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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.
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.