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In field tests, device harvests water from desert air
- anonyx69 9y agoHouse Harkonnen will be pissed.
- deleted 9y ago[deleted]
- bdevine 9y agoOk, I have a dumb question about this sort of technology. Aren't these devices essentially just borrowing from tomorrow by capturing moisture that would have eventually collected as clouds? Are there any long-term ramifications to using these?
- rukittenme 9y agoThere's no long term ramifications because these devices simply do not work as advertised.
- Zaak 9y agoThe MIT team explicitly addresses the limitations of refrigerated dew collection systems and claim that their system does not share those limitations. In what way would this particular device not work as advertised?
- rukittenme 9y agoIt does share those limitations because physical reality requires it to! There is no technological way out. Thermodynamics asks for some amount of energy in exchange for some amount of condensed water. The amount of energy is astronomical compared to the meager amount of water. You see the giant ass heatsink at the bottom of the image? Why do you think that exists? The water is condensing on a peltier heat pump. In a desert, to get a single bottle of water you're going to have to blow hundreds of thousands of liters of air (at perfect efficiency) over the pump. And that's for a single water bottle! Oh and this is assuming that your peltier device can get cold enough to produce a 100% humidity atmosphere. Because if it doesn't you get no water.
- adrianmonk 9y ago"They have developed a completely passive system that is based on a foam-like material that draws moisture into its pores and is powered entirely by solar heat." http://news.mit.edu/2017/MOF-device-harvests-fresh-water-from-air-0414 http://news.mit.edu/2017/MOF-device-harvests-fresh-water-fro...
- tytytytytytytyt 9y ago> The current version can only operate over a single night-and-day cycle with sunlight, Kim says, but “continous operation is also possible by utilizing abundant low-grade heat sources such as biomass and waste heat.” Why can it only un for a single day on solar?
- hexane360 9y agoIt can operate for multiple days, but it only generates water once a day. At night the foam absorbs moisture, and then sunlight provides energy to release it as water.
- nkurz 9y agoThe water is condensing on a peltier heat pump. What makes you so confident that they are using a Peltier? Here's their description of the operation of the device: During adsorption, air is circulated around the MOF layer and water from air is adsorbed. Passive radiative cooling lowers the MOF layer temperature below the ambient by dissipating thermal radiation to the clear cold sky to increase the effective RH for adsorption. During water production, the OTTI aerogel is stacked on top of the MOF layer to suppress convective heat loss from the solar absorber. The desorbed vapour is condensed on a condenser and the heat of condensation is rejected to the ambient by a heat pipe heat sink. And here's the more complete description of the condenser: The condenser of the device was fabricated with a copper plate (4 cm by 4 cm and 0.6 cm thick) attached to a commercial air-cooled heat sink (NH-L9x65, Noctua) to efficiently dissipate the heat from condensation to the ambient. Are you still sure it's condensing on a Peltier cooler? The paper never mentions "Peltier". If the "condenser" is actually an electrically driven Peltier, this would seem like a fraudulently bad description, justifying retraction of the paper. Is it possible that you are wrong? Still, I agree that you might be right about the physical limitations of scaling. You seem knowledgeable about the field, and I'd be interested to hear your impression after you read the actual paper: https://www.nature.com/articles/s41467-018-03162-7 https://www.nature.com/articles/s41467-018-03162-7. (I am genuinely interested in hearing your opinion about what they are doing, but would strongly suggest less overconfidence and more humility when offering bombastic pronouncements on papers you haven't read.)
- cornholio 9y agoClouds are quite cheap. Most of them drop most of their water over areas that would not significantly suffer from a marginal reduction of rainfall (the oceans, the arctics, mountain ranges). And a dryer average atmosphere should be partially compensated by increased evaporation from the oceans. Overall, this technology should be applicable on a continental scale before it shows any measurable effect on other areas.
