Thermal energy storage is widely recognised as a demand-side management technology for shifting cooling electrical demand from peak daytime periods to off-peak nighttime and weekend periods when utilities have reserve generating capacity. It enables users to significantly reduce their electricity costs by reducing peak demand and taking advantage of lower off-peak rates - often with large utility incentive payments and sometimes with reduced capital costs. Also, it enables utilities to reduce peaks and fill valleys, thereby improving system load factors, reducing reliance on peaking units, increasing utilisation of base load units, and postponing the construction of additional generating units. Because thermal energy storage has been so strongly categorised as a demand-shifting technology, its potential for energy conservation has received little recognition. Certainly, there are many existing thermal energy storage systems that use more electricity than conventional cooling systems and are beneficial only for shifting demand. However, recent advances have produced more efficient and better integrated thermal energy storage systems that use less electricity and natural gas than conventional cooling/heating systems. So, in order to apprise interested engineers of the technology's potential for energy conservation, this paper studies the design and operation of a thermally stratified chilled-water storage system in an industrial retrofit application that has achieved such results.

KEYWORDS: energy conservation, energy storage, temperature stratification, chilled water supply, industrial, modernising, performance, heat gain, heat recovery, energy consumption, costs.