An industrial power plant at sunset

Thermal Energy Storage Systems

Thermal Energy Storage Systems are used to collect thermal energy and use that the energy at a later time for heating, cooling, or power generation.  These systems are designed to store thermal energy for hours, days, weeks, and sometimes even months.  The reasons behind why it is beneficial or necessary to store thermal energy vary depending on the facility; however, common purposes include the following:

  • To operate equipment when the price of electricity is lowest and use the stored energy to operate equipment when the price of electricity is high (Peak Shaving)
  • To balance thermal energy demand for the facility between daytime and nighttime
  • For storing excess electrical energy produced by renewables that exceeds grid demand as thermal energy, and to convert that thermal energy to electrical energy for sale when renewables can no longer satisfy the grid demand (low solar irradiance, low wind speed)
  • Seasonal thermal energy storage such as storing thermal energy in the summer for winter heating and thermal energy in the winter for summer air conditioning.

When used in the power industry, especially for renewables, the installation of Thermal Energy Storage Systems can have a tremendous impact on the bottom line and can serve to drive up profits in the long term.  Renewable facilities can maximize their generation without regard to current grid demand, a problem well known in the California ISO (CAISO), as described in a great article by the Los Angeles Times1.  Cooling and heating plants can take advantage of these systems by balancing demand and operating fewer boilers and chillers at times when the price of electricity is higher, increasing profits.  Even conventional power plants can benefit and increase efficiency and profits through the installation of seasonal storage.

There are many types of Thermal Energy Storage Systems being installed throughout the country at many types of facilities: large, heavily-insulated water tanks and pumps, molten salt storage, heat storage in rock caverns, cryogenic energy storage, ice storage, so on and so forth.  No matter the type of storage system installed, it is of the utmost importance that operators are properly trained on accurate and efficient operations of these systems.  Without fully understanding the control schemes, operational sequences, system flowpaths, and how to operate the system in the most efficient manner possible, the profits and/or cost reductions seen by facilities installing these systems will not be maximized.  It is prudent that mangers take this into consideration when installing one of these systems and take appropriate steps to ensure workers are properly trained prior to and after these systems are brought online.

Facilities undergoing or that have undergone an installation of a Thermal Energy Storage System(s) will maximize the performance of these systems with Proper Operator Training, helping them realize their Return On Investment (ROI) on, or potentially even ahead, of schedule.


  1. Ivan Penn. (2017). California invested heavily in solar power.  Now there’s so much that other states are sometimes paid to take it.  Retrieved from