The colours of hydrogen

Prelims and MainsCurrent affairs on this: Hydrogen and bioenergy

Hydrogen has to be made, and the colours are a shorthand for how. Grey, nearly all of today's supply, comes from natural gas reacted with steam, releasing roughly 10 kilograms of carbon dioxide per kilogram of hydrogen. Blue is the same with the carbon dioxide captured. Green is made by electrolysis of water on renewable electricity, with no carbon dioxide at the point of production. Brown and black come from coal, pink from nuclear electricity, turquoise from methane pyrolysis, white from rock. India's rule for what counts as green is an emissions limit, not a route: at most 2 kilograms of carbon dioxide equivalent per kilogram of hydrogen, well to gate.

Grey, blue and green

	Grey	Blue	Green
Feedstock	natural gas	natural gas	water
Process	steam methane reforming	steam methane reforming plus carbon capture	electrolysis
Energy source	heat from gas	heat from gas	renewable electricity
CO2 at production	about 10 to 12 kg per kg H2	most captured, some leaks	near zero
Share today	nearly all	small	very small
Cost in India	lowest	higher	three to four times grey

India defines green by an emissions limit, 2 kg CO2e per kg measured well to gate, not by the colour.Source: MNRE Green Hydrogen Standard, 18 August 2023; IEA Global Hydrogen Review

Emissions by route, on the accounting of the International Energy Agency (IEA): grey about 10 to 12 kg CO2e per kg at the plant and 10 to 14 once upstream methane is counted; coal about 22 to 26, roughly double gas; green near zero. The first market for green hydrogen is replacing the grey hydrogen refineries and fertiliser plants already use. The IEA is moving from colours to measured intensity, which is the Mains point: a colour says nothing about actual emissions.
Two electrolyser types: alkaline, cheaper and more mature, and proton exchange membrane, more compact and better at following variable wind and solar. India's Strategic Interventions for Green Hydrogen Transition (SIGHT) programme funds electrolyser manufacturing regardless of type, 3,000 MW a year allocated so far, with a carve out for indigenous technology.
India's standard, set by MNRE on 18 August 2023, is the 2 kg limit above, with the scope defined separately for the electrolysis and biomass routes; matching standards followed for green ammonia and green methanol.
Demand today is grey and sits in refineries and fertiliser: about 5 million tonnes a year in the mission document, almost 6 million on NITI Aayog's 2020 basis. The National Green Hydrogen Mission, approved on 4 January 2023 with Rs 19,744 crore, targets at least 5 million tonnes a year of production capacity by 2030 with about 125 GW of added renewable capacity; the 60 to 100 GW of electrolysers often quoted is a ministerial estimate, not a mission target.
Cost is the barrier: green hydrogen in India runs at three to four times grey, Rs 300 to 400 per kg in 2025 against a target of Rs 100. A consumption obligation is enabled by the mission but not notified, so demand rests on public sector procurement; the order of use is refining and ammonia first, then steel by direct reduction, then shipping and aviation, and road transport last.

Mains: Green hydrogen is a way to store and move renewable electricity as a fuel; it is worth making only where the electricity is cheap and the alternative is fossil hydrogen already in use, which is why refineries and fertiliser come first and road vehicles last.

UPSC has asked

Prelims 2023: the heavy industries green hydrogen is expected to decarbonise

Further reading: Green Hydrogen Standard for India (MNRE)