Ennore power plants violated emission norms 50% of time: TNPCB data

CHENNAI: The thermal power plants in Ennore, operated by the State utility and a central PSU, have violated air pollution monitoring and emission norms for nearly half of the time during the winter season between November 2024 and January 2025, alleged the Save Ennore Creek Campaign, Namakkana Ennore Iyakkam, and local residents, citing the data collated by the Tamil Nadu Pollution Control Board.

The organisations studied the real-time air monitoring data recorded by the Tamil Nadu Pollution Control Board (TNPCB) during the three-month period to arrive at the conclusion.

“The findings reveal a reckless disregard for public health both by the power plant operators - Tangedco and NTECL Vallur - and the TNPCB, which has failed to take corrective action despite court orders and government assurance of better regulation following the protests against the Coromandel gas leak," they said in a joint release.

The study titled 'Breathless in Ennore - 2025' analysed online stack/chimney emission monitoring data published in TNPCB’s CARE AIR Centre for North Chennai Thermal Power Station (NCTPS) Stages I and II, and NTPC Tamil Nadu Energy Company Limited (NTECL) Vallur thermal power plants. The latter is a joint venture between NTPC, a Maharatna category firm, and Tangedco.

The winter season was chosen, as the weather conditions trap pollutants in the air, and aggravate ground-level pollution impacts in the city.

The organisations recalled that during the hearing in a fisher-led case on ash remediation in Ennore creek, the pollution control board was directed to monitor the functioning of NCTPS and take action, including prosecution, if violations are detected.

However, it did not take any regulatory action, which was exposed by the emission norm violations, they alleged. “Given the high proportion of historically marginalised communities - including SC, ST, and Most Backward Classes – in the region, TNPCB’s lax attitude exposes them to allegations of environmental casteism," the release said.

The release alleged that NCTPS-II operated in violation of norms throughout the three-month winter period. The PCB data was invalid 96% of the time. And in the remaining 4% of time, emissions of all pollutants, namely, particulate matter, Sulphur dioxide (SO2), and nitric oxide and nitrogen dioxide (NOx), exceeded permissible levels. NTECL Vallur violated SO2 emission norms for 80% of the winter period across all three units, they said.

"A 2021 court-appointed joint committee report states that the Manali industrial area is already over-polluted with SO2, with estimated emissions from four industries – Tamil Nadu Petroproducts, Manali Petrochemicals, Madras Fertilizers, and Chennai Petroleum – exceeding safe levels by more than 36 times,” said A Bhagath Singh, Namakkana Ennore Iyakkam.

The study report demanded the government to hold regulatory bodies accountable for failing to monitor and take action against emission violations.

"The government of Tamil Nadu should put in place a detailed time-bound local-level action plan to clean Ennore- Manali airshed. TNPCB should put in place an effective monitoring system that accounts for invalid data and reverse exceedances immediately," the report urged.

Will review report, take action: TNPGCL

The concerns and data inconsistencies highlighted in the report would be taken up for detailed review and follow-up to ensure that gaps in data validity and regulatory action were addressed, the Tamil Nadu Power Generation Corporation Ltd (TNPGCL) has assured.

"The thermal power stations remain under continuous scrutiny, and regulatory measures are being strengthened to ensure full compliance and safeguard the public. Further, we are also studying other non-structural measures such as the extensive afforestation with viable species to support the structural, technical, and monitoring efforts," it added.

As of January, the data from the real-time monitoring system is live-streamed to both the TNPCB and CPCB, it said, adding that the State body has deployed an inbuilt alert system to automatically notify both the industry and the District Environmental Engineer (DEE) when emissions exceed permissible limits.

Also, the TNPCB has initiated steps to improve the detection and redressal of invalid data such as ‘NA’, ‘zero’, or negative values within OCEMS logs to ensure continuous reliability among other measures, the utility added.

It has also assured that it would coordinate with TNPCB and stakeholders to address the concerns raised on emissions from thermal power plants in Ennore.