> which was tested on an MIT building rooftop. The system delivered pure water that exceeded city drinking water standards, at a rate of 5.78 liters per square meter
I would be very interested to see data on this vs. sunlight and climate conditions, in what weeks/month of the year they tested it. I think its effectiveness would be highest at MIT's location from late April to end of September and considerably less in colder/overcast/less sunny weather and winter.
"They have developed a completely passive system that is based on a foam-like material that draws moisture into its pores and is powered entirely by solar heat."
> They assert that if the system is scaled up to the size of a small suitcase, it could produce about 4 to 6 liters (1 to 1.5 gallons) of drinking water per hour and last several years before requiring replacement parts. At that scale and performance, the system could produce drinking water at a rate and price that’s cheaper than tap water.
> A scaled-up device could passively produce enough drinking water to meet the daily requirements of a small family. It could also supply off-grid coastal communities near seawater.
> Is it portable? For example, the article mentions Burning Man. Could you theoretically bring this to a desert and extract water from the air? There's probably enough sunlight in a typical desert to power the solar panels, but is there enough water moisture in the air to extract?
You could not do this at Burning Man. During the event, the humidity level is something like 3%. You literally don't sweat at Burning Man.
> Last year, he formed a company called Water Harvesting that this fall plans to release a microwave-size device able to provide up to 8 liters per day. The company promises a scaled-up version next year that will produce 22,500 liters per day, enough to supply a small village. “We’re making water mobile,” Yaghi says. “It’s like taking a wired phone and making a wireless phone.”
Any ballpark estimates on the cost for a residential use unit? i.e. 200L-1000L/day
Also, is it feasible for this to markedly effect downstream areas?
i.e. If there's eastwardly wind flowing through Nevada where machines are extracting humidity at an extreme scale, how might the 30%+ humidity-requiring plants (i.e. that Jamaican Yerba) in Utah hold up?
water wars 2.0, version: air.
humidity credits & humidity sink surveillance with humidobfuscation 'consultants'.
I read that differently. On the one hand, there is the experimentally confirmed drop a minute. On the other hand, they do not state that that half liter has been confirmed experimentally.
I still doubt that number. Looking at http://atmosphericwatersolutions.com/wp-content/uploads/2012..., I see a machine that weighs 38 kg, consumes 373W of power, and produces 'up to 17 liters of water a day'. This thing would be an order of magnitude smaller, and produce almost the same quantity of water. Possible? Maybe. Likely? No. Because of that, I would like to see experimental confirmation of that half a liter per hour before accepting it as a given.
Also, see http://en.m.wikipedia.org/wiki/Atmospheric_water_generator which claims the U.S. army and FEMA use a system that needs a gallon of fuel for 'up to' five gallons of water. If something like this were known to be more efficient, I think it is likely they would use it.
"When one end of the panel is placed in dirty water, it draws a thin layer of water upwards, which evaporates in the sun, purifying it. By placing the panel inside a glass box, the team collected the evaporated water for use, separating it from the dirty water with a layer of insulation."
3 cm^2 of the material produced 5 ml of water in 2 hours. They don't say what it cost to make.
Don't forget that most of the water you sprinkle onto the roof will collect in the gutters which can feed immediately back into the tank, so you only need enough water for a few cycles plus 24 hours of evaporation loss - still a decent amount of water, but a lot more like a large garden water-butt than an industrial tank.
>Eventually it’s hoped that buildings will be completely self-sufficient, or “water neutral,” using the same water over and over, potable and nonpotable, in a closed loop.
I can't see that working have they not heard of evaporation? It would work but need a top up. It's a good idea to save water but it may need some fine-tuning for technical reasons and for acceptance by people.
I'm a little confused then, later in the article it says "The team estimates that a system with a roughly 1-square-meter solar collecting area could meet the daily drinking water needs of one person." So something doesn't add up.
[Edit: the paper is available at https://pubs.rsc.org/en/content/articlehtml/2020/ee/c9ee0412.... It says, "To meet the average daily water intake for one adult (˜3.2 L),49 100 TMSS devices can be placed into a 10 × 10 array, filling an 1 m2 area, which would provide approximately 10–20 L of clean water every day depending on the weather condition."
The lower bound of 10l is outdoor performance on a partly sunny day. So I think they are just being conservative by saying it would meet the requirements of one person - coastal areas are frequently cloudy, and in some locations, there might be little sun for extended periods of time.]
Its much more than that. Here are the requirements they met (listen in the second paragraph)
"easily deployable high-volume water generator that can be used in any climate, meeting the competition parameters of extracting a minimum of 2,000 liters of water per day from the atmosphere using 100 percent renewable energy, at a cost of no more than two cents per liter."
> ...which harnesses a temperature difference within the device to allow an adsorbent material — which collects liquid on its surface — to draw in moisture from the air at night and release it the next day.
Device harness water from "dry" air ... by collecting from "wet" air and dispensing water when it detects a camera. What a crock.
>>Eventually it’s hoped that buildings will be completely self-sufficient, or “water neutral,” using the same water over and over, potable and nonpotable, in a closed loop.
So a condo/apartment has it's own elevators, solar rooftop, and now a hi reliability water recycling system that can support a few hundred units.
Wow, I was under the impression that atmospheric water harvesting (AWH) was extremely inefficient. I don't have any numbers but things like [1][2] seem to indicate that AWH is currently not very useful.
The paper doesn't seem to (if I read it correctly) actually address this directly, instead it talks about how much energy is needed to extract water at different relative humidity levels and factors in the potential energy generated through solar panels. It also looks at the usefulness of this process given factors such as existing access to clean water (or lack thereof) and population. I didn't looking beyond the 'Methods' section, I hope I didn't miss anything here.
That sounds more in line with what I'd expect from Massachusetts sunshine.
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