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Context:

According to CSIR-NEERI’s draft report Analysis of Historical Ambient Air Quality Data Across India for Developing a Decision Support System, SO₂ emissions from India’s coal-based power plants are not significantly affecting ambient air quality, with standards mostly met. 

Key Details 

• The study aimed to assess the need for current flue gas desulfurization (FGD) regulations in Indian TPPs. 
• It concluded that SO₂ levels from 467 Central Control Room for Air Quality Management stations operated by CPCB and 486 sites managed by TPPs across India showed only 13 sites exceeded the prescribed limit of 80 micrograms per cubic metre and only in the fourth quartile (less than 25 per cent of data).
• IIT Delhi’s report, Study to Assess the Compliance of Thermal Power Plants in India to New SO₂ Emission Norms (2015) and Lay Out Phased Plan for FGD Implementation, recommended phased FGD implementation in thermal power plants (TPPs) across India based on SO₂ concentration data from AURA (OMI) Satellite and MERRA2 reanalysis (2015-2019).

Should FGD be installed?

• Installing FGD systems is costly, at Rs 1-2 crore per megawatts, leading to an added charge of 0.50-0.55 paise per unit, which increases electricity generation costs. 
• If FGD implementation continues, consumers may face additional costs, while coal power plants and regulators avoid accountability for market-driven technology prices.

Where is the SO₂?

In 2023, India consumed approximately 1,155.3 million tonnes of coal, with the coal-based thermal power sector accounting for 826.64 million tonnes. Indian coal has a sulphur content ranging from 0.35 to 0.4 percent, which is relatively low compared to Chinese or Indonesian coal. 

However, the calorific value (CV) of Indian coal is about half that of imported coal, leading to double the consumption for each MWe generated. During combustion, the sulphur in coal combines with oxygen, forming SO₂, which is released into the environment unless effective capture mechanisms are in place.

The SO₂ emitted from coal combustion in India is transformed into sulphates in the atmosphere, which contributes to an increase in particulate matter (PM2.5). 

India is the world’s largest emitter of sulfur oxides, emitting nearly two to three times as much as China, which has already implemented abatement measures in its power plants.

Why is it important to control SO₂ emissions?

In 2019, India surpassed China to become the largest SO₂ emitter globally, emitting nearly twice the amount of Russia, the second-largest emitter. 

SO₂, along with PM2.5 and PM10, poses severe health risks, increasing the likelihood of stroke, heart disease, lung cancer, and premature death. 

Given the harmful effects of SO₂ on human health, controlling its emissions is crucial. SO₂ also reacts with nitrogen oxides (NOx) to form PM2.5 and PM1, both of which have serious health implications and contribute to haze. High NOx levels in Indian coal-fired power plants enhance the conversion of SO₂ into fine PM.

According to the Ministry of Power, in 2024, FGDs were being installed in 537 units across the country’s coal-based TPPs. 

The current status of FGD installation as per the ministry is as follows:

• FGD installed in 39 units (19,430 MW).
• Contracts awarded or installations underway in 238 units (105,200 MW).
• Units in various stages of tendering process: 139 units (42,847 MW).
• Units in the pre-tendering process: 121 units (36,683 MW).

Flue Gas Desulfurization (FGD)

It is a process that uses a sorbent, usually lime or limestone, to react with SO2 in the flue gas and convert it into harmless products. The sorbent can be injected as a dry powder, sprayed as a wet slurry or circulated as a seawater solution. The reaction products can be collected as solid residues, dissolved in water or discharged into the sea.

Thermal Power Plants in India

Thermal Power Plant	Location	Capacity (MW)
Vindhyachal Thermal Power Station	Madhya Pradesh	4,760 MW
Mundra Thermal Power Station	Gujarat	4,620 MW
Sipat Thermal Power Plant	Chhattisgarh	2,980 MW
Tiroda Thermal Power Station	Maharashtra	3,300 MW
Talcher Super Thermal Power Station	Odisha	3,000 MW
Korba Super Thermal Power Plant	Chhattisgarh	2,600 MW
Rihand Thermal Power Station	Uttar Pradesh	3,000 MW
Sasan Ultra Mega Power Plant	Madhya Pradesh	3,960 MW
Kudgi Super Thermal Power Station	Karnataka	2,400 MW
Ramagundam Super Thermal Power Plant	Telangana	2,600 MW
NTPC Dadri	Uttar Pradesh	2,637 MW
Neyveli Thermal Power Station	Tamil Nadu	1,970 MW
Tuticorin Thermal Power Station	Tamil Nadu	1,050 MW
Kahalgaon Super Thermal Power Station	Bihar	2,340 MW
Farakka Super Thermal Power Plant	West Bengal	2,100 MW
Chandrapur Super Thermal Power Station	Maharashtra	2,920 MW
Dahanu Thermal Power Station	Maharashtra	500 MW
Simhadri Super Thermal Power Station	Andhra Pradesh	2,000 MW
Barauni Thermal Power Station	Bihar	720 MW
Udupi Power Plant	Karnataka	1,200 MW
Bhusawal Thermal Power Station	Maharashtra	1,210 MW
Mejia Thermal Power Station	West Bengal	2,340 MW
Raichur Thermal Power Station	Karnataka	1,720 MW
Parli Thermal Power Station	Maharashtra	1,130 MW
Jharsuguda Thermal Power Plant	Odisha	2,400 MW
Anpara Thermal Power Plant	Uttar Pradesh	1,630 MW
Gadarwara Super Thermal Power Plant	Madhya Pradesh	1,600 MW
Kothagudem Thermal Power Station	Telangana	1,720 MW
Mettur Thermal Power Station	Tamil Nadu	840 MW
Panipat Thermal Power Station	Haryana	1,360 MW
Singrauli Super Thermal Power Station	Uttar Pradesh	2,000 MW
Rajpura Thermal Power Plant	Punjab	1,400 MW
Tanda Thermal Power Plant	Uttar Pradesh	440 MW
Durgapur Thermal Power Station	West Bengal	1,000 MW
Bara Thermal Power Plant	Uttar Pradesh	1,980 MW

READ ABOUT

flue gas de-sulphurisation

IMPORTANT COAL FIRED THERMAL POWER STATIONS 

Source:

DOWNTOEARTH

PRACTICE QUESTION Q.Discuss the significance of Flue Gas Desulfurization (FGD) in mitigating sulfur dioxide (SO₂) emissions from thermal power plants in India. Evaluate the challenges and opportunities associated with the implementation of FGD technologies in the context of India’s energy policy and environmental sustainability. (250 words)