What is grid-scale energy storage and name two technologies used for it?

• A. Small-scale storage such as household batteries.
• B. Grid-scale storage uses only pumped hydro.
• C. Large-scale storage to balance supply and demand; pumped hydro and large-scale battery storage (e.g., Li-ion).
• D. Storage has no role in grid.

Answer: (C)

Grid-scale energy storage means storing very large amounts of electrical energy to balance what the grid produces with what people and devices demand, keeping the system reliable as supply and demand shift. It’s about utility-scale capabilities, not household batteries. A key example is pumped hydro, which stores energy by pumping water to a high reservoir when there’s excess generation and releasing it through turbines to produce electricity when demand rises. Another major example is large-scale battery storage, such as lithium-ion systems, which store energy chemically and can discharge quickly to address short-term gaps or provide fast response.

This combination—big, long-distance storage with both pumped hydro and large-scale batteries—captures how the grid can smooth out variability and maintain steady supply. Choices that describe only small-scale storage or claim storage isn’t used on the grid don’t reflect how energy systems actually balance supply and demand.