THDC India (THDCIL) has commissioned a total capacity of 750 MW out of its 1 GW variable-speed pumped storage project (PSP) at Tehri in Uttarakhand to full capacity.

The company recently commissioned its third 250 MW unit. The fourth unit is under construction.

According to THDCIL, the project is India’s first variable PSP and the largest one implemented by any central public sector enterprise.

Variable-speed PSPs are an advanced form of PSP that use variable-speed motor-generator units to inject power based on grid demand.

THDCIL had commissioned the first and second units in Tehri in June and July of 2025. The first two commissioned units of the PSP have achieved a round-trip efficiency of approximate 80%.

According to the Energy Storage Landscape 1H 2025 Report by Mercom India Research, the country has an operational pumped storage capacity of 5 GW. PSPs have over 81 GW in the pipeline, including approximately 12.4 GW under construction, about 3.3 GW in pre-construction, over 2.4 GW under examination after detailed project report submission, and nearly 63 GW in the survey and investigation phase.

To reduce costs and promote investment in PSPs, the Forum of Regulators recommended exempting the electricity duty and cess on the input energy for pumping. They said that input energy for pumping in PSPs should not be treated as ‘consumption,’ and therefore, electricity duty should not be levied on these projects, it has said.

In February this year, the Ministry of Power issued tariff-based competitive bidding guidelines to procure stored energy from existing facilities, under-construction facilities, or PSPs.

In 2024, THDC India invited bids for the development of 600 MW to 2,000 MW on/off-stream pumped storage projects on a turnkey basis, with operation and maintenance for 15 years, across various states in India.

Apart from PSP, THDCIL has also been investing in solar projects. In August, it invited bids to develop a 53.9 MW ground-mounted solar project at Karnataka Power Corporation’s thermal power project in Raichur, Karnataka.