It is the most abundant chemical element. Hydrogen is present in our body, in the air we breathe, in the water we drink, but also in plants and animals, as well as in the stars and planets that make up the universe. Lighter than air, colorless, odourless and extremely flammable, hydrogen is, despite its simplicity, one of the greatest hopes for the future of the planet.

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Green hydrogen, without any polluting emissions associated with its use and production, is one of the final stages of a five-century scientific and technological journey. And it is a safe bet towards global energy efficiency and carbon neutrality goals.

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What is Hydrogen?

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Hydrogen (H2) is the first chemical element in the periodic table. It is also the lightest and simplest element, as it consists of an atom comprising only an electron around a proton. Hydrogen is basically a component of other elements and structures. It cannot be extracted, so its full potential requires industrial-based production.

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How Hydrogen is produced?

Hydrogen can be produced in multiple ways, but two methods stand out: steam reforming, which is still the most commonly used method, and water electrolysis, whose potential is beyond doubt.

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Steam reforming: In the most widely used technique today, hydrogen is obtained by heating a fossil fuel - usually natural gas - at high temperatures. Contact with water steam causes hydrogen molecules to separate, which also releases carbon dioxide (CO2). Ways to make this technique more efficient include using biomass as a source of methane to serve as fuel, and capturing the emitted CO2.

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Water electrolysis: When passing electric current through water in an electrolyzer, it decomposes into its constituent elements - oxygen and hydrogen. If using electricity from renewable sources, this process produces green H2. The electrolyzer always works with a cathode, which "concentrates" hydrogen bubbles, and an anode, where oxygen is added.

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Hydrogen can be stored in three ways:

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• As compressed gas.

• In liquid form.

• Integrated into sponge-like materials.

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Despite the fact that it is highly flammable (even in liquid form) and despite the technical complexity of keeping it at low temperatures, one of the great advantages of hydrogen is that it can be stored in the long run without deterioration or losses.

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The main challenge, for now, is its volume. Scaling down storage to smaller tanks and bottles with high energy capacity - so that this can be a truly viable solution for everyday applications - will be a major turning point in the way we perceive and use energy.

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If you want to read the full version of the article, you can find it on the EDP website, a partner of the GreenH2Atlantic project.