Solar Reactor Creates Clean Hydrogen

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  • by retroworks (652802) on Wednesday April 04, 2012 @06:50PM (#39579025) Homepage Journal
    Finally, a source of clean hydrogen.
    • by Fluffeh (1273756) on Wednesday April 04, 2012 @06:55PM (#39579081)

      Finally, a source of clean hydrogen.

      That is true, but isn't one of the big problems with Hydrogen storing it [wikipedia.org], not just producing it? I mean, don't get me wrong, it is excellent to see that part of this "we want to use hydrogen" problem solved, but a lot more still needs to be done.

      • by v1 (525388) on Wednesday April 04, 2012 @06:58PM (#39579131) Homepage Journal

        One reason storing it is such a big deal is because generating it can be expensive. Make hydrogen easier to produce and it lowers the demands on storage.

        • by Fluffeh (1273756) on Wednesday April 04, 2012 @07:14PM (#39579347)

          Hydrogen stored under pressure has a considerably lower energy density compared to hydrocarbons that we use. Hydrogen is great when you look at the energy by weight, but if a tank is sitting in the back of a car, it doesn't matter whether it weighs an extra twenty kilos, what matters is how far a tank can make a car drive.

          Like I said, don't get me wrong, I think it is a fantastic breakthrough to have - a cheap, clean and sustainable way to make Hydrogen gas, but a lot of work still needs to be done before we can all whizz around in clean cars and certainly before we have large scale power stations powered by burning Hydrogen.

          Having said that, burning Hydrogen makes water, this process turns water into Hydrogen. It would make for a wonderful closed circuit...

          • by icebike (68054) *

            What happened to all those storage schemes that involved Metal hydrides and all sorts of other esoteric stuff. Did any of that end up being useful?
            I saw one demonstration where they shot a cylinder with a rifle and all it did was hiss quietly.

            • by TapeCutter (624760) on Wednesday April 04, 2012 @08:21PM (#39579973) Journal
              The problem with hydrogen is that the pressures required for a cars fuel tank are such that hydrogen simply seeps through ordinary steel cylinder walls, it's like trying to fill a spagetti strained with water. I belive that about 10yrs ago BMW were the first to come up with a 'certified' hydrogen cylinder that was both practical and safe to use in a car. I'm not sure if it's the same fuel tank that Honda's H2 car uses, but either way the safe storage and energy density arguments seem to have evaporated after BMW and Honda's efforts.

              The biggest hurdle would seem to be infrastructure. It's catch 22, mass production and distribution of H2 requires a H2 market to sell to, and vica-versa. Petrol did not really have this problem, the first generation of car owners bought their fuel in cans from the local pharmacy. The car and car fueling infrastructure evolved together, by the second generation of car owners we had two new major industries led by companies such as Ford and Standard Oil.

              So here we are in the 21st century and FF transport is ubiquiotous, the no way a competing technology such as H2 will never gain a foothold with current market fources. It would have to be a cooperative effort between government and industry to deliberatly kill off FF cars, that's already happened with lightbulbs but transport is a much bigger challenge and (for some people) it beccomes as personal as a cowboy's horse.
              • by c0lo (1497653) on Wednesday April 04, 2012 @09:14PM (#39580371)

                The biggest hurdle would seem to be infrastructure. It's catch 22, mass production and distribution of H2 requires a H2 market to sell to, and vica-versa. Petrol did not really have this problem, the first generation of car owners bought their fuel in cans from the local pharmacy.

                Hell, that's an idea! Let's sell H2 canisters at pharmacies.

                (ducks)

              • H2 gas has around 1/3 the energy density of methane, the largest component of natural gas. Rather than saying "Hydrogen sucks because I can't put it my car," we should be asking, "Can we replace natural gas with hydrogen?" I use natural gas for heating, cooking, and it's increasingly used in power generation. Do we need all new pipelines, or can we use some of the existing infrastructure? I've never heard anyone complain that natural gas is too expensive for the providers to store at various places alon

          • Re: (Score:2, Insightful)

            by FatdogHaiku (978357)

            It would make for a wonderful closed circuit...

            For a closed circuit wouldn't we also end up with a pile of zinc oxide?

