To overcome the water shortage problem in the case of widespread deployment of hydrogen production, a team of researchers from Australia, the United Kingdom and China has demonstrated a method of producing high purity hydrogen from the air by using hygroscopic electrolyte soaked in a porous medium as the moisture absorbent.
Hydrogen is the ultimate clean energy. Despite being the most abundant element in the Universe, hydrogen exists on the earth mainly in compounds like water.
The green hydrogen — hydrogen produced by water electrolysis using renewable energy — represents the most promising energy carrier of the low-carbon economy.
Hydrogen can also be used as a medium of energy storage for intermittent energies such as solar, wind, and tidal.
The deployment of water electrolyzer is geographically constrained by the availability of freshwater, which, however, can be a scarce commodity.
More than one-third of the Earth’s land surface is arid or semi-arid, supporting 20% of the world’s population, where freshwater is extremely difficult to access for daily life, let alone electrolysis.
In the meanwhile, water scarcity has been exacerbated by pollution, industrial consumption, and global warming.
In new research, Dr. Gang Kevin Li from the Department of Chemical Engineering at the University of Melbourne and colleagues developed a prototype electrolyzer that harvests humid air instead of liquid water.
Their device absorbs moisture out of the air and splits the collected water into hydrogen and oxygen.
The researchers powered the device using renewable energy (solar or wind power) and were able to operate it for 12 consecutive days.
They also demonstrated that the device can operate efficiently in a dry environment of around 4% humidity, without the need for liquid water.
“Such direct air electrolysis devices hold the potential for generating abundant hydrogen in arid and semi-arid areas with negligible disrupt to the regional air humidity and minimal impact to the environment,” the authors said.
“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 direct air electrolysis units.”
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