NHacker Next
  • new
  • past
  • show
  • ask
  • show
  • jobs
  • submit
Low-cost gel film can pluck drinking water from desert air (news.utexas.edu)
jvanderbot 672 days ago [-]
"In a typical fabrication, LiCl powder (0.32–0.82 g) is added into 10 mL HPC solution (0–2.0 wt%) forming solution A. The pH of solution A can be tuned by NaOH or HCl solution. 0.44 g KGM powder is added into solution A and quickly cast into the petri dish after vortex. The gelation takes place within 2 min, and sit in room temperature for 15 min. Then, the film is placed in the fridge (−4 °C) for 3 h followed by 15 min freeze in liquid nitrogen. Last, the gel film is ready to use after 12 h freeze-drying. The final LiCl concentration in SHPFs is characterized by TGA."

"Before the water vapor sorption measurement, all samples are dried in a vacuum oven at 90 °C for at least 2 h. "

- Fridge cooling

- liquid nitrogen bath

- 12h freeze drying

That doesn't sound low-cost / easy to manufacture.

https://www.nature.com/articles/s41467-022-30505-2

Figure of test rig: https://www.nature.com/articles/s41467-022-30505-2/figures/4

That looks like you capture using a very cold, porus material (cold, dry sponge that collects dew, essentially), then heat this "sponge" so the water then travels up to a condenser which causes it to "dew" and run into a collection chamber.

It's not magic water-cloth, and I don't think it's a weekend project, but it's pretty low tech.

What did I get wrong? I'm sure there's something.

robonerd 672 days ago [-]
FWIW real "magic water-cloth" actually exists, but only works some places some of the time: https://en.wikipedia.org/wiki/Fog_collection

> The mesh netting is where the condensation of water droplets appear. It consists of filaments knitted together with small openings, coated with a chemical to increase condensation. Shade Cloth is used for mesh structure because it can be locally sourced in underdeveloped countries. The filaments are coated to be hydrophilic and hydrophobic, which attracts and repels water to increase the condensation.[1] This can retrieve 2% of moisture in the air. Efficiency increases as the size of the filaments and the holes decrease. The most optimal mesh netting is made from stainless steel filaments the size of three to four human hairs and with holes that are twice as big as the filament. The netting is coated in a chemical that decreases water droplet's contact angle hysteresis, which allows for more small droplets to form. This type of netting can capture 10% of the moisture in the air.[2]

etskinner 672 days ago [-]
How can something be both hydrophilic and hydrophobic?
GauntletWizard 671 days ago [-]
Different filaments. You form a mesh that creates "hotspots" of attraction for water.
bordercases 671 days ago [-]
I'm not sure, this looks like it can be done in a college chemistry lab without too much retooling. A dedicated factory process could be even stronger. Lithium is found and wasted wherever vapes are sold, so it's not like there aren't economies of scale for material supply available.
conductr 672 days ago [-]
At scale, this seems awful for desert ecology. Plants and animals have evolved to survive on bare minimum water. The tiny morning dew may be all they get for days/weeks. Now we want to pluck it out before they can get any.

It’s certainly an interesting technology and achievement but one that could be easily misused with “unintended consequences”; or so it seems.

colechristensen 672 days ago [-]
It could also do the opposite, if used correctly.

Strong Dune vibes.

You could use these to water plants and set up a cycle where a significant portion of the water lost through evaporation was reclaimed and gradually accumulated locally. Dot a landscape with solar powered stacks of these things feeding appropriately selected plantations and you might make the desert bloom or help prevent the spread of deserts.

conductr 672 days ago [-]
That's an interesting concept I had not considered. I also am not sure if "we" (collective) would roll it out that way. We have a track record of consuming resources in the easiest/cheapest way with minor consideration of the environment. I don't think we'd even view this as a worthy investment if all it did was help prevent the spread of deserts. We still can't even agree if climate change is real and what we should do about it.
colechristensen 672 days ago [-]
conductr 672 days ago [-]
That's interesting. Reminds me of when I was a kid and thought I had a completely unique idea to fill the Sahara with water! It will quickly evaporate and turn to a rainforest in no time!!

https://en.wikipedia.org/wiki/Sahara_Sea

dylan604 672 days ago [-]
I have little trust in the "we" doing anything like this correctly, at first. By that, I mean that it will be the corps to do this as they are the ones with the money to do it. Corps being corps, they will lean into being themselves and extract all of the everything they can with little respect for anything other than their bottom line.