          • by c0lo (1497653) on Wednesday April 04, 2012 @09:13PM (#39580365)

            Hydrogen stored under pressure has a considerably lower energy density compared to hydrocarbons that we use. Hydrogen is great when you look at the energy by weight, but if a tank is sitting in the back of a car, it doesn't matter whether it weighs an extra twenty kilos, what matters is how far a tank can make a car drive.

            Well... one can always mix hydrogen with some carbon to store it, can't one now?

            (ducks)

          • by viperidaenz (2515578) on Wednesday April 04, 2012 @09:24PM (#39580449)
            Yep, according to wikipedia, petrol contains 6x more energy per litre than hydrogen compressed to 700bar (which to those Americans is over 10,000psi). It's kind of irrelevant that hydrogen contains 3x more energy per kilgram. Hydrogen is only 2-3x better than a lithium ion battery when you compare it with volume. You can't engineer better bydrogen but you can engineer better batteries.
          • by compro01 (777531)

            Hydrogen stored under pressure has a considerably lower energy density compared to hydrocarbons that we use.

            Hydrogen+CO2+energy=hydrocarbons, specifically methane (aka natural gas), and water.

            Use nuclear/hydro/solar/wind/whatever for the energy source, and you've got a closed carbon cycle fuel with only fairly minimal changes needed.

        • by Solandri (704621) on Wednesday April 04, 2012 @08:06PM (#39579857)

          One reason storing it is such a big deal is because generating it can be expensive. Make hydrogen easier to produce and it lowers the demands on storage.

          Eh? Those have nothing to do with each other. Hydrogen storage is a pain because of density and sealing. At STP, hydrogen is a very low density gas. To get decent energy density out of it, you either have to compress it to ridiculously high pressures, or chill it to ridiculously low temperatures. Di-atomic hydrogen gas molecules are about the smallest molecules that exist. They will leak through anything. A seal which is water-tight and air-tight is not necessarily hydrogen-tight. Couple this with high pressures and you have a major storage PITA.

          Unless we discover some sort of hydrogen sponge which soaks up H2 gas and easily holds it at an energy density competitive with batteries and chemicals, I really doubt the hydrogen economy will take off. OTOH if someone can tweak this process so it can convert CO2 + 2 H2O ==> CH4 + 2 O2, then we have a winner. Methane, while not as ideal for storage as a liquid hydrocarbon (most oil wells and refineries just burn it off rather than try to capture and store it), is much easier to work with than H2 gas and has nearly 4x the volumetric energy density.

          Long-term, I think alcohol biofuels will win out. Alcohol is nearly as good a storage medium as gasoline/diesel. First you use photosynthesis to create sugar: CO2 + H2O + sunlight ==> O2 + (CH2O)n. Plants are basically made of really long sugar molecules (cellulose). You then ferment the sugar to create alcohol: (CH2O)n ==> C(n)H(2n+1)OH. At some point we'll probably figure out a way to go straight from the raw ingredients (CO2 + H2O + sunlight) to alcohol, at which point you're converting solar energy straight into liquid fuel.

      • by Anonymous Coward on Wednesday April 04, 2012 @07:42PM (#39579647)

        it can be stored in vast quantities in the form of formic acid and then released and restored in a continual cycle. there is obviously efficiency losses but apparently its very practical as it allow storage of large amount of hydrogen at a very high density in a room temperature atmospheric pressure liquid,
        that is basically as safe as vinegar.

        I was thinking this clean hydrogen would be perfect in so many parts of the world where their is plenty of sunlight but the land is otherwise of low value.

        ps: its the nail polish like odor that gets released when ants die, and more specifically when they get crushed. its probably something they are sensitive to, so hopefully our green cars in the future dont get covered with ants in because of the pheromone.

      • by dbIII (701233) on Wednesday April 04, 2012 @10:26PM (#39580797)
        A lot of fertilizer (ammonium nitrate) is made from oil or natural gas purely because that's the easiest way to get hydrogen. There are a lot of other industrial uses for hydrogen which currently mean chemical plants are close to oil refineries and natural gas pipelines.
        As a fuel hydrogen gas is a pain to store and transport in comparison to butane, propane etc or a liquid fuel, but if you can make it at sane costs where you need it then you don't need to store or transport much of it.
      • by init100 (915886)

        Hydrogen has many uses that do not rely on being able to store it. For example, the Sabatier reaction [wikipedia.org] combines hydrogen with carbon dioxide in the presence of a nickel catalyst to produce methane and oxygen. And methane is the primary component of natural gas, so I'm sure that you can see why that is useful.

