Energy density of compressed air energy storage

What determinants determine the efficiency of compressed air energy storage systems?

Research has shown that isentropic efficiency for compressors as well as expanders are key determinants of the overall characteristics and efficiency of compressed air energy storage systems . Compressed air energy storage systems are sub divided into three categories: diabatic CAES systems, adiabatic CAES systems and isothermal CAES systems.

What is the performance characteristic of compressed air storage?

The performance characteristic of the compressed air storage is a crucial factor that determines the roundtrip efficiency and energy density of the system. Many researchers have focused on the improvement and extension of A-CAES system, such as tri-generation systems , , hybrid systems with wind , or solar energy.

Where can compressed air energy be stored?

The number of sites available for compressed air energy storage is higher compared to those of pumped hydro [, ]. Porous rocks and cavern reservoirs are also ideal storage sites for CAES. Gas storage locations are capable of being used as sites for storage of compressed air .

How does a compressed air energy storage system work?

The performance of compressed air energy storage systems is centred round the efficiency of the compressors and expanders. It is also important to determine the losses in the system as energy transfer occurs on these components. There are several compression and expansion stages: from the charging, to the discharging phases of the storage system.

What determines the design of a compressed air energy storage system?

The reverse operation of both components to each other determines their design when integrated on a compressed air energy storage system. The screw and scroll are two examples of expanders, classified under reciprocating and rotary types.

What is a conventional compressed air energy storage system?

Schematic of a generic conventional compressed air energy storage (CAES) system. The prospects for the conventional CAES technology are poor in low-carbon grids [2,6–8]. Fossil fuel (typically natural gas) combustion is needed to provide heat to prevent freezing of the moisture present in the expanding air .