Humidity can cause all sorts of problems, some serious (making high temperatures dangerous for human health) and some mildly annoying (frizzy hair). What if it also could help in our response to the climate crisis?
In a study out this week, scientists at the University of Massachusetts Amherst say they have created a device that can harvest electricity from humidity in the air.
The device, called an Air-gen, right now is a fingernail-sized harvester made from thin material with holes less than a thousandth of the width of a human hair — called nanopores — that makes electricity by allowing electrically charged water molecules in the air to pass through. Harnessing the same forces that make lightning, that movement through the membrane creates an electrical imbalance that produces current.
“Throughout history, we haven’t been able to find any means to capture the electricity in the air. It’s dangerous. It’s unpredictable. But I think this technology essentially turns that dream into reality,” said Jun Yao, assistant professor of electrical and computer engineering in the College of Engineering at UMass Amherst and the paper’s senior author.
As of now, the Air-gen can create enough electricity to power a small sensor, like a heart-rate monitor, but the authors say the technology has the potential to be made at a much larger scale and used as a clean energy source that might help augment wind and solar.
Perhaps the most significant finding, the authors write in the journal Advanced Materials, is that any number of materials, including cellulose, which is found in the cell walls of plants, can be used for the device, provided they can be engineered with small enough pores. That could open the door for inexpensive mass production. Unlike batteries that require minerals like lithium or solar panels that require silicon, there would be no mining required, the researchers said.
The technology could be employed for small personal tasks, like charging cellphones, and on a larger scale to help feed the power grid when solar and wind are not generating enough. They said the device works in the humidity range of 20 to 100 percent, noting that the Sahara Desert has an average humidity of 25 percent. The higher the humidity, though, the larger the power output.
“Since air humidity essentially is everywhere, we can constantly get electricity from the air,” Yao said. “I call it a sustainable, continuous, and ubiquitous powering solution.”
Some scientists hailed the possibilities in what many saw as a novel and innovative discovery. James Tour, a professor of chemistry and nanoengineering at Rice University in Texas who was not involved in the study, called it remarkable and said it could have “an enormous impact.”
“Its simplicity in deployment makes it super attractive,” he said.
Guihua Yu, a materials science and mechanical engineering professor at the University of Texas at Austin who was not involved with the study, called it a very novel piece of research work that was technologically significant. “The sustainability is the very key significance,” he said.
But some scientists also said the published work’s scientific conclusions do not yet provide the kind of detail necessary to gauge its practicality, particularly on a large scale.
“Hard to know what to make of this,” said Donald Sadoway, a professor emeritus of materials chemistry at the Massachusetts Institute of Technology. “It’s not apparent what kind of practical numbers can emerge. Investors would ask what we can expect in terms of power output in watts and the cost.”
He noted that one of the materials used in the current device is gold.
“That’s not good from a cost perspective,” he said.
The finding builds on earlier discoveries, including by Yao, which showed that the idea of making electricity from humidity could work, but only in limited situations — with a specific material, or in specific situations, like when a device is exhaled into. In their latest work, Yao and his coauthors describe a technology with many possible uses.
The authors envision scaling up to deliver kilowatt-level power for general electric utility usage — enough to meet household demand. The uber-thin devices could be stacked vertically, they write, driving up the amount of energy produced while keeping a relatively small footprint.
Sorin Grama, CEO of Transaera, a clean energy startup working on improving air conditioning, said he has a hard time imagining the Air-gen competing against wind or solar, which have already scaled up, but said he could see it finding its place in the market. “It could find its niche perhaps in smaller powered devices,” he said.
The authors, meanwhile, are hoping to see the technology take off.
“We are kind of chasing the concept of energy sustainability,” said Yao. “What I envision is that sometime in the future, we can get clean electricity wherever we go.”