The novel electricity collecting device works on a similar principle to the storm clouds that generate lightning.
Engineers at the University of Massachusetts Amherst in the US have shown that it is possible to build devices that harvest electricity from moisture in the air. The researchers argue that virtually any material with nanopores can deliver cost-effective, scalable, and seamless electricity.
“The air contains a huge amount of electricity,” explains Jun Yao, one of the lead authors of the research. “Think of a cloud, which is nothing more than a mass of water droplets. Each of those drops contains a charge, and when the conditions are right, the cloud can produce lightning, but we don’t know how to capture the electricity from lightning reliably.What we have done is create a small-scale cloud built by humans that produces electricity for us in a predictable and continuous way so we can harvest it,” he added.
The device was built from a specialized material made of protein nanofibers, grown from the bacterium Geobacter sulphurreducens. This material, which was the result of previous research, constitutes the core of the small artificial cloud.
“What we realized after making the ‘Geobacter’ discovery is that the ability to generate electricity from air, what we later called the Air-gen effect, turns out to be generic: literally any type of material can collect electricity from the air, as long as it has a certain property,” says Yao. What is that property? “It needs to have holes smaller than 100 nanometers, or less than one thousandth the width of a human hair.“, he indicated.
This diameter is on the order of the ‘mean free path’ of water molecules when they are suspended in air. The ‘mean free path’ is understood as the distance that a molecule travels before colliding with another molecule of the same substance.
The device thus constructed would allow water molecules to pass from the top to the bottom of a thin layer of material filled with nanopores. These would limit the passage of water molecules when hitting their edges. In this way, the large accumulation of charge-carrying water molecules in the upper part of the material with respect to the lower part would create a potential difference similar to what happens in a cloud. This battery would work as long as there is moisture in the air. The research was recently published in Advanced Materials.
Nearly inexhaustible clean energy
“The idea is simple, but it’s never been discovered before, and it opens up all kinds of possibilities,” Yao says. According to the authors, the features of this electricity harvester offer extensive options for cost-effective and environmentally adaptable fabrications. “You could imagine harvesters made of one type of material for rainforest environments and another for more arid regions,” Yao says.
the combine would work 24 hours a day, 7 days a week, in practically any condition where there is environmental humidity, which is an advantage over other clean technologies, such as wind or solar, which only work in certain conditions. Another advantage of the device has to do with the ability to pack many thousands of these thin layers of nanopores in order to efficiently increase the amount of energy, without significantly increasing the size of the device.
Such a device is thought to be capable of delivering power at the kilowatt level. “Imagine a future world where clean electricity is available wherever you gosays Yao. “The generic Air-gen effect means that this future world can become a reality,” he added. “This is very exciting,” says Xiaomeng Liu, another lead author. “We are opening a wide door to harvesting electricity clean from scratch,” he stressed.