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A Device That Can Pull Drinking Water From the Air Just Won the Latest XPrize (fastcompany.com)
Two years ago, XPrize, which creates challenges that pit the brightest minds against one another, announced that it would give any startup or company $1 million that can turn thin air into water. This month, it announced that the challenge has been concluded. From a report: A new device that sits inside a shipping container can use clean energy to almost instantly bring clean drinking water anywhere -- the rooftop of an apartment building in Nairobi, a disaster zone after a hurricane in Manila, a rural village in Zimbabwe -- by pulling water from the air. The design, from the Skysource/Skywater Alliance, just won $1.5 million in the Water Abundance XPrize. The competition, which launched in 2016, asked designers to build a device that could extract at least 2,000 liters of water a day from the atmosphere (enough for the daily needs of around 100 people), use clean energy, and cost no more than 2 cents a liter.
"We do a lot of first principles thinking at XPrize when we start designing these challenges," says Zenia Tata, who helped launch the prize and serves as chief impact officer of XPrize. Nearly 800 million people face water scarcity; other solutions, like desalination, are expensive. Freshwater is limited and exists in a closed system. But the atmosphere, the team realized, could be tapped as a resource. "At any given time, it holds 12 quadrillion gallons -- the number 12 with 19 zeros after it -- a very, very, big number," she says. The household needs for all 7 billion people on earth add up to only around 350 or 400 billion gallons. A handful of air-to-water devices already existed, but were fairly expensive to use. The new system, called WEDEW ("wood-to-energy deployed water") was created by combining two existing systems. One is a device called Skywater, a large box that mimics the way clouds are formed: It takes in warm air, which hits cold air and forms droplets of condensation that can be used as pure drinking water. The water is stored in a tank inside the shipping container, which can then be connected to a bottle refill station or a tap.
"We do a lot of first principles thinking at XPrize when we start designing these challenges," says Zenia Tata, who helped launch the prize and serves as chief impact officer of XPrize. Nearly 800 million people face water scarcity; other solutions, like desalination, are expensive. Freshwater is limited and exists in a closed system. But the atmosphere, the team realized, could be tapped as a resource. "At any given time, it holds 12 quadrillion gallons -- the number 12 with 19 zeros after it -- a very, very, big number," she says. The household needs for all 7 billion people on earth add up to only around 350 or 400 billion gallons. A handful of air-to-water devices already existed, but were fairly expensive to use. The new system, called WEDEW ("wood-to-energy deployed water") was created by combining two existing systems. One is a device called Skywater, a large box that mimics the way clouds are formed: It takes in warm air, which hits cold air and forms droplets of condensation that can be used as pure drinking water. The water is stored in a tank inside the shipping container, which can then be connected to a bottle refill station or a tap.
It's called a dehumidifier.
Dave from EEVBlog loves to rip these kinds of scams apart, he's already done a good number of rant-videos on similar "water out of thin air" - systems. I'm waiting excitedly for one on this shit, too!
That's not infeasible. It's just incredibly inefficient, that's all.
1500 times 67.6 cu m is just over 100,000 cubic metres.
I just pulled up a building-site fan - Clarke CAM110 30â Drum Electric Fan (110V) - 350W
Max air flow 200m3/min.
So it would take 500 minutes to pull through that much air, which is just 8 1/3 hours. So just a bog-standard, low-power building-site fan on the side, ducted to pull fresh air in, circulate it through the system, and then blow it out, would be able to do three times that in a day. I'm sure a lower power solution would exist to do just what the system can take and no more.
Take into account the halved humidity and it's still viable.
The question is really whether or not after pumping 100,000 cubic metres of outside air through it the water is contaminated with all kinds of crap, not to mention having to clean and change filters constantly. That kind of fan would build up a layer of dust-strands, hairs, etc. with in days even in a relatively clean air, then you're blowing that through a system trying to collect water from it, and having to filter it. Things like airborne dust etc. are going to need lots of filters in the path of both the air, and the water collection.
That's not to say it's completely ridiculous. It would, indeed, be able to make water out of thin air. I would just posit that it's probably easier and cheaper to ship a few bottles, or dig a well.
Especially if you consider that to be self-powered, it probably needs an entire roof of solar - anywhere people are desperate for water, shipping an entire container of very expensive (and valuable, which is different) electronics and metals out there probably is going to be subject to short-sighted selfishness, otherwise known as theft. Solar panels and refrigeration equipment like that is going to be worth a fortune in such a place.
Though it could probably "profit" after a number of years of flawless operation without maintenance costs, I could easily imagine that production costs, transport, maintenance, etc. would make it less viable than just shipping some Evian or a well-borer.
