Highlighting six colours of the hydrogen rainbow
By Emokpaire Tijani Agba
Green hydrogen Made by using clean electricity from renewable energy technologies to electrolyse water (H2O), separating the hydrogen atom within it from its molecular twin oxygen. Currently expensive.
Blue hydrogen Produced using natural gas but with carbon emissions being captured and stored, or reused. Negligible amounts in production because of a lack of carbon capture projects.
Grey hydrogen This is the most common form of hydrogen production. It comes from natural gas via steam methane reformation but without emissions capture.
Brown hydrogen The cheapest way to make hydrogen but also the most environmentally damaging because of the use of thermal coal in the production process.
Pink/purple hydrogen Made using nuclear energy to power the electrolysis.
Turquoise hydrogen Uses a process called methane pyrolysis to produce hydrogen and solid carbon. Not proven at scale. Concerns around methane leakag