Flue Gas Desulphurisation (FGD)

Flue Gas Desulphurisation (FGD): Union Environment Ministry is being urged to roll back its 2015 policy mandating all of India’s 537 coal-fired plants to install Flue Gas Desulphurisation (FGD) equipment to reduce sulphur dioxide (SO₂) emissions.

• About Flue Gas Desulphurisation (FGD): It is a technology to eliminate sulphur compounds from exhaust emissions.

o Flue gas is the emitted material produced when fossil fuels such as coal, oil, natural gas, or wood are burned for heat or power.

o FGD process involves the addition of absorbents, which can remove up to 95% of the sulphur dioxide from the flue gas.

o Absorbents such as ammonia or sodium sulphite are used; however, the use of lime or limestone slurry (wet limestone scrubbing) is also widespread.

o Uncleaned flue gas is sprayed in a scrubber tower (absorber tower) with a mixture of water and limestone (scrubbing slurry), whereby most of the sulphur dioxide is bonded by chemical reaction.

• About Sulphur Dioxide & their Impact: Sulphur dioxide is a major air pollutant which impacts all life. It is also a precursor of acid rain, which has significant adverse impacts on forests, freshwaters, and soils.

o Acid rain can kill insect and aquatic life forms, cause paint to peel, corrosion of steel structures such as bridges, and weathering of stone buildings and statues.