Description

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Context

A recent study commissioned by the Principal Scientific Adviser recommends rolling back the 2015 mandate requiring all 537 coal-fired plants to install Flue Gas Desulphurisation (FGD) units.

FGD should only be mandatory for plants using imported coal or high-sulphur coal (>0.5%).

Current Status

Original deadline for FGD installation: 2018 → deadlines extended to 2027-2029.

Compliance status

Only 8% of plants have installed FGDs.

230 plants are installing FGDs; 260 plants have not yet placed orders.

Cost and Capacity

Cost of FGD installation: ₹1.2 crore per MW.

Current coal capacity: 218,000 MW, projected to reach 283,000 MW by 2032.

Rationale for Policy Change

92% of coal used in India has low sulphur content (0.3%-0.5%).

Existing norms: 220-metre stack heights and Indian climatic conditions already minimize SO₂ impact on local air quality.

IIT-Delhi study (2024): Acid rain is not a major issue in India.

Environmental Impact

Installing FGDs would increase

Freshwater consumption,

Power consumption,

CO₂ emissions by 69 million tonnes (2025–30),

While reducing SO₂ emissions by 17 million tonnes.

Recommendations

Focus efforts on controlling Particulate Matter pollution instead of SO₂ due to the high ash content in Indian coal.

About FGD

Flue Gas Desulphurisation refers to a set of technologies used to remove sulphur dioxide from the exhaust (flue) gases of fossil fuel power plants and industrial facilities.

It is an important environmental control measure aimed at reducing air pollution, acid rain and health hazardscaused by SO₂ emissions.

Why is FGD Needed?

Environmental Impact

SO₂ is a major contributor to acid rain which damages crops, forests and aquatic ecosystems.

SO₂ emissions contribute to particulate matter (PM 2.5) formation aggravating respiratory and cardiovascular diseases.

Regulatory Requirement

In India the Ministry of Environment, Forest and Climate Change notified tighter emission norms for thermal power plants in December 2015.

Plants are required to limit SO₂ emissions by installing FGD units.

International Commitments

Aligns with India’s obligations under agreements like the Paris Agreement to reduce environmental pollution.

How does FGD Work?

Flue gascontaining sulphur dioxide passes through a scrubber.
The scrubber uses a sorbent(usually limestone or lime slurry) to absorb or neutralize SO₂.
The chemical reaction produces gypsum(calcium sulphate), a by-product that can be commercially utilized.

Chemical Reaction: SO₂ + CaCO₃ → CaSO₃ → CaSO₄·2H₂O (gypsum)

Cleaned flue gas is then released into the atmosphere with significantly reduced SO₂ levels.

Types of FGD Systems

Type	Description	Key Points
Wet FGD	Uses a slurry of limestone or lime to absorb SO₂.	Most common. High removal efficiency (~90-98%). High water usage.
Dry FGD	Uses dry sorbents (lime) sprayed into flue gas.	Lower water requirement. Lower SO₂ removal efficiency (~70-90%). Suitable for water-scarce regions.
Semi-Dry FGD	Combines features of wet and dry systems using a moist sorbent.	Moderate efficiency. Lower operating cost.

By-products of FGD

Gypsum (Calcium Sulphate Dihydrate)

Used in cement manufacturing and construction material.

Fly Ash

Can be used in brick making and road construction.

Advantages of FGD

Significant reduction in SO₂ emissions.

Helps in compliance with national and international environmental standards.

Gypsum by-product promotes resource recovery and circular economy.

Improves air quality and reduces health impacts on nearby populations.

Challenges

Challenge	Details
High Capital and Operating Costs	FGD units are expensive to install and maintain, especially for older thermal plants.
Water Consumption	Wet FGD systems consume large amounts of water, problematic in water-scarce areas.
Space Requirement	Requires additional land for equipment and gypsum storage.
Waste Management	Disposal of waste material (if not reused) can cause environmental concerns.
Technical Expertise	Operation and maintenance demand trained personnel.
Delayed Implementation	In India, many plants have sought extensions due to financial and logistical constraints.

Status of FGD in India

The Central Electricity Authority and MoEFCC have set phased deadlines for the installation of FGD systems in thermal power plants.

Deadlines are differentiated based on proximity to cities and critical areas.

As of 2024 progress is slow; several plants have faced issues like

Delayed tenders

Technology sourcing challenges

Financial non-viability for older plants

Sources:

HINDU

PRACTICE QUESTION

Q.Flue Gas Desulphurisation (FGD) technology is critical for achieving India's air quality and environmental goals, but its implementation faces serious challenges. Discuss. 250 Words.