Technology

Harvester pulls 1.5 gallons of drinking water from arid air per day

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MIT has developed a new device that can harvest drinkable quantities of water from dry air
MIT has developed a new device that can harvest drinkable quantities of water from dry air
A diagram illustrating the design of the new water harvester
Xiangyu Li

It’s an unfortunate irony that while many regions struggle to find enough water, there’s trillions of liters of the stuff floating around in the air everywhere. A new water harvester design from MIT can pull enough fresh water out of the air to meet the daily needs of several people.

Water harvesters are usually made up of adsorbent materials, meaning they collect water on their surfaces. To maximize the surface area exposed to the air, this new device is made up of a series of vertical fins spaced 2 mm (0.08 in) apart. These fins are made up of copper sheets, sandwiched in copper foams and then coated with a specialized zeolite material which is often used for water adsorption.

A diagram illustrating the design of the new water harvester
Xiangyu Li

After an hour the fins are saturated with water, so the copper sheets are heated up to release it. If this cycle is performed 24 times per day, in air with 30% humidity (classed as arid), the team estimates the harvester can produce up to 1.3 L (0.3 gal) of drinkable water per day per liter of the adsorbent coating used. Scaled up, that’s 5.8 L (1.5 gal) per kilogram (2.2 lb) of material used per day, which is enough to satisfy several people’s daily water needs.

While there’s no shortage of other water harvesters in the works, this one has a few advantages. For one, it collects more water than most – some can only fetch 100 ml (1.5 oz) of water per kg of material. A Johns Hopkins design sounds particularly impressive, harvesting 8.66 L (2.3 gal) per day per kg of material, but these tests were conducted at 70% humidity. The new design can also work consistently throughout the day and night, where others collect their water overnight and release it in the morning.

The potential downside is that this system requires energy to release the water – the base of the device needs to reach 184 °C (363 °F) to wring it out. But the team says the device can tap into waste energy or heat from other systems, like buildings or vehicles.

The research was published in the journal ACS Energy Letters.

Source: American Chemical Society

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11 comments
warmer
"1.5 gal) per kilogram (2.2 lb) of material used per day, which is enough to satisfy several people’s daily water needs". <--- is that a quote from the maker or the author of this article? Either way that is 100% not accurate. That is hardly enough drinking water for 1 human. Several? Wtf are you smoking
Captain Danger
Warmer, not everyone needs to be sucking back water at a gallon a day.
1.5 gallons (us)= 192 oz even at 64 oz per day (which is a lot) that works out to 3 people which a a few.
Shorter rations can boost that up to several.
And this at %30 humidity. I expect performance would improve at higher levels.

Expanded Viewpoint
At basal metabolic rate (resting), the average Human body radiates about 1/3 pint of water per hour just to maintain a proper temperature. I recall that factoid from my 8th grade biology class. Have Human bodies changed that much since 1969?
Baker Steve
This is exactly the same principle as commercial absorptive dehumidifiers. i don't think they heat their Zeolite to such a high temperature though.

Warning: the resulting 'water' will contain a lot else than water.
David F
As a lower energy alternative to heating, could suitable vibration of the plates dislodge accumulated water.
joeblake
During summer in Perth, Western Australia it can reach 43 degree C and one portable refrigerated air conditioner (drawing 1150 watts of solar power) has produced 10 litres (2.1 Imperial gallons) of water just as a by-product. When filtered through a reverse osmosis cartridge and sterilised with UV light it provides far more water than I can drink comfortably in a day, and I ride a bicycle every day.
Karmudjun
@Warmer - human hydration requirements under normal conditions (not extreme conditions, just daily life conditions) are just under 2 Liters, here in the States we recommend people drink 2 quarts (1.89 L/day) unless pregnant, lactating, or children. The elderly tend to drink less in 'normal life', but they still require the similar amount. In common parlance, several people easily means 3 people, and 1.5 gallons is 5.67 Liters. If your anecdotal drinking water needs exceed 3 Liters, unless you work outside in extreme heat, you should see a physician as there are several conditions that increase water consumption. If you have none of those conditions, my apologies!
Karmudjun
Michael, I am always interested in ways we can reduce climate change and alter our dependence upon our "natural" resources. Here in USA several states have pulled their aquifers into deficit conditions with subsequent reduction in land height to sea level. Florida has frequently had to abandon wells due to saltwater infiltration. I read the source article and nowhere did I figure out if this was financially feasible to scale up - frankly I don't know the cost of zeolite material application and the durability, so I can't even fathom the cost of commercialization. Still, a long camping trip could be easier with this device and solar cells. Thanks
PaulD
Some wonderful Technology right there. Regardless of which one does the best job at it, and at lowest cost or highest yield, can we get a glimpse int other surrounding issues? How does it deal with airborne dust which is so prevalent in Arid and Semi arid environments? How is the hygiene of the device taken care of to ensure the water is truly safe for human consumption? What are the consumable portions of the materials used? Regardless of the answers, I would go with the Copper based devices and much less the polymeric ones primarily due to the fear of microplastics in the water. Although I must say the tech is much needed now as more and more cities and populations face or experience severe water shortages. Let the technology be made affordable and it will see wide adoption, especially in developing countries where drinkable water is scarce or very expensive.
Jeff
Would this make arid locations more arid? Taking what little water there is out of the environment, might make regional vegetation and animals dehydrate?