CHENNAI: Tamil Nadu government is planning to build its largest hydroelectricity and first Pumped Storage Project (PSP) in Nilgiris submerging hundreds of acres of forest land. Two reservoirs across Sillahalla and Kundah rivers are proposed to be built for the purpose. Conceptualised at an estimated cost of Rs 4,200 crore by Tangedco, the Sillahalla Pumped Storage Hydro-electric Project Stage-1 will house four power plants with a combined capacity of 1,000 MW.
As per official documents, an upper dam across Sillahalla river and lower dam across Kundah river downstream of existing Kundah Palam dam will be built and interconnected by a tunnel to generate electricity for peak hours (6 hours daily) and recycle the water from lower to upper dam at the time of non-peak hours using reversible turbine/generator.
About 421 acres of land shall come under submergence. Additional land required for constructing dams, water conductor system, power house and other project appurtenances works out to 356 acres. The total land proposed to be acquired for the project is 777 acres, of which 445 acres is forest/government land and the remaining is private land. The construction would cause a permanent change to riverine system, the documents reveal.
However, Tangedco officials said the project site does not fall within any reserve forest or national park. “Impacts on flora and fauna on account of submergence of forest area will be assessed and appropriate management measures will be taken as part of Environment Impact Assessment (EIA) study.”
As per the feasibility study conducted by WAPCOS Limited, the proposed project is likely to have negative environmental impacts. However, adverse impacts can be ameliorated to a large extent by implementing appropriate mitigation measures.
“Land requirement of 315 hectares is on lower side considering the size of the project of 1,000 MW. Tamil Nadu and Tangedco do not have reliable hydro potential of this scale,” study said.
Tangedco officials said both Sillahalla and Kudah are seasonal rivers and dry up or have little flow in non-monsoon or lean seasons.
Kundah Hydro Electric Complex in Nilgiris hills is already one of the biggest electricity generating schemes in Tamil Nadu with installed capacity of 585 MW. The group of peaks Devarbatta, Karaikada, Koulingabetta and Porthimund, all over 2,400 Metres ASL (above sea level) drain into two streams, Avalanche and Emerald. Avalanche and Emerald Dams, along with Upper Bhavani, form the major source of water for the Kundah hydro-electric project.
K Subash Chandra Bose, Chief Engineer (Projects-1), Tangedco, has submitted the project proposal to Union Environment Ministry seeking prior environmental clearance last month.