Tag Archives: megadrought

Pulling water from the air

Adele Peters’ May 27, 2022 article for Fast Company describes some research into harvesting water from the air (Note: Links have been removed),

In Ethiopia, where an ongoing drought is the worst in 40 years, getting drinking water for the day can involve walking for eight hours. Some wells are drying up. As climate change progresses, water scarcity keeps getting worse. But new technology in development at the University of Texas at Austin could help: Using simple, low-cost materials, it harvests water from the air, even in the driest climates.

“The advantage of taking water moisture from the air is that it’s not limited geographically,” says Youhong “Nancy” Guo, lead author of a new study in Nature Communications that describes the technology.

It’s a little surprising that Peters doesn’t mention the megadrought in the US Southwest, which has made quite a splash in the news, from a February 15, 2022 article by Denise Chow for NBC [{US} National Broadcasting Corporation] news online, Note: Links have been removed,

The megadrought that has gripped the southwestern United States for the past 22 years is the worst since at least 800 A.D., according to a new study that examined shifts in water availability and soil moisture over the past 12 centuries.

The research, which suggests that the past two decades in the American Southwest have been the driest period in 1,200 years, pointed to human-caused climate change as a major reason for the current drought’s severity. The findings were published Monday in the journal Nature Climate Change.

Jason Smerdon, one of the study’s authors and a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory, said global warming has made the megadrought more extreme because it creates a “thirstier” atmosphere that is better able to pull moisture out of forests, vegetation and soil.

Over the past two decades, temperatures in the Southwest were around 1.64 degrees Fahrenheit higher than the average from 1950 to 1999, according to the researchers. Globally, the world has warmed by about 2 degrees Fahrenheit since the late 1800s.

It’s getting drier even here in the Pacific Northwest. Maybe it’s time to start looking at drought and water shortages as a global issue rather than as a regional issue.

Caption: An example of a different shape the water-capturing film can take. Credit: The University of Texas at Austin / Cockrell School of Engineering

Getting back to the topic, a May 23, 2022 University of Texas at Austin news release (also on EurkeAlert), which originated the Peters’ article, announces the work,

More than a third of the world’s population lives in drylands, areas that experience significant water shortages. Scientists and engineers at The University of Texas at Austin have developed a solution that could help people in these areas access clean drinking water.

The team developed a low-cost gel film made of abundant materials that can pull water from the air in even the driest climates. The materials that facilitate this reaction cost a mere $2 per kilogram, and a single kilogram can produce more than 6 liters of water per day in areas with less than 15% relative humidity and 13 liters in areas with up to 30% relative humidity.

The research builds on previous breakthroughs from the team, including the ability to pull water out of the atmosphere and the application of that technology to create self-watering soil. However, these technologies were designed for relatively high-humidity environments.

“This new work is about practical solutions that people can use to get water in the hottest, driest places on Earth,” said Guihua Yu, professor of materials science and mechanical engineering in the Cockrell School of Engineering’s Walker Department of Mechanical Engineering. “This could allow millions of people without consistent access to drinking water to have simple, water generating devices at home that they can easily operate.”

The researchers used renewable cellulose and a common kitchen ingredient, konjac gum, as a main hydrophilic (attracted to water) skeleton. The open-pore structure of gum speeds the moisture-capturing process. Another designed component, thermo-responsive cellulose with hydrophobic (resistant to water) interaction when heated, helps release the collected water immediately so that overall energy input to produce water is minimized.

Other attempts at pulling water from desert air are typically energy-intensive and do not produce much. And although 6 liters does not sound like much, the researchers say that creating thicker films or absorbent beds or arrays with optimization could drastically increase the amount of water they yield.

The reaction itself is a simple one, the researchers said, which reduces the challenges of scaling it up and achieving mass usage.

“This is not something you need an advanced degree to use,” said Youhong “Nancy” Guo, the lead author on the paper and a former doctoral student in Yu’s lab, now a postdoctoral researcher at the Massachusetts Institute of Technology. “It’s straightforward enough that anyone can make it at home if they have the materials.”

The film is flexible and can be molded into a variety of shapes and sizes, depending on the need of the user. Making the film requires only the gel precursor, which includes all the relevant ingredients poured into a mold.

“The gel takes 2 minutes to set simply. Then, it just needs to be freeze-dried, and it can be peeled off the mold and used immediately after that,” said Weixin Guan, a doctoral student on Yu’s team and a lead researcher of the work.

The research was funded by the U.S. Department of Defense’s Defense Advanced Research Projects Agency (DARPA), and drinking water for soldiers in arid climates is a big part of the project. However, the researchers also envision this as something that people could someday buy at a hardware store and use in their homes because of the simplicity.

Yu directed the project. Guo and Guan co-led experimental efforts on synthesis, characterization of the samples and device demonstration. Other team members are Chuxin Lei, Hengyi Lu and Wen Shi.

Here’s a link to and a citation for the paper,

Scalable super hygroscopic polymer films for sustainable moisture harvesting in arid environments by Youhong Guo, Weixin Guan, Chuxin Lei, Hengyi Lu, Wen Shi & Guihua Yu. Nature Communications volume 13, Article number: 2761 (2022) DOI: https://doi.org/10.1038/s41467-022-30505-2 Published: 19 May 2022

This paper is open access.