Colours of hydrogen

Hydrogen is an invisible gas. That’s what chemistry taught us.

But now we are told there are different colours of hydrogen – grey, blue and green in particular.

What’s going on?

Well, the above colours are applied depending on how the gas is produced.

Grey hydrogen refers to hydrogen produced from natural gas – this process emits CO2 and thus the rather unimpressive color grey.

Blue hydrogen is also produced from natural gas but here, the CO2 emissions are captured and stored – so a more endearing colour.

Green hydrogen, the one in the limelight now, typically refers to hydrogen produced by splitting water through electrolysis – which is in turn powered by renewable sources of electricity such as solar or wind energy.

Green hydrogen carries a very small production carbon footprint compared to that for grey or blue hydrogen, and is hence expected to be an important driver for a low carbon economy.