Molten salt refers to any salt in a liquid state. While different types of salts feature different properties, most have a very high melting point. For example, standard table salt melts at 1,472 degrees Fahrenheit (800 degrees Celsius). By the time these salts melt into a liquid state, they have absorbed and retained a tremendous amount of heat energy. This high melting point and ability to retain heat energy allow molten salts to be used for everything from energy production to metallurgical processes.
For many years, manufacturers and industrial firms have relied on molten salts to transform or protect various types of metal. For example, these salts play a key role in the heat treatment of steel and metal alloys. It is also used to quench, annel, and temper steel. Molten salt can also be used to enhance the natural properties of metal, or even to alter the surface finish. This liquid salt is used to anodize aluminum, for example, or to enhance the strength and corrosion-resistance of other metal alloys.
Molten salt also plays an important role in modern energy production, and may allow power plants to utilize solar energy even when the sun isn't shining. Solar facilities use large mirrors or solar panels to heat a large tub or tower filled with a molten salt mixture. This mixture naturally stores heat energy, which is pumped to a nearby steam generator. This generator powers an electrical turbine to produce clean, eco-friendly electricity. The natural properties of molten salt allow it to store heat energy for many hours, which means that these plants can produce electricity round the clock using this technology.
Molten salts also represent a promising new method for storing energy in batteries or fuel cells. In this type of application, the molten salt acts as the electrolyte. Each battery contains an internal heat source to warm the molten salt and activate the energy-producing capabilities of the battery. Some researchers believe that molten salt batteries may serve as an effective power source for hybrid or electric vehicles. This technology requires additional research due to the highly corrosive nature and short lifespan of these batteries.
Due to its ability to store heat energy, molten salt may help to reduce dependence on traditional energy sources, such as fossil fuels. This can reduce air and water pollution associated with these fuel sources while helping to preserve limited world supplies. One limitation to this technology is the high heat levels associated with molten salt, which require specially designed containment and cooling systems.