It's difficult to generalize about when cool storage systems will be cost-effective, but if you meet one or more of the above criteria, it may be worth doing a detailed analysis. The storage medium determines how large the storage tank will be and the size and configuration of the HVAC system and components. Overall, ice systems offer the densest storage capacity but the most complex charge and discharge equipment. Water systems offer the lowest storage density, but are the least complex.
Eutectic salts fall somewhere in between.
Comparing storage media Chilled water systems require the largest tanks, but they can easily interface with existing chiller systems. Ice systems use smaller tanks and offer the potential for the use of low-temperature air systems, but they require more complex chiller systems. Eutectic salts can use existing chillers but usually operate at the warmest temperatures. They operate at temperature ranges compatible with standard chiller systems and are most economical for systems greater than 2,000 ton-hours in capacity. To store energy at the temperature of ice requires refrigeration equipment that provides charging fluids at temperatures below the normal operating range of conventional air-conditioning equipment.