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Power Science

Solar Panel Splits Water To Produce Hydrogen (ieee.org) 96

Posted by BeauHD from the green-tech dept.
schwit1 shares a report from IEEE Spectrum: A team at Katholieke Universiteit Leuven, or KU Leuven, says it has developed a solar panel that converts sunlight directly into hydrogen using moisture in the air. The prototype takes the water vapor and splits it into hydrogen and oxygen molecules. If it scales successfully, the technology could help address a major challenge facing the hydrogen economy. A small but growing number of facilities are producing "green" hydrogen using electrolysis, which splits water molecules using electricity -- ideally from renewable sources such as wind and solar. Other researchers, including the team in Belgium, are developing what's called direct solar water-splitting technologies. These use chemical and biological components to split water directly on the solar panel, forgoing the need for large, expensive electrolysis plants.

KU Leuven sits on a grassy campus in Flanders, the Dutch-speaking northern region of Belgium. Earlier this month, professor Johan Martens and his team at the Center for Surface Chemistry and Catalysis announced their prototype could produce 250 liters of hydrogen per day on average over a full year, which they claim is a world record. A family living in a well-insulated Belgian house could use about 20 of these panels to meet their power and heating needs during an entire year, they predict. The solar panel measures 1.65 meters long -- roughly the height of a kitchen refrigerator, or this reporter -- and has a rated power output of about 210 watts. The system can convert 15 percent of the solar energy it receives into hydrogen, the team says. That's a significant leap from 0.1 percent efficiency they first achieved 10 years ago.
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Solar Panel Splits Water To Produce Hydrogen More

Solar Panel Splits Water To Produce Hydrogen

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  • Nice Wording (Score:2, Interesting)

    by mentil ( 1748130 )

    a solar panel that converts sunlight directly into hydrogen using moisture in the air

    I didn't realize hydrogen was made out of sunlight. Perhaps the writer meant "converts moisture in the air directly into hydrogen using sunlight"? Although I still wonder what happens to that oxygen, I guess it goes poof, or transmutes into hydrogen.

    • Also, it looked to me like the cart was following the horse as there isnt much of a hydrogen economy for challenges to manifest within.

      • Re: Nice Wording (Score:2, Informative)

        by Anonymous Coward

        Huh?
        Hydrogen can be used to generate electricity. So it can be used for storing solar energy and then used during the nights.
        Also some cars and busses are using hydrogen as their power source.

        • True. But, at a 15% lab efficiency level, it is much less efficient at producing hydrogen than current solar to electric technologies. Furthermore, the compression/storage/fuel cell/inverter storage system required to utilize the hydrogen is far less efficient and more expensive than the charger/battery/inverter based storage system required to utilize the output of solar electric cells.

          Higher efficiencies can be achieved with fuel cells if you also collect and use the waste heat, but that requires even mor

          • Re: (Score:2)

            by tsa ( 15680 )

            And of course this new technology which isn’t even out of the lab stage yet can’t be improved anymore?
            Why are there always people who dismiss new developments on the spot because they don’t suit their personal needs?

          • Babies are useless, why do we have them?

      • Hydrogen fuel cells already exist. If this technology is effective and becomes common place you’ll see a larger amount of usage and the hydrogen economy will expand. Make something cheap and plentiful and it will become popular in the marketplace.

    • Re: (Score:2)

      by gtall ( 79522 )

      Don't be daft, anyone with a high school education realizes it means convert moisture in the air to hydrogen and oxygen.

      • A great deal of my time is spent converting such misquotes and mis-statements into what the person must have really meant. It can be very difficult when the order or the technical specifications are re-interpreted by 3 or more managers, each of whom demands that it be summed up in a way _they_ can understand and pass along. It becomes especially difficult when the original request is for something opposite or non-standard, and the intervening managers transform the request into something they themselves exp

    • It was the "Hydrogen gas is an energy vector that can easily be stored and transported" bit that annoys me. No it is not.

    • "I didn't realize hydrogen was made out of sunlight."

      You got it backwards, sunlight is made of hydrogen.

