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Comparing Elastocaloric Cooling and Desiccant Wheel Dehumidifiers for Atmospheric Water Harvesting

Technologies   2024 ,  12 (10), 178; https://doi.org/10.3390/technologies12100178

Submission received: 24 August 2024 / Revised: 13 September 2024 / Accepted: 26 September 2024 / Published: 30 September 2024

A new type of prototype water harvester promises to be simpler and more efficient than traditional variations of the device at pulling drinking water from the air, a new study suggests. Built using temperature-sensitive materials, a nickel titanium-based dehumidifier could pull more water out of the atmosphere in 30 minutes on average than an alternative dehumidifier system, using only about half the energy. 

As more than 2 billion people around the world are estimated to lack access to clean drinking water, improving conventional ways to collect such a valuable resource would make it significantly more attainable for water-scarce regions, said  John LaRocco,  lead author of the study and a research scientist in psychiatry at  The Ohio State University College of Medicine . 

“You can survive three minutes without air, three weeks without food, but only three days without water,” said LaRocco. “But with it, you can begin to solve a lot of problems, like national security, mental health or sanitation, just by improving the accessibility of clean drinking water.”

Whereas many existing water harvesting technologies are large, energy-intensive and slow, this team’s device is unique due to elastocaloric cooling, which uses materials that can reduce energy use, size and complexity. This design is what also allowed their prototype to become portable enough to fit inside a backpack, said LaRocco. 

Researchers compared their creation with a dehumidifier that operates using desiccant wheels, rotating cylinders lined with hydrophilic materials that work to trap and remove humidity from the surrounding airflow. They tested the performance of each device in sessions of 30 minutes each, evaluating their energy consumption, heat generation and water-harvesting efficiency.

From left to right: John LaRocco, John Simonis and Qudsia Tahmina

The study was recently published in the journal  Technologies.

The trial’s results revealed significant differences in power consumption and highlighted what conditions their prototype might be best suited for. For example, said John Simonis, co-author of the study and an undergraduate student in  electrical and computer engineering , the humidity level of the region where their device is used could influence the effectiveness of its water collection capabilities. 

“Compared to the traditional desiccant wheel system, our system has the ability to scale more dynamically to fit the needs of the environment,” said Simonis. “Because our device is more modular, there’s room for a lot of adaptability.”

The authors noted that places like the Philippines, Indonesia, Haiti, and even Ohio are a few of the places where the standard humidity would fall just right enough for their prototype to achieve maximum efficiency. 

The water produced from their device is readily drinkable, said Simonis, but because their device is also made with 3D printed materials that can degrade over time, must be heavily filtered to limit the amount of microplastics someone could ingest if they drank it immediately. 

According to  statistics  provided by the United Nations, only about 0.5% of Earth’s water is freshwater and safe for human consumption. Environmental changes caused by war, pollution and climate change also remain risk factors for an ongoing global water crisis. 

Because natural disasters and international emergencies will continue to exacerbate these issues, it’s imperative to find ways to creatively harvest water to support marginalized populations, said Qudsia Tahmina, co-author of the study and associate professor of practice in  electrical and computer engineering .

That said, being able to ensure consistency of devices that can harvest a renewable resource out of thin air will help make the process both more economical and more feasible, the study notes. It’s a goal that if achieved, will impact every facet of life on Earth, said LaRocco. 

“We’re hoping that clean water for the rest of the world isn’t just a pipe dream,” he said. 

Using  the team’s models , it is possible for the public to experiment with creating a dehumidifier of their own. But while their prototype is as of now meant for individual use, in the future, it could be easily optimized to care for the needs of a household or larger community, said Simonis. 

“It is possible to develop an incredibly large version of our prototype,” he said. “It could extract as much water in a limited amount of time and get the same energy efficiency as somebody who may have a smaller device who’s running theirs continuously.”

Vidhaath Vedati of Ohio State was also a co-author. 

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Taxonomy

• Atmospheric Water Generator
• Atmospheric Water Generation