Reviewing FGD Rules for Coal Power Plants | 19 Apr 2025

Source: TH 

Why in News? 

A study commissioned by the Principal Scientific Adviser’s Office recommended rolling back the 2015 mandate requiring Indian coal-fired plants to install Flue Gas Desulphurisation (FGD) systems. 

• The Ministry of Environment, Forest & Climate Change (MoEFCC) in 2015 mandated all of India’s 537 coal-fired plants to install FGD systems to reduce sulphur dioxide (SO2) emissions.   
• Under a 2022 notification, penalties for non-compliance increase based on the delay in implementation. The penalties are applied per unit of electricity, with higher charges for longer delays. 

What is Flue Gas Desulphurisation (FGD)? 

• About: FGD is a process that removes sulphur dioxide (SO₂) from exhaust gases (flue gas) produced by burning fossil fuels (coal, oil). 
  • It is commonly used in coal-fired power stations. 
  • Common reagents used include limestone (CaCO₃), lime (CaO), and ammonia (NH₃). 
• Purpose: Coal contains sulphur, leading to high SO₂ emissions when burned causing acid rain. 
  • FGD purifies exhaust gases and prevents acid rain, which damages crops, infrastructure, soil, and aquatic ecosystems. 

• Types: FGD systems are mainly of three main types: 
  • Dry Sorbent Injection: It uses limestone to remove SO₂ from flue gas before dust control systems, often referred to as dry injection or spray drying systems. 
  • Wet Limestone-Based System: It is suitable for large-scale flue gas treatment, using low-cost limestone to remove SO₂ efficiently and produce gypsum. 
  • Seawater-Based System: It uses alkaline seawater to reduce SO₂ by 70–95%. It is typically used when emission norms are less stringent and offers a lower initial cost. 

What the Study Revealed About FGD Installation? 

Challenges in FGD Installation Policy  

• High Costs: FGD installation costs Rs 1.2 crore per MW, adding financial strain to India’s 218,000 MW coal capacity (expected to rise to 283,000 MW by 2032). 
• Low Sulphur Content: 92% of Indian coal has low sulphur content (0.3%-0.5%), making FGD less critical. 
• Existing Pollution Control Norms: Thermal plants’ stack heights (220m) and India’s climate already dilute SO₂ emissions, preventing local air quality threats. 
• Minimal Acid Rain Threat: IIT-Delhi’s 2024 study (cited in the current research) found acid rain was "not a significant issue" in India. 
• Climate Impact: Energy-intensive FGD processes will lead to an additional 69 million tonnes of CO₂ emissions (2025-30) for just a 17 million tonne reduction in SO₂. 
  • SO₂ has a short-lived cooling effect on global warming, removing it while increasing CO₂ would worsen climate change. 
  • The study argues that SO₂ emissions offset 0.5°C of global warming from 2010–2019 relative to 1850-1900. 
• Poor Compliance: Although coal plants were supposed to install FGD by 2018, only 8% have done so after deadline extensions.  
  • Currently, 230 plants are installing FGD, while 260 have not yet placed orders. 

Recommendations of the Study  

• The study suggests tackling particulate matter (PM) pollution due to the high ash content in Indian coal. 
  • Electrostatic precipitators (ESP) can cut PM pollution by 99% at just Rs 25 lakh per MW. 
• The study recommended that FGD systems should only apply to those plants using imported coal or high (>0.5%) sulphur coal.