Invisible gas, rainbow colours?
Hydrogen is a colourless gas but it is categorised using colours including black, green and pink, depending on how it is produced.
The hydrogen rainbow has different colours which relate to the source of the hydrogen production and the carbon emissions released during the process.
Green is the cleanest method of hydrogen production as no carbon emissions are released, whilst Black releases large amounts of carbon dioxide emissions.
Black Hydrogen
Produced by gasification using black coal. High CO2 emissions
Brown Hydrogen
Produced by gasification using brown (ignite) coal. High CO2 emissions
Grey Hydrogen
Generated through SMR using natural gas or fossil fuels
Blue Hydrogen
Generated through SMR with carbon capture using natural gas or fossil fuels
Turquoise Hydrogen
Produced by methane pyrolysis. Solid carbon is produced.
Green Hydrogen
Generated through electrolysis using renewable energy
Yellow Hydrogen
Generated through electrolysis using solar power, specifically
Pink Hydrogen
Generated through electrolysis using nuclear energy