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Science Technology

Crystalline Nets Harvest Water From Desert Air, Turn CO2 Into Liquid Fuel (sciencemag.org) 151

Omar Yaghi, a chemist at the University of California, Berkeley, reported that he and his colleagues have created a solar-powered device that uses porous crystalline material, known as a metal-organic framework (MOF), to suck water vapor and carbon dioxide (CO2) out of the air and then release it as liquid water. Science Magazine reports: One recent market report predicted that sales of MOFs for applications including storing and detecting gases will balloon to $410 million annually over the next 5 years, up from $70 million this year. "Ten years ago, MOFs showed promise for a lot of applications," says Omar Farha, a MOF chemist at Northwestern University in Evanston, Illinois. "Now, that promise has become a reality." One application is Yaghi's, which he hopes will help provide drinking water for the estimated one-third of the world's population living in water-stressed regions. Yaghi and his colleagues first developed a zirconium-based MOF in 2014 that could harvest and release water. But at $160 per kilogram, zirconium is too expensive for bulk use. So, last year, his team came up with an alternative called MOF-303, based on aluminum, which costs just $3 per kilogram. In the desert of Arizona, Yaghi and his team placed their MOF in a small, clear plastic container. They kept it open to the air at night, allowing the MOF to absorb water vapor. They then closed the container and exposed the MOF to sunlight, which drove liquid water from it -- but the harvest was only about 0.2 liters per kilogram of MOF per day.

At last week's meeting of the American Chemical Society and in the 27 August issue of ACS Central Science, Yaghi reported that his team has devised a new and far more productive water harvester. By exploiting MOF-303's ability to fill and empty its pores in just minutes, the team can make the new device complete dozens of cycles daily. Supported by a solar panel to power a fan and heater, which speed the cycles, the device produces up to 1.3 liters of water per kilogram of MOF per day from desert air. Yaghi expects further improvements to boost that number to 8 to 10 liters per day. Last year, he formed a company called Water Harvesting that this fall plans to release a microwave-size device able to provide up to 8 liters per day. The company promises a scaled-up version next year that will produce 22,500 liters per day, enough to supply a small village. "We're making water mobile," Yaghi says. "It's like taking a wired phone and making a wireless phone."

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Crystalline Nets Harvest Water From Desert Air, Turn CO2 Into Liquid Fuel

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  • You can't fool thermodynamics. Where's the energy inputs?

    • by Ungrounded Lightning ( 62228 ) on Wednesday September 04, 2019 @10:23PM (#59160200) Journal

      You can't fool thermodynamics. Where's the energy inputs?

      Applying heat or pump-driven air pressure changes to drive the captured and concentrated water out of the MOF that grabbed and is holding on to it.

    • by Jeremi ( 14640 )

      You can't fool thermodynamics. Where's the energy inputs?

      Have you tried reading the article? Here's a key sentence for you: "Supported by a solar panel to power a fan and heater [...]"

      • by Cyberax ( 705495 )
        The thing is, it's going to be energetically cheaper to run a simple air conditioner with evaporator below the dew point and then gather the condensation.
        • Holy Dunning Krugers Batman!
          • by Cyberax ( 705495 )
            Uhm, whut? It's basic thermodynamics. If you want to get water out of air then you need to somehow absorb the energy equal to the latent heat of evaporation of the condensed water. The theoretically most efficient way to do it is to use a perfect reverse Carnot-cycle freezer. The best approximation is a regular freezer.
            • It's a molecular trap.
              Basically a solar panel for condensation. Instead of producing electricity it sucks up water from air when exposed to sunlight.
              It works even without an active energy source, only not as efficiently as when it gets drained of captured water.
              Energy needed is provided by the Sun.

              That's why the same technology can be adapted to any gas.
              So it can be made to capture water vapor with an "aluminum-based metal-organic framework" - or with a "lanthanum-based framework" it can break down mustard

              • trap or no trap you still have to pay the free energy cost. either at the time of manufacture or during operation. While it's possible to use more energy that required, the lower bound is the same for all methods. it makes no difference if it's a trap or a chiller.

              • by Cyberax ( 705495 )
                So think about it. You have a trap that is full of water. How do you drive it out? Easy, you need to heat it up. So you do it and get a hot water vapor (in the atmosphere) as a result. But the amount of energy for heating will be more than the latent heat of evaporation of water, otherwise water molecules wouldn't have bonded with the MOF crystals in the first place (as it's more energetically favorable to stay in the free air).
            • I'll tell you what ... learn how to spell the word "what" before tackling issues that require an advanced education, and you'll be fine. The trick is to realize you are uneducated. Until you do it won't occur to you that you need one.
            • And the MOF is more or less like that ...

