Flue Gas Desulphurization (FGD)

Flue Gas Desulphurization (FGD) : Recently, the Central Scientific Committee suggested removing the rule that requires most coal-fired thermal power plants (TPPs) in India to install Flue Gas Desulphurization (FGD) units..

• About FGD: Systems remove sulfur compounds, mainly sulfur dioxide (SO₂), from exhaust gases of fossil-fuel power plants.

o The process uses absorbents to capture up to 95% of SO₂ from flue gas emissions.

o Common absorbents include ammonia, sodium sulfite, and widely used lime or limestone slurry.

o In this process, uncleaned flue gas passes through a scrubber tower where it is sprayed with a water-limestone mixture.

o A chemical reaction in the scrubber binds the sulfur dioxide, effectively cleaning the gas before release.

• Environmental Trade-Offs of FGD: FGDs increase auxiliary power use in power plants, leading to higher carbon dioxide (CO2) emissions.

o Installing FGDs on all plants by 2030 may add around 69 million tons of CO2 emissions.

o This CO2 increase outweighs the benefit of reducing sulfur dioxide (SO2) emissions by 17 million tons.

o Since SO2 is a short-lived pollutant and CO2 is a long-lived greenhouse gas, the overall impact could worsen global warming.