In the context of which one of the following are the terms 'pyrolysis and plasma gasification' mentioned?
- (a) Extraction of rare earth elements
- (b) Natural gas extraction technologies
- (c) Hydrogen fuel-based automobiles
- (d) Waste-to-energy technologies ✓ UPSC's answer
Why the answer is (d)
• Pyrolysis heats waste in the absence of oxygen to yield syngas, bio-oil and char; plasma gasification uses a plasma torch at 3,000–7,000 °C to convert waste into syngas and inert slag.
• Both are thermal waste-to-energy technologies used for municipal solid waste and plastics — option (d).
• They are distinct from rare-earth extraction (a), gas fracking (b) or hydrogen vehicles (c), though the syngas produced can contain hydrogen.
• India's Solid Waste Management Rules, 2016 encourage such technologies for non-recyclable waste.
• Hence option (d).
Why the other options are wrong
- (a) Extraction of rare earth elements
- Rare-earth extraction uses solvent extraction, not these processes.
- (b) Natural gas extraction technologies
- Natural gas extraction uses drilling/fracking.
- (c) Hydrogen fuel-based automobiles
- These are waste-treatment, not vehicle, technologies.
Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2019, held on 2 June 2019. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.