        Hydrogen can also be used together with carbon monoxide in the Fischer-Tropsch process [wikipedia.org] to create liquid hydrocarbons, which could be used as synthetic petroleum. In other words, another very advantageous

    • by DigiShaman (671371) on Wednesday April 04, 2012 @07:01PM (#39579165) Homepage

      But is mining for zinc just as clean? I know you have to start somewhere. Just thought I'd throw that out there for discussion sake.

      • by mingot (665080) on Wednesday April 04, 2012 @07:05PM (#39579219)

        When we (the US) get rid of the penny there will be a HUGE supply of zinc out there.

        • by Trogre (513942)

          Agreed. Any denomination less than 5c is just dead weight now. I would say 10c should be the smallest were it not for the ubiquitous quarter.

          • by amiga3D (567632)

            How about we just adjust the currency. Let's shift it one decimal point and everything that costs a dollar is now 10 cents and if you make 3000 dollars a month it's now 300 dollars. New currency can be issued and all the old money face value is now down one decimal place. Then a coke will be 6 cents at work instead of 60 and the penny is relevant again. No more trying to feed worn bills into the vending machine.

      • by reverseengineer (580922) on Wednesday April 04, 2012 @07:09PM (#39579289)
        This process looks like UT actually starts with zinc oxide which gets photolyzed to produce zinc vapor, which grabs oxygen from the water to get back to zinc oxide. This process would of course not be infinitely sustainable, and eventually the zinc oxide and ceramic surface would need to be replaced, but it has the potential for minimal use of resources.
    • by icebike (68054) * on Wednesday April 04, 2012 @07:13PM (#39579339)

      Clean in this context probably refers to not requiring fossil fuels.

      Apparently the Zink Oxide is recoverable as well:

      As well as a lack of emissions, the other good news is that the zinc oxide can apparently be reused, meaning the solar reactor is theoretically self sustaining as it only relies on materials and energy that are renewable.

      although it isn't spelled out how that is performed, or if any processing is required, and if so, at what cost.

      To heck with scaling this up. Lets scale it down so I can have one in my back yard, or at every corner gas station. A small reactors working any time there is sunlight and water scaled just large enough to keep your car topped off makes a lot more sense than trucking hydrogen around. Especially if the zink oxide recovery can be built in.

      Then maybe hydrogen cars can become a realistic option rather than the proof of concept models and conversion kits for fleet vehicles.

      • by CrimsonAvenger (580665) on Wednesday April 04, 2012 @07:25PM (#39579471)

        To heck with scaling this up. Lets scale it down so I can have one in my back yard, or at every corner gas station. A small reactors working any time there is sunlight and water scaled just large enough to keep your car topped off makes a lot more sense than trucking hydrogen around.

        It operates at ~1700C. You're not going to get sustained temps like that without large mirrors and large reactor vessels. So it's not going to scale down terribly well.

        • by icebike (68054) * on Wednesday April 04, 2012 @07:41PM (#39579637)

          Well, scaled really small, it just works slower to fill your H2 tanks.
          Photo-voltaic panels ---> Electricity--> heat small continuous flow reactor chamber (maybe no bigger than your thumb). Maybe the whole package sits beside your house in a package the size of an air conditioning compressor, while the panels are on the roof. We got a boat load of roofs in this country.

        • by mellon (7048) on Wednesday April 04, 2012 @08:45PM (#39580167) Homepage

          You can melt steel with a 10' mirror. You can't melt *much* steel, but getting high temperatures isn't a problem; the question is whether the yield is enough per square meter of mirror to be worth it, and whether it scales up to higher efficiencies as you increase the area of the mirror and the size of the reactor vessel.

