Can you imagine that most cars run on green hydrogen ? Hydrogen is a carbonless fuel that produces only water as a byproduct when burned. However, pure hydrogen is not abundant in nature and producing it requires an energy input that usually involves fossil fuels that generate carbon emissions.
Addressing the issue of water scarcity in the event of widespread deployment of hydrogen production, a team of researchers from Australia, the UK and China has demonstrated a method of producing high-purity hydrogen from air by use of hygroscopic electrolyte soaked in a porous medium as the moisture absorber.
sustainable alternatives
Green hydrogen, produced by electrolyzers that use water and electricity, is an interesting alternative to fossil fuels that emit CO2 and other greenhouse gases.
The current device, in addition, works with solar energy that produces hydrogen fuel directly from the humidity of the air. According to its inventors, the prototype produces hydrogen with a purity greater than 99% and can work in dry air with a relative humidity of 4% . The device would make it possible to produce hydrogen without carbon emissions even in regions where water on land is scarce, say the authors who publish their work in the journal Nature Communications.
“In this work, we corroborate that air moisture can be used directly for hydrogen production through electrolysis , due to its universal availability and natural inexhaustibility,” the researchers write in their paper.
In the device, electrodes sit on either side of a water collection unit, a sponge-like material that absorbs water from the air but also acts as an electrolyte reservoir. It works by placing two electrodes in water and passing an electrical current through them. Both electrodes are isolated from the air, which means that the hydrogen and oxygen can be collected as pure gases once the split has occurred. During the experiments, one of the many configurations the researchers tested was able to run successfully for 12 consecutive days.
“This so-called direct air electrolysis (DAE) module can work in a totally dry environment with 4 percent relative humidity, overcoming water supply issues and producing green hydrogen sustainably with minimal impact on the environment.” “, point out the scientists.
The problem with this is that it requires liquid water, so such electrolysis must be done in a place where there is enough of it so that it does not limit the supply of drinking water. If this water is airborne, as is the case with the prototype that collects it, then it eliminates this problem and the cost associated with it. And it allows hydrogen to be produced anywhere in the world (running on renewable solar or wind energy).
“Such direct air electrolysis devices have the potential to generate abundant hydrogen in arid and semi-arid areas with negligible disruption to regional air humidity and minimal impact on the environment. Further improvement of surface-to-volume ratio through channels Engineering or increasing the aspect ratios of the sponge material will ensure the rate of water absorption, which is essential for scaling up direct air electrolysis units, ” the researchers conclude.
Referencia: Jining Guo, Gang Kevin Li et al. 2022. Hydrogen production from the air. Nature Communications 13, 5046; doi: 10.1038/s41467-022-32652-y
