Guwahati: Power generation is set to commence at the highly controversial Subansiri Lower Hydroelectric Project, a run-of-river big dam constructed on the Subansiri River, located on the Assam-Arunachal Pradesh border near Gogamukh in Dhemaji district, from next year.
The project, which is nearing completion, is initially targeting 750 MW of power generation from March 2025 and full capacity of 2000 MW by March 2026.
Over 93 per cent of the construction work for the 2000 MW NHPC project has been completed. NHPC completed the construction of the 116-metre-high concrete gravity dam in June 2023 and work on the power-house and hydromechanical components is progressing rapidly.
The NHPC plans to start power generation in March 2025 after completing the remaining radial gate work following the end of the monsoon season. A N Mohammad, PR Consultant (PT) for the Subansiri Lower Hydroelectric Project, said, NHPC is technically ready to generate power. According to the plan, the project will initially generate 750 MW of power in March 2025 using 3 of the 8 turbines to be installed in the powerhouse. Two turbines have already been installed, and the third is in the process of installation.
Power Generation to Start After Installation of 3 Spillway Radial Gates :
NHPC 's last plan was to complete the dam and start power generation by December 2024, but natural obstacles prevented this. The diversion tunnels, essential for dam construction, were damaged by natural disasters, leaving only one operational out of the five.
A major landslide on October 27, 2023, blocked the only operational diversion tunnel, hindering the installation of the rest of the Spillway Radial Gates, which control water flow in and out of the main dam. While 6 of the 9 radial gates have been installed, 3 remain to be installed. NHPC installed 6 radial gates before this year's monsoon. NHPC is now focusing on installing the remaining gates after the monsoon season.
2000 MW Power Generation from 8 Turbines in March 2026:
NHPC aims to fully commission the project in March 2026 with 8 turbines generating 2000 MW of power. The radial gates could not be installed completely during the 2024 monsoon season due to water flowing over the dam because the only operational diversion tunnel was closed. However, two large turbines for power generation were installed in the power house.
NHPC is ready to start power generation in next March by installing the third turbine. Each turbine can generate 250 MW of power. The company aims to generate 750 MW by March by commissioning three turbines. The dam will use 8 tunnels to channel water to 8 turbines, generating a total of 2000 MW. NHPC officials state that once the remaining Spilway Radial Gates are installed, they will be able to commission all 8 turbines and generate 2000 MW of power by March 2026.
Construction Delayed for 8 Years Due to Public Opposition:
A central Government body Brahmaputra Board submitted a DPR for this dam on the Subansiri River, flowing from Arunachal Pradesh to Assam, in 1983. NHPC, the construction agency, received central government departmental clearances in October 2004. Construction began in January 2005 but was halted due to protests from the downstream residents and other orgainisations of Assam.
A committee formed by the Assam government recommended against constructing the dam on the fragile hills of Gerukamukh in seismic zone 5. Due to widespread protests and concerns about safety of the downstream people's life and property, construction was suspended from December 2011 to October 2019. Construction of the project resumed in October 15, 2019, after various procedures and clearance by the National Green Tribunal.
Construction Cost is expected to reach Rs 22,000 crore:
A N Mohammad, PR Consultant (PT) for the project, told ETV Bharat that as on March 31, 2024, 93 percent of the project's construction was complete, costing Rs 20,834 crore. According to another NHPC source, the cost is expected to reach Rs 22,000 crore upon full commissioning with 8 turbines generating 2000 MW. The project's estimated cost in 2002 was Rs 6,285 crore.
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