I don't have faith gov't will do it either. Those opposed to climate change will argue it is money spent on fake science. It'll die in congress (for US, s/congress/localGovUselessBody/ for other places).

Someone might get popular enough to crowd source fund it with an NGO type thing, but I'm not holding my breath there either.

yonaguska 672 days ago [-]
I hope you'll be more optimistic about government outcomes, at least as far as opposition is concerned. I think I'd fall under your bucket of people that are "opposed to climate change", and I put that in quotes, because, it's not that I don't believe in climate change or anything like that. I just don't believe that the current "green" initiatives are the correct way to go about solving climate issues. I do however consider myself an environmentalist. I care more about the non C02 pollution that we are causing than simply trying to reduce C02 emissions.

I think you'd be hard pressed to find organic opposition to tackling environment issues that aren't related to the relatively abstract C02 pollution issues. I say organic because the corporations responsible for pollution will always find ways to manufacture consent that protects their own best interests. But, your stereotypical human-caused climate change denier is likely someone that hunts, fishes, or resides in a rural area, where environmental and conservationist concerns are taken very seriously, regardless of political affiliation. Your opposition is only going to come from people whose livelihood is affected by pollution controls. A broader swathe of people will always oppose addressing C02 related climate concerns because it affects literally everyone's bottom line in the form of rising cost of goods with energy prices going up, and it has abstract consequences, rather than concrete ones like your local streams being poisoned, or your well water going bad because the aquifer has been contaminated.

konschubert 671 days ago [-]
We could maybe do this with todays technology already - solar powered desalination plants.

There are plenty of desert coastlines.

Not sure how much that would cost per square meter of forest/agriculture, tbh.

bobthepanda 671 days ago [-]
The appeal of relying on nature is that if the conditions are right, nature becomes a self sustaining, nearly zero maintenance solution.

Solar powered desal is pretty expensive.

jhgb 671 days ago [-]
> Now we want to pluck it out before they can get any.

I suspect that if you think that this is going to give us the ability to suck out all the water out of thousands of cubic kilometers of desert air any time soon, you're probably being a little too optimistic.

rhexs 671 days ago [-]
This is entirely dependent on whether or not Nestlé MBAs calculate they can make a profit with this bottling "Desert Air Water".
nopenopenopeno 671 days ago [-]
Yup. That is precisely how global warming works.
blacksqr 672 days ago [-]
The amount of water vapor in the air is functionally infinite with respect to any practical means to extract it.
rtkwe 672 days ago [-]
Only true on the large scale but locally you'll still create a depleted zone near the ground down wind of a hypothetical extraction plant.
grishka 671 days ago [-]
But the water someone plucked out of desert air and drank doesn't poof out of existence. They'll eventually pee and sweat it out.
a1369209993 671 days ago [-]
> They'll eventually pee and sweat [the water] out.

It's infuriatingly hard to find good citations, but I think they actually mostly breathe it out. IIRC, the water breakdown for some (spacecraft) life support system was something like 50% from respiration, 30% in urine, 10% in sweat, and 10% in feces.

ttul 672 days ago [-]
At 20C, the maximum water content in air is 17.3 x 10^-3 kg/m^3.

At 15% relative humidity, then, you can extract a maximum of 0.15 x 17.3g = 2.6g from every 1,000L of air.

If a person needs 5L/day for survival (I am making this up), then you’d need to dry out 5000 / 2.6 = 1,923L of air each day — that’s just short of two cubic meters…

If the density of people living in an area is 50 per square km, drying the air out to extract water would deplete the first meter of the atmosphere by 10%.

bufferoverflow 672 days ago [-]
> If a person needs 5L/day for survival (I am making this up), then you’d need to dry out 5000 / 2.6 = 1,923L of air each day

You made a unit conversion mistake there. It's 1923 cubic meters, not liters.

ttul 672 days ago [-]
Correct. 5,000g / 2.6 g per m^3 = 1,923 m^3

Okay let’s say the bottom 10m of atmosphere is available for water making. That means there are 10 million cubic meters of air per square km, or per 50 people. We will need to dry out 1,923 x 50 = 96,150 cubic meters of air. But there is 10,000,000 available, meaning we are only drying out just under 1% of the air.

