How it works
Mechanical storage lifts water or compresses air. Electrochemical storage moves ions between electrodes. Thermal storage heats or cools a medium. Chemical storage makes a fuel that can be burned or used in a fuel cell later.
Key facts
- Electricity storage is a set of technologies, not a single device.
- Round-trip efficiency and duration are first-order design parameters.
- Pumped hydro dominates installed energy capacity in many countries.
- Batteries excel at fast, short-duration services.
Environment
Impacts are those of mining, manufacturing, reservoirs, or caverns, plus end-of-life handling. Storage enables cleaner grids when it reduces fossil peaking, but it is not automatically green.