Aussie scientists make electricity out of thin air

The hero at the centre of the Monash University discovery is a hydrogen-munching enzyme from a common bacterium found in soil.

And it brings the holy grail of battery-free, air-powered personal devices a big step closer to reality.

The discovery began years ago with the work of Professor Chris Greening, who worked out that some bacteria living in nutrient-poor environments use the small amounts of hydrogen in the atmosphere as an energy source.

"But we didn't know how they did this until now," Prof Greening said.

The "how" is an enzyme called Huc, which the researchers went looking for on the back of Prof Greening's work.

The enzyme, from a soil bacterium called Mycobacterium smegmatis, was then isolated and extracted and tests have since shown Huc turns hydrogen gas into a current that can power a small electrical circuit.

The next step will be working out how to harness the "natural battery" to power devices.

Dr Rhys Grinter, who leads the research team, says an obvious place to start is devices that need a sustained supply of low-voltage power.

"For stuff that runs passively on air we'd imagine it's going to be devices like medical sensors, wearable exercise monitors or a clock - or perhaps a small computer circuit," he said.

There could also be industrial applications, such as powering implanted medical devices and remote sensing equipment.

Dr Grinter doubts the enzyme will ever be a viable way to produce large amounts of electricity.

"If you're talking about something like a power plant - town or city scale - I think the amount of enzyme we could make would be too small and there are other solutions that are more economically viable."

But its applications could still be vast with more research and development.

One of the biggest potential benefits is a move away from batteries that eat up precious resources including rare earth elements.

Lab work by PhD student Ashleigh Kropp has also shown Huc has what it takes to endure tough conditions.

"It's possible to freeze the enzyme or heat it to 80C and it retains its power to generate energy ... reflecting how it helps bacteria survive in the most extreme environments," she said.

The bacteria that produce enzymes such as Huc are common and can be grown in large quantities, meaning ready access to a sustainable source of the enzyme.

And money - not time - will probably be the determining factor in how quickly the technology might appear in the market.

"It comes down to the amount of resources we can get to do this research," Dr Grinter said.

There's been some federal government investment so far but rapid development will mean finding a keen investor.

"Once we've done a bit more work that's definitely where we are looking - for an investor, or company, interested in the technology," Dr Grinter said.

"If we could secure that I'd say within a decade we could probably have something."

Dr Grinter likes to imagine the likes of Apple could see the technology's applications for its wearable products.

"That's something I like to think about," he said.

Australian Associated Press