npc12345 672 days ago [-]
Aren't they equivalent?
tomrod 672 days ago [-]
liter = 0.001 Cubic meter

I was curious so I looked it up because I also did not know, ref: https://www.google.com/search?q=liters+in+cubic+meter&oq=lit...

martyvis 671 days ago [-]
Or to better visualise it, it is a 10x10x10 centimetre (cm) cube. (Or just a bit less than a 4x4x4 inch cube for the unmetrical )
npc12345 670 days ago [-]
Oh my you're right.
conductr 672 days ago [-]
If those people are living there 5L/day is nowhere near enough water. They are doing more than just surviving. Using Arizona as an example, Google tells me 550L/day/person is actual usage. I know you just put an assumption in but this is a big gap.
function_seven 672 days ago [-]
1,923,000L per day, right? So each person would need just short of 2,000 m³ of air.
ttul 671 days ago [-]
And, for comparison, “ A 4-stroke engine with one litre displacement operating for 60 minutes at 2500 rpm is estimated to consume 1 L x 2500/2 rpm x 60 minutes/hour = 75,000 litres of air.”

https://collaboration.cmc.ec.gc.ca/science/rpn/SEM/dossiers/...

TwistedWave 672 days ago [-]
1,923m^3, not 1,923L
klvino 672 days ago [-]
That was my first thought as well, heavy use within an existing desert environment would likely have negative ecological impact.

When reading through the article, it has potential application in areas where a local water supply may not be clean enough to drink or lacks sufficient water treatment & filtration.

buu700 672 days ago [-]
On the flip side, could it potentially be a cost-efficient method of dehumidifying cities/towns/villages for human comfort?
conductr 672 days ago [-]
Could even replace desalination since humidity has no salt and it is generally occurring in a similar area/climate.
sandworm101 672 days ago [-]
Humidity theoretically doesn't contain salt, but air does. Any technology that is harvesting moisture from air will involve large amounts of air. That air contains dust and sea salt which can contaminate the process. Setup a moisture farm to harvest sea breezes and you will have to address a salt problem.

In many industries this airborne salt can cause corrosion. Talk to anyone with a classic car in LA/SF, both cities with sea breezes. They don't want to leave them outside too much. That's why the aircraft "boneyards" are all in the interior, across the mountains from the sea.

bushbaba 672 days ago [-]
And dryer air can absorb more water from the nearby sea...so there might not be a huge impact if placed in the right spot
Robotbeat 672 days ago [-]
Would it? The water will eventually evaporate again. It’s not like the water is burned up to nothing in a fusion reactor.
flockonus 672 days ago [-]
Could be easily drained down a pipe, the evaporation then is not as relevant even if some of it does, efficiency would most likely be acceptable.
throwaway894345 672 days ago [-]
Deserts are expanding; it seems fine to offset that expanse as long as you're somewhat careful not to wipe out an entire ecosystem.
tomcam 671 days ago [-]
Sort of an interesting point. But don’t forget, in the Sahara, for example, there was less vegetation only 5000 or 6000 years ago
AnimalMuppet 671 days ago [-]
Less vegetation 5000 years ago? Are you sure you don't mean more?

Wikipedia speaks of an "abrupt desertification" 5400 years ago.

tomcam 671 days ago [-]
Yes I meant more. Downvotes absolutely justified.
AnimalMuppet 671 days ago [-]
Yeah, well, I've never mis-spoken in a post on HN. Never. (Furtively checks posting history) Or at least not today....
tomcam 671 days ago [-]
I’m always grateful for the corrections, but thank you for doing it so gracefully.
jmyeet 672 days ago [-]
With the very real risks of climate change and rising sea levels I'm wondering how long it will take before someone decides to flood the Sahara.

It's worth noting that sea level rise is kinda complex.

First, if an iceberg floating on the ocean melts it doesn't raise sea levels. That's the buoyancy principle of displacing an object's weight in water.

Second, a lot of ice (eg Antarctica, Greenland) is on land so the first point doesn't apply to all ice as some deniers have tried to claim.

Third, the sea level rise is partially from ice melt but also from thermic expansion.

Fourth, even if you flooded all the below sea level parts of the world, it would only account for a fraction of the sea level rise so it's not a permanent solution.

