📘 Q.12 IAS Prelims 2023 — Environment & Ecology (Carbon Capture & Sequestration)
📌 The Question:
Consider the following activities:
- Spreading finely ground basalt rock on farmlands extensively
- Increasing the alkalinity of oceans by adding lime
- Capturing carbon dioxide released by various industries and pumping it into abandoned subterranean mines in the form of carbonated waters
How many of the above activities are often considered and discussed for carbon capture and sequestration?
(a) Only one
(b) Only two
(c) All three
(d) None
✅ Correct Answer: (c) All three
🧑🏫 Classroom Explanation
Statement 1 is correct
This method is called Enhanced Rock Weathering (ERW). Finely crushed basalt reacts chemically with atmospheric CO₂ when spread on farmland, converting it into stable bicarbonates.
✔ Potential to remove up to 2 billion tonnes of CO₂ annually
✔ Also improves soil nutrients and crop productivity
Statement 2 is correct
This approach is known as Ocean Alkalinity Enhancement (OAE).
Adding lime neutralizes ocean acidity, increases carbonate ions, and allows oceans to absorb more atmospheric CO₂, storing it in dissolved form for thousands of years.
Statement 3 is correct
This is Geological Carbon Sequestration.
Captured CO₂ is injected deep underground into depleted oil fields, saline aquifers, or abandoned mines, often as carbonated water, where impermeable cap rocks prevent leakage.
All three are recognized CCS/Negative Emission Technologies discussed globally.
⚡ Curiosity Raiser
Can rocks, oceans, and abandoned mines quietly clean the sky while humans sleep? 🌍
📚 Enrich Notes (UPSC Edge)
- Carbon capture pathways:
- Biological (forests, soils)
- Chemical (alkalinity, mineralization)
- Geological (deep underground storage)
- CCS is essential for:
- Cement
- Steel
- Fertilizer
- Hard-to-abate industries
- IPCC: Net-Zero without CCS is nearly impossible
🕊️ IAS Monk Whisper
“When carbon sinks grow deeper than politics, the planet breathes again.”