Seawater can do more
An inexpensive process with which natural seawater can be split into oxygen and hydrogen with almost 100 percent efficiency - researchers from Australia, China and the USA are currently working on this together.28 Feb 2023
Nowadays, a colour code is often added to the element hydrogen to indicate the production process. This is because hydrogen hardly ever occurs in nature in an unbound form. Currently, the colour scale has nine different methods for dissolving hydrogen from its compounds. But of these nine methods, only green hydrogen is considered to be the only environmentally friendly, climate-neutral way of producing hydrogen. Produced with solar or wind power, for example, it can be processed into carbon dioxide-neutral energy carriers. In addition to clean energy, the basis is of course water, which at first glance should be more than plentiful. Strictly speaking, however, this only applies to salt water or seawater - but it is precisely this water that has seemed unsuitable so far, as it has to be purified at great expense of energy before hydrogen can be produced from it.
A solution is emerging
For this reason, hydrogen is currently produced primarily from natural gas. For the reasons mentioned above, production from water by means of electrolysis is currently limited to fresh water, which cannot be a permanent solution either, since fresh water is also increasingly threatening to become a scarce resource - and far more than just energy production depends on its existence and availability. But a solution is emerging that, if it can be developed as hoped, could represent a major step forward towards climate-neutral energy sources.
A plea for global cooperation
The hope is pinned on a consortium of scientists from Australia, China and the USA. Under the leadership of the University of Adelaide, a process has now been published with which, according to the study recently published in Nature Energy, natural seawater can be split into oxygen and hydrogen with almost 100 percent efficiency.
An inexpensive catalyst makes it possible
The basis for this spectacular success is a commercially available electrolysis device and an inexpensive catalyst: cobalt oxide coated with chromium oxide. According to the researchers, they were able to achieve the same performance with this combination as an electrolyser that uses expensive catalysts made of platinum and iridium and is fed with highly purified, deionised water.
And yet danger looms
It must be added, however, that this success has so far only been achieved on a small scale. In the next step, the researchers want to build a larger prototype and at the same time address the peripheral challenges, such as material wear. The aggressive salt water naturally attacks the components of the electrolysis devices much more than purified water. Maintenance costs that are too high in the long run would indeed be capable of shattering the dream of low-cost seawater electrolysis after all, according to the scientists involved. Nevertheless, the team is confident that the larger prototype will be comparably robust as the small one they have been working with so far.
The principle of hope
Should the breakthrough really succeed, the low-cost conversion of seawater to hydrogen could indeed make a significant contribution to mitigating the effects of climate change. Especially since the process can be used wherever there is plenty of sun and salt water, but hardly any fresh water.
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