Scientists at the University of Melbourne have developed an electrolyser capable of absorbing water from the air, even in dry environments, to split it into its two components: hydrogen, which can be used as fuel, and oxygen, which is released into the atmosphere. The device is powered by renewable energy, solar or wind, and could be used in remote regions.

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Green hydrogen, produced by electrolysers using water and electricity, represents a potential alternative to fossil fuels that emit CO2 and other greenhouse gases.

These devices can be powered by renewable energy sources, such as solar and wind, but often require complex components and access to fresh water that is unavailable or scarce in many parts of the world. This limits their widespread application and drives up costs.

Using solar or wind power, the device is able to absorb water from the air and split it into its two components: hydrogen, which can be stored as fuel, and oxygen, which is released into the atmosphere.

Now, chemical engineers at the University of Melbourne, Australia, have developed a prototype electrolyser that harnesses moist air instead of liquid water. The system is able to absorb it in gaseous form and split it into its two components: hydrogen and oxygen, they report in the journal Nature Communications.

“The hydrogen is produced and collected in a cathode compartment at the top of the electrolyser, and then transported to a gas reservoir,” explains lead researcher Gang Kevin Li, “while the oxygen is released in the anode compartment at the bottom, and since we don’t collect it for any specific application now, it is simply released into the atmosphere.

Direct air electrolyser
The prototype tested by the authors includes five direct air electrolysers (DAE) stacked vertically and in parallel. They used a commercial silicon solar panel and, in another test, a small wind turbine to obtain the energy.

In this way, they were able to run it for 12 consecutive days. They also demonstrated that it can operate effectively in a dry environment of around 4 % humidity, without the need for liquid water.

The researchers stress that this technology is scalable and could be used to supply hydrogen fuel in remote, arid and semi-arid regions, with minimal environmental impact. Their findings could enable future solar-to-fuel systems to operate anywhere on Earth.

“Our direct-air electrolyser can produce hydrogen without relying on fresh water, as long as power is supplied,’ says Gang Kevin Li, who reminds us: ‘Especially for renewable energies such as solar and wind, there is a geographical mismatch, as most areas with abundant solar energy suffer from water scarcity, such as desert, arid and semi-arid regions.

Moreover,” he concludes, “the DAE unit is autonomous and independent, which means that it can also be deployed in remote and dispersed areas with limited facilities.