Two ways to store electricity
You cannot store electricity directly at grid scale — you have to convert it into something else and turn it back later. Pumped hydro and batteries are the two dominant ways India does this, and they work on completely different principles.
- Pumped hydro storage (PHS) is a giant water battery. When power is cheap and plentiful — typically midday, when solar is flooding the grid — pumps push water from a lower reservoir up to a higher one. When the grid needs power in the evening, that water flows back down through turbines to generate electricity. The “charge” is stored as the height of the water.
- Battery storage (BESS) stores energy chemically inside lithium-ion cells. It charges and discharges by moving ions between electrodes, with no moving water, no reservoirs and no turbines. If you are new to the technology, our explainer on what a BESS is covers the basics.
Both give the grid the same service — soak up surplus energy now, release it later — but their costs, build times and ideal jobs are very different.
The head-to-head
| What matters | Pumped hydro (PHS) | Battery storage (BESS) |
|---|---|---|
| Typical duration | 6+ hours, up to a full day | 2–4 hours today, longer possible |
| Response speed | Seconds to a minute | Milliseconds |
| Round-trip efficiency | ≈70–80% | ≈85–92% (AC-to-AC) |
| Build time | 5–8 years | 12–18 months |
| Siting | Needs specific hilly terrain and water | Almost anywhere, including cities |
| Asset life | 40+ years | ≈15 years (with augmentation) |
| Best fit | Long-duration bulk shifting | Fast response, peak shaving, flexibility |
Where pumped hydro shines
Pumped hydro is the cheapest way to store very large amounts of energy for many hours. Once the reservoirs and turbines are built, adding more storage hours costs relatively little — you are essentially storing more water. Plants routinely deliver six hours or more of continuous output, last 40 years or longer, and provide heavy spinning inertia that helps keep grid frequency stable.
India is betting heavily on this. The Central Electricity Authority’s January 2026 roadmap targets about 100 GW of pumped storage capacity by 2035–36, up from roughly 7.2 GW operational today, with another 11–16 GW under construction. The CEA puts India’s total pumped-storage potential near 267 GW. The catch is that PHS needs the right geography — two reservoirs at different heights, close together, with water — plus long environmental and land clearances, which is why a project can take five to eight years to build.
Where batteries shine
Batteries trade bulk duration for speed and flexibility. A BESS responds in milliseconds, making it ideal for frequency regulation and ancillary services, for smoothing the sharp swings of solar and wind, and for peak shaving at a factory or substation. It has a higher round-trip efficiency (85–92% versus roughly 70–80% for pumped hydro), so less energy is lost in each cycle. And crucially, a battery can be sited almost anywhere — a rooftop, a city substation, a remote solar park — in a containerised or cabinet system that installs in 12 to 18 months.
That deployment speed is why India’s battery pipeline is exploding right now, even as pumped hydro is planned for the next decade. When a standalone storage tender needs capacity online in 18 months, batteries are often the only option that can meet the timeline.
It is not either/or
The most important point is that India does not have to choose. The CEA’s storage planning explicitly splits future needs between the two: of the roughly 411 GWh of storage the grid is projected to need by 2031–32, about 175 GWh is earmarked for pumped hydro and 236 GWh for batteries. They complement each other — pumped hydro handles the long, bulk evening shift and the deep multi-hour reserves, while batteries handle the fast, precise, distributed work that hydro is too slow and too site-bound to do.
As lithium prices keep falling, batteries are stretching into longer durations too, and newer chemistries like vanadium flow target the long-duration niche from a different angle. The storage mix a decade from now will be a blend, matched job by job.
What this means for you
If you are a developer or an industrial buyer, the practical lesson is to match the technology to the duty. For fast response, peak-hour cost savings under Time-of-Day tariffs, or any project that must be built quickly and sited flexibly, a battery system is almost always the right tool — and it is the one you can actually procure and commission this year. Pumped hydro is a grid-scale, long-horizon asset that utilities and large IPPs build over many years. To work out what size and duration of battery fits your own load and tariff, try our BESS savings calculator or talk to our team and we will help you scope it.
Figures reflect CEA planning documents and industry data as of July 2026. Storage targets, project pipelines and policy support evolve by notification — verify current numbers before financial decisions.