But several thousand eyars ago the Sahara was arable land. Some parts of the Sahara were >400 feet below sea level so this would be a significant body of water. Even as seawater this would inject a lot of water into the environment through evaporation and normal water cycles.

Obviously this would have an impact on the ecosystem and displace some people but we've displaced far more people for less (eg the Three Gorges Dam).

This seems like something we should do, no?

lainga 672 days ago [-]
> But several thousand eyars ago the Sahara was arable land.

I think the desert status of the Sahara has more to do with a combination of oceanic gyre patterns and the structure of the Hadley circulation. The Sahara and other latitudes around 30N are constantly under a high-pressure zone of descending hot dry air which is part of the northern Hadley cell. The exception is over India where the Eurasian landmass pulls the ITCZ (ascending side of the Hadley cell) way far North and causses the monsoons.

I don't think flooding the Sahara would change its aridity any more than the Arabian peninsula, despite being surrounded by water, is still a desert away from the immediate coastline. It's a matter of air moisture, not sea or ground moisture. You could try irrigation, though. The Libyans abortively tried that under Gaddhafi.

lordofgibbons 671 days ago [-]
I'm not an expert in any of this but from what I know, portions of the Arabian peninsula sure do get plenty of rain for agriculture from the red sea in the western part.

>don't think flooding the Sahara would change its aridity any more than the Arabian peninsula

There's something to be said about the lake effect. It certainly happens in U.S and Canada where areas just east of the Great Lakes get much more precipitation than other parts

lainga 671 days ago [-]
I think the lake effect requires air which is colder than the water. The lowermost level of air warms and accepts water vapor, which immediately rises, re-freezes, and is entrained as ice and blown out onto land. Lake-effect precipitation does form over seas, but you need the air temperature above the surface layer to fall below zero.

As for the rain in Saudi Arabia, there is a mountain range along the coast south of Mecca, and I think the area gets rain because of orographic uplift. When the wind blows across the Red Sea it does pick up a lot of moisture, just not enough to cause rain, because the air is so hot and can hold so much moisture overall. But it gets forced up over the mountains, cools, and passes saturation humidity, and the excess water becomes rain. You can see where the mountain range ends on an annual precipitation map of SA.

Sorry to rain on your parade.

lizknope 672 days ago [-]
Some people had ideas to flood the Qattara Depression in northwest Egypt.

https://en.wikipedia.org/wiki/Qattara_Depression_Project

It would have provided hydroelectric power and as the water evaporated and formed clouds it may have increased rainfall.

The United States wanted to use nuclear bombs to excavate the channel to the Mediterranean Sea.

Consequently, use of nuclear explosives to excavate the canal was another proposal by Bassler. This plan called for the detonation in boreholes of 213 nuclear devices, each yielding 1.5 megatons (i.e. 100 times that of the atomic bomb used against Hiroshima). This fit within the Atoms for Peace program proposed by President Dwight Eisenhower in 1953. Evacuation plans cited numbers of at least 25,000 evacuees.

Project Plowshare was pretty crazy. Use nuclear bombs for excavation. There were ideas to create artificial harbors by using a bombs.

https://en.wikipedia.org/wiki/Project_Plowshare

wklauss 672 days ago [-]
> Obviously this would have an impact on the ecosystem

Anticipating the impact is probably a fool's errand, since climate is extremely complex and changes on one part of the world affect others. It's not just about displacing people in the area, you risk altering the patterns that bring rain to places as far as Germany or help grow crops in Brazil. Sahara sand plumes play a role in replenishing phosphates in the Amazon, for example. Even blanketing some parts with solar panels will probably alter global weather patterns significantly.

bushbaba 672 days ago [-]
We'd need to flood it with salt water. Best example as to why this shouldn't be done is the California Salton Sea ecological disaster.
henearkr 672 days ago [-]
What if we do not flood it, but instead make circulate a lot of salt water in open-roofed canals (but with leak-proof floor and walls) crisscrossing the desert?

Then the humidity would trigger rains and help grow a vegetation, and the salt residues would remain inside the canals.

Then at some point the vegetation would self-maintain the necessary humidity level.

filoeleven 672 days ago [-]
There are lots of ideas around for desert greening; see the linked article for a list. Canals are unlikely to work well, but seawater farming is kind of close to your proposal. It requires greenhouses to be built though, so I don’t know how well it scales.

