Summarized from Southwest Research Institute,, 2022

Problem: Energy harvested during the day using solar voltaics cannot be stored efficiently during off-peak production times. 

Potential Solution: Molten Salt Thermal Energy Storage Systems have proven to be an effective battery (>80% efficient) to store solar energy for use at night. 

What is the current dilemma with renewable energy storage?

The sun shines all day, and solar panels harvest energy from the sun during this time using Solar Voltaics. The intake on these panels does not adjust to demand changes, and power from solar panels during the day remains relatively constant. At night, however, solar panels gather no energy, leaving significant gaps in time in which there is an energy production shortfall. This is the main drawback of solar and wind energy: Energy is lost when demand is below what is being harvested, and energy shortfalls can occur when neither the sun is shining, nor the wind is blowing. 

 What creates 24-hour energy security?

When energy demand spikes today, coal and natural gas power plants can increase their production quickly to keep up with demand, they can similarly reduce production to maintain efficiency. The only way to allow renewable energy to be used when environmental factors prevent production is to store energy from when it can be produced and use that energy when production is hindered. 

How does a Molten Salt Thermal Energy Storage System function?

Energy from the sun is directed to a point on a tower using a collection of concave mirrors. Within the tower is “cold” molten salt (260ºC) moving through the point on the tower. This salt is heated to a minimum temperature of 550ºC to be stored in a tank for later use. Since salt is held together at the molecular level by ionic bonds, tremendous energy can be stored in these bonds, unlike hydrogen bonds in water.  This molten salt can remain a liquid for days, up to weeks, depending on the storage container used. This molten salt can heat water to its flash point to generate steam, turn a turbine, and produce electricity on demand to send it out into the grid. 

Why is this Important?

In order to move into a future dependent on renewable energy, we need to be able to rely on its power just as we rely on coal and natural gas right now. Energy production shortfalls are unacceptable now, just as they will be in the future, and revolutionary solutions to solve this issue of renewable energy storage are needed to assure a resilient power grid in the world’s green energy transition. While Molten Salt Thermal Energy Storage remains expensive to implement, it is important to examine and understand all of the aspects and ideas for a realistic and dependable transition from fossil fuel based energy production.  

For more information regarding the scientific basis for Molten Salt Thermal Energy Storage Systems, its development, uses, and the economics behind its implementation, please feel free to visit the sources listed below. 


Southwest Research Institute, “Thermal Energy Storage”, SWI 2022.

Richard Dieterich, “24-Hour Solar Energy: Molten Salt Makes It Possible, and Prices Are Falling Fast”, Inside Climate News, 2022.

John Dodaro, “Molten Salt Storage”, Stanford University, 12/15/2015.
Mark Bergen, “ Alphabet Wants to Fix Renewable Energy’s Storage Problem — With Salt”, Bloomberg, 7/31/2017.

Featured Image from Just Energy

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