The central government this week overturned a decade-old mandate to install flue gas desulphurisation (FGD) systems in thermal power plants. From now on, only about 11 percent of India’s 600 thermal power plant (TPP) units have to mandatorily install FGD systems, which are pollution control devices designed to remove sulphur dioxide (SO₂) from the flue gas produced during the combustion of coal in TPPs.
The 11 percent of the plants are the ones located within a 10 km radius of the National Capital Region or are cities with a population of at least a million, as per the 2011 Census. For such plants, the government in its latest decision has extended the FGD installation deadline to December 30, 2027, from 2017.
The latest decision is also expected to cut electricity costs by 25–30 paise per unit, according to a section of the industry, as 78 percent of the coal-fired power plants, including private ones, will not have to install the FGD systems, the cost of which ranges between Rs 50 lakh per megawatt, as per state-run NTPC, and Rs 1.2 crore per megawatt, as per private players.
The relaxation in the norms comes at a time when India is rushing to add 90 gigawatts (GW) of coal-fired power generation capacity in the coming six years to meet the country's growing energy needs. India's peak power demand is projected to touch 458 GW by 2032, and to meet that, the country plans to increase its overall power generation capacity to 900 GW from the current 476 GW.
FGD mandate 2015 – a knee-jerk decision?
Air pollution had become a severe public health crisis in India by 2015, with major cities like Delhi, Mumbai, Kolkata, and Bengaluru experiencing dangerously high levels of fine particulate matter (PM2.5) and other pollutants. This was largely due to emissions from vehicles, industrial processes, and power plants, particularly coal-fired TPPs.
Besides, in 2015, India had just participated in the Paris Agreement under the UN Framework Convention on Climate Change (UNFCCC). As part of its climate action goals, India committed to reducing carbon intensity and increasing its reliance on renewable energy.
To tackle air pollution and reduce carbon intensity, the Union environment ministry and the Central Pollution Control Board (CPCB) identified flue gas from thermal power plants as one of the target areas. Flue gas is the mixture of gases such as carbon dioxide, sulphur dioxide, nitrogen oxides, and carbon monoxide that is produced as a byproduct of combustion in power plants or any industrial process that burns fuel.
Back then, the government, based on an IIT Kanpur report, stated that sulphur dioxide (SO₂), a byproduct of coal combustion in power plants, was a significant contributor to air pollution, leading to smog and health problems. Hence, the Union environment ministry decided to mandate all existing thermal power plants as well as upcoming ones to get FGD systems installed.
The Ministry of Power, NTPC and independent power producers had all urged the environment ministry to impose the mandate in a phased manner by either asking the old plants due for repair and maintenance to be taken up first or ruling it for upcoming plants. However, the environment ministry, backed by orders from the Supreme Court, refused to budge.
NTPC Ltd ended up being the only power producer which installed FGD systems in about 11 percent of its power plants, which cost it about $4 billion, or Rs 50 lakh, per megawatt.
"SO₂ levels in the plants which do not have FGD range from 800-1200 micrograms per cubic metre, and units which have FGD, the levels are coming between 20-25 (µg/m³). But there's not much impact in PM2.5 and PM10. In fact, we have seen that the desulphurisation process also releases some PM2.5. We had opposed the move since the beginning, but NTPC was compelled to comply as we had to submit an affidavit in the Supreme Court," said a senior NTPC official requesting anonymity.
Private players such as Adani Power, JSW Energy and Tata Power continued to wait and watch and did not install FGD systems, saying that implementing it would result in a rise in cost of electricity to the end consumer.
Why is the govt exempting thermal power plants now?
Justifying its reversal of the mandate, the environment ministry on July 14 said the decision was a “scientifically justified shift towards more targeted, cost-effective and climate-coherent regulation.”
“Current exposure levels provide no credible evidence to suggest that SO₂, under prevailing ambient conditions, is a major public health concern. Moreover, sulfate aerosols formed from SO₂ constitute a relatively small fraction of PM2.5,” the Ministry of Environment and Climate Change said in a statement.
A detailed analysis carried out by IIT Delhi shows that sulfate contributes only 0.96 percent to 5.21 percent of PM2.5 and 0.57 percent to 3.67 percent of PM10 in cities near TPPs, it added.
The government said that the new notification is “based on extensive consultations with stakeholders and research institutions” regarding the effectiveness and rationale behind stack emission standards for SO₂ on 537 TPPs throughout the country, and its role in overall ambient air pollution of the region.
This time the government mentioned that the latest decision was based on research studies by IIT Delhi, the National Institute of Advanced Studies, as well as by the National Environmental Engineering Research Institute (NEERI) — a constituent laboratory of the Council of Scientific and Industrial Research (CSIR), besides scientific examination by the Central Pollution Control Board.
Dilution of anti-pollution measures?
According to Shreya Verma, programme manager, Centre for Science and Environment (CSE), the new SO₂ norms fall short of India’s clean air commitment. "Nearly a decade after SO₂ limits were first notified in 2015, MoEF&CC’s revised rules also leave Category B plants to case-by-case discretion — effectively mandating SO₂ norms for only 11 percent of capacity (Category A). This weakens regulatory intent, delays pollution control, and poses a risk to public health. SO₂ is a major contributor to PM2.5 — we cannot afford diluted action. India needs strong, uniform standards to meet its clean air goals," she said.
The notification states that Category B – located within a 10 km radius of critically polluted areas (CPA) or non-attainment cities (NAC) – may or may not have to install FGD. This would depend upon a decision by a committee of experts (Expert Appraisal Committee) – an existing body constituted by the environment ministry that grants environment clearances to proposed TPP projects.
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