Australian researchers have identified an exceptionally durable enzyme that extracts energy from trace amounts of atmospheric hydrogen, potentially opening a new route to battery free sensors and other low-power devices.
Australian scientists have identified an enzyme from soil bacteria that can generate electricity by extracting energy from the tiny amounts of hydrogen naturally present in the atmosphere, a finding that could eventually enable a new generation of small, air powered electronic devices.
Researchers at the Monash University Biomedicine Discovery Institute isolated the enzyme, named Huc from Mycobacterium smegmatis a harmless soil bacterium. Their research showed that the enzyme can use atmospheric hydrogen as an energy source and convert the resulting electron flow into an electrical current.
The findings, published in *Nature*, help explain how some soil microorganisms survive by consuming hydrogen even though the gas exists in the atmosphere at extremely low concentrations.
Enzyme works with trace atmospheric hydrogen
Hydrogen accounts for only about 0.00005 per cent of the atmosphere yet many soil bacteria use it as an energy source when other nutrients are scarce.
Huc separates hydrogen molecules into their component protons and electrons. The electrons are then transferred through the bacterium’s respiratory system, producing an electrical current in the process.
The researchers found that Huc is unusually efficient at capturing hydrogen from air. Its structure also helps it overcome a major problem faced by many hydrogen processing enzymes: oxygen sensitivity.
Most hydrogenases, enzymes that oxidise hydrogen, can be damaged or deactivated when exposed to oxygen. Huc, however, remains functional in the presence of air.
Molecular structure helps exclude oxygen
Researchers used cryo electron microscopy to determine the structure of Huc and found that the enzyme contains channels leading towards its active site.
According to the research team, these channels are sufficiently wide to allow hydrogen molecules to enter while restricting the larger oxygen molecules. This allows Huc to continue extracting energy from hydrogen under atmospheric conditions.
The discovery provides an explanation for how bacteria can exploit an energy source that exists only in minute quantities in the environment.
Extreme durability could aid future devices
Another notable characteristic of Huc is its stability.
The purified enzyme remained capable of generating electricity after being frozen or heated to 80°C according to the researchers. Such durability could be important for any future technology that uses the enzyme outside living cells.
Potential applications could include extremely low power sensors, environmental monitoring equipment and other devices that need to operate for long periods without conventional batteries.
However, the research is not yet equivalent to demonstrating a commercially viable air powered battery. The amount of electricity generated by small quantities of the enzyme remains limited.
Research moves towards practical applications
Subsequent research has explored how Huc could be integrated into an electrical circuit. In 2025, a separate Monash University engineering team connected the enzyme to a carbon-nanotube mesh.
The resulting cell generated 1.72 milliwatts per square centimetre when operating on pure hydrogen and continued functioning with hydrogen contaminated by substances such as carbon monoxide.
The researchers have also found that M. smegmatis adjusts production of Huc depending on the availability of other food sources. When richer nutrients are present, the bacterium reduces production of the enzyme and increases it as conditions become more limited.
Possible use as hydrogen sensor
The electrical response generated by Huc could have another application: detecting hydrogen.
Because the enzyme responds to extremely small concentrations of the gas, researchers have suggested that Huc based systems could potentially be used to detect hydrogen leaks from pipelines, storage systems or other infrastructure.
The findings therefore point to two possible technological applications energy harvesting from atmospheric hydrogen and highly sensitive hydrogen detection.
For now, significant engineering challenges remain, particularly around increasing power output and producing stable quantities of the enzyme for practical devices. But the discovery demonstrates that a gas present only in trace amounts in the atmosphere can be exploited by biological machinery to produce usable electrical activity.
If the technology can be scaled effectively, Huc could provide a novel way of powering ultra low energy devices without conventional batteries or external fuel supplies.