New power plant to use domestic coal, to spew three times more ash in North Chennai

CHENNAI: The Tamil Nadu Generation and Distribution Corporation Ltd (Tangedco) decision to shift from using 100% imported coal to a 50:50 blend of imported and domestic coal to run 800 MW North Chennai Thermal Power Station (NCTPS) Stage III will increase ash generation to nearly three times.

The Ministry of Environment, Forest and Climate Change (MoEF&CC) has approved an amendment to the Environmental and Coastal Regulation Zone (CRZ) clearance for the NCTPS Stage III.

The approval allows the Tangedco to revise the coal sourcing strategy and use 1.04 million tonnes per annum (MTPA) of imported coal and 1.65 MTPA of domestic coal, primarily from the Kalinga block of Talcher, Mahanadhi, and IB Valley coal fields. The project is expected to generate nearly 2,209 tonnes of ash per day — significantly higher than the previously estimated 807 tonnes/day when only imported coal was planned.

Tangedco has committed to 100% dry ash handling and utilisation, including supply to cement and brick industries. NCTPS stage III will dispose of ash slurry only in emergencies, as both fly ash and bottom ash are disposed of in dry form. It will use the existing ash slurry pipelines of NCTPS Stage I and II instead of constructing new pipelines.

The amendment comes amid ongoing scrutiny, as the NCTPS has been involved in multiple legal cases concerning environmental violations, including illegal fly ash disposal into the Buckingham Canal and the Kosasthalaiyar River. In compliance with the NGT directives, Tangedco paid a Rs 50 lakh fine and has pledged to implement stringent monitoring, pipeline replacements, and ecological restoration.

The Expert Appraisal Committee (EAC) reviewed the proposal over several meetings, citing compliance with the Ministry’s Office Memorandum dated December 6, 2023, and November 11, 2020, that permitted changes in fuel mix for thermal projects under amended environmental norms. While recognising the potential for increased particulate matter (PM10) levels, the EAC noted mitigation measures, including the installation of high-efficiency electrostatic precipitators, dry flue gas desulphurization units, and low-NOx burners.

The MoEF&CC has attached several conditions to the amended clearance, including annual environmental audits, groundwater monitoring for heavy metals, plastic waste segregation, and expansion of the greenbelt area. A capital investment of Rs 1,185 crore and an annual recurring expenditure of Rs 98 crore have been earmarked for the Environmental Management Plan.

Tangedco has awarded an imported coal contract to Smartgen Infra for buying 24.75 lakh tonnes of 4,600 GAR imported steam coal for the period from 2024-25 to 2026-27. Total coal procurement cost is Rs 1,652.68 crore for 24.75 lakh tonnes.

Initial Plan

· 100% imported coal for power generation

· Imported coal requirement: 2.09 million tonnes/year

· Ash generation: 806.9 tonnes/day

Revised Plan

· 50:50 blending of imported and domestic coal for power generation

· 1.04 million tonnes/year of imported coal and 1.65 million tonnes/year of domestic coal

· Ash generation is 2,209.32 tonnes/day