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The Hydrogen rainbow

Hydrogen is everywhere - literally & figuratively...but what do the different colours mean?

Hydrogen seems to be everywhere at the moment - both literally and figuratively. Hydrogen is the most abundant element in the universe, present in 75% of all matter. But it's also a hugely hot topic in the press as an energy source.

Hydrogen is light, can be stored easily and doesn't produce any pollution itself.

Hydrogen however does not begin as a source of energy - it needs a process to extract it and turn it to a useable fuel.... and not all of these processes are sustainable. And this is where the colours enter - referring not to the gas itself (which is colourless) but to the extraction process:


Grey hydrogen is currently the most common and cheapest form of hydrogen production. It is used as a fuel and doesn't generate greenhouse gas emissions itself, but its production process does. Grey hydrogen is created from natural gas using steam reforming, which separates the hydrogen from the natural gas. However, the technologies used don’t capture the carbon emissions created during the process, which are instead released into the atmosphere.


Blue hydrogen is also extracted using the same steam reforming process as with grey hydrogen, but it differs from grey as the carbon emissions released are captured and stored, which reduces the emissions in the atmosphere. Blue hydrogen is sometimes called ‘low-carbon hydrogen’ as the production process doesn’t avoid the creation of greenhouse gases, just stores them away.


Green hydrogen doesn’t generate any emissions in its entire life cycle as it uses renewable energies in the production process, making it a true source of clean energy. It is made by electrolysing water using clean electricity created from surplus renewable energy from wind and solar power. The process causes a reaction that splits water into its components of hydrogen and oxygen, resulting in no carbon emissions being released in the process. It’s a great alternative to grey and blue, but for now the main challenge is in reducing the production costs.

Black and Brown

Black and brown hydrogen is created using either type of coal in the extraction process - black coal or brown coal. This gasification process is on the opposite end of the spectrum from green hydrogen’s electrolysis. It’s an established process used in many industries that convert carbon-rich materials into hydrogen and carbon dioxide. The emissions however are then released into the air, causing pollution, making this the most harmful hydrogen for the environment.


Pink (sometimes referred to as purple or red) hydrogen is extracted through electrolysis powered by nuclear energy.


Turquoise hydrogen is in its infancy and we are still in the process of discovering if it can be used well at large scale. It's made using a process called ‘methane pyrolysis’, which produces hydrogen and solid carbon by using heat to break down a material’s chemical makeup. No carbon is released into the air, instead it’s stored in the solid carbon created. If proven to be effective, turquoise may join blue as a ‘low-carbon hydrogen’ if the carbon can be permanently stored in an environmentally safe way.


Yellow hydrogen is another new entry and is made through electrolysis specifically using solar power, similar to the process used to create green hydrogen, but with a sunnier name.


White hydrogen is found naturally in underground deposits of geological hydrogen. It’s extracted through a process called fracking, which is the process of drilling into the earth and directing a high-pressure mix of water, sand, and chemicals at the rock to release the gas inside. At the moment there are no plans to use this type of hydrogen as an energy source.

This new emerging hydrogen market is growing extremely rapidly, but it is important to understand that hazardous nature of the gas.

If you are looking to provides products intended for use in this marketplace, Jigsaw Controls can help you every step of the way. With many years experience producing products for use in hazardous areas, we can help ensure your products meet the strict safety regulation required.

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