Scientists have isolated an enzyme from soil bacteria that can convert air into electricity, which they say could be developed into a renewable power source for small devices.
The Monash University research, published in the peer-reviewed journal Nature, shows that the enzyme called "Huc" can turn tiny amounts of hydrogen present in the air into an electrical current.
An enzyme is a type of protein that can speed up chemical reaction in cells.
Huc is a "natural battery", the scientists said, and while their research is in its very early stages, their discovery has the potential to be a low-cost power source for small objects.
"We've shown that when we isolate [Huc] in the lab we can put that into an electrical circuit and it produces electricity," co-lead researcher Rhys Grinter said.
Only very small devices could be powered this way, because there are such low levels of hydrogen in the air — just 0.00005 per cent, he said.
Larger objects would need an external source of hydrogen to add more electrical power.
"We're looking at very small things like a biometric monitor or an environmental sensor that would need sustained levels of power," Dr Grinter said.
"However if you give our enzyme more hydrogen, it will make more power.
"In something like a fuel cell it could potentially produce enough power to power a wristwatch or a smartphone."
"The dream", Dr Grinter said, would be to develop a power source that doesn't require much to keep it going and "basically passively powers itself from air".
He said the plan was to scale up production of the enzyme and then work with engineers to design devices powered by the enzyme's use of air.
Powering small devices a 'big reach', hydrogen energy expert says
Macquarie University's Robert Willows, who owns a start-up hydrogen energy company, said Monash researchers had made a significant finding in getting an enzyme to create electricity with hydrogen.
But he said the idea of generating power from thin air was "over excited".
"That's really a big reach," the hydrogen energy expert said.
"They're proposing it could be used to generate electricity from air. That's a very long bow to draw," he said.
"There's just not enough hydrogen present in air to be useful to make electricity.
"For something that has extraordinarily small current requirements, that might be feasible, but for something like a wristwatch ... that's never going to work."
The main significance of the scientific findings, which Professor Willows fully supports, is that the scientists managed to generate electricity in the presence of oxygen.
Usually bacteria that make hydrogen are too sensitive to oxygen.
"This work [gives an] idea of how to make these enzymes insensitive to oxygen," he said.
Technology could revolutionise daily life
Director of future lower-energy electronics technologies at Monash University, Michael Fuhrer, who was not involved in the enzyme research, said a low-cost energy source for smart devices could be game changing.
"Think about a sensor that's stuck to the side of your milk jug in your fridge but tells Alexa — or any smart device — that your milk has gone off and that you need to buy another one when you go to the grocery store," Professor Fuhrer said.
"If you could manufacture that for 5 cents then it's probably worthwhile.
"This idea is sometimes called the internet of things — that we want everything to be connected to the internet."
Professor Fuhrer said the latest research was new to him, but that extracting very small amounts of energy from the environment was an active area of research.
"It's a first step and it sounds exciting."
