Subject: GS 3: Environment
Context: A CREA report found that 81% of sulphur dioxide (SO₂) emissions from coal plants within 300 km of Delhi-NCR come from plants exempted from mandatory Flue Gas Desulphurisation (FGD) installation under the July 2025 notification.
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Key Findings of the Centre for Research on Energy and Clean Air (CREA) Report
- Pollution Despite Relaxed Norms: The report highlights that 78% of India’s coal-fired power plants are no longer required to install FGDs following the July 2025 revision of emission norms.
About Centre for Research on Energy and Clean Air (CREA)
- Founded in 2019, it is an independent international research organisation working on air pollution, energy transition and climate policy.
- Objective: Supports governments, researchers and civil society through scientific analysis and evidence-based policy recommendations for improving air quality and accelerating the transition to clean energy.
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- Health Concerns: Sulphur dioxide (SO₂) is a major precursor of secondary PM2.5, contributing to respiratory diseases, cardiovascular disorders, stroke and premature deaths.
- Regional Pollution: Since SO₂ can travel hundreds of kilometres before converting into PM2.5, emissions from distant thermal power plants can significantly affect air quality in Delhi-NCR.
- Performance of FGD-equipped Plants: Coal plants equipped with FGD systems emitted significantly lower SO₂ compared to similar-capacity plants operating without pollution control technology.
Background- Evolution of SO₂ Emission Norms
- 2015: The Government mandated the installation of Flue Gas Desulphurisation (FGD) systems in all coal-fired thermal power plants.
About Flue Gas Desulphurisation (FGD)
- FGD is an air pollution control technology installed in thermal power plants to remove sulphur dioxide (SO₂) from flue gases before they are released into the atmosphere.
- Working Principle: It uses alkaline absorbents, commonly limestone or lime, to chemically capture SO₂ and convert it into gypsum, which can be utilised in the cement and construction industries.
- Efficiency: Capable of removing up to 95% of SO₂ emissions from coal-fired power plants.
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- 2021: Thermal power plants were categorised into Category A, B and C based on their location and pollution sensitivity, with different compliance timelines.
- July 2025 Notification:
- Category A: Mandatory FGD installation by 2027.
- Category B: Requirement decided on a case-by-case basis.
- Category C: Exempted from mandatory FGD installation; these plants constitute about 78% of India’s coal-fired power plants.
What is Sulphur Dioxide (SO₂) and Why is it a Concern?
- It is a colourless, reactive gas with a pungent odour, released mainly during the combustion of sulphur-containing fossil fuels, especially coal.
- It is a major air pollutant, causing respiratory and cardiovascular diseases, and contributes to acid rain, particulate matter (PM2.5) formation, and ecosystem degradation.
- India is the world’s largest emitter of SO₂, primarily due to its heavy dependence on coal-based thermal power plants.
- Precursor to PM2.5: Reacts in the atmosphere to form secondary fine particulate matter (PM2.5), a major contributor to urban air pollution.
Recommendations by CREA
- Universal FGD Installation: Reinstate mandatory FGD installation for all coal-fired power plants, irrespective of category.
- Greater Transparency: Make Continuous Emission Monitoring Systems (CEMS) data publicly available in real time.
- Regular Disclosure: Publish the operational status and compliance reports of FGD systems.
- Strengthen Air Quality Management: Improve monitoring and enforcement to reduce SO₂ and PM2.5 pollution, particularly in high-risk regions such as Delhi-NCR.
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