  • Not bad, but... (Score:3)

    by JaredOfEuropa ( 526365 ) on Saturday March 16, 2019 @05:24AM (#58282898) Journal
    The average Northern European home can't fit 20 of these panels on its roof. Unlike PV solar panels, these things have an added benefit: the hydrogen can be stored for later use without the need for expensive batteries... but you will likely need to compress the hydrogen which requires a fair bit of energy. Do they foresee these panels being used in residential installations, or are they more suited for solar farms?

    Regardless, it's an interesting development. Good advances in hydrogen storage and transport have been made, and there's already a few hydrogen cars on our roads, but the production of green hydrogen (i.e. not produced from natural gas) has been expensive and troublesome thus far. Though the secrecy surrounding this project is generally a red flag for inflated expectations.

    • Re:Not bad, but... (Score:4, Interesting)

      by ZombieEngineer ( 738752 ) on Saturday March 16, 2019 @07:03AM (#58283042)

      Probably easier to use classic PV panels and a separate electrolysis cell.

      There are electrolysis cells that can directly provide 120-200 bar hydrogen without an additional compressor.
      https://en.wikipedia.org/wiki/... [wikipedia.org]

      • The problem with making steam or splitting water is the minerals and gunk in the water eventually foul the solar panels. This is why, fo example, a recent innovation in non-contact low emissivity steam generators is a big deal. It's not that they improved the low emissivity desgin it's that they came up with a way to heat the water radiatively without it touching the expensive and hot parts.

        Second if you are going to use electrcity to split water then, since solar panel electricity generation is ineffieine

        • The problem with making steam or splitting water is the minerals and gunk in the water eventually foul the solar panels.

          This problem is simply solved by using solar water distillers. However, that requires more space. The whole idea of trying to make all-in-one solar panels which produce water is dumb. Some things are best centralized, and water is one of them. Power is best served with a mix of centralized and decentralized resources.

      • 200 BAR = 2900 PSI.

        That's handy to know about though.

        Most of the cars on the road run at 5000 PSI (344 BAR). The Mirai is an exception at 10000 PSI. The Nicola One truck deliberately avoided 10000.

        • All FC "current" cars are 700 bar (~10,000 psi). Busses are often 350 bar, but are moving to 700 bar. Trucks from Nicola were announced at 350 bar, but may actually ship at 700 bar. Nicola are committed to 700 bar fueling stations regardless. The first Kenworth prototype was 350 bar, but the new projects with Toyota are 700 bar. The Toyota prototypes in Long Beach are all 700 bar.

          Bottom line is that 700 bar is getting easier to do. If you store "cryo" as liquid H2, then compressing to 700 bar can be d

      • Probably easier to use classic PV panels and a separate electrolysis cell.

        Especially in dry areas, because you could use wastewater as an input. The output would be more concentrated wastewater. In sunny humid places (FL, HI) you could use the direct process described in the article, and it would work better than in the rainy Netherlands.

  • A month ago the Belgian media suddenly started churning out news bouts how hydrogen "could save us" (see bible for other stories).
    I will not deny that hydrogen has a good potential for storing energy - although at very low efficiency.
    The only thing I like about this fairy tale is that the professors in the old lab where I once was a technician, and where I found my wife, finally started working together.
    20 panels of 1.65m to provide energy for one house and a little hydrogen storage somewhere against cos

  • What happened to Mars. (Score:4, Interesting)

    by orlanz ( 882574 ) on Saturday March 16, 2019 @05:36AM (#58282922)

    This is what the Martians did. They became a full hydrogen economy. They converted a lot of their planet's water into hydrogen and it escaped into space! They didn't have enough fresh water left to sustain their economies. The resulting wars left lots of craters.

    And their atmosphere got so thin without moisture that it was blown away by the solar winds. Over thousands of years, the solar radiation and planetary dust storms degraded everything and turned it all to dust.

    • Or, with so much hydrogen around, someone lit a match.

    • This is what the Martians did. They became a full hydrogen economy. They converted a lot of their planet's water into hydrogen and it escaped into space! They didn't have enough fresh water left to sustain their economies. The resulting wars left lots of craters.

