Thermal energy storage (TES) is a method by which cooling is produced and stored at one time period for use during a different time period. Air conditioning of buildings during summer daytime hours is the single largest contributor to electrical peak demand. Realistically, no building air conditioning system operates at 100% capacity for the entire daily cooling cycle. Air conditioning loads peak in the afternoon -- generally from 2 to 4 PM -- when ambient temperatures are highest, which put an increased demand for cooling and electricity. Electricity is a commodity that cannot be stored economically while it is transmitted through grid and is consumed as it is produced. The electricity generation (MW) depends on the downstream consumption, which is generally at peak (maximum) during afternoon and evening hours and low (lean) at nights and morning hours. While the utilities are committed to deliver the peak demand by increasing their generation capacity, during lean periods when the demand is low, the power plants are forced to operate at low load factor.