This Device Pulls Water From Thin Air—Even in Death Valley

It’s easy to take safe drinking water for granted. In most developed countries, access to safe water takes a simple flip of a kitchen tap or a run to the grocery store.

But over two billion people worldwide lack easy access to clean water, which can lead to diseases such as cholera. And the problem is getting worse as demand for water in farming and other industries increases.

One blue-sky solution may literally come from the sky. A team from MIT developed a window-sized portable device that pulls water vapor from the atmosphere. The sandwich-like contraption includes an origami-like hydrogel to capture moisture at night. As day breaks, it releases water vapor onto glass panels where the vapor condenses into drinking water.

The device, dubbed atmospheric water harvesting window, or AWHW, generated a modest amount of water in different environments—including a humid urban setting in Massachusetts and the desert of Death Valley.

It’s performance is “remarkable,” wrote Jiabin Liu and Shaoting Lin at Michigan State University, who were not involved in the work.

Liker solar panels, the device could produce more water if it was bigger or multiple were stacked into vertical “water farms.” For now, its portability could potentially aid thirsty hikers or soldiers trekking through hot terrain.

“We imagine that you could one day deploy an array of these panels, and the footprint is very small because they are all vertical,” said study author Xuanhe Zhao in a press release.

Compared to bottled water, the device is highly cost-effective. “The economic advantage makes it a potentially off-grid solution for communities facing persistent water scarcity,” wrote Liu and Lin. The device “offers a practical and deployable solution for providing affordable family-scale drinking water.”

Cheers

Thirst is deadlier than hunger. Our bodies need water to work. Without enough hydration, fatigue and dizziness rapidly set in. The brain struggles to process thoughts, while rising heart and breathing rates add stress to the body. Extended periods of dehydration can lead to multiple organ failure.

It’s no wonder people have invented ways to harvest drinkable water for millennia. From South America’s Atacama Desert to Egypt, archaeologists have found human-made piles of stone arranged so condensation from fog or dew trickles down the walls and is stored within.

We no longer need stones, but harvesting atmospheric water vapor as drinking water is just as valuable today. In one estimate, the air around us holds roughly 13,000 trillion kilograms of water—an abundant resource ripe for collection.

How? One idea is to use hydrogel as a sponge. Like the materials used in diapers, hydrogels soak up water vapor, but coaxing them to release it has been a challenge. Earlier approaches involved water-absorbing desiccants—like the packets inside some crunchy foods—that release water when heated. But this setup requires an additional energy source and is hard to scale up.

Another problem is that most hydrogels are rather “salty.” These soft and porous materials have microscopic networks of interconnecting channels that capture water vapor. It’s common to  spike them with a type of naturally absorbent salt to capture even more. But these salts can leak into the water during extraction and make in undrinkable.

The new design prevented salt from leaking into the water a dab of syrupy glycerol. An initial lab test found salt levels in the water were far below the threshold for safe drinking water.

The team also shaped the hydrogel into a dome-like origami array, like a sheet of bubble wrap. The unique structure increased surface area and maximized how much the material could swell so it would hold more water vapor. The team then sandwiched the gel between two glass panels roughly the size of a small window, both coated with a cooling chemical layer, and added tubing to collect the water.

The device captures moisture from ambient air at night. As the sun rises, the temperature of the hydrogel increases, and it releases water as vapor. The vapor hits the glass, cools and condenses on the panels, and drips into the collection tube.

Early stress tests found the panel stood the test of time, retaining roughly 90 percent capability after 340 cycles—equivalent to nearly one year of continuous use every day.

Road Trip

For the ultimate test, the team traveled to California’s Death Valley, one of the driest and hottest places in the world. They monitored the panel’s performance for a week with humidity ranging from 21 to 88 percent—the latter mostly at night—as the panel was blasted by relentless dry heat.

On the higher end, the device captured a respectable 161.5 milliliters, or roughly 5.5 ounces, of water. That’s still a far cry from a small cup of coffee, but the drippings came from just a single, unpowered panel in the desert. The team estimates the panels should last at least a year, “setting the benchmark in daily water production and climate adaptability,” they wrote.

The water harvester is the latest in a push to draw drinkable water from air. A complementary design, called the metal-organic framework, also uses natural cooling and ambient sunlight as energy to capture water in porous channels. The design’s materials more rapidly release water compared to hydrogels, making them potentially more efficient, but they store less.

Cost is always an issue for practical use. Another recent study showed hydrogels could be made from plant-based materials commonly found in food waste. The dirt-cheap biomaterials were tweaked to rapidly expand upon absorbing water and shrink when heated—like a sponge squeezing out water. This design needs to reach at least 60 degrees Celsius or 140 degrees Fahrenheit to release stored water. But with power from  solar panels, it could be useful in emergency situations or off-grid communities.

For now, the MIT team is trying to make arrays out of their device. “It’s a test of feasibility in scaling up this water harvesting technology. Now people can build it even larger, or make it into parallel panels, to supply drinking water to people and achieve real impact,” said Zhao.