Hydrogen has huge potential as a clean fuel: it's abundant (mainly in compounds like water), it doesn't produce any damaging emissions, and it can also be used to store energy from solar, wind, and tidal sources.
There are challenges in producing enough of the stuff in a practical and affordable way, however. Splitting hydrogen from water can require complicated technology and also relies on pure freshwater – not something that's plentifully available everywhere.
Now, scientists have come up with a new prototype device that can harvest water from humid air, before splitting it into hydrogen and oxygen.
What's more, it's capable of operating in areas where the humidity – the concentration of water vapor in the air – is as low as 4 percent.
"In this work, we corroborate that moisture in the air can directly be used for hydrogen production via electrolysis, owing to its universal availability and natural inexhaustibility," write the researchers in their published paper.
The device put together by the researchers is a prototype electrolyzer, powered by electricity from renewable energy, to break water into its elements, hydrogen and oxygen. In one test with a solar power source, five electrolyzers were working in parallel.
The electrodes sit on either side of a water harvesting unit, a sponge-like material that absorbs water from the air but which also doubles up as an electrolyte reservoir. Both electrodes are isolated from the air, which means hydrogen and oxygen can be collected as pure gases once the split has happened.
A number of different materials and setups were tested to get the prototype device working at a satisfactory level, and one of the configurations the researchers tried was able to operate successfully for 12 consecutive days.
"This so-called direct air electrolysis (DAE) module can work under a bone-dry environment with a relative humidity of 4 percent, overcoming water supply issues and producing green hydrogen sustainably with minimal impact to the environment," write the researchers.
Clean drinking water is at a premium in most places, so this device could be used in any location without depleting reserves. However, it's likely to be of most use in arid or semi-arid regions where there's not much water around at all.
We've seen another important breakthrough in terms of hydrogen fuel production recently, with aluminum and gallium used to split up hydrogen and oxygen molecules in water. Scientists now have multiple avenues to pursue when it comes to making hydrogen power a more widespread reality.
It's worth remembering that this technology is still in its early stages: different DAE setups and materials resulted in different results in terms of efficiency and power generation. However, the team is confident that their device can be improved and scaled up.
"Further improvement of the surface-to-volume ratio by engineering channels or increasing the aspect ratios of the sponge material will guarantee the rate of water uptake which is essential to the upscaling of the DAE units," write the researchers.
The research has been published in Nature Communications.