With a new technique, scientists have essentially figured out how to create power from thin air. Their tiny device generates electricity from the air’s humidity, and it can be made from nearly any substance, scientists reported this month in the journal Advanced Materials.
The invention involves two electrodes and a thin layer of material, which must be covered with tiny holes less than 100 nanometers in diameter—thinner than one-thousandth the width of a human hair, according to a statement from the University of Massachusetts, Amherst, where the researchers work.
As water molecules pass through the device, from an upper chamber to a lower chamber, they knock against the tiny holes’ edges, creating an electric charge imbalance between the layered chambers. In effect, it makes the device run like a battery. The whole process resembles the way clouds make electricity, which we see in the form of lightning bolts, according to Inverse’s Molly Glick.
“What we have invented, you can imagine it’s like a small-scale, man-made cloud,” Jun Yao, a co-author of the new paper and an electrical engineer at the University of Massachusetts, Amherst, tells the Washington Post’s Dan Rosenzweig-Ziff.
Currently, the fingernail-sized device can only create continuous electricity equivalent to a fraction of a volt, writes Vice’s Becky Ferreira. But the researchers hope it can someday become a practical, sustainable source of power.
“The entire Earth is covered with a thick layer of humidity,” Yao tells the Washington Post. “It’s an enormous source of clean energy. This is just the beginning in making use of that.”
But other researchers cast doubt on whether the device can be scaled up enough to be useful.
“Hard to know what to make of this,” Donald Sadoway, a materials chemist at MIT who did not contribute to the study, tells the Boston Globe’s Sabrina Shankman. “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.”
Humidity, or the amount of water vapor in the air, is in large supply on Earth. A device generating power from humidity could work in almost any location on the planet, at any time of day. How much water vapor the air can hold depends on temperature—warmer air can hold more water vapor.
Scientists have previously tried harnessing humidity to generate electricity, but their attempts have often only worked for a short amount of time or relied on expensive materials, per Vice. In 2020, Yao and other researchers found a way to continuously collect electricity from humidity using a material grown from bacteria.
But now, the new paper shows that such a specific material isn’t necessary—just about any material works, such as wood or silicon, as long as it can be punctured with the ultra-small holes. This finding makes the device much more practical; it “turns an initially narrow window to a wide-open door for broad potential,” Yao tells Vice.
James Tour, a chemist at Rice University who did not contribute to the research, tells the Boston Globe that the finding is remarkable and could have “an enormous impact.”
Next, the researchers want to try stacking the devices on top of each other to produce more energy. It’s not yet clear whether the generators would become competitive with established clean energy sources, such as wind and solar, but the team envisions them powering electronics in all sorts of environments, per Inverse.