Thermal Storage Systems at IBM Facilities

In 1979, IBM commissioned its first large scale thermal storage system with a capacity of 2.7 million gallons of chilled water and 1.2 million gallons of reclaimed, low temperature hot water. The stored cooling energy represents approximately 27,000 ton hours. Through reduced chiller plant capacity and annual operating cost savings in primarily electric demand charges the payback will be approximately 3 1/2 years. The water is stored in multiple, insulated tanks, located above the ground. A similar but smaller system at IBM's Charlotte, North Carolina plant has no provisions for heat reclaim. Instead, it uses cooling tower water directly in the chilled water circuit when outside conditions permit. This paper presents system designs, control modes and economic considerations and describes IBM's experience to date with large volume storage systems