Why in news?
The Chief Minister of Himachal Pradesh visited the under‑construction Shongtong–Karcham hydro project in April 2026 and directed engineers to commission the first generating unit by January 2027. With work nearly three‑quarters complete, the run‑of‑river project on the Sutlej River is expected to add 450 MW of clean power to India’s grid.
Background
The Shongtong–Karcham project is being developed by the state‑owned Himachal Pradesh Power Corporation Limited (HPPCL) near Powari and Ralli villages in Kinnaur district. It is a run‑of‑river scheme designed to harness the flow of the Sutlej without building a large reservoir. Water from the river is diverted by a 102.5 m long concrete barrage into four 300 m long underground sedimentation chambers that remove silt. From there, it enters an 8 020 m long circular headrace tunnel 10 m in diameter, which ends in a 39.5 m diameter surge shaft. Three 211 m long steel pressure shafts then convey the water to an underground powerhouse containing three vertical‑axis Francis turbines of 150 MW each. The gross head available is about 128.6 m and the design energy in a 90 percent dependable year is roughly 1 594 million units.
Key features
- Capacity: The project will generate 450 MW through three units of 150 MW each. It is expected to produce more than 1.5 billion units of electricity annually.
- Run‑of‑river design: By avoiding a large storage dam, the project reduces displacement and environmental impact while still using the Sutlej’s strong flow.
- Underground powerhouse: Locating the power station underground minimises surface disturbance and protects the machinery from extreme weather.
- Economic benefits: Once operational, it is expected to contribute around ₹900 crore annually to the state’s revenue and help achieve energy self‑reliance.
Conclusion
The Shongtong–Karcham project illustrates how mountainous states can harness river flows without major reservoirs. Completion of the project will increase Himachal Pradesh’s renewable energy capacity and support economic development in the region.
