Wiki - All about hydrogen

Updated on 9 June 2024

Hydrogen from electrolysis

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Hydrogen production via electrolysis involves the decomposition of water (H₂O) into its constituent elements, hydrogen (H₂) and oxygen (O₂), using an electric current. This method is particularly significant in the context of sustainable energy, as it offers a way to produce hydrogen without the direct emission of greenhouse gases, provided the electricity used is sourced from renewable energy.

The process #

The process occurs in an electrolyzer, which typically consists of two electrodes (an anode and a cathode) placed in an electrolyte. When an electric current is applied, water molecules are split at the electrodes: at the cathode (negative electrode), a reduction reaction takes place, producing hydrogen gas:

2H2​O + 2e → H2​ + 2OH

Meanwhile, at the anode (positive electrode), an oxidation reaction occurs, releasing oxygen gas and protons:

4OH → O2​ + 2H2​O + 4e

The overall chemical equation for the process is:

2H2​O (l) → 2 H2​ (g) + O2​ (g)

The technology #

There are several types of electrolyzers, e.g., alkaline electrolyzers, see here for more information. Efficiency and scalability are critical challenges for hydrogen production via electrolysis. Current efficiency levels typically range between 60% and 80%. Innovations in electrode materials, membrane technology, and system integration are ongoing to reduce costs and improve efficiency. They are transforming electrolysis into a cornerstone of the hydrogen economy. An interesting insight into the improving maturity of the different technologies can be found in this image (IEA).

Renewable electricity to synthetic methane project realized by GRZ Technologies. Alkaline electrolysis generates the hydrogen.
Renewable electricity to synthetic methane project realized by GRZ Technologies. Alkaline electrolyzer shown in the middle.

Electrolysis is not the only way to generate hydrogen, a more general overview can be found in this article. In any case, hydrogen gas is crucial for energy companies. It enables carbon-free energy storage, transportation, and generation, supporting sustainability goals.

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