India has taken another major step towards clean and sustainable energy with the commissioning of Unit 2 (250 MW) of the Subansiri Lower Hydroelectric Project. The project which is a located on the Subansiri River along the Arunachal Pradesh–Assam border, is the largest hydropower project in India and a key pillar of India’s renewable energy strategy.
About Subansiri Lower Hydroelectric Project
- The Subansiri Lower Hydroelectric Project is a 2,000 MW run of the river hydropower project being developed by NHPC.
- It consists of eight units of 250 MW each and is designed to generate clean electricity while ensuring flood moderation and regional development.
- This project plays a crucial role in meeting India’s rising power demand while reducing dependence on fossil fuels.
Key Development of Unit-2 Commissioning
The commercial operation of Unit-2 was inaugurated virtually by Manohar Lal, Union Minister of Power, Housing and Urban Affairs. With this, the project moves closer to full-scale operation.
The commissioning is significant as it,
- Adds 250 MW of renewable energy to the national grid
- Strengthens power supply in the North-East region
- Reinforces India’s commitment to Net Zero and green energy goals
Project Timeline and Future Plan
- With Unit 2 now operational, the next phase of commissioning is already planned.
- Three more units (250 MW each) to be commissioned in the near term
- Remaining four units scheduled for phased commissioning during 2026-27
- Once completed, the project will generate 7,422 million units (MU) of electricity annually
- This will significantly improve grid stability and renewable energy availability in eastern and north-eastern India.
Engineering Features and Flood Control Role
- The Subansiri Lower Project is notable for its advanced engineering design.
- It has a 116-metre-high concrete gravity dam, the largest dam in North-East India
- Designed as a run of the river scheme with small pondage
- Acts as the first cascaded dam on the Subansiri River
A major additional benefit is flood moderation. About one-third of the reservoir capacity (around 442 million cubic meters) is kept empty during monsoon periods to absorb excess floodwater, helping protect downstream areas in Assam.
Socio-Economic Impact on the Region
- Beyond power generation, the project has delivered strong socio-economic benefits.
- Around 7,000 local people were employed daily during construction
- Power will be supplied to 16 beneficiary states
- Free power allocation to Arunachal Pradesh and Assam
- 1,000 MW reserved for the North-East region
NHPC has also invested in riverbank protection, local livelihood support, and CSR activities, contributing to long-term regional development.
Key Takeaways
- Subansiri Lower Hydroelectric Project capacity: 2,000 MW
- Number of units: 8 units of 250 MW each
- Unit-2 commissioned in December 2025
- Largest hydropower project in India
- Located on the Subansiri River (Arunachal Pradesh–Assam)
- Developed by NHPC
- Features the largest dam in North-East India
- Provides flood moderation and renewable power
Question
Q. The project is situated along the border of which two states?
A. Assam and Meghalaya
B. Arunachal Pradesh and Assam
C. Sikkim and West Bengal
D. Nagaland and Manipur
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