THE recent announcement of the Union Government of an Rs. 20,000 crore (Rs. 19,794 crore) National Green Hydrogen Mission has created two kinds of questions. The most common reaction is what is green hydrogen? And do we have a plan for a green hydrogen path for which Rs. 20,000 crore is being earmarked?Let us get one fact straight: all shades of hydrogen—green, blue or grey—are only on how hydrogen is produced, not the colour of the gas. Regardless of how hydrogen is generated, it remains the same colourless, odourless gas.