Where is India’s SO₂ control from TPPs headed? NITI Aayog’s memo over FGDs fuels debate

Sub: Env

Sec: Pollution

Context:

NITI Aayog’s recent memorandum questioned the need for flue gas desulfurisation (FGD) in India’s TPPs, following recommendations by CSIR-NEERI at a meeting on August 21, 2024.
CSIR-NEERI’s analysis, based on data from various monitoring stations and TPPs, found that only 13 sites exceeded SO₂ limits, leading to its recommendation against additional FGD installations.
The draft report backing this claim remains unavailable to the public and regulatory bodies.

CSIR-NEERI’s Findings:

Data from 467 Central Control Room stations and 486 TPP-managed sites indicate that ambient SO₂ levels rarely exceed permissible limits.
Instead of focusing on SO₂, NEERI suggested prioritizing the control of particulate matter (PM), which frequently surpasses limits based on Online Continuous Emission Monitoring System (OCEMS) data.
Contrasting Evidence from IIT Delhi:
- IIT Delhi’s report advocates phased FGD implementation based on SO₂ data from satellite and reanalysis sources (2015-2019).
- This contradiction raises questions about the accuracy of NITI Aayog’s reliance on CSIR-NEERI’s findings alone.

Historical Timeline of SO₂ Compliance Deadlines:

2015: MoEF&CC introduced strict emission norms, targeting a 2017 compliance deadline for TPPs.
2017: An extension was granted, pushing deadlines to 2022.
2020-2021: Compliance categories (A, B, and C) were created, each with staggered deadlines based on pollution and population levels.
- The compliance deadlines for parameters other than SO₂ norms varied by category. Category A covered plants located within a 10-kilometre radius of NCR or cities with populations exceeding one million. These plants must meet compliance requirements by December 31, 2022.
- Category B included plants within a 10-km radius of critically polluted areas or non-attainment cities, with a deadline of December 31, 2023. Lastly, Category C encompasses all remaining plants, which were expected to comply by December 31, 2024.
- The categorisation by the task force puts approximately 22 per cent of the capacity in Category A and Category B. Nearly 78 per cent of the coal power capacity is placed under Category C.
2022: Revised deadlines extended the final SO₂ compliance date to 2026 for Category C plants.
Current Status of FGD Installation:
- FGD is installed in 39 units (19,430 MW) and is in progress in 238 units (105,200 MW).
- Tendering is ongoing in 139 units (42,847 MW), and pre-tendering for 121 units (36,683 MW) is underway.

Health and Environmental Concerns:

India, as the world’s top SO₂ emitter since 2019, has been urged to control SO₂ due to severe health risks linked to respiratory and cardiovascular diseases.
SO₂ emissions from coal combustion contribute to particulate pollution (PM2.5), which worsens air quality and health outcomes.

Flue Gas Desulphurisation (FED):

Removal of Sulfur Dioxide is called as Flue-gas Desulphurization (FGD).
It seeks to remove gaseous pollutants viz. SO2 from exhaust flue gases generated in furnaces, boilers, and other industrial processes due to thermal processing, treatment, and combustion.
FGD systems may involve wet scrubbing or dry scrubbing.
In wet FGD systems, flue gases are brought in contact with an absorbent, which can be either a liquid or a slurry of solid material. The sulfur dioxide dissolves in or reacts with the absorbent and becomes trapped in it.
In dry FGD systems, the absorbent is dry pulverized lime or limestone; once absorption occurs, the solid particles are removed by means of baghouse filters.

Benefits of Flue Gas Desulphurisation (FED):

According to the Centre for Atmospheric Science, IIT Delhi, an FGD unit can remove anywhere between 50 and 99.8 per cent of SOx emissions, depending on the power plant’s vintage.

Sulphur Dioxide Pollution:

According to a report by Greenpeace (an environmental Non-Governmental Organization), India is the largest emitter of Sulphur Dioxide (SO2) in the world
The primary reason for India’s high emission output is the expansion of coal-based electricity generation over the past decade.

Source:

The largest source of SO2 in the atmosphere is the burning of fossil fuels by power plants and other industrial facilities.
Smaller sources of SO2 emissions include: industrial processes such as extracting metal from ore; natural sources such as volcanoes; and locomotives, ships and other vehicles and heavy equipment that burn fuel with a high sulfur content.

Impact: SO2 can affect both health and the environment.

Sulphur dioxide is bad for health and the environment.
Short-term exposures to SO2 can harm the human respiratory system and make breathing difficult. People with asthma, particularly children, are sensitive to these effects of SO2.
SO2 emissions that lead to high concentrations of SO2 in the air generally also lead to the formation of other sulfur oxides (SOx). SOx can react with other compounds in the atmosphere to form small particles. These particles contribute to particulate matter (PM) pollution.
Small particles may penetrate deeply into the lungs and in sufficient quantities can contribute to health problems.
At high concentrations, SO2 can harm trees by damaging foliage and stunting growth. When the gas mixes with falling raindrops, we get a shower of sulphuric acid.

Source: DTE