Question 77 from UPSC CSE 2023 - Environme nt

Question

Consider the following activities:
1. Spreading finely ground basalt rock on farmlands extensively
2. Increasing the alkalinity of oceans by adding lime
3. 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?

IASCODEX · Accepted Answer

Correct Option: C. All three

Strategy: - Spreading basalt rock for enhanced mineral weathering to draw down CO2.
- Increasing ocean alkalinity to facilitate greater CO2 absorption.
- Injecting CO2 into underground formations for geological storage.

These are core carbon capture and sequestration methods widely discussed in climate mitigation.

Key Info: Carbon capture and sequestration (CCS) refers to technologies and approaches that prevent atmospheric release of carbon dioxide, a major greenhouse gas.

- **Spreading finely ground basalt rock on farmlands (Enhanced rock weathering):** Basalt and other silicate rocks, when finely ground and spread on soil, accelerate natural chemical weathering. This reaction absorbs atmospheric CO2 and converts it into stable carbonates, locking away carbon for long durations. The process also increases soil fertility.

- **Increasing ocean alkalinity by adding lime:** The intentional introduction of alkaline substances like lime (calcium oxide or hydroxide) into the ocean raises the seawater's ability to neutralize carbonic acid formed from dissolved CO2. Enhanced alkalinity promotes greater absorption and long-term storage of atmospheric CO2 in the form of bicarbonate and carbonate ions, mitigating ocean acidification. This method is proposed at experimental and pilot scales.

- **Capturing CO2 and injecting it into subterranean mines (Geological storage):** After capturing CO2 from industrial sources, it can be compressed and injected into deep underground geological formations, such as depleted oil and gas fields, deep saline aquifers, or abandoned mines. The CO2 may be injected as a supercritical fluid or dissolved in water ('carbonated water' method), and is trapped physically or via mineralization, ensuring long-term sequestration. Safeguards like cap rocks are crucial to containing CO2.

These techniques are actively researched and considered as part of broader climate change mitigation portfolios by organizations such as the IPCC, with varying degrees of technological readiness and deployment.

IASCODEX · Answer

Option A: Only one

IASCODEX · Answer

Option B: Only two

IASCODEX · Answer

Option D: None of the above statements is correct