In the context of mitigating the impending global warming due to anthropogenic emissions of carbon dioxide, which of the following can be the potential sites for carbon sequestration?
- 1.Abandoned and uneconomic coal seams
- 2.Depleted oil and gas reservoirs
- 3.Subterranean deep saline formations
Select the correct answer using the code given below:
Answer & explanation
Answer: (d) 1, 2 and 3
Geological carbon storage injects captured CO2 deep underground into porous rock sealed by an impermeable cap. Saline formations, oil and gas reservoirs and unmineable coal seams are all standard candidate sites, so all three are correct.
- ✓ 1. Coal that cannot be mined economically can adsorb CO2 on its surfaces; unmineable coal seams are one of the formation types studied for storage.
- ✓ 2. Oil and gas reservoirs held fluids for millions of years under a sealing layer, so once depleted they can hold injected CO2; injection can also push out extra oil.
- ✓ 3. Deep saline formations (porous rock filled with brine) have the largest storage capacity and are the main target for large-scale storage.
Remember · Geological CO2 storage sites: deep saline formations, depleted oil and gas reservoirs, unmineable coal seams (also organic-rich shales and basalt).
Sources
- US Department of Energy, NETL: Carbon Storage FAQs ↗ “The U.S. Department of Energy (DOE) is investigating five types of underground formations for geologic carbon storage: Saline formations Oil and natural gas reservoirs Unmineable coal seams Organic-rich shales Basalt formations … Carbon capture and storage (CCS) is the separation and capture of carbon dioxide (CO 2 ) from the emissions of industrial processes prior to release into the atmosphere and storage of the CO 2 in deep underground geologic formations.”
Question and answer: UPSC's official GS Paper I (2017, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·