- thaumasiotes 9y ago> areas that would not significantly suffer from a marginal reduction of rainfall (the oceans, the arctics, mountain ranges) Agreed as to the ocean and the arctic, but precipitation over mountain ranges is generally recovered by lower-altitude communities when the water eventually flows down to them. Snowmelt has been a major source of water historically.
- eloff 9y agoAlso the artics are essentially cold deserts, they don't get much precipitation and there is likely very little that could trace its origin to the hot deserts of the world.
- Cogito 9y agoThat's not really true. Parts of the arctics are definitely deserts, but that is not true for all of the arctic regions. Looking at the relevant parts of wikipedia [0] and [1], "annual precipitation averaged over the whole planet is about 1000 mm" while "parts of southeast Greenland [recieve] over 1200 mm". Antarctica has a lot less precipitation in general, but there are still large parts of it that are not classified as desert. [0] https://en.wikipedia.org/wiki/Climate_of_the_Arctic#Precipitation https://en.wikipedia.org/wiki/Climate_of_the_Arctic#Precipit... [1] https://en.wikipedia.org/wiki/Climate_of_Antarctica#Precipitation https://en.wikipedia.org/wiki/Climate_of_Antarctica#Precipit...
- ianai 9y agoHere’s hoping it somehow aids in carbon sequestration tech development...
- pjc50 9y ago.. in a different place. Damp air is pretty mobile. It also tends to equilibrium over bodies of water.
- jerf 9y agoIn some sort of absolute sense, sure, water in the device is not water somewhere else. But with something like 326,000,000,000,000,000,000 gallons of water on Earth, it's well below the noise threshold. Even "dry desert air", if you work it out, has massive (heh, literally) amounts of water in it. Plus the impact is even less than you think, because air that has been made dry is more able to pick up water, so you have to work even harder than you'd think to have any impact.
- ttul 9y agoI used a moisture calculator to determine that 10% humidity desert air at 30 degrees celsius and 1013.25hPa air pressure contains 3.03g/m³ of water. At that rate, the air above a 100x100m football field (to altitude of 100m) contains 303kg of water, or 303L at 4 degrees celsius. So you'd be "drying out" a very tiny cube of air to produce the water needed by an entire family per day even given desert conditions with one of these appliances. In the first world, we use 100L/day for all our needs. That means if everyone in America lived in a desert, we might need 107,491,749,174,917.5 cubic meters of air to supply us with all our water. If that sounds like a lot of air, consider that Death Valley is 7.8e+9 square meters in area; thus, to supply ALL Americans with fresh water, you'd just need to suck Death Valley's air dry to an altitude of 10,000m or so.
- thaumasiotes 9y ago> you'd just need to suck Death Valley's air dry to an altitude of 10,000m or so It seems likely that, as the atmosphere becomes less dense with increasing altitude, so does atmospheric water. One cubic meter of air at sea level contains a lot more air than one cubic meter of air at 6,000m. Does your figure include that effect?
- tylerhou 9y agoIf you assume atmospheric water has the same density up to around 3000 feet, then you'd have to dry out 3 Death Valleys. Still pretty reasonable.
- DougN7 9y agoI've had the same thought about solar. The area under the panel used to get sunlight, and if nothing else, warmed up. Not that it's necessarily bad, but widespread usage would have to have _some_ environmental impact.
- cirgue 9y agoThe same thing can be said of agriculture, and there are definitely environmental impacts, but we generally don't worry about the ground cover aspect.
- DougN7 9y agoThat is a really great point I had never thought of. Thank you.
- photojosh 9y agoNow the panel warms up instead of the area underneath. What's the difference?
- dreamcompiler 9y agoA small fraction gets turned into electricity. Which ultimately gets turned into...heat. So the net amount of heat reaching earth doesn't change.
- adrianN 9y agoUnless you build solar panels on top of a very low albedo ground, the amount of heat actually increases because less is reflected back to space.
