Compressed Air Energy Storage 

CAES is a way to store electrical energy using compressed air. 
 

Phase 1: Storage 

An air compressor uses electrical energy to compress ambient air. 

The compressed air is stored in an underground reservoir. 
 

Phase 2: Release 

The compressed air is removed from the reservoir. 

It is injected into a combustion chamber along with natural gas and then fed through a turbine connected to a generator to convert the energy back into electricity.