Flue Gas Desulphurisation (FGD) for Coal Plants in India

A recent study commissioned by the Office of the Principal Scientific Adviser and conducted by the National Institute of Advanced Studies (NIAS), Bengaluru, has urged the Union Environment Ministry to reconsider its blanket mandate requiring all coal-fired thermal power plants to install Flue Gas Desulphurisation (FGD) systems.

What are Flue Gas Desulphurisation (FGD) systems?

Flue Gas Desulphurisation (FGD) systems are technologies used to remove sulfur dioxide (SO2) from flue gases produced by combustion processes, such as in power plants. This process helps reduce air pollution and mitigates acid rain formation. FGD systems come in various types, including wet and dry systems, each with its own advantages and applications. 

Background: FGD Mandate and Compliance Status

• In 2015, the Environment Ministry mandated all 537 coal-fired power plants in India to install FGD units to control sulphur dioxide (SO₂) emissions.
• The deadline was initially set for 2018, but multiple extensions have pushed full compliance to 2027–2029, depending on the plant category.
• Current compliance status:
  • Only 8% of plants have installed FGD systems.
  • 230 plants are in different stages of installation.
  • 260 plants have not yet placed FGD orders.
• The installation cost is ₹1.2 crore per megawatt (MW).
• With India’s installed coal capacity at 218,000 MW, rising to 283,000 MW by 2032, the cost and logistical burden are substantial.

Key Finding: Most Indian Coal is Low in Sulphur

• The NIAS study highlights that 92% of Indian coal has a low sulphur content (0.3%-0.5%).
• Only plants using imported or high-sulphur coal (>0.5%) pose a significant risk of SO₂ pollution.
• Existing mitigation measures—such as 220-meter tall stacks mandated by the Central Pollution Control Board (CPCB)—combined with Indian atmospheric conditions, effectively disperse SO₂ emissions.
• A 2024 IIT-Delhi study found acid rain not to be a significant concern in India.

Environmental Trade-Offs

• Universal FGD installation could lead to:
  • Higher water consumption
  • Increased power usage
  • An additional 69 million tonnes of CO₂ emissions (2025–2030)
• This would reduce SO₂ emissions by 17 million tonnes, but at a substantial environmental and financial cost.
• The study also references IPCC assessments, noting that SO₂ emissions have a cooling effect, masking global warming by 0.5°C between 2010 and 2019 compared to pre-industrial levels.

Policy Recommendation

• The study strongly recommends:
  • Rolling back the universal FGD mandate
  • Focusing only on plants using imported or high-sulphur coal
• This targeted approach would ensure cost-effective pollution control while minimizing unintended climate impacts.

A Call for Evidence-Based Environmental Regulation

The study challenges the one-size-fits-all FGD policy, arguing that a science-backed, differentiated strategy would better balance air quality concerns, climate implications, and economic feasibility. As India rapidly expands its power generation capacity, policies must evolve in tandem with scientific findings and contextual realities.

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