What are Flue Gas Desulphurisation Units?, Pg10

Key Highlights:

• A committee headed by Principal Scientific Advisor Ajay Sood recommended rolling back the 2015 policy mandating FGD units in coal-fired thermal power plants (TPPs).
• FGD (Flue Gas Desulphurisation) units are systems used to remove sulphur dioxide (SO₂) from the flue gas emitted by coal combustion.
• SO₂ is a major air pollutant, contributes to PM2.5 formation, and causes respiratory illnesses and global warming.

Types of FGD Systems:

• Dry Sorbent Injection: Uses powdered limestone or other alkaline sorbents; reaction forms compounds removed via filters or electrostatic precipitators.
• Wet Limestone Scrubbing: Most common; SO₂ reacts with limestone slurry to produce gypsum, which is reusable.
• Seawater FGD: Used in coastal power plants; seawater absorbs SO₂ and is treated before release.

Why SO₂ Emissions Matter:

• SO₂ leads to secondary PM2.5 formation, which accounts for 15% of India’s ambient PM2.5, with 80% of that due to SO₂ from coal plants.
• Causes acid rain, air pollution, and public health issues, particularly respiratory and cardiovascular diseases.

Status in India:

• 2015 policy mandated FGDs in 537 TPPs; first deadline was 2018, repeatedly pushed to 2027-2029.
• As of April 2025, only 39 of 537 TPPs have installed FGDs.
• December 2024 notification extended deadlines by three years, without citing reasons.

Cost Concerns:

• Estimated cost is ₹1.2 crore per MW to install FGD units.
• Government projects ₹97,000 crore cost for installing FGDs in upcoming 97,000 MW capacity.
• Tariff increase due to FGD is estimated at ₹0.72 per kWh, with low variable cost volatility.

Arguments For and Against FGD Rollback:

• Government View: High installation costs may burden tariffs and slow economic expansion.
• Experts’ View: Rolling back FGDs threatens air quality, public health, and clean air targets.
• Health costs and environmental impact may outweigh short-term savings.

Alternatives to FGDs:

• No known alternatives exist to remove SO₂ from flue gas emissions effectively.
• Delaying FGD compliance risks non-achievement of emission standards under India’s National Clean Air Programme (NCAP).

Mains Mock Question:

Q. Discuss the role of Flue Gas Desulphurisation (FGD) units in India’s clean air efforts. Critically examine the economic and environmental implications of rolling back FGD mandates.