Dream of producing electricity from air may be closer – 07/24/2023 – Market

No one in the lab could believe what they were seeing. An experimental device, a humidity sensor, started generating electrical signals.

But that shouldn’t be possible.

“For some reason, the student working on the device forgot to turn on the power,” recalls Jun Yao of the University of Massachusetts Amherst.

“That’s the beginning of the story.”

Since that moment five years ago, Yao and his colleagues have developed a technology that can obtain electricity from moist air, which is called hygroelectricity.

It is an idea that has been around for many years. Famed inventor Nikola Tesla (1856-1943) and others have investigated this possibility in the past, but have never achieved promising results. But finally that may be about to change.

Several research groups around the world are discovering new ways to extract electricity from water molecules that naturally float in the air.

This is possible because these molecules can transfer small electrical charges to each other – a process that researchers want to master.

The challenge is getting enough electricity for the technology to be minimally useful. But scientists now believe they can get enough to power small computers and sensors.

Hygroelectricity holds the tantalizing prospect of a new form of renewable energy whose source may be floating all around us.

In 2020, Yao and his colleagues published a scientific article that described how tiny protein nanowires, produced by a bacterium, were able to collect electricity from the air.

The exact mechanism is still up for debate, but the tiny pores in the material appear to be able to trap water molecules. As they rub against the material, the molecules appear to provide a charge.

Yao explains that, in such a system, most molecules stay close to the surface and generate a lot of electrical charge, while others penetrate deeper. This creates a charge difference between the outside and inside of the material.

“Over time, you see there’s charge separation going on,” says Yao. “This is what happens in a cloud.”

On a much larger and more dramatic scale, thunderstorm clouds also incorporate an accumulation of opposing electrical charges that eventually discharge in the form of lightning.

Thus, by controlling the movement of water molecules and creating the right conditions for charge separation, it would be possible to generate electricity.

“The device can literally work anywhere on Earth,” says Yao.

Yao and his colleagues published a new 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, albeit with some minor differences. This suggests that the structure is what matters, not the material itself.

In experiments so far, devices thinner than a human hair have generated very small amounts of electricity, equivalent to a fraction of a volt.

Yao says that with bulkier material, it is possible to start getting payloads, with several volts.

He suggests that even a liquid to be sprayed with spray on surfaces could provide an instant energy source.

“I think it’s really exciting,” says Reshma Rao, a materials engineer at Imperial College London in the UK who was not involved in the study.

“There’s enormous flexibility in the type of materials you can use.”

However, it may not be realistic to imagine such technology powering entire buildings or energy-hungry machines like cars, cautions Rao.

The humidity may be just enough to power “internet of things” type devices (internet of thingsin English, which refers to everyday objects that are connected to the internet), such as sensors or small electronics.

Yao’s team is far from the only one investigating moist air as a potential energy source. In 2020, a group from Israel published that they managed to collect electricity by passing moist air between two pieces of metal.

This type of phenomenon was first recorded in 1840, when a driver in a coal mine north of Newcastle, England, felt a strange tingling sensation in his hand while operating the train.

Afterwards, he noticed a small spark jumping between his finger and one of the vehicle’s levers. Scientists investigating the incident concluded that the friction of the steam against the metal in the engine’s boiler caused the charge to build up.

Colin Price, a researcher in atmospheric sciences at Tel Aviv University in Israel, who co-authored the 2020 paper, says that the charges generated in laboratory experiments with small pieces of metal were very low.

However, he claims that he and his colleagues are working to improve the system. Still, a limitation could be that the group works with a minimum humidity of 60% in the experiments, while the devices of the group led by Yao start generating electricity at a relative humidity of around 20%.

Meanwhile, a team in Portugal is working on an EU-funded project called Catcher, which also aims to harness moist air as a source of energy.

Svitlana Lyubchyk, a materials scientist at the Lusófona University of Lisbon in Portugal, coordinates the project and co-founded a company called CascataChuva.

“I think the prototype will be ready by the end of this year or so,” says Lyubchyk, as his son Andriy Lyubchyk, who is also a co-founder of the company, shows a video of a small LED light being turned on and off.

He holds up a gray disc about 4 cm in diameter made of zirconium oxide, explaining that this material can capture water molecules from humid air and force them to flow through tiny channels.

He says that a single disk generates enough electrical charge to deliver about 1.5 volts. Just two disks are enough to power the LED light, he says, adding that many more pieces of material can be chained together to produce even more.

However, while some information about the work is available online, full details about the team’s most recent experiments have yet to be published or peer-reviewed.

The group also declined to share any material showing how the disks are connected to the LED to power it.

Many questions remain about the mechanisms behind all these hydroelectric inventions, says Rao.

“There’s a lot more to be investigated in terms of the fundamentals of why this works.”

There is also the issue of marketing. Anyone looking to sell technology like this will need to prove that this form of energy production is competitive, self-sufficient and economically advantageous compared to other renewable sources, says Sarah Jordaan, civil engineer at McGill University in Canada.

Jordaan studies the environmental and economic aspects of energy sources.

More established renewable energy technologies, such as wind and solar, clearly have the upper hand. They are likely to be even more important in the next decade, a time when moving away from fossil fuels will be particularly urgent.

Despite these challenges, Rao says there is still a “ray of hope” that new technologies will emerge from research into hygroelectricity.

This text was originally published here.