New Delhi: State-owned NHPC Limited said on Tuesday that it has started the commercial supply of electricity from the fourth unit of its 2,000 MW Subansiri Lower Hydroelectric Project. The third unit of the hydropower project was commissioned in February 2026. With the commencement of power supply from the fourth unit, a total of 1,000 MW of Subansiri Lower Hydroelectric Project now stands commercially operational.
NHPC is constructing the hydroelectric project near North Lakhimpur on the border of Arunachal Pradesh and Assam. The other remaining units of the hydropower plant are slated to start commercial production by the end of 2026.
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In an exchange filing, the company said, "It...declares commercial operation (CoD) of Unit 4 of Subansiri Lower HE Project from 00:00 hours on 08.05.2026."
With this, four units of the project has been declared commercially operational and the CoD of remaining units will be intimated in due course, NHPC said.
As India's largest hydropower project, the Subansiri project is designed as a run-of-the-river scheme with small pondage, diverting water through eight head race tunnels (HRTs) to generate 7,422 million units (MU) of renewable electricity annually.
NHPC's Subansiri project was originally scheduled for completion in December 2012. The project cost has escalated more than four times to around Rs 27,000 crore at the time of completion from the initial estimate of Rs 6,285 crore in December 2002.
The Subansiri Lower Hydroelectric Project has faced multiple bottlenecks since its inception stage, has been delayed several times and its deadline for commissioning has been revised on many occasions.
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NHPC had commenced the construction work of the Subansiri project in January 2005 after obtaining forest clearance in October 2004. However, construction work of the ambitious project on River Subansiri was stalled from December 2011 to October 14, 2019 due to protests by locals and many groups fearing safety and downstream impact.
After clearing all the legal issues raised by the National Green Tribunal (NGT), NHPC re-started construction of the project from October 15, 2019.
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