Air Pollution

Expert Committee recommends ending mandatory Flue Gas Desulphurisation (FGD) 

Why in the News?

A high-powered committee chaired by Principal Scientific Advisor (PSA) Ajay Sood has proposed that India should discontinue the mandatory use of Flue Gas Desulphurisation (FGD) units in most coal-fired Thermal Power Plants (TPPs).

Why mandatory FGDs are opposed?

  • Low SO Levels: India’s SO₂ levels (10–20 µg/m³) are already below the permissible limit of 80 µg/m³.
  • Low Sulphur Coal: Indian coal naturally has low sulphur content.
  • Minimal Impact: Studies show no major air quality difference between plants with and without FGDs.
  • Limited PM Reduction: FGDs have minimal effect on particulate matter levels.
  • Environmental Trade-Offs:
    • CO Increase: Installing FGDs would add 69 million tonnes of CO₂ emissions (2025–2030).
    • SO Reduction: Emissions would fall by 17 million tonnes, but the climate cost outweighs the benefit.

About Flue Gas Desulphurisation (FGD):

  • Purpose: FGD is a technology used to remove sulphur dioxide (SO) from flue gases produced by burning coal and oil, especially in thermal power plants.
  • Environmental Benefit: It helps prevent acid rain, which harms crops, buildings, soils, and aquatic ecosystems.
  • Chemicals Used: Common absorbents include limestone (CaCO), lime (CaO), and ammonia (NH).
  • Types of Systems:
    1. Dry Sorbent Injection: Cost-effective, but less efficient.
    2. Wet Limestone-Based: Effective and used in large plants, produces gypsum.
    3. Seawater-Based: Uses alkaline seawater, ideal for coastal areas.

FGD Mandate in India:

  • Current Status: FGD units are being installed in 537 coal-based thermal power units, but 92% of India’s 600 plants still lack them.
  • Committee Recommendation: An expert panel advised exempting 80% of plants from FGD requirements due to feasibility issues.
  • Implementation Barriers: Limited vendors available; High costs and risk of increased electricity tariffs.
[UPSC 2023] Consider the following:

1. Carbon monoxide 2. Nitrogen oxide 3. Ozone 4. Sulphur dioxide Excess of which of the above in the environment is/are cause(s) of acid rain?

Options: (a) 1, 2 and 3 (b) 2 and 4 only* (c) 4 only (d) 1, 3 and 4

 

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