      And their atmosphere got so thin without moisture that it was blown away by the solar winds. Over thousands of years, the solar radiation and planetary dust storms degraded everything and turned it all to dust.

      Careful, you might start a new Woo-Woo trend like Flat Earthers, Global Warming Denialists, Moon Hoaxers, and Creationists -- all people who prefer beliefs over reality.

      The Warming Denialists and Creationists, are probably the most well organised and dangerous.

  • The solar panel measures 1.65 meters long -- roughly the height of a kitchen refrigerator, or this reporter -- and has a rated power output of about 210 watts. The system can convert 15 percent of the solar energy it receives into hydrogen, the team says.

    So decomposing 1 liter of water (1 kg) into elemental H2 and O2 requires -(-237.14 kJ/mole) * (1000 g/kg) / (18.015 g/mole) = 13163 kJ/kg = 13.163 MJ/kg.

    • 210 Watts peak * 15%

    • Re:Large expensive electrolysis plant still prefer (Score:4, Informative)

      by JaredOfEuropa ( 526365 ) on Saturday March 16, 2019 @05:52AM (#58282942) Journal

      210 Watts peak * 15% efficiency

      WP already includes the efficiency figure, it's the maximum power put out by the panel under ideal conditions. At peak production, 210 W will go into hydrogen production.

      • 210 Watts peak * 15% efficiency

        WP already includes the efficiency figure, it's the maximum power put out by the panel under ideal conditions. At peak production, 210 W will go into hydrogen production.

        Actually the GP read it right I think. I agree the wording in the article is not perfectly clear so your reading might be right also but to me it seems to say that the panel uses it's 210 watts and with that the conversion effeicieny to hydrogen is 15%. I base this reading on the next sentence that says the conversion used to be less than 1%. Any solar panel would be more than 1% efficient in making power, ergo this must be referring to the conversion to hydrogen bond breaking not the solar panels energy

        • That makes no sense. The panel doesn't produce 210W of electricity to use for hydrogen conversion (the rest going dissipating as heat?), it's 210W worth of direct hydrogen conversion. 210W is 15% of all the sunlight hitting it, as the article states. Slightly less efficient than a PV panel, which usually have a similar listed peak power of 200-300W at a somewhat smaller panel size.
      • Typical comercial PV panels are rated at about 125-165 Watts/m^2. So panels 1.66 x 1 meters yielding 210 Watts would correspond with 125 W/m^2 panels.

        If the 210 Watts were after the 15% efficiency of electrolysis, then your panel would be producing 210W/0.15 = 1400 Watts. That exceeds the amount of solar energy the sun puts out. The solar constant [wikipedia.org] (total energy of sunlight reaching the Earth) is only 1362 W/m^2. And that's out in space. The Earth's atmosphere absorbs roughly half that, leaving about
        • The article states: "The system can convert 15% of the solar energy it receives into hydrogen". Not 15% of the solar energy it converted into electricity which it does not do, it uses "direct solar water-splitting", whatever that means. There's no intermediate step with an efficiency of 15%, that figure is for received solar power to hydrogen, for an equivalent of around 210WP. Just think: if the actual output was 15% of 210WP, then 20 of these panels would be nowhere near enough to power and heat a home

    • Depending on the form of the vapor it may have a lower free energy to release the gas than a full liquid

    • 210 Watts peak * 15% efficiency = 31.5 Watts going into decomposing water at peak production.

      re-read the article. 210W *is* peak efficiency -- it's 15% of the average daily insolation, as the article plainly states. The article's numbers add up, and yours do not.

      Absent this error, your argument for a large centralized processing plant collapses. It's almost as if you deliberately misread the article because you have some vested interest in preserving the current centralized power infrastructure. I have to ask: are you now, or have you ever received funding from any Koch-backed source?

      I'll bet the a

  • Currently, from an energy ROI POV, hydrogen as a fuel is just about useless; it can either be produced from fossil fuels, which is exactly what we do not want, or we can make it through electrolysis, but this approach is wildly inefficient compared to just using the electricity directly, like we do now.