- DougN7 9y agoThe final heat would most likely be produced in a different location. It would take a very large scale installation to have an impact. I guess I'm thinking of weather patterns when you see those images that say "if we covered 1/4 of Arizona in solar panels we could power the world!". More of a thought experiment than anything I guess.
- oh_sigh 9y agoMaybe, but the scale here is gigantic, and it will take a lot of work for humans to make an impact. Consider that a single cumulus cloud can weigh 2 million pounds(that is, 900 cubic meters of liquid water). If you were going to be worried about things like this, wind farms will probably pose a bigger problem than water collection, unless we start building large cities in the desert relying only on air moisture collection.
- incompatible 9y agoI guess a lot of it ends up back in the atmosphere once humans have used it. Perhaps some is piped in sewerage all the way to the nearest ocean?
- natecavanaugh 9y agoLong term ramifications I'm sure of. Long term harmful ramifications? I doubt it. That water has to go somewhere, whether it's captured in the ground or evaporates in the skies, the machinery of nature will keep ticking :)
- cwkoss 9y agoI wonder if these could be used for irrigation without having to run water lines. How much does the MOF cost to produce? What is flow rate? How would wide-scale use of these in an area effect the regional climate?
- portofcall 9y agoMOF’s are not mass produced, and while a method has been proposed to scale up production, as far as I know it’s never been tested. It’s also a solvent-heavy process, and often uses a lot of benzene. MIT the university is an amazing thing, but MIT the press release machine is pathetic.
- gene-h 9y agoMOFs aren't mass produced, but it is possible to produce large quantities of them. BASF has been able to make double-digit tonnage quantities of MOFs per a single production run[0]. It much simpler to make MOFs than other nanomaterials like carbon nanotubes and graphene. The MOF used in the paper is somewhat expensive as it uses zirconium, but it is possible that MOFs based on other metal ions could be used. [0]https://cen.acs.org/articles/91/i51/Materials-Chemistry-Metal-Organic-Frameworks.html https://cen.acs.org/articles/91/i51/Materials-Chemistry-Meta...
- philipkglass 9y agoZircon (zirconium raw material) isn't very expensive. Removing hafnium from zirconium compounds to reach nuclear-application purity is expensive. Reducing zirconium compounds to metal is expensive. The authors start with zirconyl chloride, which doesn't have either of those expensive requirements. For anyone else wanting to read the full paper, it's open access in Nature Communications: https://www.nature.com/articles/s41467-018-03162-7 https://www.nature.com/articles/s41467-018-03162-7
- portofcall 9y agoIt much simpler to make MOFs than other nanomaterials like carbon nanotubes and graphene. Well yes, but nanomaterials are tough to make, and mass produced graphene is a nightmare. None of that changes the energy requirements to make the stuff, or the hazardous byproducts of production. If it’s not energetically and financially efficient, then it doesn’t compete with desalination, and is useless.
- thisacctforreal 9y ago>The system [...] was positioned on a Arizona State University roof. It’s still early stages, and the water only measured in the millimeters Millimeters is not a useful unit of collected water! Granted millilitres wouldn't be much better without time as well.
- srott 9y agoNot bad for a roof of concept...
- organsnyder 9y agoMillimeters over what area, though? A millimeter depth over a kilometer^2 area is a decent amount of water; a millimeter depth over a meter^2, less so.
- extrememacaroni 9y agoIt's a millimeter towards around up.
- froindt 9y agoThey're measuring in a volumetric unit, and you switched it to a linear unit. They're using milliliters not millimeters. 1 milliliter = 1 cm^3 237 ml = 1 cup EDIT: Nevermind regarding the unit confusion. I'm still learning how to read.
- itp 9y agoUnless I'm missing something, (s)he didn't switch any units. The original article as I am reading it clearly just says "millimeters" without any associated area or timeframe.
- froindt 9y agoHrm...yep...you're right. I read the first comment and could have sworn the quote from the article said milliliter. My eyes are playing tricks on me!
