Thermal Storage

Thermal storage provides a critical solution to district heating, district cooling, and electric grid systems.  Tanks of varying scale are used within integrated systems to shave peaks, increase system stability, and allow greater flexibility in energy production from alternative fuels.  District cooling systems integrate the use of thermal storage to enable the system to shift a significant portion of the cooling load to off-peak hours.  District heating systems can utilize thermal storage to reduce the temperature of the loop and incorporate waste heat, solar, and other alternatives.  Thermal storage capacity benefits customers and electric utilities on high peak-loading days and is an ideal solution for data centers that demand reliable cooling.

With electric rates on the rise across the nation, it makes sense to conserve energy and to run appliances and air conditioners during off-peak hours. Businesses can keep their employees cool during peak hours but still enjoy the benefits of lower electric rates thanks to chilled water storage. District Energy is finalizing a major conversion project that will allow one of our two thermal storage tanks to seasonally transition between hot and chilled water storage. This will be a groundbreaking project for this industry and allow for additional integration of renewable and efficient heating sources for District Energy.

How it Works
A chilled water storage system cools water at night using off-peak electricity and then stores the water in a multi-million gallon tank.  Chilled water is distributed through the district cooling system to customers during the day at a reduced cost.


  • Increases cooling capacity
  • Reduces regional peak electric demands
  • Improves air quality
  • Provides greater rate stability
  • Provides high overall system reliability
District Energy St. Paul is operated and managed by Ever-Green Energy.