Relief for TN thermal plants as Centre eases SO2 emissions norms
According to a notification issued by the ministry on July 11, thermal power plants have now been categorised based on their geographical location and the sensitivity of surrounding environments to pollution.
Ennore Thermal Power Station
CHENNAI: In a major relief to Tamil Nadu’s state-run thermal power stations, the Union Ministry of Environment, Forest and Climate Change (MoEF&CC) has relaxed the timelines for complying with sulphur dioxide (SO₂) emissions standards.
The revised rules provide additional time for installing flue gas desulphurisation (FGD) systems and exempt units that are set for retirement, easing the burden on Tamil Nadu Power Generation Corporation Ltd (TNPGCL), which operates several ageing coal-fired power plants across the state.
According to a notification issued by the ministry on July 11, thermal power plants have now been categorised based on their geographical location and the sensitivity of surrounding environments to pollution. Each category is assigned a different deadline for FGD system installation to control SO₂ emissions.
Five units at North Chennai Thermal Power Station (Stages I, II and III) fall under category A, as they are located within a 10-km radius of Chennai, a city with a population exceeding one million. These units must comply with the SO₂ norms by December 31, 2027.
Meanwhile, the Mettur and Tuticorin thermal stations have been classified as category B, which includes plants located in critically polluted areas. Their compliance will be evaluated individually. If not granted exemptions, they must install FGD systems and meet the standards by December 31, 2028. Under previous regulations, the installation of FGDs at these sites was compulsory.
Units under category C are exempt from mandatory FGD installation, provided they meet stack height requirements by December 31, 2029.
Additionally, thermal power units that are officially declared for retirement before December 31, 2030, will not be required to meet SO₂ emissions norms. However, operators must submit undertakings to the Central Pollution Control Board and the Central Electricity Authority.
If these plants continue operations beyond the declared retirement date without compliance, they will face an environmental compensation charge of ₹0.40 per unit of electricity generated.
Green activists raise concerns about relaxation norms
The updated rules also outline penalties for delays beyond the compliance deadlines. Depending on the duration of the delay, compensation will range from ₹0.20 to ₹0.40 per unit.
A senior official from TNPGCL noted that the utility had previously suspended its FGD tendering process, anticipating changes to national emissions regulations. “TNPGCL had appointed MECON Ltd to conduct feasibility studies and prepare detailed project reports. These activities were put on hold while awaiting the Union government’s final decision,” the official said.
Plans to retrofit Electrostatic Precipitators (ESPs) were also deferred. The utility had been advised to opt for semi-dry FGD systems, which could address both SO₂ and particulate matter emissions.
With the revised rules now in effect, TNPGCL sources said the corporation would review the changes and take steps to comply. The utility has renewed its request for central financial assistance to implement pollution control measures, reiterating its earlier appeal for ₹3,220 crore in grants from the Ministry of Power to mitigate financial pressure and avoid electricity tariff hikes for consumers.
Environmental activists have raised concerns about the relaxation. V Prabhakaran, an environmental engineer and member of Poovulagin Nanbargal, said the new norms provide thermal plants with loopholes that may allow them to delay compliance. “Of the 40 thermal units in Tamil Nadu, only two private units have installed FGDs. TNPGCL’s six units in North Chennai Stages I, II and III, along with the Vallur Thermal Power Plant (a joint venture), fall under category A. Yet, the bidding process has not even begun for North Chennai Stages I and II. Meeting even the extended deadline will be difficult,” he said.
He further criticised the decision to allow units to pay a penalty in lieu of compliance. “Highly polluted sites like NLC will fall under category C, which gets exemption. No plant should be allowed to operate past the deadline without installing FGDs. Permitting continued operation by simply paying a fine is completely unacceptable,” he added.
