RAS question
Blue hydrogen differs from grey hydrogen in that:
Correct answer: (A) It captures and stores the CO2 emissions from natural gas reforming.
Blue hydrogen differs from grey hydrogen because it is produced from fossil sources such as natural gas, with carbon capture and storage or carbon capture and use technologies added to reduce carbon emissions.
Explanation
Grey hydrogen is produced through carbon-intensive fossil-fuel routes, including steam methane reforming of natural gas or methane. Blue hydrogen retains this fossil-source base but adds carbon capture. The National Green Hydrogen Mission describes it as hydrogen produced through natural gas or coal gasification combined with carbon capture and storage or carbon capture and use technologies to reduce carbon emissions. Thus, the distinction is not renewable electricity or water electrolysis; it is the capture of CO2 from a fossil-source production route for storage or use. Hydrogen made through water electrolysis powered by solar or wind energy belongs to the separate green-hydrogen category.
Why the other options are wrong
- (B) Hydrogen made by water electrolysis powered by solar energy is green hydrogen, not blue hydrogen. The defining feature is renewable electricity rather than carbon capture on a natural-gas route.
- (C) Hydrogen made by water electrolysis powered by wind energy also belongs to the green category. It does not explain the distinction between grey and blue hydrogen, which turns on adding carbon capture to fossil-source production.
- (D) Hydrogen produced from water through electrolysis is classified as green or pink depending on the power source. Blue hydrogen instead comes from natural gas or coal gasification combined with carbon capture and storage or use.
Concept
Hydrogen colour categories distinguish production routes in environment and energy-transition policy. For RAS, the key comparison is whether emissions are avoided through renewable-powered electrolysis or reduced through carbon capture during fossil-source production.