The 1000 MW Tehri Pumped Storage Project (PSP), one of India’s most critical hydropower balancing facilities, has officially entered its final phase of commissioning. Two of the four units are already commercially operational, and the remaining units—Unit-3 and Unit-4—are set to be commissioned shortly. Once completed, the project will deliver 1,000 MW of vital peaking capacity to strengthen and stabilize the northern grid.
The PSP operates using the existing Tehri and Koteshwar reservoirs as its upper and lower basins, enabling a closed-loop “water recycling” system. During off-peak hours, the reversible units pump water from the lower reservoir to the upper one; during peak demand, the same machines generate electricity by releasing that stored water. This setup provides the type of flexibility that intermittent renewable sources cannot independently supply and gives grid operators a reliable tool for load balancing, frequency stabilization, and meeting evening peak requirements.
The project includes four reversible 250 MW units located in an underground powerhouse on the left bank of the Bhagirathi, designed for high-head operation with a head variation of nearly 90 meters. Once fully operational, the PSP will supply 1,000 MW of peaking power, and when combined with the existing Tehri and Koteshwar stations, the Tehri Hydro Power Complex will reach a total capacity of 2,400 MW.
With the final units advancing on schedule, officials describe the project as being “on the threshold of full-scale delivery,” a milestone expected to draw interest from power sector experts, policymakers, and grid planners.
As India’s renewable energy capacity grows quickly, grid-balancing systems like the Tehri PSP are increasingly viewed as vital infrastructure. The commissioning of the last two units will represent not only the conclusion of a technically challenging undertaking but also a major enhancement in the nation’s capability to manage power system variability.
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