Years ago I read about a system that seemed successful. Ridges were built up at the desert’s edge, and salt-tolerant trees and shrubs were planted on hem to keep the ground stable. This change in microclimate promoted more greening in the valleys between, which increased overall moisture levels. Once this is established, more ridges can be constructed further out to repeat the process. It’s not an easy thing to search the web for, and I don’t recall how long it takes for one ridge to be productive, but I recall thinking it was shorter than I expected (still on the order of years, of course).

https://en.m.wikipedia.org/wiki/Desert_greening

3-cheese-sundae 672 days ago [-]
Canals would silt up very fast. Also, I don't know about leak-proof water canals when humanity can't seem to make leak-proof sealed oil pipelines, and that's with significant financial incentive to do so.
PeterisP 672 days ago [-]
> Then the humidity would trigger rains

Not necessarily, given the weather conditions there it's quite plausible that all the evaporation would form clouds which would only rain elsewhere and not in that desert.

tharkun__ 672 days ago [-]
Interesting, I had to read up on that. Could you elaborate how that is related to that though and what makes it a bad idea in particular?

From what I just read up on, the Salton Sea over the millennia would periodically flood, become a small lake or dry out to desert levels. The change that occurred was that humanity changed the rhythm of this artificially to a 'flood it' state for a prolonged period of time.

They are now complaining that when they changed it to the 'small lake' state again, well, shrinking lakes create a certain situation.

The problem I do see is really the way the 'flood' state was created and other usages of the lake. Runoff from agriculture with way too much fertilizer, waste dumping etc. and now they wonder why the dust is toxic and stinks.

How would that apply to flooding the Sahara w/ sea water perpetually?

sandworm101 672 days ago [-]
>> Second, a lot of ice (eg Antarctica, Greenland) is on land so the first point doesn't apply to all ice as some deniers have tried to claim.

But what about ice that is 'on land' but also below sea level? Iirc roughly half of Antarctica's glacier ice is sitting dry ground that is below sea level. Whether melting that ice will raise or lower sea levels is more complicated, with variables for amounts above/below various points.

tomrod 672 days ago [-]
After deglaciation, land will also rebound over the long term, further displacing volume the water/ice occupies.
sandworm101 672 days ago [-]
Earth is a finite volume. So if the land rebounds in one area, does it not have to subside elsewhere?
tomrod 672 days ago [-]
It's more decompression, to my understanding

https://en.wikipedia.org/wiki/Post-glacial_rebound

sumtechguy 672 days ago [-]
You may want to look into what the permaculture people are doing. That is something that can be done today and has worked many times. Many are seeing really good results. The issue for that area is most of the vegetation was clearcut for firewood. Basically with permaculture they try to put the system back to the way it was before it was clearcut.
jfoutz 672 days ago [-]
there's another fun aspect that I think is neat. water is free to move around a little more than ice (especially ice on land). The earth is spinning, so the inertia of the water will sort of fatten the equator and thin the poles. Sea level might go down a little bit at the poles and go up around the equator.
quaintdev 672 days ago [-]
That did notmcross my mind. But this depends on whether there is enough water to cause this phenomenon or it might simply have no effect.
spenrose 672 days ago [-]
Source paper:https://www.nature.com/articles/s41467-022-30505-2

Extracting ubiquitous atmospheric water is a sustainable strategy to enable decentralized access to safely managed water but remains challenging due to its limited daily water output at low relative humidity (≤30% RH). Here, we report super hygroscopic polymer films (SHPFs) composed of renewable biomasses and hygroscopic salt, exhibiting high water uptake of 0.64–0.96 g g−1 at 15–30% RH. Konjac glucomannan facilitates the highly porous structures with enlarged air-polymer interfaces for active moisture capture and water vapor transport. Thermoresponsive hydroxypropyl cellulose enables phase transition at a low temperature to assist the release of collected water via hydrophobic interactions. With rapid sorption-desorption kinetics, SHPFs operate 14–24 cycles per day in arid environments, equivalent to a water yield of 5.8–13.3 L kg−1. Synthesized via a simple casting method using sustainable raw materials, SHPFs highlight the potential for low-cost and scalable atmospheric water harvesting technology to mitigate the global water crisis.

lr 672 days ago [-]
How about in wet, hot environments (or even cold ones), like on a boat? Watermakers are very expensive and use a lot of electricity. If one could do this on a boat to generate clean drinking water, that would be pretty amazing. Especially if one could use a tube solar oven to heat up the substance.
timerol 672 days ago [-]
Third paragraph of TFA:

> The research builds on previous breakthroughs from the team, including the ability to pull water out of the atmosphere[1] and the application of that technology to create self-watering soil[2]. However, these technologies were designed for relatively high-humidity environments.

