In field tests, device harvests water from desert air

http://news.mit.edu/2018/field-tests-device-harvests-water-desert-air-0322

by evo_9 • 8 years ago

103 123 8 years ago

news.mit.edu

anonyx69• 8 years ago

House Harkonnen will be pissed.

bdevine• 8 years ago

Ok, 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?

rukittenme6• 8 years ago

There's no long term ramifications because these devices simply do not work as advertised.

Zaak2• 8 years ago

The 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?

cornholio• 8 years ago

Clouds 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.

thaumasiotes2• 8 years 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.

ianai2• 8 years ago

Here’s hoping it somehow aids in carbon sequestration tech development...

ethagknight• 8 years ago

A far more accurate response is “we have no idea and no way of knowing there wouldn’t be major negative ramifications but it would seem like...”

My biggest gripe with climate science in popular media is the presentation of sparse data and unproven models as fact that should be take at face value. Milking clouds in one region will have an impact elsewhere, that’s the only guarantee.

pjc50• 8 years ago

.. in a different place. Damp air is pretty mobile. It also tends to equilibrium over bodies of water.

jerf2• 8 years ago

In 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• 8 years ago

I 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.

DougN73• 8 years ago

I'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• 8 years ago

The same thing can be said of agriculture, and there are definitely environmental impacts, but we generally don't worry about the ground cover aspect.

photojosh• 8 years ago

Now the panel warms up instead of the area underneath. What's the difference?

oh_sigh• 8 years ago

Maybe, 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.

incompatible2• 8 years ago

I 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• 8 years ago

Long 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 :)

cwkoss8• 8 years ago

I 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?

portofcall4• 8 years ago

MOF’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• 8 years ago

MOFs 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-Meta...

Johnny555• 8 years ago

Given that it's generating "millimeters" of water (I assume they mean milliliters), it seems unlikely that it's going to scale up to where the water can be dumped into the ground for irrigation, or even used for hydroponic growing. Many food crops lose a lot of water through leave, for example, it takes about 15 gallons of water to grow a head of lettuce, while a human can subsist on about a gallon a day.

https://www.treehugger.com/green-food/from-lettuce-to-beef-w...

DubiousPusher• 8 years ago

A pure MOF based irrigation system that produces enough on demand seems a little far fetched but you don't have to go that far to see something like this as potentially powerful. You could run this thing all year and store the water underground and that could have some cool consequences. Imagine an area with good soil that gets enough rain to take plants 60% of the way through their growing season. Something like this might be able to supplement that supply enough to make it practical to grow there. Or, regions that are normally good for growing but have regular droughts could maybe use it to offset the reduced water. Or, if you can store up enough water through winter, maybe you could run a conventional irrigation system purely off the water from the MOFs.

Maybe transporting water is already a way better mitigation to the above scenarios. It really depends on how fast and cheap you can deploy something like this.

thisacctforreal• 8 years 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• 8 years ago

Not bad for a roof of concept...

organsnyder• 8 years ago

Millimeters 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.

firethief• 8 years ago

That seems like exactly the unit. Just like when measuring rainfall, the amount collected scales with the area of the equipment. What would you prefer, mm/(mm)^2?

I would assume time is on the scale of per day; that seems, at least to me, the only time unit they wouldn't have specified here. Of course, in an article this bloggy it's not a given that the reasonable interpretation of such vague units is the interpretation intended--but I think that there is a reasonable interpretation.

delecti• 8 years ago

Volume per unit of collection area per unit time at a given absolute humidity.

It might be a bit too technical, but anything less really can't give you a sense of scale.

CamperBob2• 8 years ago

That seems like exactly the unit. Just like when measuring rainfall, the amount collected scales with the area of the equipment.

If you live in a desert, you're not trying to measure the water. You're trying to drink it.

nkurz11• 8 years ago

The actual MIT press release has much better information than the Techcrunch article:

The test device was powered solely by sunlight, and although it was a small proof-of-concept device, if scaled up its output would be equivalent to more than a quarter-liter of water per day per kilogram of MOF, the researchers say. With an optimal material choice, output can be as high as three times that of the current version, says Kim.

http://news.mit.edu/2018/field-tests-device-harvests-water-d...

Edit: And the underlying paper is here: https://www.nature.com/articles/s41467-018-03162-7

sctb• 8 years ago

Thanks! We've updated the link from https://techcrunch.com/2018/03/22/mits-new-device-can-pull-w....

Animats• 8 years ago

That's a desert survival device. Not a useful source of water for anything other than dire emergencies.

incompatible2• 8 years ago

It's ambiguous anyway what "only measured in the millimeters" refers to. You can measure any length you like in millimeters, like the distance to the moon. Perhaps they mean less than a meter?

ghawkescs• 8 years ago

What's the difference between MIT's prototype and Zero Mass Water?

https://www.zeromasswater.com/

Is it the minimum humidity rating?

dogma11383• 8 years ago

Looks like a peltier dehumidifier powered by a solar panel any one has any idea what the breakthrough is exactly?

Zaak2• 8 years ago

No, 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

dogma11383• 8 years ago

Thanks 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.

abakker• 8 years ago

How much can it reduce indoor humidity in San Francisco...I'd love to have that be a more energy efficient process, too.

sungx105• 8 years ago

MOFs are generally notoriously unstable in water. Would a scaled-up system be able to perform while maintaining functionality over many cycles?

fernly2• 8 years ago

right 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• 8 years ago

Reminds me of Dune...

rglovejoy• 8 years ago

More like Tatooine.

davidw• 8 years ago

Was looking for the comments about getting a droid that understands the binary language of their moisture vaporator.

fernly2• 8 years ago

right, the words that popped into my mind were, "Fremen stillsuit".

patrickxie• 8 years ago

could 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• 8 years ago

Leave it to Silicon Valley to reinvent rain.

beamatronic• 8 years ago

s/reinvent/disrupt

NegativeLatency• 8 years ago

Aside 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• 8 years ago

What about sandstorms?

mchannon• 8 years ago

You'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• 8 years ago

I 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?!

nkurz11• 8 years ago

No 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

beautifulfreak• 8 years 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?

dieg03• 8 years ago

Yes, 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• 8 years ago

Did you read the article at all? This applies to places under 50% humidity, not just deserts.

rukittenme6• 8 years ago

You 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).

flukus2• 8 years ago

It 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.

tomc19853• 8 years ago

You 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.

dieg03• 8 years ago

Air already has X amount of water, you cannot get more than X. It doesn't matter if X is very tiny like in deserts or very large like in the middle of the pacific ocean.

dieg03• 8 years ago

I meant "these" projects. Not this project specifically

cwkoss8• 8 years ago

Develop industry that produces steam upwind!

ChuckMcM• 8 years ago

This 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/p...

danbruc2• 8 years ago

Condensing water requires 2.265 MJ/kg, go figure how viable this is.

danbruc2• 8 years ago

Let 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/water...

[2] https://en.wikipedia.org/wiki/Thermoelectric_cooling#Perform...

jessaustin• 8 years ago

ISTM 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?

nkurz11• 8 years ago

I 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• 8 years ago

Now, can they make one that harvests drinkable water from the ocean?

tomc19853• 8 years ago

Didn'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• 8 years ago

Couple 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• 8 years ago

A quarter liter per day could easily water a tree. Reforestation seems possible with this device.

hexane3602• 8 years 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• 8 years ago

Gah, 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

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• 8 years ago

Could 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/

cwkoss8• 8 years ago

Very 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• 8 years ago

This 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-w...

- https://www.waterseer.org/

They're all bust because it can't work.

In field tests, device harvests water from desert air

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