Context: The Ministry of Environment, Forest and Climate Change (MoEF&CC) has recently notified Sulphur dioxide (SO2) emission norms.

Sulphur dioxide (SO2) emission norms

• All Thermal Power Plants have to comply with the emission norms notified by the MoEF&CC and directions given by Central Pollution Control Board (CPCB).

• For compliance to Sulphur dioxide (SO2) emission norms, Thermal Power Plants are installing Flue Gas Desulphurisation (FGD) equipment.

• Areas are divided into main three categories on the basis of their location and have different timelines to comply with the norm.

• Category A includes the thermal power plants within 10 km radius of the National Capital Region (NCR) or cities having a million plus population (as per the 2011 census of India).

• They can comply to emission norms before the end of 2024.

• Category B includes locations within 10 km radius of Critically Polluted Areas or Non-attainment cities.

• They can comply to emission norms before the end of 2025.

• Category C includes all the remaining who has to comply with the norms before the end of 2026

About the Flue Gas Desulphurization

• Flue-gas desulphurization (FGD) is a set of technologies used to remove SO2 from exhaust flue gases of fossil-fuel power plants and from the processes such as waste incineration, petroleum refineries, cement and lime kilns.

• Most FGD systems employ two stages: fly ash removal and SO2 removal.

• At present, 22 units in India has a total capacity of 9280 MW have installed and operationalized FGDs in their facility.

SO2 can be removed from flue gases by following methods

• Wet scrubbing using a slurry of alkaline sorbent, usually limestone or lime, or seawater to scrub gases.

• Spray-dry scrubbing using similar sorbent slurries

• Wet sulphuric acid process recovering sulphur in the form of commercial quality sulphuric acid.

• SNOX Flue gas desulfurization removes sulphur dioxide, nitrogen oxides and particulates from flue gases.

• Dry sorbent injection systems that introduce powdered hydrated lime (or other sorbent material) into exhaust ducts to eliminate SO2 and SO3 from process emissions.

Thermal Power Plants in India

• Thermal power is the largest source of power in India.

• There are different types of thermal power plants based on the fuel that is used to generate the steam such as coal, gas, and diesel, natural gas.

• About 71% of electricity consumed in India is generated by thermal power plants.

• More than 62% of India's electricity demand is met through the country's coal reserves.

• As of April 2023, only 5% of the India’s installed coal-based thermal power generation capacities had the FGD mechanism in place.

• 17% of the overall coal power capacity are still at the initial stages of compliance.

• The public sector undertaking National Thermal Power Corporation (NTPC) and several other state-level powers generating companies operates coal-based thermal power plants.