1: https://news.utexas.edu/2019/03/13/solar-powered-moisture-ha...

2: https://news.utexas.edu/2020/11/02/self-watering-soil-could-...

CapricornNoble 672 days ago [-]
How do I use this to make Dune-style stillsuits? Maybe the gel is attached to a flagpole on your back (large surface area with airflow is what I'm thinking here), like medieval samurai, and your body's movement generates the heat that activates the thermo-responsive cellulose? The water needs to then collect in a built-in hydration bladder (aka Camelbak).
dwighttk 672 days ago [-]
Need something to cool off the human inside the stillsuit
apienx 672 days ago [-]
Thermal degradation plus oxidative processes make the claimed "scalable" water-capturing application unfeasible IMHO. The authors extract the water by heating to 60 °C. I'm surprised neither the Nat. Comm. editor nor any of the reviewers asked for a thermo-gravimetric analysis of the material.
fallat 672 days ago [-]
Ok so it's a sponge soaked in konjac and then dried? Damn, that is simple. Could easily make this yourself. I don't even see how this is patentable...

> renewable cellulose and a common kitchen ingredient, konjac gum, as a main hydrophilic (attracted to water) skeleton

(artificial sponges are made of cellulose - I learned this just last year when washing my dishes and thinking... wtf is this made of?)

---

Seems then you can:

0. Go to the dollar store

1. Buy a thin sponge

2. Buy konjac gum

3. Buy a tray

4. Place the thin sponge in the tray, mix the konjac gum with water, and pour it into the tray, and place it into your freezer, waiting for the water to evaporate...?

5. Place it now somewhere in a humid place to pull the water out of the air

---

Industrial version of this is probably a ton of thin wafers side-by-side in a cube-like fashion, so they can easily come off an assembly line

bradrn 672 days ago [-]
It doesn’t look quite that simple. The paper describes the procedure as follows:

> In a typical fabrication, LiCl powder (0.32–0.82 g) is added into 10 mL HPC solution (0–2.0 wt%) forming solution A. The pH of solution A can be tuned by NaOH or HCl solution. 0.44 g KGM powder is added into solution A and quickly cast into the petri dish after vortex. The gelation takes place within 2 min, and sit in room temperature for 15 min. Then, the film is placed in the fridge (−4 °C) for 3 h followed by 15 min freeze in liquid nitrogen. Last, the gel film is ready to use after 12 h freeze-drying.

[https://doi.org/10.1038/s41467-022-30505-2]

natch 672 days ago [-]
Dude you don’t have liquid nitrogen in your fridge? Such common kitchen ingredients. /s
dubswithus 672 days ago [-]
After the water is in the gel, how does one get it out?

Edit:

> Another designed component, thermo-responsive cellulose with hydrophobic (resistant to water) interaction when heated, helps release the collected water immediately so that overall energy input to produce water is minimized.

robinsoh 672 days ago [-]
"The captured water in the SHPF can be released by >70% within 10 min through mild heating at 60 °C under a wide range of RH (Fig. 3b and Supplementary Fig. 15). This mild heating temperature is realized by introducing the hydrophilic thermoresponsive HPC with optimized molecular weight, concentration, and pH of the initial precursor (Supplementary Figs. 9–14 and Supplementary Table 2)42"
seanw444 672 days ago [-]
So is this essentially just a non-mechanical dehumidifier? How is there enough water to pluck, when the point of an arid climate is that it's... well, arid? The air is usually as dry as the ground in those places. Or so I thought.
NickRandom 672 days ago [-]
TFA mentions some figures in paragraph 2

"The team developed a low-cost gel film made of abundant materials that can pull water from the air in even the driest climates. The materials that facilitate this reaction cost a mere $2 per kilogram, and a single kilogram can produce more than 6 liters of water per day in areas with less than 15% relative humidity and 13 liters in areas with up to 30% relative humidity."

onlyrealcuzzo 672 days ago [-]
So for about $26 - you could extract enough water to water a fruit tree indefinitely.