- ghawkescs 9y agoWhat's the difference between MIT's prototype and Zero Mass Water? https://www.zeromasswater.com/ https://www.zeromasswater.com/ Is it the minimum humidity rating?
- dogma1138 9y agoLooks like a peltier dehumidifier powered by a solar panel any one has any idea what the breakthrough is exactly?
- Zaak 9y agoNo, this device is explicitly not one of those: > The system, based on relatively new high-surface-area materials called metal-organic frameworks (MOFs), can extract potable water from even the driest of desert air, the researchers say, with relative humidities as low as 10 percent. Current methods for extracting water from air require much higher levels ... above 50 percent for dew-harvesting refrigeration-based systems
- dogma1138 9y agoThanks for trying to explain instead of simply cluelessly down voting but this still does not answer my question. This is a Peltier device you can see the power wires and the heat sink on the hot side. Are MOFs used in the construction of the Peltier for example are Cu3-BTC MOFs used to increase the surface area of the cold plate which improves condensation or are MOFs used as a membrane to increase the humidity in the condensation chamber to above ambient? I really don’t understand why people get triggered by honest questions and decide to burry them.
- philipkglass 9y agoThe full paper is open access. Those wires are going to thermocouples, not Peltier devices: https://www.nature.com/articles/s41467-018-03162-7/figures/2 https://www.nature.com/articles/s41467-018-03162-7/figures/2 There is a heat sink, but it's not dissipating electrically produced heat. From the paper: During day-time water production, the enclosure is closed and the solar absorber side is covered with an optically transparent thermal insulator (OTTI aerogel). The MOF layer is heated by exposure to solar irradiance, causing water release (desorption). The desorbed water vapour diffuses from the MOF layer to the condenser due to a concentration gradient. Accumulation of vapour in the enclosure leads to saturation conditions and consequently, the condensation process occurs at ambient temperature. The heat of condensation is dissipated to the ambient by a heat sink.
- abakker 9y agoHow much can it reduce indoor humidity in San Francisco...I'd love to have that be a more energy efficient process, too.
- sungx105 9y agoMOFs are generally notoriously unstable in water. Would a scaled-up system be able to perform while maintaining functionality over many cycles?
- fernly 9y agoright right right -- you have an extremely high surface area of metal and you expose it to air and moisture. Why would it not oxidize in like minutes?
- wiz21c 9y agoReminds me of Dune...
- patrickxie 9y agocould this idea work? tie these devices to balloons, so they can reach the high humidities of the clouds, then when waters collect the balloons will drop to the ground, dumping the water into a collector. as the water is dumped the device rises again to continue humidity collection.
- rungcc 9y agoLeave it to Silicon Valley to reinvent rain.
- deleted 9y ago[deleted]
- beamatronic 9y agos/reinvent/disrupt
- deleted 9y ago[deleted]
- NegativeLatency 9y agoAside from the engineering challenges of this, think of the geopolitical and environmental impacts that something like this would have. The water extracted was probably going to fall somewhere else, but now it won't.
- mirekrusin 9y agoWhat about sandstorms?
- mchannon 9y agoYou're taking something simple and making it very complicated. The reason clouds form is not because there's more water up there, but because temperatures and pressures are lower and the air can't hold on to the water anymore, and the water separates into droplets of liquid water or ice. There's plenty of water at ground level, even in lip-cracking low humidity, as long as it's not also freezing. The trick is getting what water there is to leave the air and to collect in your bucket, and collecting a meaningful amount.
- black_puppydog 9y agoI don't see a link to the actual paper, or the title... Is the press office concerned about scaring the general public with links to actual science?!
