Compressed Air Systems and Storage

The elementary principles related to compressed air are presented, describing the basic compression and expansion characteristics. The adiabatic, polytropic and isothermal phenomena are described together with the definitions of the energy content of a given volume. Different loss factors related to compressed air are enumerated together with the advantages and drawbacks of pneumatic technology. Then, the possibility of storing energy under low pressure conditions as the so-called Underwater CAES system is discussed. Such systems have the interesting property of being realized with a very low amount of grey energy.