CONTEXT  

•  A high-powered expert committee, led by Principal Scientific Adviser Ajay Sood, has recommended ending the mandatory requirement for installing Flue Gas Desulphurisation (FGD) units in all coal-fired Thermal Power Plants (TPPs).
• The policy has been in place for over a decade, aiming to reduce sulphur emissions from thermal power generation.
• The shift reflects technological, cost, and policy reconsiderations in India’s evolving energy and environmental strategy.

CONCEPT (WHAT IS FLUE GAS & FGD?)

Flue Gas:

• Refers to the exhaust gas emitted from combustion plants, especially coal-fired boilers and furnaces.
• It contains:
  • CO₂, CO, NOₓ, SO₂, H₂O vapor, particulate matter, and trace pollutants.
• Released via chimneys or ducts called flues.
• Flue gas analysis is essential for:
  • Air-to-fuel optimization → for better energy efficiency.
  • Burner performance monitoring → to lower fuel usage.
  • Pollution control → especially NOₓ and SO₂ compliance.

Flue Gas Desulphurisation (FGD):

•  A pollution control technology designed to remove sulphur dioxide (SO₂) from flue gas.
• Uses absorbents like:
  • Lime or limestone slurry (wet scrubbing)
  • Ammonia or sodium sulphite
• Process:
  • Flue gas is sprayed with scrubbing slurry inside an absorber tower.
  • Up to 95% SO₂ removal is achieved via chemical reactions.

CURRENT

• India has over 200 thermal power plants, many struggling with costly FGD retrofits.
• High capital costs, supply delays, and low sulphur coal usage in India weaken the cost-benefit case for FGD.
• The shift reflects a move toward:
  • Flexible emission standards
  • Emphasis on renewables and low-emission technologies
•  Removing the FGD mandate could reduce power costs, but raises concerns over environmental trade-offs.