- nkurz 9y agoNo link, but at least they give enough information to search for it. I think it must be this one: https://www.nature.com/articles/s41467-018-03162-7 https://www.nature.com/articles/s41467-018-03162-7
- beautifulfreak 9y ago"Here, we demonstrate an air-cooled sorbent-based atmospheric water harvesting device using the metal−organic framework (MOF)-801 [Zr6O4(OH)4(fumarate)6] operating in an exceptionally arid climate (10–40% RH) and sub-zero dew points (Tempe, Arizona, USA) with a thermal efficiency (solar input to water conversion) of ~14%. We predict that this device delivered over 0.25 L of water per kg of MOF for a single daily cycle." So what does a kilogram of the MOF cost, compared to the ordinary costs of acquiring water in dry places?
- dieg0 9y agoYes, you can extract water from air. You have just re-invented distillation, in a painfully mind blowing way. In Chile we have the driest desert on earth, the Atacama desert, this projects have “tried” to address the challenge of getting fresh water in remote communities located in such places. State funds have been directed toward similar "science" projects. TV has dedicated time and resources to explore this "idea". This has to stop, the amount of water that you can extract from air is related to the amount of humidity in that place's air. You don't need much to understand that the amount of water in the air isn't much in places such as deserts. And if you have lots of humidity in the air, you can probably get water from other sources, such as rain.
- mplewis 9y agoDid you read the article at all? This applies to places under 50% humidity, not just deserts.
- rukittenme 9y agoYou are absolutely right. No matter how many down-votes you receive. The scientific illiteracy on HN is astounding considering the audience it tries to cater to (college-educated software engineers).
- flukus 9y agoIt really is astounding. About the wettest the atmosphere can get is a rain cloud and one several kilometres in height and several kilometres in length will drop a few millimetres of water. Yet people seriously believe that these little things will suck more water out of much less atmosphere.
- tomc1985 9y agoYou said it yourself, the Atacama is the driest desert on earth. I imagine that environment would be the most difficult to extract water from. Develop the tech in easier locales then, once the major details are worked out, target the outliers.
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- ChuckMcM 9y agoThis is pretty neat. From previous papers it is using temperature swing adsorption[1] pull the water out of the air. Basically their MOF material collects on its surface (adsorbtion) water at one temperature and releases it (desorption) at the other. In this way, just by putting their material out in the Sun light the day/night cycle will collect and then dispense the collected water all passively. The 'catch' is how expensive is it to produce the MOF and how long does it work before it needs to be replaced. In an ideal world, with a cheap catalyst and infinite lifetime, you could build a large tower full of this stuff and it would pour water out during the desorption process. [1] https://www.ethz.ch/content/dam/ethz/special-interest/mavt/process-engineering/separation-processes-laboratory-dam/documents/education/rcs%20notes/ArvindRajendran_AdsorptionBasics.pdf https://www.ethz.ch/content/dam/ethz/special-interest/mavt/p...
- danbruc 9y agoCondensing water requires 2.265 MJ/kg, go figure how viable this is.
- danbruc 9y agoLet me elaborate because this received a couple of downvotes. They only use the metal-organic framework to adsorb water vapor from the atmosphere during the night and then use sunlight to desorb it during the day which leaves them with water vapor again. Now they still have to condense that into water and their 2017 paper [1] shows that they use a Peltier element paired with a big heat sink to do this. But this is the process that actually requires the most energy, disiapating 2.265 MJ/kg of water which is enough energy to heat the same amount of water by 541 K. Maybe I am missing something but to me it seems like that metal-organic framework at best provides a marginal benefit over simply condensing water on a Peltier element directly, which will, with an efficiency of 15 % [2], still require about 4.2 kWh/kg. [1] https://globalscience.berkeley.edu/sites/default/files/waterharvesting.pdf https://globalscience.berkeley.edu/sites/default/files/water... [2] https://en.wikipedia.org/wiki/Thermoelectric_cooling#Performance https://en.wikipedia.org/wiki/Thermoelectric_cooling#Perform...