Doesn't seem like this would be used for agriculture at scale - but it sure could beat digging a well to get water for a house.

astroid 672 days ago [-]
I'm going to copy this comment I saw on slashdot re: this yesterday that seemed to let some of the air out of the whole press release:

"The salt mentioned is not table salt, but lithium chloride. Lithium chloride - which makes up a half by weight of the film, and is also in obvious demand for batteries, is $70/kg or so in bulk."

I haven't really dug in deep myself, but this is the comment that deflated me when reading about this yesterday, so worth looking into at least imo

UncleEntity 672 days ago [-]
> The air is usually as dry as the ground in those places.

The ground isn’t all that dry, you can dig a hole, cover it with plastic and get enough water through evaporation/ condensation to hopefully not die of dehydration if you get stranded in the desert.

Something like this would be very helpful for troops in the desert since water is heavy and resupply is very critical to keep up combat readiness. Back when I was a “speed bump in the sand” they drove us out into choke points in the Saudi desert to take out a few Iraqi tanks before they overran us in case of invasion. Assuming we were able to somehow escape contact our mission was to then try to make it to the coast and steal a boat through we probably wouldn’t have had enough water to accomplish the second part. Not even exaggerating a little bit, such is the life of a paratrooper.

pengaru 672 days ago [-]
There's never really 0% humidity in the air, I have a cabin near Joshua Tree and it rarely goes below 10% there. It tends to increase substantially at night too, which maybe something like this can harness then retain through the daytime.
paulsmith 672 days ago [-]
Gel? What I really need is a droid that understands the binary language of moisture vaporators.
WhitneyLand 672 days ago [-]
$2/kg of material to get 6 liters of water per day.

But what’s the total yield for the $2? In other words single or multiple use?

In some areas of the world there’s a serious fresh water crises. Very poor people are left buying expensive bottled water to avoid disease.

numtel 672 days ago [-]
Seems even better than MOF-based approaches [0]

The linked self-watering soil article [1] makes me wonder if the material could be used to reverse desertification.

[0] https://wahainc.com//smithsonian [1] https://news.utexas.edu/2020/11/02/self-watering-soil-could-...

devit 672 days ago [-]
Isn't this revolutionary for agricultural use?

What's the catch?

UncleEntity 672 days ago [-]
> What's the catch?

Wide scale harvesting of water from the air will change the local climate in unpredictable ways?

LNSY 672 days ago [-]
TBF, that's basically how our entire economy runs, so
qayxc 672 days ago [-]
One catch might be that it hasn't been tested at scale. The results are extrapolations from lab testing in a controlled environment.

There's quite a number of inventions and breakthroughs that looked great in the lab but never made it to real world applications.

Remains to be seen if this approach can work in practice and at scale and what the real-world implications would be.

ThinkBeat 672 days ago [-]
In my experience, just in the US the desert air is really dry. The expression "but it is dry heat", is true. I find hot desert weather much better than hot weather in humid areas.

I cant see this scaling. There is not much water to collect to begin with.

A person using it sure. A platoon sure.

But if a city of 2000 people started using I cant see it working well.

Further the moisture extracted from the air in that city would mean even drier air in other places?

mikepurvis 672 days ago [-]
Agree, yeah. Despite the lead of "more than a third of the world’s population lives in drylands", I would see this as being much more applicable to transient usage than long term. A few litres of lukewarm water per day would be perfect for backcountry camping, or topping up the reservoir in an RV, or something. But for anywhere even remotely permanent it almost certainly makes more sense to dig a well.
felipemnoa 672 days ago [-]
>>Further the moisture extracted from the air in that city would mean even drier air in other places?

I imagine moisture from other places would simply travel to his low humidity place to replace the one taken out. Should be limitless.

burlesona 672 days ago [-]
They say this material is cheap and can pull “ 13 liters in areas with up to 30% relative humidity” …

Now I’m wondering if you could use this stuff like crazy in hot, humid places and whether (a) it could pull enough water to be useful for drinking or irrigation, and (b) whether it’s possible to “locally” lower the ambient humidity (like the reverse of the urban heat island effect).

qayxc 672 days ago [-]
Getting the water out from the spongy material could pose a challenge in hot environments.

