"Long-duration storage is the missing link in India's renewable energy transition." Examine the role of Pumped Storage Projects alongside BESS.

Solar and wind output varies by hour and season, so renewable capacity alone cannot meet demand at every hour of the day. India had only about 5.5 GW of storage against 243 GW of renewables [2]. The CEA projects a need of 73.93 GW by 2031–32 [1], which makes storage the binding constraint.

Why long-duration storage is the missing link

• Time-shifting: surplus solar power at noon must reach the evening peak. Otherwise coal fills the gap, which undermines the 500 GW non-fossil target by 2030 [3].
• Peaking support: storage reduces dependence on fossil fuels for meeting peak demand [3].

Role of PSPs: the "water battery"

• Long duration, long life: PSPs store energy as potential energy for many hours. They use domestic water and civil works, not imported cells [3].
• Grid flexibility: Tehri is India's first variable-speed PSP [5]. It can adjust its pumping power to help balance the grid.
• Hybrid model: Pinnapuram (Andhra Pradesh) combines 4,000 MW solar, 1,000 MW wind and 1,680 MW PSP [6].
• Viability: the government holds that PSP storage costs are viable without VGF [8].

Role of BESS: the complement

• Speed and siting: BESS has a short gestation period and covers short-duration needs [3]. The CEA plan assigns it 47.24 GW [1].
• Policy support: the Cabinet approved a dedicated VGF scheme for BESS [7].
• Limit: it depends on imported battery cells [3].

Challenges for PSPs

• Slow pace: capacity rose from 4,745.6 MW in 2023 [4] to only 7.43 GW by August 2026 [3]. That is under 1 GW a year, against roughly 3.5 GW a year needed to reach 26.69 GW.
• Gestation and sites: long build times, dependence on suitable sites, and environmental clearance [4].
• Cost: the Standing Committee on Energy named high cost as the main reason storage is slow [2].

Way forward

• Ensure the 11 PSPs (15,870 MW) under construction are finished on time [9], with a public tracker for each project.
• Prioritise off-stream sites to reduce the impact on river ecology [3].
• Give targeted support to stalled projects, and share benefits with the states that host them.

PSPs provide the durable, many-hour backbone, and BESS adds speed and flexibility. They are complements, not rivals. Speeding up the PSP pipeline while scaling up BESS can turn India's renewable capacity into reliable, round-the-clock power and advance SDG 7 and the Panchamrit commitments.