It is being recognized that an increase in the electricity generated from central facilities of time-varying renewable energy sources will require some means of smoothing the variations with time. While thermal storage may be appropriate for solar trough and tower plants, additional approaches for storage might prove to be beneficial for other types of generation schemes. One approach to storage that has been examined to varying degrees over the years is Compressed Air Energy Storage (CAES). Compressed air can be supplied to large size tanks or underground caverns, and later this stored air can be used to generate power to shave the peak demand of electricity or maintain nearly uniform levels of power generation. The tank discharge process is time dependent on the temperature, pressure, and mass flow rate of the air leaving. Of course, this time dependency also affects the power output of the system. In the following analysis an attempt was given to determine: 1- an analysis of the charging and discharging processes; 2- a power-time relation during the discharge process; 3- an approximation for the size required for a certain energy generated (m3/MW h) as a function of the initial air pressure; 4- a relation between the discharge area and the time to stabilize the mass flow; and 5- a supplemental heat input is examined in the discharge process to maintain nearly constant discharge power. Using a thermodynamic analysis for the system the power-time history is found.

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