Subansiri Lower: first unit of India’s largest hydro project starts
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What happened
- Unit-2 (250 MW) of the 2,000 MW (8×250 MW) Subansiri Lower hydroelectric project began commercial operation on 23 December 2025 [PIB].
- NHPC runs the project, which PIB calls the country’s largest hydropower project [PIB].
Background
- Subansiri is a tributary of the Brahmaputra. The dam is at Gerukamukh on the Assam-Arunachal Pradesh border (Dhemaji and Kamle districts) [NHPC].
Why it matters
- Big dams in a seismic zone draw local protests. Mains answers should weigh clean power against downstream risk.
How to use this in Mains
- As per PIB (2025-12-23): unit-2 (250 MW) of the 2,000 MW (8x250 MW) Subansiri Lower hydroelectric project began commercial operation on 23 December 2025.
- Big dams in a seismic zone draw local protests. Mains answers should weigh clean power against downstream risk.
Quotable data pointUnit-2 (250 MW) of the 2,000 MW (8x250 MW) Subansiri Lower hydroelectric project began commercial operation on 23 December 2025.
PIB: MoP: Subansiri Lower unit commissioned, 23 Dec 2025
Exam angle
UPSC
Prelims: Subansiri, Brahmaputra tributaries.
Practice MCQs
Original practice questions (not PYQs).
Practice · UPSC
Installed capacity of Subansiri Lower
Answer (b) & explanation
PIB.
Practice · UPSC
Subansiri is a tributary of
Answer (b) & explanation
PIB.
Practice · UPSC
Operator
Answer (b) & explanation
PIB.
Go deeper
ExplainerRenewable Energy in India: Potential, Installed Capacity, 500 GW Target, Key Schemes (PM-KUSUM, PM Surya Ghar), Challenges and Way Forward (UPSC Notes + PYQs)ExplainerGreen Hydrogen: Colours of Hydrogen, Electrolysis, National Green Hydrogen Mission, Uses, Costs and Challenges (UPSC Notes + PYQs)
Official source: PIB: MoP: Subansiri Lower unit commissioned, 23 Dec 2025
facts from cited sources only; faculty review pending