The transition to clean energy is one of humanity’s main challenges to counteract global warming. And one of the most recent and innovative proposals to make it possible is a project that seeks to harvest clean energy from the air 24 hours a day, 365 days a year.
According to a team of engineers at the US University of Massachusetts Amherst, their device, called the Air-gen, could offer a cheap and sustainable source of energy for cars, trains and planes.
“Air contains an enormous amount of electricity,” Jun Yao, an assistant professor of electrical engineering and computer science in the UMass Amherst College of Engineering and lead author of the paper, explains to Metro.
And he adds: “Think of a cloud, which is nothing more than a mass of water droplets. Each of those droplets contains a charge, and when the conditions are right, the cloud can produce lightning, but we don’t know how to reliably capture the electricity from lightning. What we have done is create a small-scale man-made cloud that predictably and continuously produces electricity for us so we can harvest it.”
The heart of the artificial cloud relies on what Yao and his colleagues call the “generic Air-gen effect,” whereby electricity could be harvested from the air continuously using a specialized material made of protein nanowires grown from the bacterium Geobacter sulfurreducens.
“What we realized after the discovery of the Geobacter,” explains Yao, “is that the ability to generate electricity from air – what we then called the ‘Air-gen effect’ – turns out to be generic: literally any type of material can harvest electricity from the air, as long as it has a certain property.”
And that property is having holes smaller than 100 nanometers (nm), that is, less than one thousandth of the width of a human hair.
Yao and his colleagues realized that they could design an electricity harvester based on this figure. This harvester would be made of a thin layer of material filled with nanopores smaller than 100 nm that would allow water molecules to pass from the top to the bottom of the material. But because each pore is so small, water molecules would easily hit the edge of the pore when going through the thin layer. This means that the top of the layer would be bombarded with many more charge-carrying water molecules than the bottom, creating a charge imbalance, like a cloud, as the top would increase its charge relative to the bottom. the bottom. This would create a battery that would work as long as there was moisture in the air.
The researchers believe that such a collector could be designed with all sorts of materials, offering vast possibilities for environmentally adaptable and cost-effective manufacturing. And since humidity is always present, the harvester would work 24 hours a day, 7 days a week, rain or shine, at night and with or without wind, which solves one of the main problems of technologies such as wind or the solar, which only work under certain conditions.
Furthermore, since moisture in the air diffuses into three-dimensional space and the thickness of the Air-gen device is only a fraction of the width of a human hair, many thousands of them can be stacked, effectively increasing the amount of energy without increase the size of the device. Thus, the Air-gen device would be capable of supplying power at the kilowatt level for general use from the electrical grid.
Metro spoke with Jun Yao to find out more.
“We are opening a great door to obtaining clean electricity from the air.”
— Xiaomeng Liu, an electrical and computer engineering student at UMass Amherst’s College of Engineering
How can Air-gen contribute to the transition to clean energy?
-Air and water molecules are everywhere and are continuous 24 hours a day, 7 days a week. They spread out in three-dimensional space.
-This means that multiple nanoporous thin films can be stacked in vertical space to increase the volume of energy.
-The collector has the potential to increase the volume of energy by making it larger in flat and vertical spaces.
-This device can be placed anywhere to generate electricity continuously.
Interview
Jun Yao
assistant professor of electrical and computer engineering at the UMass Amherst College of Engineering, USA.
Q: How did you come up with the idea to create Air-gen?
– It was a fortuitous discovery that was not planned. At first, we only hoped to make an ambient gas sensor. But the student working on it forgot to plug it in and still saw an electrical signal output. This turned our attention to the feasibility of generating electricity from ambient air…and then the journey began.
Q: How is it possible to get clean electricity from the air?
– The basis is that the air (or, more accurately, the water in the air) contains electricity, which can be evidenced by lightning that carries a large amount of electricity during a thunderstorm. The movement of water from air ultimately leads to the separation of charges between the upper and lower interfaces of a cloud to produce lightning/electricity.
Q: How did you manage to build a small-scale artificial cloud that produces electricity?
– The Air-gen device is made of a thin film that contains many small pores (or nanopores), with a diameter less than 10,000th of the diameter of a human hair. The upper interface of the film is exposed to air, but the lower interface is sealed (eg, sitting on a substrate). Water molecules from the air can pass through these nanopores and reach the lower interface. However, since the pore size is so small, they can easily impinge on the pore surface. One can imagine that the top interface will crash more frequently than the bottom one. The water molecules in the air carry a charge (as shown by lightning) and give up a part of the charge to the thin film. This also means that the top of the thin film receives more charge than the bottom (since the top interface is hit more often), causing charge separation similar to what occurs in a cloud during a thunderstorm. . If we connect the upper and lower interfaces of the film, a flow of charge or electricity occurs.
Q: Tell us more about the generic Air-gen effect.
– Based on what I explained before, you can imagine that any type of “nanoporous” film can do the job. Of course, they can differ in efficiency, that is, some can produce more electricity than others with the same size. For example, some materials can more easily receive the charge of water molecules in the air than others.