New technology can generate electricity from humidity in air

With the study, whose results are published in the journal Advanced Materials, the researchers have proven that nearly any material can be turned into a device that continuously harvests electricity from humidity in the air, according to UMass. The trick is that the material will need to have “nanopores” which have a diameter of less than 100 nanometres in diameter.

“The air contains an enormous amount of electricity. Think of a cloud, which is nothing more than a mass of water droplets. Each of those droplets contains a charge, and when conditions are right, the cloud can produce a lightning bolt—but we don’t know how to reliably capture electricity from lightning,” said Jun Yao, corresponding author of the research article, in a press statement.

According to Yao, who is an assistant professor at UMass, the researchers have essentially created a small human-built cloud that can produce electricity predictably and continuously so that it can be harvested.

Researchers have previously shown that electricity can be harvested from the air using a special material made of nanowires using the bacteria Geobacter sulfurreducens.

Yao and the team built on that research and discovered that the “air-gen” effect of the nanowires is actually generic, meaning that any kind of material can harvest electricity from air, as long as it has a certain property. The property here being that the material needs to have those holes that are smaller than 100 nanometres in diameter.

The team built an electricity harvester based on this design. The device was made with a thin layer of material filled with nanopores. These nanopores would let water molecules pass from the upper part of the material to the lower part. But each pore would be so small that water molecules would bump into the pore’s edge as it passes through the thin layer.

Since the upper part of the layer would be bumped by many more charge-carrying molecules than the lower part, it would create a charge imbalance. This difference in charge between the upper and lower part would in effect, create a battery. This “battery” can run as long as there is humidity in the air.