Electrolyzers

Saving renewable energy for a rainy day

An electrolyzer produces hydrogen by splitting water using electricity. When the electricity comes from renewable energy without any carbon emissions, such as from solar and wind farms, the hydrogen produced is called green hydrogen. No matter its origin, hydrogen functions as an energy carrier that can be used directly, or stored and transported to accommodate energy needs when and where it is needed.

The electrolyzer consists of a stack of anodes and cathodes submerged in an electrolyte. The structure and build-up, as well as the different electrolytes differ depending on the electrolyzer technology. Most well-known technologies are alkaline and proton-exchange membrane (PEM) electrolyzers, while solid-oxide (SO) and anion exchange membrane (AEM) electrolyzer technologies are in earler development phases.

Alkaline electrolyzers have been available commercially for many years and are the most mature technology for volume hydrogen production. Alkaline electrolyzers have some drawbacks, including low current density, corrosivity, sensitivity to impurities, and slow response. As a result, they are typically less compatible with the fluctuating energy that is typical from renewable energy sources. PEM electrolyzers, however, have fast response times and are ideal to produce green hydrogen by using e.g. renewable energy from e.g. solar and wind.

During the electrolysis process, the electrolyzer components, such as separator plates and porous transport layers (PTLs) in a PEM electrolyzer stack, are subjected to harsh environments that require protective coatings to achieve a very low contact resistance, protection against corrosion and hydrogen embrittlement. For commercial viability a PEM electrolyzer system needs to maintain its performance up to 80,000 hours, equivalent to 9 years, in continuous operation.

Why PVD technology for PEM electrolyzers

• Protection: PVD coatings provide excellent surface protection, which is crucial for the longevity and efficiency of electrolyzer components.
• Reduced contact resistance: The coatings help reduce interfacial contact resistance (ICR), improving the overall electrical conductivity and efficiency of the electrolyzer.
• Cost efficiency: PVD allows for the application of thinner layers of precious metals compared to traditional methods like electroplating. This results in lower material consumption and cost savings.
• Durability: PVD coatings are highly durable and can withstand the harsh operating conditions in the electrolyzer stack which is needed to maintain stack performance.
• Scalability: PVD technology is adaptable for large-scale production, making it suitable for high-volume manufacturing of electrolyzer plates.
• Embrittlement protection: With PVD it is possible to engineer coatings with barrier layers to prevent hydrogen from permeating metal substrates. This prevents hydrogen embrittlement of key components.
• Environmental benefits: PVD processes are generally more environmentally friendly than alternative technologies.