Compressed air energy storage
Cylinder pressure p1 MPa
Ambient pressure p2 MPa
Cylinder volume v1 10-3 m3
Cylinder temperature T1 K
Specific heat capacity cp kJ/(kg·K)
Specific heat capacity cv kJ/(kg·K)
Gas constant R=cp-cv kJ/(kg·K)
Isentropic coefficient k=cp/cv -
mass weight m=p·V/(R·T) kg
Isothermal expansion Adiabatic expansion
Expanded volume v2 m3 m3
Energy released W kJ kJ
Temperature T2 K K
Compared to batteries, compressed air is favorable because of a high energy density, low toxicity, fast filling at low cost and long service life. These issues make it technically challenging to design air engines for all kind of compressed air driven vehicles (http://en.wikipedia.org/wiki/Compressed-air_energy_storage).
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