Can air be used for hydrogen production?

A hydrogen production breakthrough: an electrolyser that collects atmospheric water vapor, including from seemingly “bone dry” air, and converts it into hydrogen has been developed by Australian and international researchers.

The breakthrough, led by a team at the University of Melbourne, paves the way to renewable hydrogen production without the need to consume precious drinking water. The researchers test their prototype electrolyser under a range of relative humidity levels, going as low as 4%, and find that it steadily produces high purity hydrogen – in one case for a period of more than 12 consecutive days – without any input of liquid water.

This is important, because current hydrogen electrolyser technology usually requires access to increasingly limited resources of pure water, whereas this device could be scaled to provide fuel in remote, arid and semi-arid regions.

How does it work?

The team’s Direct Air Electrolysis (DAE) module is made up of a water harvesting unit in the middle and electrodes on both sides, paired with gas collectors and integrated with a renewable power supply – in this case, a lot of the testing was done using solar. A porous medium such as melamine sponge is then soaked with a hygroscopic (or water attracting) substance to absorb moisture from the air via the exposed surfaces.

hydrogen production

The team tested a range of hygroscopic materials, including potassium acetate, potassium hydroxide, and sulfuric acid and found that all three materials spontaneously absorbed moisture from the air and formed ionic electrolytes. It found that the direct air electrolysis modules were able to produce hydrogen gases successfully at a very low level of relative humidity, or at a higher humidity for a period of more than 12 days, with a continual supply of air and power.

A solar-driven prototype with five parallel electrolysers has been devised to work in the open air, achieving an average hydrogen production rate of 745 L per day−1 m−2 cathode and a wind-driven prototype has also been demonstrated, the team says.

Original source H2 View

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