Different Types of Hydrogen
Green hydrogen: It is defined as hydrogen produced by splitting water into hydrogen and oxygen using renewable electricity.
This is a very different pathway compared to both grey and blue.
Grey hydrogen: It is traditionally produced from methane (CH4), split with steam into CO2 – the main culprit for climate change – and H2, hydrogen.
Grey hydrogen has increasingly been produced also from coal, with significantly higher CO2 emissions per unit of hydrogen produced, so much that is often called brown or black hydrogen instead of grey.
It is produced at an industrial scale today, with associated emissions comparable to the combined emissions of the UK and Indonesia.
It has no energy transition value, quite the opposite.
Blue hydrogen
It follows the same process as grey, with the additional technologies necessary to capture the CO2 produced when hydrogen is split from methane (or from coal) and store for the long term.
It is not one colour but rather a very broad gradation, as not 100% of the CO2 produced can be captured, and not all means of storing it are equally effective in the long term.
The main point is that by capturing a large part of the CO2 , the climate impact of hydrogen production can be reduced significantly.
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