And it has zero value in any place that's not literally desert... nobody's going to buy an incredibly expensive box in order to get a few thousand litres out of it if there's a river even within a hundred miles. Thus the market is really quite tiny.
It's the kind of thing you'll see in a science museum in 50 years, just sitting them offering a free cup of water to visitors.
To condense water out of the air you need to dissipate _at_ _least_ the latent energy of evaporation. That's 2.2MJ/kg or 0.7 kWh*hr in other words, A LOT. If you want to use a solar panel, that would be around 4 square meters to produce that much energy in 1 hour, even taking into account that freezers have >100% efficiency.
So a fairly large 4x4 meter solar panel (that would cost around $5000 to install) will produce around 50 liters of water per day (that's an optimistic estimate), or around 18 tons of water per year. If usable life of the device is 10 years then we're looking at about 200 tons for about $5000, or 4 cents per kg.
To be fair, it's not well-reported but the other half of the technology is these biomass gasifiers: http://allpowerlabs.com/ This is not ambient atmosphere water extraction but extraction from biomass. Also not a scam. Get educated before you throw around your armchair physicist hot takes, guys.
Nothing new here folks.
Commercial Atmospheric water generators have been around for a long time
see https://en.wikipedia.org/wiki/...
The military routinely use them in desert areas.
They do take a fair amount of energy to run, but not as bad as you might think if transverse flow heat ex changers are used to recover lost heat (and cold).
100 % humidity means 30 grams (0.03l) of water per cubic meter. Today in the UK we are at 70%, so lets say theres 20g on a bright autumn morning.
You'd be lucky, 100% humidity is only 30 grams at 30 degrees C. At 10 degrees, more typical for a UK autumn morning it is less than 10g per litre. I Nairobi it is 20 degrees C now so your figure is closer there (17g/m^3 100% humidity).
Water content depends on the temperature too, so you only get 30 g per m^3 at 30 deg and 1 atm. If the temperature is lower you get less. So your estimate of 20 g in the UK is most likely too high (unless it was 30 deg near you). Yesterday it was 18 deg and 64% RH at my local RAF base, which gives only 10 g/m^3.
Anyway, take Nairobi, today it'll be 24 deg and 38% RH, which gives 9 g/m^3, in the evening it'll be 18 deg and 72% RH, which gives 11 g/m^3 (about the same which makes sense). So the volume flow through the container will need to be 200,000 m^3 per day, which is about 3,000 cycles per day. To be fair, while that sounds like a lot, 200,000 m^3 per day is only 2.3 m^3/s. To put that into perspective that's 1 m/s airflow through a 1.5 x 1.5 metre aperture.
The other thing to look at is the power consumption - a portable "industrial" dehumidifier extracts 70 litres / day, consuming 1.35 kW - that is 0.466 kWh / litre. We'll be generous and assume this device is twice as efficient, so that gives us 466 kWh to provide 2,000 litres of water, which is just under 20 kW power consumption.
The numbers don't sound altogether unreasonable. Unlike so of the other water out of air "solutions" - *cough* WaterSeer - they're not assuming they can do it passively, so that's a start...
I have a dehumidifier. Over time, there is stuff building up, but compared to the amount of water, it is not much. If the choice was between no water and the dehumidifier water, the choice is really simple.
In addition, filtering the water is a very simple thing to do.
Have a look at their web site: https://islandsky.com/products...
They have a range of these things and seem to be selling a reasonable number. Most are much smaller than required for the X Prize. So they stuck a few of them in a shipping container, and added a biomass generator to meet the carbon neutral / low running cost requirements.
You need a lot of energy for those things. The 378L/day one (at 50% RH) needs 4.2kW. They claim that biofuel gassifiers are already in use in India.
It's marginal but interesting. Their use case if where there is local water available but over-use is causing problems like acute droughts.
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SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
"The 378L/day one (at 50% RH) needs 4.2kW"
The bigger ones have 30KW diesel generators in them.
This isn't "water for free, forever", this is "a pittance of water at ongoing costs, fuelled by oil or wood or similar burning".
Sure, you can slap some solar panels and maybe you'd get your 4.2KW out of them... but then the purchase cost is going to be prohibitive and the running costs are going to be non-zero even then (water tanks and solar aren't the kind of things you can just leave unmaintained in a desert forever). It also makes it a target ripe for theft.
I would hazard that if you put a 30KW diesel generator, plus fuel, or 4KW of solar panels, etc. in a place where people can't afford/obtain water, it won't be long before bits "go missing" and end up on the black market in exchange for... well... some water, eventually, most likely.
From their own FAQ:
What happens when thereâ(TM)s low humidity in the air?
When the humidity is low, all air to water machines are challenged. Skywater machines are not designed for dry or cold climates and are not marketed there.
