Why in News?

A study by the National Institute of Advanced Studies, commissioned by the Office of the Principal Scientific Adviser, has recommended that the Union Environment Ministry roll back its 2015 policy mandating all 537 coal-fired power plants to install Flue Gas Desulphurisation (FGD) units.

Instead, the installation should be limited to plants using imported coal or coal with high sulphur content (>0.5%), ensuring a more cost-effective and targeted approach to reducing sulphur dioxide emissions.

What’s in Today’s Article?

• Flue Gas Desulphurisation (FGD)
• Key Highlights of the Study

Flue Gas Desulphurisation (FGD)

• Flue Gas Desulphurisation (FGD) is a process used to remove sulphur dioxide (SO₂) from the exhaust gases of fossil fuel power plants and industrial sources.
• SO₂ is a harmful air pollutant that causes acid rain and respiratory issues. FGD helps reduce its presence in the atmosphere.
• Working of FGD
  • Absorption: An absorbent like lime, limestone, or ammonia reacts with SO₂.
  • Scrubbing: The absorbent, often in slurry form, is sprayed into a scrubber tower to contact flue gases.
  • Chemical Reaction: SO₂ reacts with the absorbent to form compounds like calcium sulphite or calcium sulphate.
  • Byproducts: Some systems produce useful byproducts like gypsum, which is used in construction.
• Regulatory Mandate in India
  • The MoEF&CC has made FGD installation mandatory for all coal-fired thermal power plants to curb SO₂ emissions and comply with environmental norms.
• Timeline of compliance extensions
  • 2015: Emission Norms Introduced
    • MoEF&CC introduced strict SO₂ emission norms for coal-fired thermal power plants (TPPs).
    • Initial compliance deadline set for 2017.
  • 2017: First Extension Granted
    • Ministry of Power requested a 7-year extension.
    • Supreme Court allowed a 5-year extension till 2022.
    • Plants in Delhi-NCR were to comply by 2019.
  • 2021: Task Force and Categorization
    • April 1: MoEF&CC issued a notification to form a task force.
    • April 16: Task force created with officials from MoEF&CC, Power Ministry, CEA, and CPCB.
    • Plants categorized based on location:
      • Category A: Within 10 km of NCR/1M+ population cities — Deadline: Dec 31, 2022
      • Category B: Within 10 km of critically polluted/non-attainment cities — Dec 31, 2023
      • Category C: All other plants — Dec 31, 2024
  • 2022: Deadlines Revised
    • New compliance deadlines announced in September:
      • Category A: Dec 31, 2024
      • Category B: Dec 31, 2025
      • Category C: Dec 31, 2026
  • 2024: Final Extension Announced
    • December notification revised deadlines again for non-retiring plants:
      • Category A: Dec 31, 2027
      • Category B: Dec 31, 2028
      • Category C: Dec 31, 2029

Key Highlights of the Study

• FGD Mandate Should Be Rolled Back
  • The study recommended withdrawing the 2015 policy mandating FGD installation in all 537 coal-fired power plants.
• Apply FGD Only to High-Sulphur Coal Users
  • FGDs should be mandatory only for plants using imported or high-sulphur coal (>0.5%), not for those using domestic low-sulphur coal.
• Poor Compliance Despite Extended Deadlines
  • Although the original deadline for installing FGDs was 2018, only 8% of plants have complied, with deadlines now pushed to as late as 2029.
  • Of the 537 plants, 230 are in various stages of installing FGDs, while 260 have yet to place orders.
• High Costs Make FGD Economically Unviable
  • FGD installation costs ₹1.2 crore per MW. With coal capacity expected to reach 283,000 MW by 2032, the financial burden is massive.
• Indian Coal Emits Less SO₂
  • The study pointed out that 92% of Indian coal has low sulphur content (0.3%–0.5%).
  • Furthermore, existing pollution control norms—such as mandatory 220-metre stack heights—combined with Indian climatic conditions, are adequate to prevent harmful SO₂-related effects like acid rain.
    • A 2024 IIT Delhi study referenced in the report confirms that acid rain is not a major concern in India.
• FGDs Could Worsen Global Warming
• The report warns that widespread FGD installation could backfire environmentally.
• It would raise freshwater and power consumption in plants and add 69 million tonnes of CO₂ between 2025 and 2030, while only reducing SO₂ emissions by 17 million tonnes.
• Given that SO₂ helps mask global warming, indiscriminate removal of SO₂ emissions could actually intensify global warming, the study argues, referencing Intergovernmental Panel on Climate Change (IPCC) findings.
• Focus Should Shift to Particulate Matter
  • Instead of targeting SO₂, the study recommends focusing on reducing particulate matter pollution, primarily caused by the high ash content in Indian coal.
  • Installing electrostatic precipitators—available from Bharat Heavy Electricals Limited—could reduce PM emissions by 99% at a cost of just ₹25 lakh per MW, making it a more cost-effective and impactful solution.