Flue Gas Desulphurisation (FGD)

Flue Gas Desulphurisation (FGD) removes sulphur dioxide (SO₂) from exhaust gases in fossil fuel power plants, reducing air pollution and environmental harm. Read more about Flue Gas Desulphurisation (FGD), Technology Types, Recent Policy Changes, News

Flue Gas Desulphurisation

Flue Gas Desulphurisation (FGD) Latest News

Recently, the Environment Ministry has exempted most coal-fired plants in India from installing Flue Gas Desulphurisation (FGD) systems aimed at reducing sulphur dioxide (SO2) emissions.

About Flue Gas Desulphurisation (FGD)

  • Flue Gas Desulphurisation (FGD) is a pollution-control process that removes Sulphur Dioxide (SO₂) from the flue gases produced by the combustion of fossil fuels, especially coal.
  • The key aim of FGD is to reduce SO₂ emissions, which are major contributors to acid rain and particulate matter pollution, harming crops, soil, water bodies, infrastructure, and human health.
  • FGD systems typically use limestone (CaCO₃), lime (CaO), or ammonia (NH₃) to react with and neutralize SO₂ in flue gases.

FGD Technology Types

  • Dry Sorbent Injection (DSI): Injects limestone or lime into the flue gas before it passes through dust collectors.
  • Wet Limestone Scrubbing: Uses a slurry of limestone (CaCO₃) to absorb SO₂ and convert it into gypsum (CaSO₄·2H₂O).
  • Seawater FGD: Uses the alkalinity of seawater to neutralise SO₂, common in coastal plants, with low installation costs but limited applicability.

Recent Policy Changes and Issues

  • In 2015, India’s Environment Ministry mandated that all coal-fired thermal power plants must install FGD systems by 2017 to curb SO₂ pollution. There are about 180 such plants, comprising 600 individual units.
  • This exemption decision was based on scientific studies suggesting:
    • Indian coal has low sulphur content.
    • SO₂ levels near plants with and without FGDs were similar.
    • Sulphates may have a cooling effect, counteracting global warming.
  • As of now, only ~8% of these units have installed FGDs, with most installations by NTPC (public sector). The rest failed due to vendor shortages, high costs, COVID-related delays, and an anticipated rise in power tariffs.

Source: TH

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Flue Gas Desulphurisation (FGD) FAQs

Q1. What is Flue Gas Desulphurisation (FGD)?+

Q2. Which substances are commonly used in FGD systems?+

Q3. What are the main types of FGD technologies?+

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