When thermal power plants burn coal to generate electricity, sulphur mixes with oxygen to release sulphur dioxide – or SO2 – in the air. In 2019, India became the largest emitter of this toxic gas.
But four years before the country achieved this feat, the Narendra Modi government set up a two-year deadline to install flue gas desulphurisation – a process to regulate SO2 emissions – at all the coal-powered plants across India. That deadline has been missed three times, with the union power ministry seeking its fourth extension last month. And only around 7 percent, or 44 of the total 600, thermal power plants implementing the FGD so far.
However, the government’s apex think-tank, NITI Aayog, doesn’t seem to be on the same page as the environment ministry as far as the impact of FGD is concerned. In a note in September, the Aayog cited a draft report by the Council of Scientific and Industrial Research-National Environmental Engineering Research Institute.
“The data do not suggest that SO2 emission from Indian coal base power plants is adversely impacting the ambient air quality,” the Aayog’s note said.
“In respect of SO2, only the ambient air quality standard needs to be met to conserve eco-system and protect human health. Therefore, there is no advantage of installing FGD in Indian coal-based low sulphur TPP. This will only increase power generation cost,” it said, underlining the need for regulatory controls for particulate matter.
NITI Aayog’s note said that the Central Electricity Authority’s chairperson had cited a similar study by IIT-Delhi which made such claims. “Chairperson, CEA informed that IIT Delhi had conducted a similar study on comprehensive measurement-based survey of ambient air SO2 concentrations and the recommendations are also in line with CSIR-NEERI recommendations.”
But no such claim was made by the IIT Delhi study – titled ‘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’.
“Our study finds that while implementation of FGD in TPPs can result in significant decreases (up to 55 percent) in SO2 concentrations that are mostly confined in the immediate surrounding areas of the TPP and up to a maximum distance of 60 to 80 km from the location of the TPP and in the direction of maximum dispersal of the air pollutants but, significant decreases (up to 30 percent) in the surface concentrations of sulfate (SO4) aerosols can be expected at locations which could be as far as 200 km from the location of the TPP,” it said.
Manoj Kumar N, a researcher at Centre for Research on Energy and Clean Air, said it’s clear that SO2 has an impact on particulate matter in the atmosphere.
“Once SO2 is released into the atmosphere, it will get converted into secondary particulate matter, PM. So if you control SO2 with any technology, you can see a reduction not only in SO2 but particulate matter…location of the monitor is also very important. To avoid penalisation, they are giving extensions.”
Environment expert Sunil Dahiya termed the NITI Aayog’s observations wrong. “If SO2 is seen as the sole indicator, then it is not a major reason…But sulphur dioxide reacts with other particles present in the air and forms PM 2.5… If you want to see the role of a power plant in air pollution, then instead of just looking at SO2, you should look at the role of the particulate matter that is formed as a result.”
In Delhi, about 15 to 20 percent of the contribution towards PM levels is made by thermal power plants, according to Dahiya.
Meanwhile, a senior power ministry official said several power plants are avoiding FGD installation as it is quite costly.
Though in a study that looked at cost-benefit analyses of emissions standards for thermal power plants in 2018, the think-tank Center for Study of Science, Technology and Policy said power generators need to invest significantly to install control technologies and that it would eventually save up more money across the country.
The study estimated a market opportunity worth around Rs 2,50,000 crore over the next 15 years. On the upside, it said, it could prevent 3.2 lakh premature deaths, 5.2 crore respiratory hospitalisations, 12.6 crore work loss days, and save up to Rs 9,62,222 crore in monetised health benefits.
Auditing the FGD implementation
In a letter on November 20, Jitendra Mishra, under-secretary at the power ministry, wrote to environment secretary Leena Nandan seeking a three-year extension for categories A, B and C.
Plants in category A are placed within a 10-km radius of towns with a population larger than a million, category B within a 10-km radius of critically polluted or non-attainment cities, and all the remaining plants in category C. The previous compliance deadline for these three categories was the last date of 2022, 2023 and 2024, respectively.
These categories were introduced with the new deadlines in 2022, after the power ministry had already sought two extensions – in 2017 and December 2022.
But after these extensions, 556 coal-based power stations are yet to install FGD.
According to a study conducted by the Centre for Research on Energy and Clean Air, there are 11 coal-based thermal power plants within a 300-km radius of Delhi - Dadri TPP, Guru Hargobind TPS, Harduaganj TPS, Indira Gandhi STPP, Mahatma Gandhi TPS, Panipat TPS, Rajiv Gandhi TPS, Rajpura TPP, Ropar TPS, Talwandi Sabo TPP and Yamuna Nagar TPS. But only two of these have FGD installed.
Newslaundry reached out to NITI Aayog for comment. This report will be updated if a response is received.
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