According to the paper, they use heating (60°C) to extract the water. In hot environments, however, ambient temperatures get quite close to that already (see India at the moment).

The answer to b) would be a no. The technique doesn't work in high humidity environments.

bell-cot 672 days ago [-]
With a somewhat different material, optimized for that situation, could this be made to work well in hot, humid environments?

If so, then I'm smelling a plausible solar-powered, cheap, modular "emergency life support" system for people threatened by extreme web bulb temperature conditions.

cookingrobot 672 days ago [-]
Are you sure it’s the absolute temperature of 60d that matters, or is the requirement that the sponge is hotter than the surrounding air?
qayxc 671 days ago [-]
According to the paper, it's the absolute temperature that matters. The desorption is optimal at about 60°C to 70°C, meaning the absorption-desoprition cycle wouldn't work anymore if the ambient temperature is too high. The absorption phase took place at 25°C ambient - the provided data suggests that the desorption would dominate over the absorption above about 50°C.

In conclusion, if the environment is 50°C or hotter, the sponge cannot absorb much water from the atmosphere, because the kinetics imply that the water would evaporate too quickly.

c_o_n_v_e_x 671 days ago [-]
Seems like this could have potential for recovering water that you intentionally evaporate such as evaporative cooling towers
natch 672 days ago [-]
> researchers used renewable cellulose and a common kitchen ingredient, konjac gum

“konjac gum” a common kitchen ingredient, eh? Let me just check my pantry. Odd, seems I am fresh out.

TrueDuality 672 days ago [-]
It is commonly used in Vietnamese cooking. The Konjac plant is kind of like corn. Konjac gum is like corn starch.
c_o_n_v_e_x 671 days ago [-]
Konjac noodles are a thing in Japan. They are low carb friendly as well.
russellbeattie 672 days ago [-]
California's coast is lined with mountains which capture huge amounts of water from the air as it comes in from the Pacific, usually as fog. This is why the redwoods are so massive. I have no idea if this technology works at the scale of Cali's water deficit, but I've wondered why we haven't lined the peaks of the mountains with mesh screens already. Seems like free water we're just ignoring.
samstave 672 days ago [-]
SHPF == Shit Hits the Proverbial FAN.

Would this be viable in a Window Casing/Screen? system where-by you have, instead of a "screen" you have this mesh - then with a window moulding application that funnels the water to either an "ITS ALL PIPES" type of reclaimation.....

https://www.youtube.com/watch?v=s09pfBEJYHc

WheelsAtLarge 671 days ago [-]
Desalinization plants are horrible for the environment. In short they destroy the water environment around them because they dispose of the waste left after the water is extracted from the salt water right back into the ocean. Raising the salt level to a point where few animals can live in the water.

My question is can this process be scaled to the point of replacing the standard desalinization plant?

josephcsible 671 days ago [-]
Oceans are big, and there's no barriers to diffusion. Why would the extra salt be concentrated enough to cause a problem?
WheelsAtLarge 671 days ago [-]
It is hard and expensive to diffuse the brine that's left after the freshwater is extracted. The whole ocean is not affected but it's the area around the plant. Which can be a very large.

https://www.scientificamerican.com/article/slaking-the-world....

miguelmichelson 671 days ago [-]
This is happening in the driest desert in the world, this is a simpler but effective technique to get water out of the desert fog https://youtu.be/w5cBSORuB6w?t=35
Animats 672 days ago [-]
It's from U. Texas. Texas has the climate in which that technology should work, and a need for more water. This ought to be fundable and buildable entirely within Texas. When will the first plant be built?
rodolphoarruda 672 days ago [-]
"Proudly made in Arrakis"

Fremen Inc.

mise_en_place 672 days ago [-]
I’ve been hearing about so-called hydropanels too. Maybe they work similarly? It looked like junk science when I initially saw one producer of these, called Source Global. It seems to be a real thing, however.
1minusp 672 days ago [-]
any experts who can verify the validity of the claim of being low cost?
aaron695 671 days ago [-]
silencedogood3 672 days ago [-]
silencedogood3 672 days ago [-]
Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact
Rendered at 07:02:05 GMT+0000 (Coordinated Universal Time) with Vercel.