It is often said that necessity is the mother of invention. So, it’s only fitting that Mother Nature is forcing us to innovate around one of the longest droughts the Southwest has ever seen. And the solution to our survival may be hidden right in front of us.
H. Jeremy Cho, an assistant professor in UNLV’s department of mechanical engineering, leads a research team that’s studying atmospheric water harvesting — or capturing water vapor in the air around us and transforming it into drinkable water.
“There is a vast quantity of water in the air,” said Cho. “It’s kind of a hidden ocean. But you can’t just swing a net and catch all that water and turn it into a liquid. You have to play some thermodynamic tricks to get it into that form.”
The process has its roots in nature – and that is exactly where he looked for inspiration. Specifically, desert air plants hydrate themselves by absorbing water through osmosis in their leaves. That’s the driver behind the creation of a new device capable of capturing, storing, and releasing water.
His particular approach is designed for low-humidity environments, relies on solar energy, and requires lithium-based materials to function.
“Those are ingredients that exist naturally here in Nevada, creating the perfect cocktail of conditions for this to work,” said Cho. “If I can demonstrate it here in Las Vegas, which happens to be the driest major city in America and is always in the redzone for water scarcity, then I think this research will really resonate with the local population.”
Water capture is measured by how many liters of water are created every day, per square meter footprint of a device. In short, liters per square meter per day. For competing research that has occurred in more humid locations, daily yields of 1-3 liters per square meter has been demonstrated in non-desert environments replete with water.
Cho and his team are attempting to replicate, or exceed, these capture results in Las Vegas’ arid conditions, where humidity levels hover at or below 10-20%.
“There are other groups working on similar devices, but they’re doing so in locations that are not arid,” said Cho. “Here, we’re living through it every single day, and there’s a heightened sense of urgency because our livelihoods are on the line.”
Nevada can only take about 1.8% of what comes out of the Colorado River. As such, Las Vegas has the leading policies in water usage and the most advanced technologies in terms of water recycling.
Cho grew up in Hawaii, and says he has made it his personal mission to solve the water crisis on the so-called ninth island of Las Vegas. He started turning the wheels on his research in 2021 following his studies at the University of Michigan and in Massachusetts at MIT. But he found that Southern Nevada offered an ideal environment for his project, which could provide some significant water security for the area.
“At UNLV, I’ve come to meet water experts and people who think about water problems in so many ways I didn’t know existed,” he said. “This is the region that’s working on solutions the most because it needs them the most.”
Cho recently received the National Science Foundation (NSF) Career Award, along with $596,487 to further his team’s advances in the subject of atmospheric water harvesting.
“The award’s going to be immensely helpful for providing long-term funding and freedom to do this research for the next few years,” said Cho. “It gives me the license to look at any related research problem to this technology. We’ve demonstrated the most central aspect – capture and storage – and the next step will be showing how we release that water.”
This also includes educational plans, working with local high schools to produce small-scale prototypes of the tech and use them practically around the Valley – creating both useful data and a chance for locals to understand its value.
”This is only possible here because this community appreciates the water issue,” said Cho. “Elsewhere, people likely wouldn’t be as receptive to this, and we could possibly silence all of the critics with this technology.”
An integral part of getting the public onboard for any project is safety. Environmentally, Cho says his team’s done its homework and that the device poses an “extremely minimal” footprint on the planet.
“The reason is because despite it being dry here, the atmosphere is so vast,” he said. “If we take any water, we’re barely skimming the surface. If you took all of the water Clark County uses in a day – roughly 250 millions gallons – you could find that amount of water in the atmosphere within just 30 feet of air.”
As for the possibilities, Cho hasn’t ruled anything out. He says that it could end up being a device that unfolds and creates drinking water for people off-grid, applied to homes in a similar fashion to solar panels, or be installed at large scales to supplement municipal water supplies.
“It still sounds almost too good to be true. It sounds like science fiction – it literally is science fiction: the Skywalkers in Star Wars were moisture farmers – but it’s actually possible. I still have to pinch myself that we’re actually doing that.”
The UNLV students involved on Cho’s research team include doctoral student Yiwei Gao; former master's student Ryan Phung; and undergraduates Addison Cobb, Areianna Lewis, and Santiago Ricoy.