2023-07-17 16:58:55
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Article informationAuthor, Par Chris BaraniukRole, BBC Future
35 minutes ago
The famous physicist Nikola Tesla wanted to obtain electricity from the humidity of the air, by exploiting the processes that take place in storm clouds: decades following his death, this idea might finally come to fruition.
No one in the lab might believe what they were seeing. An experimental device, a humidity sensor, had begun to generate electrical signals. All right, you think, but that shouldn’t have been possible.
“For some reason, the student working on the device forgot to plug in the power,” says Jun Yao of the University of Massachusetts Amherst. “This is the beginning of the story.
Since that moment, five years ago, Jun Yao and his colleagues have developed a technology capable of generating electricity from moist air: a concept known as hygroelectricity.
The idea has been around for many years. Nikola Tesla and others have studied it in the past, but never found promising results. However, the situation may well be regarding to change.
Many research groups around the world are discovering new ways to draw electricity from water molecules that naturally float in the air. This is possible because these water molecules can transfer tiny electrical charges between them – a process the researchers are trying to control. The challenge is to capture enough electricity to be usable. But scientists now think they might harvest enough to power miniature computers or sensors.
It raises the tantalizing prospect of a new form of renewable energy that might float all around us, virtually 24/7.
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image caption,
Moisture is caused by water vapor suspended in the air, but these water molecules carry tiny electrical charges that can be transferred to other materials
In 2020, Yao and his colleagues published a scientific paper describing how tiny protein nanowires, produced by a bacterium, might pick up electricity from the air. The exact mechanism is still under investigation, but the material’s tiny pores seem capable of trapping floating water molecules. By rubbing once morest the material, the water molecules seem to give it a charge.
Yao explains that in such a system, most molecules stay close to the surface and deposit a lot of electrical charge, while a few others penetrate deeper. This results in a difference in charge between the upper and lower parts of the material layer.
“Over time, you see a separation of charges,” says Yao. “That’s actually what happens in a cloud. On a much larger and more dramatic scale, thunderclouds also create a buildup of opposing electrical charges that eventually discharge as lightning.
This means that by influencing the movement of water molecules and creating the ideal conditions for the separation of charges, it is possible to generate electricity. “The device can operate literally anywhere on Earth,” says Yao.
The 2020 article turned out to be the tip of the iceberg.
Dr. Yao and his colleagues published a companion study in May 2023, in which they created the same type of structure, filled with nanopores, but using a variety of different materials – from graphene oxide flakes and polymers to wood-derived cellulose nanofibers. They all worked, with a few small differences. This suggests that it is the structure that matters, rather than the material itself.
In experiments conducted so far, devices thinner than a human hair have generated very small amounts of electricity, equivalent to a fraction of a volt. According to Yao, it would be enough to manufacture more materials or to connect pieces of them to obtain payloads of several volts and more. The material might even be made from a liquid that might be sprayed onto surfaces to provide an instant power source, he suggests.
“I think it’s really exciting,” says Reshma Rao, a materials engineer at Imperial College London (UK), who was not involved in the study. “There is great flexibility in the type of materials that can be used”.
Still, it may not be realistic to imagine that such technology might power entire buildings or power-hungry machines like cars, Mr Rao warns. The moisture might be enough to power Internet of Things devices, such as sensors, or small portable electronics.
Anyone looking to commercialize such technology will need to prove that it produces enough energy and is cost competitive with other renewable energy sources.
Yao’s team is far from alone in studying moist air as a potential energy resource. In 2020, an Israeli group managed to generate electricity by passing moist air between two pieces of metal. The moist air induced a charge in the metal as it passed over it.
This phenomenon was first observed in 1840, when a train driver working in a coal mine north of Newcastle in northeast England felt a strange tingling sensation in his hand as he he operated the locomotive. Later, he noticed a tiny spark jump between his finger and one of the vehicle’s levers. Scientists investigating the incident concluded that the friction of steam on the metal of the engine’s boiler had caused a charge to build up.
Colin Price, an atmospheric science researcher at Tel Aviv University in Israel and co-author of the 2020 paper, explains that the charges generated during laboratory experiments with small pieces of metal were very small. He adds, however, that he and his colleagues are working to improve their system. One of the limitations of this system might be that it requires a relative humidity of 60% or more, whereas the devices of Yao and his colleagues start producing electricity from a relative humidity of around 20%.
Meanwhile, a Portuguese team is working on a European Union-funded project called CATCHER, which also aims to harness humid air as an energy source. Svitlana Lyubchyk, a materials scientist at the University of Lusófona in Lisbon, Portugal, coordinates the project and co-founded a company called CascataChuva.
“I think the technical prototype will be ready by the end of the year, more or less,” says Ms. Lyubchyk, while her son Andriy Lyubchyk, who is also a co-founder of the company, presents a video of a small LED light that turns on and off. It features a gray disc regarding 4cm in diameter, made of zirconium oxide, explaining that this material can trap water molecules from moist air and force them to flow through tiny channels. He explains that this material can trap water molecules in moist air and force them to flow through tiny channels, which generates an electrical charge, enough to deliver regarding 1.5 volts with a single disc. Just two discs are enough to power the LED, he says, adding that many more pieces of this material might be chained together to achieve even higher power.
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image caption,
High humidity was a concern at the Wimbledon Championships, but it might also be a source of energy in the future if the technology can be developed
However, while some information regarding the work is available online, full details regarding the team’s latest experiments have not yet been published or peer reviewed. The group also declined to share documents showing how the drives are connected to the LED to power it.
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