**6.4 Compressed air energy storage (CAES)**

The method to gather periodic renewable power is fixed by utilizing compressed air power storage space. This manner of storage opens up possibilities to keep power for a long-time period and then to resupply that electricity to the grid. Excess recurring electricity is made use of to compress air. Using this form of storage ensures that intermittent renewable energy may be stored for a long period of time, in contrast to flywheels or supercapacitors. The place of CAES is mainly underground, and globally, there are just a few buildings, just one in Europe-Germany and two in the U.S. CAES is normally attached to a power-producing system, such as a wind turbine, and when energy is required, compressed air is expanded and transferred back to a power-extending engine. For better perception, **Figure 6** contains how the CAES system looks exactly.

CAES systems are widely employed in the manufacturing and mining industries. However, adopting this technology in some applications, particularly residential solutions, and their installation itself might be difficult and expensive.
