Chapter 01 · Climate & transitionEnergy & Transition
Compressed air energy storage (CAES)
Definition
Compressed air energy storage converts electricity to high-pressure air stored in underground salt caverns, rock formations or purpose-built vessels, later expanding the air through turbines to regenerate power. Commercial since the late 1970s, conventional (diabatic) plants vent compression heat and burn gas during discharge, while adiabatic designs store the heat for reuse, improving round-trip efficiency; isothermal variants are under development.
References
Overview
What it means
It is one of the few technologies suited to large-scale, long-duration storage, complementing batteries and pumped hydro.
How it is used
CAES shifts surplus renewable output across many hours to days, reducing curtailment and supporting grid stability.
Why it matters
High shares of wind and solar require storage at durations and scales that CAES can provide where geology allows.