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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.
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!
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).
Indeed. A lot of people don't like the YouTuber Thunderf00t, for good reason, but he's done some good videos debunking the concept. Starting with the WaterSeer, Zero Mass Water and of course the self-filling waterbottle.
TL;DR: yes, it can be done. Yes, it's been done. But it's cheaper and easier to load a tank of water on a helicopter or truck and take it to where it needs to be.
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