Flue Gas Desulphurisation (FGD) Units

16 Jun 2025 GS 3 Environment
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Flue Gas Desulphurisation (FGD) Units Click toview full image


1. What is FGD?

  • Purpose: Removes sulphur dioxide (SO₂) from flue gas emitted by coal-fired thermal power plants (TPPs).

  • Methods:

    • Wet Limestone FGD (most common, produces gypsum for construction).

    • Dry Sorbent Injection (uses powdered limestone).

    • Seawater FGD (for coastal plants, neutralizes SO₂ before discharge).

2. Why is SO₂ Harmful?

  • Environmental Impact:

    • Contributes to global warming.

    • Forms secondary PM2.5 (15% of India’s PM2.5 linked to coal plants).

  • Health Impact: Causes respiratory diseases and acid rain.

3. Status of FGD in India

  • 2015 Policy: Mandated FGD in 537 coal TPPs (deadline extended multiple times).

  • Current Compliance (2025): Only 39 out of 537 plants installed FGD.

  • New Recommendations:

    • PSA Committee (Principal Scientific Advisor) (2025)  suggests rolling back mandatory FGDs due to high costs.

    • MoEFCC extended deadlines (2027-2029) without clear justification.

4. Challenges & Controversies

  • High Costs:

    • ₹1.2 crore/MW installation cost (~₹97,000 crore for 97,000 MW new capacity).

    • Tariff Impact: Adds ₹0.72/kWh (mostly fixed costs).

  • Alternatives?

    • None exist for SO₂ removal; experts insist FGD is essential for clean air.

  • Regional Impact:

    • PM2.5 contribution varies (e.g., Delhi less affected than cities near plants).

5. Government’s Dilemma

  • Power Minister’s Stance: Balancing costs vs. health/environmental risks.

  • Experts’ View: Delaying FGDs risks public health and air quality goals.

Why Relevant for UPSC?

Prelims (Environment & Pollution Control)

  • Keywords: FGD, SO₂, PM2.5, Wet Limestone Method, PSA Committee.

  • Data Points: 537 coal plants, 39 FGDs installed, ₹1.2 crore/MW cost.

Mains (GS-3: Environmental Pollution & Energy)

  • Potential Questions:

    • "Critically examine India’s struggle to implement FGDs in coal power plants."

    • "Can India achieve its clean air targets without FGDs? Discuss alternatives."

Key Points

  •  FGDs are vital for reducing SO₂ but face delays due to high costs.
  •  India’s compliance is poor (only 7% plants installed FGDs).
  •  Experts warn rolling back FGDs will worsen air pollution and health risks.
  •  No viable alternative exists; debate centers on cost vs. environmental priorities.



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