Key Findings of the Study
Rising Emission Trends
- Contrary to global declines, India's SO₂ emissions from Coal-Fired Power Plants (CFPPs) increased significantly:
- 2005: 2.36 thousand kilotonnes
- 2021: 5.05 thousand kilotonnes
- 2023: Further 30% spike
Secondary Pollutant Formation
- SO₂ emissions serve as primary precursors to Secondary Inorganic Aerosols (sulphates, nitrates, and ammonium)
- These significantly contribute to PM2.5 levels, a major air quality concern in India
Geographic Hotspots
- Highest avoidable mortality: Maharashtra, Tamil Nadu, and Karnataka (due to population density)
- Most dramatic air quality improvements: Chhattisgarh and Odisha
Environmental Equity
- The study uses National Family Health Survey-5 (NFHS-5) data
- Disproportionately affected groups: Scheduled Castes (SC), Scheduled Tribes (ST), Other Backward Classes (OBC), and lower-income groups
- Makes mitigation a matter of social justice
Flue Gas Desulphurisation (FGD) Technology
About
FGD is a pollution control technology used to remove SO₂ from exhaust flue gases of coal-fired power plants before release into the atmosphere.
Working Principle
- Core Principle: Chemical Absorption
- SO₂ (acidic gas) is removed by reacting with an alkaline substance (limestone or lime)
The Process
- Flue gas from boiler passes through an "absorber" or "scrubber"
- A slurry of limestone (CaCO₃) is sprayed onto the gas
- SO₂ reacts with limestone to form Calcium Sulphite
- Calcium Sulphite is oxidized to produce Gypsum
By-product
- Gypsum is a valuable commercial material sold to construction industry for drywall and cement
Types of FGD Systems
| Type | Description | End Product |
|---|---|---|
| Wet Scrubbers | Most common; flue gas saturated with liquid slurry of lime/limestone | Gypsum |
| Dry/Semi-Dry | Smaller moisture; reagent sprayed and evaporates | Dry waste material |
| Seawater FGD | Uses natural alkalinity of seawater | Sulfate salts |
Policy Context and Recommendations
Current Policy Situation
- In July 2025, the Centre relaxed the 2015 emission norms
- Nearly 79% of coal units were exempted from installing FGD systems
Policy Recommendations
- Strict enforcement of MoEFCC emission norms
- Prioritization of pollution hotspots
- Shift toward cleaner cooking fuels and electric vehicles
- Mandatory installation of FGD systems (health-related monetary gains outweigh costs)
Constitutional/Policy Framework
- Article 21: Right to life includes right to clean environment
- Environment (Protection) Act, 1986: Framework for emission standards
- National Air Quality Programme: Monitoring and mitigation framework
- MoEFCC (Ministry of Environment, Forest and Climate Change): Regulatory authority