UPSC Prelims 2024 Q38: Pumped-Storage Hydropower — Explained
Recently, the term "pumped-storage hydropower" is actually and appropriately discussed in the context of which one of the following?
- Irrigation of terraced crop fields
- Lift irrigation of cereal crops
- Long duration energy storage
- Rainwater harvesting system
Answer: (c) Long duration energy storage
Statement-wise explanation
- a: incorrect — Terraced fields are cut as steps into hill slopes. They are watered by gravity flow, small channels and rain, not by a power-storage system. Pumped-storage hydropower is about storing electricity, not about how hill farms are watered.
- b: incorrect — Lift irrigation does pump water uphill, which is why it looks close to the right idea. But it uses electricity to deliver water to fields; it does not send the water back down through turbines to produce power. In pumped storage the water is never used on crops. It goes back and forth between two reservoirs only to store and release electricity.
- c: correct — A pumped-storage plant has two reservoirs at different heights. When power is cheap or surplus, such as midday solar, it pumps water to the upper reservoir. At peak or non-solar hours it releases the water through turbines to make electricity again. It can supply power for many hours, so it is grouped with long-duration energy storage. The Ministry of Power issued Guidelines to promote Pumped Storage Projects on 10 April 2023 to store surplus renewable power.
- d: incorrect — Rainwater harvesting collects and stores rain from rooftops or catchments for water supply or groundwater recharge. It does not involve pumping water to a height to store energy, and it does not generate electricity.
How to eliminate
Read the term word by word. 'Hydropower' means electricity, and 'storage' means holding something for later use. Together they point to storing electricity, not to farming or water conservation. Three of the options are about water for agriculture or households (terraced fields, lift irrigation, rainwater harvesting), and only one is about energy. That makes the energy option stand out. The real trap is lift irrigation, because both systems pump water uphill. Remember the difference: lift irrigation pumps water up to use it on fields, while pumped storage pumps water up so it can run back down through turbines later. Fact to remember: pumped storage works like a water battery. It charges by pumping when power is in surplus and discharges by generating power when demand peaks.
Know more
How a pumped-storage plant works
A pumped-storage project (PSP) has two reservoirs at different heights, joined by a reversible pump-turbine.
- Charging: when electricity is surplus or cheap (midday solar, night-time low demand), the machine works as a pump and lifts water to the upper reservoir.
- Discharging: at peak or non-solar hours, water flows back down and the same machine works as a turbine to generate power.
The plant uses more electricity than it gives back. About 70–80% of the energy put in comes back out. Its value is in shifting energy to the hours when it is needed and in keeping the grid stable.
Why India needs it
Solar and wind output varies by hour and by season. As India moves towards its 500 GW non-fossil capacity target for 2030, the grid needs storage that can cover evenings and long periods with little wind or sun.
| Feature | Pumped storage (PSP) | Battery storage (BESS) |
|---|---|---|
| Storage medium | Water held at height | Chemical cells (mostly lithium-ion) |
| Typical discharge duration | Many hours (long duration) | Usually 2–4 hours |
| Life | 50+ years | About 10–15 years |
| Site needs | Two reservoirs with a height difference | Small footprint, can go almost anywhere |
| Build time | Several years | Months |
Policy points to remember
- Ministry of Power Guidelines to promote PSPs (10 April 2023): several ways to allot sites, exemption from free power and Local Area Development Fund obligations, and use of exhausted coal mines as reservoirs.
- Full waiver of inter-state transmission (ISTS) charges for PSPs whose construction is awarded on or before 30 June 2028.
- Installed PSP capacity was 4,745.6 MW from 8 plants (PIB, March 2023). The identified potential is about 176 GW.
Open-loop PSPs are linked to a river. Off-river (closed-loop) PSPs move the same water between two reservoirs that are not on a river.
In the news
The Ministry of Power issued Guidelines to promote Pumped Storage Projects in April 2023, and the government pushed PSPs and battery storage to balance solar and wind power. That made pumped storage a regular energy-transition topic in 2023–24.
NCERT Concepts to Revise
- Pumped storage hydropower: The term the question asks about, explained in simple words.
- Lift irrigation: The look-alike distractor: it also pumps water uphill, but for a different purpose.
- Hydroelectric power: The turbine principle that a pumped-storage plant uses when it generates power.