    Just about the only chance to make hydrogen as a fuel worthwhile (compared to electricity production) is if we can use availably energy _directly_ for electrolysis or thermal decomposition in a way that's more efficient than making electricity. Since PV panels are wildly inefficient (albeit significantly more efficient than photosynthesis), a solution like this might turn out to be a game changer, making a hydrogen economy feasible instead of a subsidy-fueled wildly inefficient pipe-dream.

    Also, for production of rocket fuel on other planets or the moon, this thing might be turn out to be big.

    • I see it as interesting byproduct of excess renewable generation capacity -- when you can make the power, but have no other useful work to do with it. At that point it's free energy.

      I also think it's kind of forward thinking, as I expect that as green energy sources proliferate there will be more surplus generation periods available. Plus some wind or solar farms may wind up become essentially surplus but before their useful generation life is passed. Putting them to work generating hydrogen seems like a

      • Re: (Score:2)

        by zmooc ( 33175 )

        Due to the inefficient conversion, using hydrogen as storage is not too good idea. We have plenty of great energy storage solutions in use now, all of which are better than storing hydrogen. Pumped hydro and compressed air are used at very large scales and are significantly more efficient than converting electricity into hydrogen.

        I repeat: hydrogen is a waste of energy and money UNLESS you can produce it directly from available energy in the environment more efficiently than you can use that energy to produ

        • Due to the inefficient conversion, using hydrogen as storage is not too good idea. We have plenty of great energy storage solutions in use now, all of which are better than storing hydrogen. Pumped hydro and compressed air are used at very large scales and are significantly more efficient than converting electricity into hydrogen.

          I repeat: hydrogen is a waste of energy and money UNLESS you can produce it directly from available energy in the environment more efficiently than you can use that energy to produce electricity or other directly and efficiently applicable forms of energy. The technology this article is about is a first in that.

          If we use upper end efficiency numbers for everything (to make comparisons fair) electrolysis is 80% efficient, fuel cell conversion back into electricity is 60% efficient (net 48%), compressed air storage is 70% efficient, and battery storage is 90% efficient. This system fixing solar energy as hydrogen at 15% efficiency is equivalent to electrolysis with a 19% efficient cell (this is higher than the market average of 17% but less than the top at 22%).

          But efficiency at fixing and storing free energy (the f

    • Just about the only chance to make hydrogen as a fuel worthwhile (compared to electricity production) is if we can use availably energy _directly_ for electrolysis or thermal decomposition in a way that's more efficient than making electricity. Since PV panels are wildly inefficient (albeit significantly more efficient than photosynthesis), a solution like this might turn out to be a game changer, making a hydrogen economy feasible instead of a subsidy-fueled wildly inefficient pipe-dream.

      Thermal decomposition [wikipedia.org] is how this would work, unless electricity becomes so cheap (or Hydrogen valuable) that the economics of electrolysis work.

      The heat might come from very high temperature steam from gas-cooled high temperature nuclear reactors. This high temperature steam could potentially have a lot of industrial applications eventually, replacing natural gas powered process heat and reducing CO2 emission and methane leaks.

      As a added bonus, higher temperatures mean higher thermodynamic efficiency, re

    • Currently, from an energy ROI POV, hydrogen as a fuel is just about useless

      If you leave out existing fuel cell powered systems, like the Mirai, that is. But then everything is just about useless if you leave out everything that uses it.

      ... but this approach is wildly inefficient compared to just using the electricity directly, like we do now.

      What size is that unit "wildly"? The stated system has reached 15% efficiency is capturing energy as hydrogen. Hydrogen fuel cells can reach 60% efficiency, so the overall efficiency of this is 9%. Current solar panels that have an efficiency of 15-17%, the top end is 22%. "Wildly" seems to be a factor ranging from 66% to 240%.

      Since PV panels are wildly inefficient (albeit significantly more efficient than photosynthesis)

      There's that unit "wil

    • a solution like this might turn out to be a game changer, making a hydrogen economy feasible instead of a subsidy-fueled wildly inefficient pipe-dream.