              If you want to get water out of air then you need to somehow absorb the energy equal to the latent heat of evaporation of the condensed water.
              While that is correct, it has nothing to do with thermodynamics. It is the first law of physics: conservation of energy. (However I'm still of the opinion that the first law should be 'conservation of momentum').

              Thermodynamics does not really work in an "open system" like earth atmosphere ... but well, you can try to fool aroun

              • by Cyberax ( 705495 )
                The first law of thermodynamics is a reformulation of the energy conservation law. And in this case the openness of the Earth's atmosphere basically gives you an infinite (for practical purposes) heat sink, but in this case it won't provide you any benefits.
        • Nope,
          it is about XXX times more expensive. E.g. you need electricity for it ... and how do you actually cool something in a desert below dew point ... sounds pretty hard.
          No idea why people on /. dismiss solution A which was crafted because solution B is so expensive as: well, B is cheaper than A ... why would anyone make an article/research project/product when your solution in the end is easier/cheaper? Does that make sense to you?

          • by Cyberax ( 705495 )
            You can have purely heat-driven absorption coolers. They are less efficient than compressor coolers but don't need electricity (or very little of it to run a small low-pressure pump).

            and how do you actually cool something in a desert below dew point ... sounds pretty hard.

            A regular air conditioner can do this just fine. And you're missing the point, this crystalline thingie will require even _more_ energy than a freezer. The laws or thermodynamics are cruel.

            No idea why people on /. dismiss solution A which was crafted because solution B is so expensive as: well, B is cheaper than A ... why would anyone make an article/research project/product when your solution in the end is easier/cheaper?

            For grant money, PR reasons, etc.

        • The thing is, it's going to be energetically cheaper to run a simple air conditioner with evaporator below the dew point and then gather the condensation.

          Economic viability makes or breaks most inventions. Reading the wikipedia article on MOF, [wikipedia.org] they basically act as catalysts. If that's the mechanism here, it should be more economical than a current condensing technology.

          • by Cyberax ( 705495 )
            Arrrrgh.... You can NOT "catalyze" condensation. Catalysts work by lowering down activation energy barrier and in this case there's no barrier.
    • You can't fool thermodynamics. Where's the energy inputs?

      The big yellow thing in the sky that emits 385 yottawatts.

    • by jbengt ( 874751 )

      Where's the energy inputs?

      The original one captures water at night, releasing heat. Then the energy of the sun is used in the day to drive the water out of the MOF and into the container. That wasn't very efficient, so now they're making one that uses heating and fans (solar powered) to cycle between the energy states faster.
      You didn't even have to RTFA, you could just RTFS to get that information.

      • Perhaps next time I have to hire one,
        I just ask him: explain me the terms RTFM, RTFA, and RTFS.
        Should I take him if he gets 2 of it right? Or should RTFM be a minimum requirement?

  • Another magical dehumidifier. How many times do these things have to be debunked?

    • Yep, but if the ability to do it at a cheaper cost, then it's a cheap dehumidifier.

      • by Chas ( 5144 )

        The thing is, you're not supposed to be drinking the water from a dehumidifier.
        It's full of all sorts of particulates from the air and is generally not safe to drink.

        Also, hasn't it already been proven that you can't harvest humidity if there IS NO HUMIDITY?

        • by Ungrounded Lightning ( 62228 ) on Wednesday September 04, 2019 @10:39PM (#59160240) Journal

          The thing is, you're not supposed to be drinking the water from a dehumidifier. It's full of all sorts of particulates from the air and is generally not safe to drink.

          Which is why you use a filter that only lets the water through. (Or in this case, a molecular-scale "filter" that has holes that a water molecule will find cuddly and a particle won't even fit.)

          Also, hasn't it already been proven that you can't harvest humidity if there IS NO HUMIDITY?

          Ain't no such thing, at least in the wild troposphere. There's low humidity, and lower humidity, and seriously parched. But there's still some water molecules banging around to be grabbed (making the exhaust air still MORE parched, but so what?)

