THDCIL’s 1 GW Tehri PSP Enters Final Phase of Commissioning

Tehri Hydro Development Corporation (THDC) has recently moved closer to commissioning its 1,000 MW Tehri Pumped Storage Project (PSP), a key hydropower balancing facility. The company has come a long way since commissioning its first unit, which has been operating since June 2025, followed by the commencement of the second unit’s COD process a month later.

THDC has already declared two of its four units commercially operational, with the remaining two units — Unit-3 and Unit-4 — expected to be commissioned shortly. This will mark the culmination of a project designed to add 1,000 MW of critical peaking capacity to the northern grid.

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.

About The Project

THDC's pumped stprage project (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. 

Project Delivery Expected By

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.