How Does Molten Salt Energy Storage Work?

One of the biggest hurdles with solar energy is that the sun doesn’t always shine. This means that we need an effective way of storing solar energy – and molten salt could be the answer.

Molten salt energy storage is typically used with a concentrated solar power plant. This type of power plant uses mirrors or lenses to focus a large amount of sunlight to generate heat. This heat is typically used  drive a steam turbine.

Solar Tower

Concentrated Solar Power Plant / Image Credit: Wikimedia Commons

So how does molten salt energy storage work? The step-by-step process is listed below:

  • The salt is kept liquid at roughly 275 C in a “cold storage” tank.
  • When the solar power plant is producing excess energy, the molten salt is pumped through the solar receiver to collect the additional heat.
  • The concentrated solar energy heats the molten salt to over 550 C. This molten salt is then sent to a “hot storage” tank.
  • When extra energy is needed (eg. at night or on a cloudy day), the molten salt from the “hot storage” tank is used to produce steam that drives a turbine and generates electricity.



The molten salt energy storage technology was first demonstrated in 1995, and has proven to be a reliable way to store energy for concentrated solar power plants. Here are some additional facts on molten salt technology:

  • The molten salt storage tanks are so well insulated they can keep the salt hot for a week.
  • Most molten salt mixtures can last for 30 years without the need for replacement.
  • Concentrated solar power plants that utilize molten salt storage can produce more than 2X the amount of energy when compared with plants that don’t utilize any energy storage.