CHENNAI: Tamil Nadu Green Energy Corporation Limited (TNGECL) has applied for terms of reference to the Union Ministry of Environment, Forest and Climate Change to obtain mandatory environmental clearance for the construction of a 1,000 MW closed-loop off-river pumped storage project at Vellimalai in Kanniyakumari district under the public-private partnership model.
The Vellimalai Pumped Storage Project aims to enhance peak power management in the State and facilitate the round-the-clock integration of renewable energy. The project will comprise four fixed-speed units of 250 MW each, with the total estimated cost, excluding transmission infrastructure, pegged at Rs 5,624 crore.
The scheme involves two newly constructed off-river reservoirs. The upper reservoir, proposed near Maruvattar Kannu village, will have a gross storage capacity of 4.39 million cubic metres, while the lower reservoir near Madathattuvilai village, upstream of the existing Mambazhathuraiyar Dam, will have a gross storage capacity of 4.91 million cubic metres.
The project is designed to pump about 3.94 million cubic metres of water to the upper reservoir over 6.94 hours during off-peak periods. Electricity generation is planned for six hours a day using stored water, with peak annual energy generation estimated at 2,080.55 GWh.
As a closed-loop off-river system, both reservoirs will be artificially created and will not be located on perennial rivers or streams. Water will be circulated between the two reservoirs in a controlled cycle with minimal reliance on natural inflows. In contrast, open-loop pumped storage projects are connected to rivers or existing reservoirs and involve continuous interaction with natural water systems, often resulting in higher environmental and hydrological impacts.
Land requirement for the project has been estimated at about 159 hectares, including around 62 hectares of forest land. This includes land for the reservoirs, water conductor systems, underground powerhouse and adits, approach roads, muck disposal areas, labour camps and colony areas. The upper reservoir will require around 28 to 29 hectares, while the lower reservoir will need between 26 and 47 hectares, depending on the layout.
While the project does not involve rehabilitation and resettlement, it will require forest clearance. As the upper reservoir falls within the eco-sensitive zone of the Kanniyakumari Wildlife Sanctuary, wildlife clearance from the National Board for Wildlife will also be mandatory.
Type: Closed-loop off-river pumped storage project
Capacity: 1,000 MW (4 × 250 MW, fixed-speed units)
Model: Public-private partnership
Location: Near Maruvattar Kannu village
Gross storage: 4.39 MCM
Location: Near Madathattuvilai village, upstream of Mambazhathuraiyar Dam
Gross storage: 4.91 MCM
Water pumped: 3.94 MCM
Pumping duration: 6.94 hours (off-peak)
Generation duration: 6 hours daily
Annual energy generation: 2,080.55 GWh
Total: About 159 hectares
Forest land: About 62 hectares
Estimated cost: Rs 5,624 cr (excluding transmission infrastructure)
Clearances required
Environmental clearance
Forest clearance
Wildlife clearance from National Board for Wildlife