The Centre for Research on Energy and Clean Air (CREA) analysed emissions from 25 of the 37 coal-fired power plants (CFPPs) located within a 300-km radius of Delhi-NCR for which public data were available. Those 25 units emitted an estimated 154 kilotonne of SO2 in 2025.
"About 90 pc of that estimated SO2 came from plants operating without FGD systems, and 81 pc of the emissions came from Category C plants, the group removed from mandatory SO2 control by the July 2025 notification," the analysis report said.
As per the government's 2015 emission standards, all CFPPs were required to install FGDs. The Ministry of Environment, Forest and Climate Change's revised notification in July 2025 changed that, with 78 pc of India's CFPP units now exempt from mandatory SO2 control, 11 pc assessed on case-to-case basis, and only 11 pc still subject to mandatory FGD requirement.
India is the world's largest SO2 emitter in the power sector, releasing over 6 million tonnes annually.
The CREA analysis highlights how FGD systems can sharply reduce emissions. Mahatma Gandhi Thermal Power Plant Units 1 and 2, fitted with FGDs, generates roughly 3,400-4,000 million units of electricity each year but emits an estimated 1,775 tonnes and 2,154 tonnes of SO2, respectively.
In contrast, the Rajpura Thermal Power Plant Units 1 and 2 log similar power generation but, without effective SO2 controls, emit an estimated 20,851 tonnes and 22,690 tonnes of SO2, making them the largest emitters in the assessed set.
"As coal-based power generation increases in line with hotter temperatures and India's expanding coal capacity, so will air pollution unless emissions are effectively controlled.
"The government should reinstate mandatory FGD installation for all coal-fired power plants, make real-time Continuous Emission Monitoring Systems (CEMS) data publicly available, and regularly disclose the operational status of FGDs. These measures will reduce SO2 and PM2.5 pollution, strengthen compliance, and improve air quality and public health," said Manoj Kumar, an analyst at CREA.