      This would need to scale several orders of magnitude to ever be considered part of the "hydrogen economy". A typical average sized steam methane reformer + shift reactor produces 90,000 Nm^3/h. At the moment this is to the hydrogen economy what solar power was to the electricity market back in the early 90s, nothing more than a novel experiment.

  • If... (Score:2)

    by DrXym ( 126579 )

    If it scales successfully, the technology could help address a major challenge facing the hydrogen economy.

    Narrator: It didn't scale successfully. I'm not surprised to see Toyota's name mentioned in the piece either. They've been flogging the hydrogen dead horse for years rather than developing their own EVs.

  • Consumables? (Score:5, Interesting)

    by Dan East ( 318230 ) on Saturday March 16, 2019 @06:58AM (#58283026) Journal

    The panel uses

    catalysts, membranes, and adsorbents

    Those sound a lot like consumables to me. That's the question with any "breakthrough" of this sort is just how much stuff does it consume and how much does that stuff end up costing (in energy, carbon emissions and pollution as well as monetarily).

    Solar panels are pretty dang amazing as they are static and essentially last forever (or at least for multiple decades), unlike pretty much every other form of energy generation we know of. So by associating the hydrogen generation with solar panels they are asserting that kind of longevity and hands-off operation.

    • The adsorbents are usually zeolites. They are reusable forever and ever amen. Membranes could last a very long time if not contaminated. But catalysts...

      • A catalyst by definition is not used in the reaction. It will only be deactivated through contamination or poisoning.

        • A catalyst by definition is not used in the reaction. It will only be deactivated through contamination or poisoning.

          That was my point. That's the expensive part that tends to get messed up here. Avoiding that generally requires a distillation phase. It can be done with direct solar, but that requires more space.

    • They don't need to be at all. Actually the very definition of catalyst means it's not consumable in the reaction itself.

      All classic ways of producing hydrogen need all of the above and in the classic ways (Partial Oxidation + shift, or Steam Methane Reforming) the catalysts don't deactivate unless you poison them (hence a SMR has a sulfide removal stage in its feed). The same goes for the adsorbents, while they are there to collect the impurities a typical design includes regeneration to drop those impuriti

  • Hydrogen and oxygen are together the most powerful non-nuclear explosive known. Lets get that into every house, huh?
    • Not to mention that the exhaust even when just used as a fuel has caused countless of deaths. Not to mention it is also a potent global warming gas. I thought the goal was to get away from such fuels?
  • Even scheme that I've seen that involves getting water from air always falls apart when you look at the energy cost to change water vapor to liquid. Why not start with a few liters of already liquid gray water to split?

    • Even scheme that I've seen that involves getting water from air always falls apart when you look at the energy cost to change water vapor to liquid. Why not start with a few liters of already liquid gray water to split?

      Because you'd probably have to distill the gray water anyway to prevent gumming up the system.

    • Re: (Score:2)

      by tsa ( 15680 )

      Because you don’t need liquid water here. The water adsorbs directly from the aitr onto the panel and is then converted into H2 and O2.

  • Please get this out there. There is a number of studies that demonstrate that H2 is bad, very bad, for the Ozone layer. The problem is that H2 is light, very light and it is subject to atmospheric escape (https://en.wikipedia.org/wiki/Atmospheric_escape). On its way up and out it will pass through the Ozone layer where H2 is highly reactive to O3. The result is H2 + O3 > H2O +O2. So you end up with either water or hydrogen peroxide in the ozone layer. That is bad for 2 reasons. 1) it causes stratospheric
  • I wonder how the build cost per square meter compares to PV panels. I saw an article a while back telling about people at Sandia inventing a way to use solar to directly split hydrogen from water. It involved making a parabolic reflector and having a small amount of catalyst at the focus. I remember thinking at the time that reflector seems much less expensive per square meter to build than does PV panel, so even if it's a less efficient use of sunlight, if you've got the space and the build is cheap, it ma
  • "Flanders, the Dutch-speaking northern region of Belgium"

    No, not really. Would you refer to Holland as the Flemish-speaking country north of Belgium? Well then!

    The difference is a bit more than the difference between Oxford English and broad Glaswegian.

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