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2.11 Cooling Thermal Storage

This part of the Energy Efficiency Manual presents the energy conservation measures that apply to cooling thermal storage. Cooling thermal storage is a technique that was originally employed to allow small cooling equipment to serve large cooling loads for short intervals. Cooling storage experienced an explosion of interest in the 1980’s that continues to the present. Now, the primary interest is in shifting the cooling load to times of day when electricity rates are lower, primarily to reduce electricity demand charges. The difference in electricity prices between different hours of the day continues to widen. This suggests that cooling storage will continue to grow in popularity.

After a rocky start, storage equipment is becoming more reliable. Several types continue to evolve, and new types occasionally appear. The growing pains have not ended yet. Although the concept is simple, cooling thermal storage is a broad subject with many complications. A chiller system with cooling storage is a challenge to design, to install, and to operate. Many systems have failed, but the initial phase of cooling storage has yielded a wealth of experience that you will gain here.

This part of the book leads you step by step through the factors to consider in deciding whether to install a cooling storage system. It covers the types of systems, including ice storage and chilled water storage. Ice storage types include ice harvesters, ice-on-coil, coil melt, ice capsule, and ice slurry systems. Chilled water storage systems include a discussion of eutectic salt systems. The advantages and disadvantages of each type are explained.