Commercial Operation of the first Unit of Country's Largest Hydropower Project
23rd December 2025
The Union Minister of Power, Housing & Urban Affairs, has inaugurated the commercial operation of Unit 2 (250 MW) of the 2000 MW (8 of 250 MW) Subansiri Lower Hydroelectric Project through virtual mode
With the commissioning of Unit # 2, the Project is moving swiftly towards commissioning of 3 Units of 250 MW each shortly, followed by phased commissioning of the remaining four units during 2026-27
As India’s largest hydropower project, the Subansiri Lower Project comprises 8 units of 250 MW each and 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 contributing significantly to India’s green energy future
The project features the largest dam in North-East India, a 116-metre-high concrete gravity dam, which not only strengthens regional infrastructure and grid resilience but also enhances flood moderation and water management in the Subansiri River basin
The Subansiri Lower H.E. Project exemplifies engineering excellence, featuring India’s heaviest hydro generator rotors, largest stators and biggest main inlet valves, along with innovations such as the nation’s largest aggregate processing plants, highest-capacity batching plant and first-ever use of Rotec’s Tower Belt for dam concreting in India
As the first cascaded dam on the Subansiri River, it provides flood moderation with a 442 million cubic metre flood cushion. With a gross reservoir storage of 1,365 million cubic metres at FRL, about one-third remains empty during floods to absorb excess water and protect downstream communities
Apart from supplying electricity to 16 beneficiary states across India, the Subansiri Lower H.E. Project will provide free power allocations to Arunachal Pradesh and Assam, while the North-East region will receive 1,000 MW from the project, significantly strengthening regional energy availability
Over the last five decades, NHPC has successfully executed hydropower projects in some of the most challenging terrains and has diversified into solar, wind, and green hydrogen, reinforcing its position as a 100% Green Energy Company. With an installed capacity of 8,333 MW from 30 power stations and 14 projects totaling 9704 MW currently under construction, NHPC continues to play a vital role in advancing India’s clean energy transition and strengthening national energy security