What is pumped storage in hydroelectric power?

• A. It stores energy by pumping water back to the reservoir behind the dam when there is excess electricity.
• B. It uses water from the dam for power generation without storage.
• C. It converts kinetic energy directly into electricity without storage.
• D. It reduces energy demand by decreasing water usage.

Answer: (A)

Pumped storage is a way to store energy in the form of gravitational potential energy using two reservoirs at different heights. When electricity is plentiful or cheap, pumps push water from a lower reservoir up to an upper reservoir, storing energy for later. When demand spikes, the stored water is released back down through turbines to generate electricity. It’s like a giant grid-scale battery that can respond quickly to shortages or surges and helps balance supply, especially with intermittent renewable sources. This system relies on geography (two suitable reservoirs) and you incur energy losses in pumping and generation, so it isn’t 100% efficient. It isn’t simply generating from water without storage, nor does it rely on converting kinetic energy directly or reducing water use.