As compressed air energy storage (CAES) is a
promising energy storage technology that has already proven its
reliability in commercial operation some basic thermodynamic
information on this process are elaborated in this paper. It shows
a comparison of the thermodynamic process cycles of the CAES
plants in Huntorf and McIntosh that has been modeled in EES
(Engineering Equation Solver). Detailed T-s-Diagrams are given
to show the differences of reversible and irreversible
thermodynamic modeling of CAES. It is demonstrated that
irreversibility assumption leads to an over estimation of the plant
efficiency and therefore newer CAES concepts (like adiabatic
CAES) should not be approximated with reversibility
assumptions to avoid misleading statements