It condenses money out of thin air!
=Smidge=
The carbon-negative claim is based upon the supposition that in its deployment, the magic water box would occasionally be near a forest with abundant dead trees that are at risk of spontaneous atmospheric carbon liberation.
(Disclosure: I am part of the team that provided the biomass gasifier.)
This is an incorrect claim. The carbon negative claim comes from the fact that the process of gasification produces charcoal as a byproduct, and charcoal does not revert to carbon dioxide without combustion (somewhat simplified but sufficient summary), whereas the biomass nearly entirely reverts to carbon dioxide in the course of decomposition. The more thorough explanation is that the charcoal has a labile (biodegradable) fraction and a recalcitrant fraction. The labile fraction takes years if not decades to decompose, and the recalcitrant fraction essentially doesn't participate in the carbon cycle.
See this on the processes of gasification:
http://www.allpowerlabs.com/gasification-explained
The charcoal is sent through the compost and used as biochar. When used in this way, it enriches the soil for the long term and results in several effects which cause the soil to take up more carbon—firstly, by increasing the soil's capacity to hold on to plant root exudates while stimulating the production of these exudates, and secondly, because the plant exudates stimulate the growth of fungal mycelia.
Fungal mycelia contain a glycoprotein called glomalin, which has a long soil lifetime—roughly 50 years. In this way, the production of charcoal and its use as biochar actually takes carbon out of the carbon cycle and parks it in the soil. Soil fungal glomalin is one of the potential carbon draw-down solutions seriously being considered to draw down carbon dioxide levels from the atmosphere.
See this about glomalin as a carbon sink:
https://www.nature.com/articles/s41598-017-12731-7
I'm on the gasifier team from All Power Labs, the company that provided the gasifier genset to the Skysource/Skywater Alliance. Bear with me as I correct some misconceptions here.
Firstly, I would like to make clear that we're not cutting down fresh trees to do this. It is not cost-effective nor sustainable to cut down fresh trees to gasify, especially when there is so much woody biomass waste. There are plenty of companies paying folks to get rid of their biomass waste, including wood chips and nut shells.
Secondly, a bit of nuance required. The machine is not "burning wood"; it is gasifying wood. Wood consists of roughly 80% volatiles, 20% fixed carbon. The gasifier pyrolyzes the wood, which produces tar gases (wood smoke); the tar gases are partially burned while thermally cracking the rest, and the combustion products are percolated through the charcoal. A portion of the charcoal is consumed via reduction reactions that convert the H2O and CO2 from burnning the tar gases into H2 and CO gas, which are then sent to power the engine. Essentially, the gasifier is burning the tar, and un-burning it with the char, then re-burning it in the engine. The heat that would otherwise be dissipated is being used to drive the CHP system.
See our explanation of how gasification works:
http://www.allpowerlabs.com/gasification-explained
Thirdly, the carbon-negative claim comes from the following accounting: the biomass waste almost entirely reverts to carbon dioxide via decomposition, but when run through gasification, a significant fraction of the fixed carbon portion is not consumed, and is pushed out of the gasifier as charcoal. Since charcoal is stable and does not revert to carbon dioxide without combustion, it is effectively removed from the carbon cycle.
Furthermore, we specifically save the charcoal for use as biochar. We send the char through the compost so it can absorb nitrates and phosphates and other nutrients that tend to leach out of compost as leachate. This also fills the char with compost microbes, and conditions the surface to have a humus like quality, which enhances the cation exchange capacity and water holding capacity of soil that is amended with this material. The effect that biochar has on soil parks even more carbon in the soil for the long term. Humified biochar (co-composted biochar) dramatically stimulates the release of plant root exudates (roughly 10 units of exudates per unit of black carbon—humus or humified biochar) and holds on to these exudates for resident microbes to use. These root exudates then stimulate a dramatic increase in soil fungal mycelia (also roughly 10x). This is sometimes referred to as the carbon multiplier effect: 1 unit of black carbon supports 10 units of green carbon (plant exudates) on an ongoing basis, which stimulates the growth of 10 units of white carbon (fungal mycelia).
Fungal mycelia contain a lot of glomalin, a glycoprotein that is a significant carbon sink. Glomalin remains in soil for an estimated 50-60 years.
See this piece from the USDA on Glomalin as a carbon sink:
https://www.ars.usda.gov/news-events/news/research-news/2008/glomalin-is-key-to-locking-up-soil-carbon/
See this piece on how biochar stimulates arbuscular mycorrhyzae (soil fungi symbiotic with plant roots, exchanging phosphorous for plant exudates):
https://www.sciencedirect.com/science/article/abs/pii/S0038071714002211