Why in News?

  • A report by the Centre for Research on Energy and Clean Air (CREA) has revealed that 81% of sulphur dioxide (SO2) emissions from coal-fired power plants within a 300 km radius of Delhi-NCR originate from plants that were exempted from mandatory installation of Flue Gas Desulphurisation (FGD) systems under the July 2025 notification.
  • The findings come one year after the Union Government relaxed emission norms for most coal-based thermal power plants.
  • Experts warn that increasing coal-based electricity generation, coupled with weaker emission controls, could worsen 5 pollution and public health outcomes.

KEY HIGHLIGHTS

Major Findings of the CREA Report
  • 81% of SO2 emissions around Delhi-NCR come from Category C coal plants exempted from FGD installation.
  • Around 90% of estimated SO2 emissions originate from plants operating without FGD systems.
  • CREA assessed:
    • 12 coal-fired thermal power plants
    • 37 generating units
    • 25 units with sufficient publicly available data.
  • Estimated SO2 emissions in 2025:
    • 154 kilotonnes (kt)
  • Category C plants alone contribute:
    • 125 kilotonnes (81%)
  • Category A plants contribute:
    • 29 kilotonnes

WHY THE REPORT IS SIGNIFICANT?

  • India is expected to witness higher coal-based electricity generation due to:
    • Rising electricity demand.
    • Reduced hydropower generation during strong El Niño
  • Increased coal consumption without effective pollution controls may further deteriorate air quality in North India.

WHAT IS SO2?

Definition
  • Sulphur dioxide (SO2) is a colourless, toxic gas produced mainly by:
    • Burning sulphur-containing fossil fuels (especially coal).
    • Industrial processes.
    • Smelting operations.
    • Volcanic activity (natural source).
Major Sources in India
  • Coal-fired thermal power plants.
  • Petroleum refineries.
  • Steel and cement industries.
  • Industrial boilers.
  • Heavy fuel oil combustion.

WHY IS SO2 A CONCERN?

Health Impacts Exposure to SO2 can cause:
  • Respiratory diseases.
  • Asthma attacks.
  • Chronic bronchitis.
  • Reduced lung function.
  • Cardiovascular diseases.
  • Stroke.
  • Premature mortality.
Children, the elderly, and people with respiratory illnesses are particularly vulnerable. Environmental Impacts SO2 contributes to:
  • Formation of PM2.5 (secondary particulate matter).
  • Acid rain.
  • Soil acidification.
  • Water pollution.
  • Damage to crops and forests.
  • Reduced visibility (haze).

HOW DOES SO2 FORM PM2.5?

Formation Process
  1. Coal combustion releases SO2 into the atmosphere.
  2. SO2 reacts with:
    • Oxygen
    • Water vapour.
    • Ammonia.
  3. Forms:
    • Sulphate aerosols.
  4. These become fine particulate matter (PM2.5).
Why PM2.5 is Dangerous
  • Diameter less than 2.5 micrometres.
  • Can penetrate deep into the lungs.
  • Can enter the bloodstream.
  • Causes long-term health problems and premature deaths.
WHAT IS FLUE GAS DESULPHURISATION? FGD is an air pollution control technology used in coal-fired thermal power plants to remove sulphur dioxide (SO2) from exhaust gases before they are released into the atmosphere. Working Mechanism
  • Flue gases pass through an absorber tower.
  • Limestone or lime slurry reacts with SO2.
  • Converts SO2 into:
    • Gypsum (Calcium Sulphate).
  • Cleaned gases are released through chimneys.
Efficiency FGD systems can remove:
  • 90–95% of sulphur dioxide emissions.
Benefits
  • Reduces SO2
  • Lowers PM2.5 formation.
  • Prevents acid rain.
  • Improves air quality.
  • Protects public health.
  • Helps meet emission standards.

INDIA’S EMISSION NORMS FOR THERMAL POWER PLANTS

2015 Notification The Ministry of Environment, Forest and Climate Change (MoEFCC):
  • Mandated FGD installation for all coal-fired power plants.
  • Original compliance deadline: 2017
Repeated Extensions The deadline was extended four times due to:
  • High installation costs.
  • Equipment shortages.
  • COVID-19 disruptions.
  • Implementation delays.
2021 Categorisation of Thermal Power Plants Plants were classified into: Category A
  • Plants located within:
    • 10 km of Delhi-NCR
    • Million-plus cities
    • Critically polluted areas
Requirement
  • Mandatory FGD installation.
Category B
  • Plants near:
    • Non-attainment cities.
Requirement
  • Compliance based on pollution levels.
Category C
  • Remaining thermal power plants.
Initially:
  • Required to install FGDs.
July 2025 Notification: Relaxation of Norms The Union Government revised emission norms. Category A
  • Must install FGDs by 2027.
Category B
  • Assessed on a case-by-case basis.
Category C
  • Exempted from mandatory FGD installation.
These plants account for nearly:
  • 78% of India's coal-fired thermal power plants.

WHY IS CREA CRITICAL OF THE REVISED POLICY?

1. Location-Based Categorisation is Inadequate The categorisation depends mainly on:
  • Whether a plant is located within 10 km of a city.
However, SO2 can travel:
  • Hundreds of kilometres before converting into PM2.5.
Thus, Even distant power plants can significantly affect Delhi-NCR's air quality. 2. Increased Coal Generation India's electricity demand continues to rise. During strong El Niño years:
  • Hydropower generation declines.
  • Coal generation increases.
Without FGDs, SO2 emissions are expected to rise substantially. 3. Weak Monitoring CREA highlights:
  • Limited public access to Continuous Emission Monitoring System (CEMS)
  • Lack of transparency regarding:
    • FGD installation.
    • Operational status.
    • Compliance.

CASE STUDIES

Mahatma Gandhi Thermal Power Plant (FGD Installed) Annual Generation
  • Around 3,400–4,000 million units
SO2 Emissions
  • Unit 1:
    • 1,775 tonnes
  • Unit 2:
    • 2,154 tonnes
Shows:
  • Effective pollution control significantly reduces emissions.
Rajpura Thermal Power Plant (Without Effective FGD) SO2 Emissions
  • Unit 1:
    • 20,851 tonnes
  • Unit 2:
    • 22,690 tonnes
It emerged as:
  • The largest SO2 emitter in the study.
WHY DOES THIS MATTER FOR DELHI NCR? According to CREA:
  • The energy sector contributes up to:
    • 16% of particulate pollution in Delhi-NCR cities.
Combined with:
  • Vehicular emissions.
  • Construction dust.
  • Biomass burning.
  • Crop residue burning.
SO2 significantly worsens winter smog.

CHALLENGES

  • Increasing dependence on coal.
  • Relaxed emission standards.
  • Slow FGD implementation.
  • Weak regulatory enforcement.
  • Poor monitoring transparency.
  • Rising electricity demand.
  • Climate-induced reduction in hydropower.

CREA’S RECOMMENDATIONS

1. Reinstate Mandatory FGD Installation
  • Make FGDs compulsory for all coal-fired power plants, irrespective of category.
2. Improve Transparency
  • Publicly disclose:
    • Real-time CEMS data.
    • SO2
    • Compliance reports.
3. Monitor FGD Performance
  • Regularly publish:
    • Installation status.
    • Operational efficiency.
    • Maintenance records.
4. Strengthen Regulatory Oversight
  • Ensure strict enforcement of emission norms.
  • Periodic environmental audits.
  • Independent verification of emissions.
5. Accelerate Energy Transition
  • Expand renewable energy.
  • Improve energy efficiency.
  • Promote battery storage.
  • Reduce dependence on coal over the long term.