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 .
Most compressed air energy storage systems addressed in literature are large-scale systems of above 100 MW which most of the time use depleted mines as the cavity to store the high pressure fluid. Three main concepts are researched; diabatic, adiabatic and isothermal.
Energy storage systems are grouped by their types of energy storage media into mechanical, electrical, electrochemical, chemical, and thermal energy storage systems. Mechanical storage systems consist mainly of pumped hydro storage, air energy storage, and flywheel storage systems.
In order to use air storage in vehicles or aircraft for practical land or air transportation, the energy storage system must be compact and lightweight. Energy density and specific energy are the engineering terms that define these desired qualities.
The air, which is pressurized, is kept in volumes, and when demand of electricity is high, the pressurized air is used to run turbines to produce electricity . There are three main types used to deal with heat in compressed air energy storage system .
The main exergy storage system is the high-grade thermal energy storage. The reset of the air is kept in the low-grade thermal energy storage, which is between points 8 and 9. This stage is carried out to produce pressurized air at ambient temperature captured at point 9. The air is then stored in high-pressure storage (HPS).
OverviewTypes of systemsTypesCompressors and expandersStorageEnvironmental ImpactHistoryProjects
Brayton cycle engines compress and heat air with a fuel suitable for an internal combustion engine. For example, burning natural gas or biogas heats compressed air, and then a conventional gas turbine engine or the rear portion of a jet engine expands it to produce work. Compressed air engines can recharge an electric battery. The apparently-defunct