The Ennore SEZ superthermal power plant is being constructed on the ashdyke of North Chennai Thermal Power Station (NCTPS). Image courtesy of Prateek Rungta.
The Ennore SEZ STPP is scheduled for commissioning in 2020. Image courtesy of Marcin Skrzątek.
The Ennore SEZ thermal power station is estimated to require 3.79 million tonnes (Mt) of coal a year. Image courtesy of oatsy40.

The Ennore SEZ super thermal power project (STPP) is a 1.3GW coal-fired power station under construction at Katupalli near Ennore, Tamil Nadu, India.

State-owned Tamil Nadu Generation and Distribution (TANGEDCO) is developing the green-field project with two 660MW supercritical units, with an estimated total investment of Rs98bn (£1.07bn).

Scheduled for commissioning in 2020, both the units are expected to produce approximately 11,914 million units (MUs) of electricity a year, operating at a plant load factor of 85%.

Ennore SEZ power plant background

TANGEDCO initially proposed to develop the project with two 800MW coal-fired units and obtained environmental clearance for the same in January 2014.

The capacity of each unit was, however, reduced to 660MW while calling engineering, construction, and procurement (EPC) tenders for the project in the same year.

Initial construction works on the project were started in October 2014, following the award of EPC contract to Bharat Heavy Electricals (BHEL).

The project development was, however, halted for two years due to a court case filed against TANGEDCO by one of the EPC bidders.

The construction works were resumed in October 2016, after the Madras High Court gave the final verdict in favour of TANGEDCO.

Project location and site details

The Ennore SEZ super thermal power station is being developed on a 408-acre site that covers a portion of the ashdyke of the existing North Chennai thermal power station (NCTPS) owned and operated by TANGEDCO.

The site is located in the Vayalur village of Thiruvallur district, near the Ennore multi-product special economic zone (SEZ) proposed by Tamil Nadu Industrial Development Corporation (TIDCO).

The Ennore port and the Athipattu Pudunagar railway station lie approximately 5km away from the project site, while the nearest airport is 60km away at Chennai.

The site is accessed via an all-weather road connecting the Thiruvottiyur-Ponneri district highway at Pattamandri.

Ennore SEZ thermal power plant make-up

The Ennore SEZ power station will be equipped with two 660MW generating units, with each unit comprising a once-through pulverised coal-fired super-critical boiler, a single reheat multi-cylinder steam turbine generator, a condenser, and a natural drought cooling tower.

The shared facilities for both the units will include a twin flue chimney of 275m height, a coal handling plant, an ash handling plant, an effluent treatment plant, water treatment facilities, and a 400kV switchyard.

Both the units will be fitted with electrostatic precipitators (ESPs) and flue gas desulphurisation (FGD) systems for pollution control.

The plant is estimated to use 12,950m³ of water an hour, which will be sourced from the fore bay of the NCTPS phase two facility.

Coal supply

The Ennore SEZ thermal power plant is expected to use 3.79 million tonnes (Mt) of imported or domestic coal a year.

The domestic coal for the plant will be sourced from the Kalinga block of the Talcher coalfields as well as the Mahanadi and IB valley coal fields of the Mahanadi Coalfields (MCL), which is a subsidiary of state-owned Coal India (CIL).

Coal will be shipped to the nearby Ennore Port, from where it is proposed to be delivered to the plant site via two 200 tonnes per hour (TPH) pipe conveyors.

Power transmission

The power generated by the plant will be evacuated into the national grid through 400kV double-circuit transmission lines.

The switchyard for the power station will comprise two generator transformer bays, one start-up transformer bay and four line bays. It will be controlled by supervisory control and data acquisition (SCADA) system.

Contractors involved

Bharat Heavy Electricals (BHEL) was awarded the EPC contract for the project in September 2014. It is also responsible for the design, supply, and commissioning of key power generation equipment for the plant.

Bhavani Erectors was contracted for the erection, testing, and commissioning of cooling water piping for the plant.