GS3 – Environment
Context:
The government has recently eased the 2015 requirement mandating coal plants to install Flue Gas Desulphurisation (FGD) units, citing high installation costs, despite SO₂’s substantial role in air pollution.
India’s SO₂ Emission Status:
- Global Ranking: India was the largest SO₂ emitter in 2022, contributing over 20% of global anthropogenic emissions (CERA).
- Primary Sources: Emissions mainly stem from coal-based thermal power plants, heavy industries, and a few natural sources.
- Regulatory Standards (Air Act, 1981):
- 24-hour limit: 80 µg/m³ (all areas)
- Annual average:
- Urban areas: 50 µg/m³
- Sensitive zones: 20 µg/m³
- Implementation Lag: Out of 537 coal plants, only 39 have installed FGD units, indicating slow progress in emission control.
Impacts of SO₂ Pollution:
- Health Risks:
- Acute exposure: Triggers asthma, coughing, and respiratory distress
- Chronic exposure: Leads to lung diseases and early mortality
- Environmental Harm:
- Causes acid rain, damaging crops, soil, and aquatic ecosystems
- Forms sulphate aerosols, reducing visibility and harming biodiversity
Control Measures:
- Pre-Combustion Techniques:
- Fuel switching, coal washing, and Fluidised Bed Combustion (FBC) reduce SO₂ at the source
- Post-Combustion Techniques:
- Dry and wet FGD systems use limestone to extract SO₂, generating gypsum as a by-product
- Innovative Methods:
- Biotech and regenerative systems convert or recover sulphur into eco-friendly forms like elemental sulphur