- jessaustin 9y agoISTM they're just waiting until night again? A simple mechanical design could contain water vapor in a chamber isolated from environmental atmosphere but not ambient temperature. Eventually it condenses and is harvested. The MOF acts as a sort of Maxwell's Demon, moving water from the environment to the isolated chamber. The trick would be to remove the MOF from communication with the chamber (e.g. at 2 PM) without allowing the chamber humidity to equalize with the environment. Probably there is some sort of airlock?
- nkurz 9y agoI downvoted the original comment because I thought it was factually accurate but misleading. The implication was that the amount of energy required made it obviously nonviable, but you didn't actually show the work to make that case. Without strong evidence, "go figure how viable this is" is an unhelpful thing to say when someone claims to have a working prototype. Your explanation here is much better (and I upvoted it), but I think it still misses the major point that the authors claim that the new device does not use a Peltier cooler. Instead, it's heated by the sun, and uses a passive heatsink. I think it's the same mentioned in the earlier paper as "We also report a device based on this MOF that can harvest and deliver water (2.8 L kg–1 day–1 at 20% RH) under a non-concentrated solar flux below 1 sun (1 kW m–2), requiring no additional power input for producing water at ambient temperature outdoors.". So I think the answer to your question is "Yes, it can be viable if you have a convenient source of heat that can produce the necessary energy". 1 MJ is about 270 Watt Hours, sunlight at noon is about 1000 W/m^2, and solar thermal collection can be more than 50% efficient. This doesn't mean it's viable, but as the new paper shows, if you have a square meter of sunlight available the energy necessary for condensation is probably less of a limiting factor than the collection of the moisture into the (currently exotic) sorbent.
- MentallyRetired 9y agoNow, can they make one that harvests drinkable water from the ocean?
- tomc1985 9y agoDidn't some kid in Africa come up with a similar device with spare parts? How come the MIT one needs all this exotic tech?
- noetic_techy 9y agoCouple this with algae growing and you could have a sustainable source of both food and water almost anywhere. Yes, algae cakes are nasty but beggars cant be choosers.
- diyseguy 9y agoA quarter liter per day could easily water a tree. Reforestation seems possible with this device.
- hexane360 9y ago>One large tree can lift up to 100 gallons of water out of the ground and discharge it into the air in a day. This won't forest the desert. It may supplement a couple areas which could almost sustain trees, but trees are some of the most water-thirsty plants around.
- s0rce 9y agoGah, their own university press office doesn't even link to the latest paper. Here is it after a quick search, open access too: https://www.nature.com/articles/s41467-018-03162-7 https://www.nature.com/articles/s41467-018-03162-7 Seems interesting, for small, possibly off the grid, desert communities. Not sure how the overall lifecycle energy demands would compare to say desalination for most of the coastal population centers.
- peterburkimsher 9y agoCould this be used on Mars? The humidity at the surface is 30 to 75 ppm [1]. Clouds have been known to form. If Elon Musk gets interested, I think the MIT researchers could get the investment they need to scale this up. I'm just grateful to read some good news about scientific progress for a change. Useful inventions like this give me more hope for humanity. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4508910/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4508910/
- cwkoss 9y agoVery cool idea. Few potential issues come to mind: - I bet dust would muck up the MOF - Dust would need to be swept off to allow sunlight energy to reach the solar chamber. - Ambient temperature on mars in below the freezing point of water. May not get enough sun to warm the MOF enough to drive off the moisture. EDIT: Found a source saying that water vaporizes during the day because of the reduced pressure - interesting.
- m1el 9y agoThis won't work. Purely because of thermodynamics. We already have devices that suck water out of the air - dehumidifiers. They don't collect enough water to drink. Similar concepts were tried before: - https://www.indiegogo.com/projects/fontus-the-self-filling-water-bottles-sport-camping https://www.indiegogo.com/projects/fontus-the-self-filling-w... - https://www.waterseer.org/ https://www.waterseer.org/ They're all bust because it can't work.