India’s first variable Speed Pumped Storage Plant, THDCIL’s 1000 MW Tehri PSP Enters Final Phase of Commissioning
India’s 1000 MW Tehri Pumped Storage Project is nearing full commissioning, with two units already operational and the remaining two set to follow soon.
Rishikesh, 25-11-2025: The 1000 MW Tehri Pumped Storage Project (PSP), one of India’s most strategically significant hydropower balancing facilities, has moved into its final stage of commissioning, with two of its four units already declared commercially operational. The remaining two units i.e. Unit-3 and Unit-4 are poised to commission shortly, marking the culmination of a project designed to add 1,000 MW of critical peaking capacity to the northern grid.
The PSP uses the existing Tehri and Koteshwar reservoirs as its upper and lower basins, enabling a closed-loop “water recycling” operation. During off-peak hours, the reversible machines pump water from the
lower to the upper reservoir; during peak demand, the same units generate power by releasing that stored water. This model supplies flexibility that intermittent renewable energy sources cannot provide on their own, and it offers system operators a dependable mechanism for balancing load, stabilizing frequency, and meeting evening peak demand.
With four reversible 250-MW units housed in an underground powerhouse on the left bank of the Bhagirathi, the project is engineered for high-head operation featuring a head variation of nearly 90 metres. Once fully operational, the PSP will contribute 1,000 MW of peaking power and together with the existing Tehri and Koteshwar plants, the completion of the PSP will raise the total capacity of the Tehri Hydro Power Complex to 2,400 MW.
With work on the final units progressing on schedule, officials describe the project as being “on the threshold of full-scale delivery,” a milestone likely to draw attention from power sector analysts, policymakers, and grid planners.
As India’s renewable capacity expands rapidly, grid-balancing assets such as the Tehri PSP are increasingly seen as essential infrastructure. The final commissioning of the remaining units will mark not only the completion of a technically demanding project but also a significant upgrade to the nation’s ability to manage variability in the power system.