    • Isn't hydrogen made from water always 'clean'? I'm not sure what the big deal is here considering that we can produce 'clean' hydrogen from electrolysis of water today...without all this zinc business.... Seems overly complicated to me...
      • by nschubach (922175) on Wednesday April 04, 2012 @07:52PM (#39579753) Journal

        Electrolysis tends to eat away at the materials causing you to have to get more. This is fairly closed loop in that the only ingredient is water and heat. Instead of mining zinc for the rectors that will run indefinitely (supposedly) you would have to continuously mine the metals used for electrodes in electrolysis. Cleaning and replacing these parts can be "dirty" where this reactor seems to eliminate that component. The only thing I think you'd have to do with this is grind the zinc back into powder. (as I assume it probably melts and coagulates?)

  • by squidflakes (905524) on Wednesday April 04, 2012 @06:53PM (#39579055) Homepage

    Great, just one more think to go wrong when pimply faced teenagers wish to live in a world without zinc.

  • by sirlark (1676276) on Wednesday April 04, 2012 @06:54PM (#39579065)
    Could it effectively be mass produced so that it could become a household item, every house having it's own hydrogen generator and turbine which can contribute to the grid? I've always thought that decentralising power production would make it greener, if only because there's less loss to long distance transmission. Either way, I'm holding thumbs for the six week trial.
    • by MachDelta (704883) on Wednesday April 04, 2012 @07:02PM (#39579187)

      It seems to me that as an energy storage medium (and that's what it is, it's not a fuel "source") Hydrogen would lose out to a plain old chemical battery when all it needs to do is sit in your basement. One of the primary pitfalls of a battery is weight and size, but that won't much matter if you just dig a deeper hole in the ground and never move it.
      Anyways, going Solar -> Hydrogen -> Electrical sounds a lot more complected (not to mention inefficient) than just Solar -> Electrical.

    • by oic0 (1864384)
      I was going to say no way... then I remembered the videos on youtube of concrete, steel, etc... being melted with a window sized fresnel lens. So... maybe.
    • by Pence128 (1389345)
      The transmission losses are trivial compared to the gains brought by economies of scale. Also, this is for generating hydrogen. Converting it to electricity at the same place or even in a non moving generator completely defeats the purpose.
  • by pushing-robot (1037830) on Wednesday April 04, 2012 @06:57PM (#39579117)

    But it's pointless to speculate about its utility without knowing how much hydrogen a given unit can produce, how much that unit costs, and how much maintenance it will need.

    And the four giant robot arms the operator wears don't fill me with confidence.

  • by sehlat (180760) on Wednesday April 04, 2012 @06:59PM (#39579137)

    But if you burn hydrogen, it creates dihydrogen monoxide, a known greenhouse gas!

    This is terrible!

  • by jiteo (964572) on Wednesday April 04, 2012 @07:02PM (#39579193)
    How do you produce the zinc oxide powder? How do you produce the cylindrical structure? Not trolling, genuinly asking. If someone with more metallurgical knowledge than me tells me zinc oxide is common and easy to mine, I'll believe it. But it's a question we must ask.
    • by gbjbaanb (229885)

      plenty of zinc in the world....aren't US pennies made of the stuff?

      Anyway, from TFA:

      As well as a lack of emissions, the other good news is that the zinc oxide can apparently be reused, meaning the solar reactor is theoretically self sustaining as it only relies on materials and energy that are renewable.

    • by DRJlaw (946416) on Wednesday April 04, 2012 @07:28PM (#39579513)

      How do you produce the zinc oxide powder?

      You burn zinc metal. Really. The zinc oxide and tower are not the interesting part. That is simply an alternative method of smelting a source of zinc to obtain zinc metal.

      The deeper linked articles say "the hoppers will feed zinc oxide powder (a benign substance resembling baking soda) onto the ceramic layer, causing a reaction that decomposes the powder into pure zinc vapor. In a subsequent step, the zinc will be reacted with water to produce solar hydrogen."

      Ok.

      Zn(s) + 2H+ -> Zn2+(aq) + H2(g)

      but

      Zn2+ + 2OH- -> Zn(OH)2(s)

      So the water that's left over will contain a zinc hydroxide particulate (or sludge).

