Unlocking the spectrum: A guide to hydrogen colors

Posted: March 27, 2024

The way you’ve probably heard people talking about hydrogen lately, you’d think it comes in about every color of the rainbow: green hydrogen, blue hydrogen, pink hydrogen, etc. Hydrogen, the simplest and most abundant element in the universe, doesn’t actually come in different colors, though. The different color terms are just labels for different processes used to produce hydrogen.

In all cases, the end product is the same: hydrogen. The color just tells a story about how environmentally friendly the process is that made that hydrogen.

• Grey Hydrogen: The most common—and least environmentally friendly—way to produce hydrogen is through a process called steam methane reforming. Hot steam extracts hydrogen from natural gas and releases carbon dioxide as a byproduct. Grey hydrogen is a significant contributor to carbon emissions.
• Blue Hydrogen: When you make grey hydrogen, but then use carbon capture and storage (CCS) technologies to ameliorate the carbon dioxide released in its production, the result is called “blue hydrogen.” Despite its “low-carbon” label, it still contributes to greenhouse gas emissions.
• Green Hydrogen: Instead of extracting hydrogen from natural gas, green hydrogen producers use electricity to split water molecules into hydrogen and oxygen. This process, called “electrolysis,” produces zero carbon dioxide. When the electricity comes from renewable sources, such as solar and wind, its environmental impact is minimal and the resulting hydrogen is called “green hydrogen.” Although currently a small fraction of overall hydrogen production, its prevalence will likely grow as renewable energy becomes more affordable.
• Yellow hydrogen:  This is really just a specific kind of green hydrogen—hydrogen produced by electrolysis powered by solar energy.
• Pink hydrogen: Produced by electrolysis like green and yellow hydrogen, pink hydrogen uses electricity generated by nuclear power sources rather than renewables like wind and solar.
• Turquoise hydrogen: This is hydrogen produced by a process called methane pyrolysis, which splits methane into hydrogen and solid carbon. If the carbon byproduct can be sequestered, turquoise hydrogen has the promise to have a smaller carbon footprint than grey hydrogen, if not the carbon neutrality of green hydrogen.

These colors aren't just about looks. They're about paving the way toward a cleaner, more sustainable future. As we strive for carbon neutrality, hydrogen stands as a crucial ally in our fight against climate change.

Optimizing hydrogen production

But where does AVEVA fit in to the hydrogen picture? Well, making hydrogen sustainable and profitable requires producing and using it as efficiently as possible. Helping companies use data to optimize production and engineering is where AVEVA excels.

For example, Topsoe will use AVEVA™ Process Simulation to model its solid oxide electrolyzer cells (SOECs) with a view toward optimizing their design and developing their control strategy.

Learn more about the factors driving investment in hydrogen technology and the digital strategies you need to meet the growing hydrogen economy head-on.