Expert Committee recommends ending mandatory Flue Gas Desulphurisation (FGD) in India

1. In June 2024, a committee chaired by Principal Scientific Adviser has recommended removing the mandatory requirement of installing Flue Gas Desulphurisation (FGD) units in all coal-fired thermal power plants (TPPs).

1. This recommendation is under review by the Ministry of Environment, Forest and Climate Change (MoEFCC) and the Ministry of Power.
2. This could mark a critical shift in India's strategy to manage sulphur dioxide (SO₂) emissions — balancing pollution control with economic and climate realities.
    

What is Flue Gas Desulphurisation (FGD)?
 

1. Flue Gas Desulphurisation (FGD) is a technology used to remove sulphur dioxide (SO₂) — a major air pollutant — from the flue gases emitted during coal combustion in power plants.
2. It helps prevent acid rain, protects respiratory health, and mitigates environmental degradation.

Chemical Process

1. The most common method involves wet scrubbing, where flue gas is passed through a tower sprayed with a limestone (CaCO₃) slurry.
2. SO₂ reacts with limestone to form calcium sulphite, which gets oxidised to calcium sulphate (gypsum).
3. The by-product gypsum is used in cement and construction, promoting a circular economy.

Types of FGD Systems

FDG Systems	Description
Wet Limestone-Based FGD	High efficiency (~95%), widely used for large coal plants.
Dry Sorbent Injection (DSI)	Involves dry lime injection; lower capital cost, suited for smaller units.
Seawater FGD	Uses alkaline seawater to reduce SO₂ by 70–95%; applicable in coastal plants with less stringent norms.

The 2015 FGD Mandate: Policy Origin

1. In December 2015, the MoEFCC revised emission norms for thermal power plants, mandating FGD installation for all coal-based power plants to curb SO₂ emissions.
2. Compliance deadlines were set between 2018 and 2022, depending on plant age, location, and pollution levels.
    

Implementation Status (as of 2024)
 

1. India has around 180 thermal power plants, comprising 600+ units.
2. 92% of these units have not installed FGDs, despite three deadline extensions.
3. The most recent compliance deadline was extended to 31 December 2024.
4. Only 14 of 66 high-priority units (Category A) have installed FGDs.
5. Penalties for non-compliance (introduced in 2022) exist on paper but have not been implemented, mainly due to repeated extensions.
    

Expert Committee’s Recommendation to Scrap the Mandate
 

1. Low Ambient SO₂ Levels

1. Studies by CSIR-NEERI, IIT Delhi, and National Institute of Advanced Studies (NIAS) report ambient SO₂ levels across most Indian regions are 10–20 µg/m³, well below the NAAQS limit of 80 µg/m³.
2. No significant difference was observed in SO₂ concentrations between areas with and without operational FGDs.

2. Low Sulphur Content in Indian Coal

1. 92% of Indian coal has a sulphur content of 0.3–0.5%, which naturally limits SO₂ emissions.

3. Stack Design and Dispersion

1. Thermal plants have stack (chimney) heights of 220m or more, aiding in wider dispersion and natural dilution of SO₂.

4. Limited Acid Rain Risk

1. A 2024 IIT Delhi study found acid rain is not a major threat in Indian climatic and atmospheric conditions.

5. Climate Impact of FGDs

1. FGD systems are energy-intensive and estimated to cause 69 million tonnes of additional CO₂ emissions (2025–30) for just a 17 million tonne reduction in SO₂.
2. SO₂ contributes to short-term global cooling. Eliminating SO₂ while increasing CO₂ could exacerbate global warming.
3. SO₂ emissions are estimated to have offset 0.5°C of global warming between 2010 and 2019.

6. High Financial Burden

1. Cost of FGD installation is ₹1.2 crore per MW.
2. India's coal capacity stands at 218 GW, projected to grow to 283 GW by 2032, implying a financial burden exceeding ₹2.5 lakh crore.
    

New Tiered Compliance Framework Proposed
 

The committee recommends differentiated compliance based on geography, pollution risk, and public exposure:

Category	Description
Category A: Mandatory FGD Installation	TPPs within 10 km of NCR or cities with >1 million population. 66 units fall in this category; only 14 have complied. Compliance deadline remains 2027.
Category B: Case-by-Case Compliance	Plants near critically polluted or non-attainment cities (72 units). Deadline: 2028. Some older units (20+ years) may be exempted.
Category C: Full Exemption Recommended	Remaining 462 units. Deadline: 2029 (original). Committee recommends complete exemption from FGD requirements.

Alternative Pollution Control Focus

1. Particulate Matter (PM) Pollution

1. Indian coal has high ash content, leading to significant PM emissions.
2. Electrostatic Precipitators (ESPs) are recommended for PM control.
3. ESPs are cost-effective: ₹25 lakh per MW (vs. ₹1.2 crore for FGDs).
4. Can remove 99% of PM, which has a more immediate impact on health.

2. Water and Efficiency Norms

1. 2015 norms for water use and PM emissions remain unchanged and are to be enforced strictly.
    

Concerns
 

1. India’s annual SO₂ emissions rose from 4,000 kilotonnes (2010) to 6,000 kilotonnes (2022) — highest globally.
2. Indonesia, despite using higher-sulphur coal, maintains lower emissions (2,000 kt), due to fewer coal-fired plants and laxer (less strict) norms (800 µg/m³ vs India’s 100 µg/m³).
3. Experts fear scrapping FGDs may reduce India’s climate credibility and contradict its air quality goals under the NCAP and international commitments.

Conclusion
 

The recommendation to scrap the universal FGD mandate is a data-backed, cost-aware, climate-sensitive policy shift. It acknowledges ground realities — low SO₂ levels, financial and implementation bottlenecks, and unintended climate consequences. Yet, the move requires cautious implementation, with clear enforcement for high-risk zones (Category A) and strong investment in alternative pollution control technologies
 

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