Pumped Hydro Storage
Energy storage using gravity potential energy of water pumped to elevated reservoir, providing flexible dispatchable energy and currently storing 90% of global grid energy.
Formula
Potential Energy = mass × g × height (E = mgh)
Real World
The Bath County Pumped Storage Station in Virginia, USA (3,003 MW capacity), charges overnight using cheap off-peak nuclear power and discharges during morning demand peaks, effectively acting as the grid's largest rechargeable battery.
Exam Focus
When comparing storage technologies, state pumped hydro's 75–85% efficiency and 50+ year lifespan alongside its geographical constraint as a balanced evaluative point.
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