      The zinc hydroxide is an emission. Might be better than a gaseous emission, but it's still a waste product. If this system is truely closed with respect to zinc, then the zinc hydroxide has to be converted into zinc oxide or somehow directly smelted back into zinc vapor. That's the missing element from the article in my opinion.

      Other questions: how fast is the aquoeous reaction (toss zinc in a glass of water -- it's slow at standard temperature and pressure); what is the equilibrium pressue of H2 above the liquid (if it's a low partial pressure, then you need to both maintain a vacuum over the liquid and compress the drawn-off gas); what is the net energy output of H2 versus the input of heat (assuming that you close the system with respect to zinc by drying and converting the sludge back to zinc metal).

      • by DRJlaw (946416) on Wednesday April 04, 2012 @07:53PM (#39579755)

        If this system is truely closed with respect to zinc, then the zinc hydroxide has to be converted into zinc oxide or somehow directly smelted back into zinc vapor. That's the missing element from the article in my opinion.

        Just to be clear, chemically this is not hard:

        Zn(OH)2 -> ZnO + H2O at about 800 C (this is a calcination reaction)

        It's a materials handling issue. Dewatering a sludge, drying a dewatered sludge, and, if necessary, calcining the zinc hydroxide separately from forming the zinc metal, all involve some technically complicated additional steps.

  • I can't find out what the reaction products are from this device. So water and ZnO goes in. What happens to the oxygen that was tied up with the hydrogen in the water?
    • Seems to be the thermal decomposition on ZnO
      Zinc Oxide --> Zinc + Oxygen

      Followed by the reduction of water:
      Zinc + Water --> Zinc Oxide + Hydrogen

      If the Zinc Oxide is reusable that's pretty decent, but I wonder how it compares energy wise to other methods of water separation.

  • Is it any easier to transport hydrogen from where the sun shines to where it's needed as fuel as compared to electricity? It seems that the energy needed for compression and leakage from storage tanks, fittings, and transmission lines would result in significant energy losses. Plus a 200 mile hydrogen pipeline from the sunny desert to a populated area seems prohibitively more expensive than a power line.

    Is this hydrogen plant really any better than just creating electricity? Granted, electricity can be hard

  • How much energy and other resources will be required to first mine all that zinc and then create the oxide to use in this device? What other costs of the process are being omitted here?

  • by ThorGod (456163) on Wednesday April 04, 2012 @07:06PM (#39579237) Journal

    I'm not an engineer, so get out your salt-lick before reading...but, they've developed a "proof of concept" device. I don't know if it's even appropriate to discuss "practical" uses of this device, yet. It's possibly a very expensive way to produce hydrogen and may not be meant to see much light of day outside academic circles.

    One interesting feature of the reactor is that, in theory, the zinc oxide byproduct created during the reaction will be re-usable, making the project self-sustaining.

    “This is probably the most complex device built by a graduate student in the history of our department,” added Prasad. “If he is successful, one day, we can imagine a huge array of mirrors out in the desert concentrating sunlight up into a large central tower containing a larger version of Erik’s reactor and making hydrogen on an industrial scale.”

    So there's "hope", but is currently experimental:

    We [they] will measure the temperature and the production of oxygen inside the reactor in real time, which will tell us how much solar fuel or zinc we are actually producing,” Koepf explained.

    All of the above from TFA.

  • by l0ungeb0y (442022) on Wednesday April 04, 2012 @07:11PM (#39579309) Homepage Journal

    We here at the Clean Alternative Fuels Committee see this as just too dangerous to allow and plead to the US Government to outlaw this potentially dangerous technology. We simply can not trust the public with the ability to produce Hydrogen which could lead to the creation of Mini-H bombs. We propose the advancement of existing Hybrid technology as the clean energy alternative for a successful future and is wholeheartedly endorsed by our Charter Members: Chevron, Exxon-Mobile and Shell.

  • What is the chemical result when hydrogen is burned? Water vapor.

    What is the atmospheric component that is the predominant contributor to the greenhouse effect? Water vapor.

    So lemme get this straight: all these disciples of the so-called hydrogen economy want us to burn hydrogen in energy-equivalent amounts as the fossil fuels we use now, thus putting more of the worst greenhouse gas of all directly into the atmosphere? Sure, some of it will change phase and precipitate back into oceans and lakes and riv

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