          Air circulates all around the planet. It gets wet when it passes over water. Oversimplified: It gets dry when it goes over cold mountains or up in high clouds, cooling and thinning out until it can't hold as much water. But that stops when it still has as much left as the thin cold air will hold. So it's at 100% relative humidity - not zero - when it quits drying. Then it comes down, compresses, and heats up. So it could hold a lot more water. But the water in it didn't go away. The relative humidity may be down in single-digit percentages, but again there's still water to be grabbed by a fancy MOF.

          (Correcting the oversimplification: If there are ice crystals, some of the water may prefer to hang out on them - just like it does on MOFs. So the cold thin air actually gets a bit drier than 100% relative humidity for that particular temperature and pressure. But still it's far from totally dried out.)
          (T

          • Ain't no such thing, at least in the wild troposphere.

            Also, umm... Desalination.
            And a very passive and automated kind to boot.
            It's basically a combination of two kinds of solar cells, a ventilator and a water tank for capturing water.
            Just put the whole thing on a tower near the seashore.

            • by Chas ( 5144 )

              At which point it's, more energy efficient, and cheaper to just treat the water normally.

              • Comment removed based on user account deletion
                • by Chas ( 5144 )

                  It might be cheaper than drilling a well, and wells get expensive!

                  Might. So, in lack of certain knowledge, let's rely on pie in the sky!

              • Depends on the cost of the MOF.

                Treating water has running costs as in energy.

                • by Chas ( 5144 )

                  Depends on the cost of the MOF.

                  Treating water has running costs as in energy.

                  As I said earlier, in lack of actual knowledge, we substitute pie in the sky.

                  Also, this technology has an energy cost as well.

          • by Chas ( 5144 )

            "Which is why you use a filter that only lets the water through."

            You misunderstand. The entire apparatus itself IS NOT AIRTIGHT. Hence, you're going to have particulate matter on pretty much every surface, inside and out.

            "Ain't no such thing in the wild troposphere."

            Should have been more accurate.

            No appreciable humidity.

            Watch and learn.

            https://youtu.be/LVsqIjAeeXw?t... [youtu.be]

            "Oversimplified: It gets dry when it goes over cold mountains or up in high clouds, cooling and thinning out until it can't hold as much wa

            • And they're talking about putting this stuff up IN A DESERT. One of the most arid regions on the planet.
              Even a desert has humidity. Which parent actually tried to explain to you quite well.

              I really wonder where this "nerdy" attitude (oops, not so nerdy) comes from that when "geeks" announce a new scientific gadget and newspaper predict a multi billion dollar annual market, that those "nerds" think: they know better. Sorry, first assumption should be: oops, what did I miss in school, what did I know wrong, o

              • by Chas ( 5144 )

                Yes, watch the video that I linked about the energy costs of pulling water out of low humidity air.

                This "attitude" comes from being able to do the math.

                And Frank Herbert's Dune series was SCIENCE FICTION.

                You had an entire civilization basically pulping it's dead for the bodily water and relying on PLANETARY SCALE windtrap networks.

                No specifics on ACTUAL humidity on a planet that happened to actually have a polar ice cap.
                Nor any sci-fi-tech used to implement and assist.

    • The problem with your idiotic rambling is that this one has been "bunked", not debunked.
      • The Laws of Thermodynamics are what one might call Settled Science. Using solar energy to pull water out of the air in the desert is neither economical nor efficient. That part has been proven over and over every time one of these schemes goes on Kickstarter. It's cheaper (and greener) to drive an 18-wheeler across the globe to deliver bottled water to those people than to try pulling it out of the air with a solar dehumidifier.

        • by gtall ( 79522 )

          The Second "Law" is more of an observation, there is no mechanism driving it other than probabilities if phase spaces.

        • by Zitchas ( 713512 ) on Thursday September 05, 2019 @07:25AM (#59161086) Journal

          That may or may not be the case (I haven't done the math), but it is much more logistically feasible to give people one object that can produce water locally than it is to set up a regular delivery of water shipments.

          I don't think anyone is arguing that this is is absolutely the best source of water ever. Just that it is more dependable and reliable way to provide water in remote arid regions where access to water or dependable transportation networks is poor or non-existent.

          If people have to pick up water shipments on a regular basis, it ends up being fairly disruptive to the local society, with the risk that if any particular shipment doesn't make it, they face death by dehydration. If every house has enough of these to provide 3L per resident, then water issues suddenly stop being a major factor in day-to-day activities and they can spend their time on other things.

