Engineers from the University of Massachusetts Amherst have discovered that nearly any material can be made into a device to capture electricity from humidity in the air, according to a new study published in the peer-reviewed journal Advanced Materials recently.
Jun Yao, assistant professor of electrical and computer engineering in the College of Engineering at UMass Amherst, and the paper’s senior author, explained that the device works similarly to a cloud and lightning.
In a cloud, which is simply a mass of water droplets, each droplet contains a charge and can lead in some conditions to the production of a lightning bolt.
"What we’ve done is to create a human-built, small-scale cloud that produces electricity for us predictably and continuously so that we can harvest it,” said Yao.
The "man-made cloud" relies on a phenomenon that Yao and his colleagues call the "generic Air-gen effect."
The origins of the 'Air-gen effect'
Yao first discovered the effect in research he conducted with co-author Derek Loley, Distinguished Professor of Microbiology at UMass Amherst, in 2020, in which they showed that electricity could be harvested from the air using a specialized material made of protein nanowires grown from the bacterium Geobacter sulfurreducens.
The engineers then realized that they could make this device out of almost any kind of material, as long as it has holes smaller than 100 nanometers (less than a thousandth of the width of a human hair).
The device consists of a thin layer of material filled with nanoholes that would let the water molecules flow through the upper to the lower part of the material. The holes are just small enough so that the water molecules create a "charge imbalance" and bombard the upper part of the layer with more charge-carrying water. This creates a phenomenon similar to the cloud as the upper part has a different charge than the lower version.
“The idea is simple,” said Yao, “but it’s never been discovered before, and it opens all kinds of possibilities.”
Humidity is constantly in the air, so the devices would be able to run constantly, no matter the weather or location. The devices are also exceedingly small, meaning it can be scaled up significantly without taking up too much space, potentially creating kilowatt-level power.
“Imagine a future world in which clean electricity is available anywhere you go,” said Yao. “The generic Air-gen effect means that this future world can become a reality.”