          From a logistics point of view, if we assume that the average microwave is about 30L in volume, and it would take two of these per person to provide a permanent source of water, that's 60L of volume. Which is roughly 20 days of water worth of volume. Which means that it is more effective to ship these devices to a drought area whenever the length of the water shortage is likely to exceed 20 days. Because at that point, one is spending more time and energy on water shipments than one would on the initial equipment delivery.

          Admittedly, that doesn't take the equipment manufacture into account, but given the number of NGOs that will pay for water delivery, I'm sure there'll be sufficient interest in paying for these instead.

        • One might call it "settled science" if one were an idiot looking to justify an incredibly stupid statement, rather than admitting that they have no clue what they were talking about. You sound like an idiot saying "Newton settled science once and for all, everybody knows there is no such thing as quantum dynamics!"
          • Here's the slashdot story about the same guy doing the same thing two years ago, before it failed to do the wonderful things he claimed it would: https://science.slashdot.org/s... [slashdot.org]

            In a couple years there will be another explaining that of course he was wrong this time too.

            • That is literally the story of his earlier success with a much more expensive material that worked but wasn't economically practical due to the high cost that is directly referred to in this story. This story is about the advancement made that takes it from something that works but isn't economically viable to something that both works and is economically viable. And oh yeah ... I almost forgot ... we have all already figured out you are an idiot. There is no need to keep announcing it.
              • If you read the actual article you'll see he was also off on how much water that more expensive material would produce - by more than a factor of 10.

                The guy is making $508k/year off the taxpayer at UC. Just add a tweak every couple years and say "this time it'll work!"

                • "The setup works so well that it pulls 2.8 liters of water out of the air per day for every kilogram of MOF it contained, the Berkeley and MIT team reports today in Science."

                  "*Update, 14 March, 12:28 p.m.: This item has been updated to reflect the fact that the device pulls nearly 3 liters of water out of the air for every kilogram of the water-absorbing material that is used."

                  ... and ...

                  "To fully utilize the steep step in water uptake in the MOF-801 isotherm, a temperature difference of ~45C between the c

        • Are you an idiot or what?

          a) what have the fucking laws of theromdynamics to do with that?
          b) what has efficiency to do with that?

          You have a device that costs nothing to operate, you either buy it or not, your financial decisssion, it pulls water "out of thin air" ... go and hand your physicist card back, moron.

          It's cheaper (and greener) how can it be greener? The MOF needs no fuel, moron. How can it be cheaper, when you have to transport less water?

          I'm really getting sick about idiots like you.

          E.g. on my bo

          • by rev0lt ( 1950662 )

            a) what have the fucking laws of theromdynamics to do with that?

            If you don't really know the answer to this, you probably shouldn't be calling anyone an idiot. You should probably have a look at classical thermodynamic systems such as Carnot engine and the Peltier effect (https://en.wikipedia.org/wiki/Carnot_heat_engine ; https://en.wikipedia.org/wiki/... [wikipedia.org] ) and tone down your atitude.

            b) what has efficiency to do with that?

            After you are familiarized with the basic concepts of eg. Peltier devices, you'll notice there is the need to have an electric current. The current is usually non-trivial compared to the wa

  • Finding area's that have higher than normal concentrations of CO2
    convert as much as possible into water.

    use the water to plant tree's
    now you have 2 forms of carbon locking

    given this is a drop in the big bucket, but over a large
    area, this might put a dent in CO2 pollution on a very localised
    level.

  • He used moisture vaporators. The binary language was really hard to understand. Fortunately I went to school and learned how to program binary loadlifters so I didnâ(TM)t have too much trouble working on the.
  • It sounds like science fiction here.

    • CO2 version makes methanol (CH3OH) from air.

      Now... should someone find a catalyst that makes C2H5OH (ethanol)...
      That'd be a very different kind of a stillsuit.

  • I see a new video any day now.

    I just love hearing him say "Bullshit!"

  • We'll need a droid that understands the binary language of moisture vaporators.

    "But I was going into Tosche Station to pick up some power converters!”

  • While I would not expect a few of these to make a difference, enough to provide water to say a million people may have some pretty dramatic effect on the area weather. Just like some of the desal plants in Israel are having some effects on salinity. So could stripping a great deal of the water vapor in a local area have consequences???
  • Yaghi's salary at the Univ of Cal in 2018 was $508,629. He just needs to keep up the tweaks every couple years to explain why the last version didn't work. No Kickstarter necessary!

  • "Show me the waters of your homeworld, Usul."

Hokey religions and ancient weapons are no substitute for a good blaster at your side. - Han Solo

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