Thermo-Solar Salts: clean energy and efficient thermal storage

Thermo-Solar Salts are a mixture of inorganic nitrates that can be heated to high temperatures, store that energy, and release it when needed.

How do Thermo-Solar Salts work?

In a Concentrated Solar power Plant (CSP) with a central receiver, molten salts circulate as a heat transfer fluid. This allows solar energy to be captured and stored, transforming it into electricity with greater efficiency than conventional systems.

SQM’s Thermo-Solar Salts, composed of a mixture of Sodium Nitrate and Potassium Nitrate, enable Concentrated Solar power Plants (CSP) to compete with fossil fuel-based thermal power plants and even nuclear plants.

• Molten Thermo-Solar Salts act as a heat transfer fluid, increasing the efficiency of solar plants.
• They can replace thermal oil in parabolic trough CSP plants.
• SQM produces more than 1 million metric tons of caliche and brine per year in northern Chile.
• From these natural resources, high-purity nitrates are obtained, which are essential to solar energy.
• SQM’s experience in leaching, crystallization, and ion exchange processes ensures a reliable and efficient supply.

Thanks to these molten salts, solar plants can operate 24/7, storing thermal energy and releasing it when the sun is not shining, ensuring continuous and stable electricity production.

Thermo-Solar Salts production in SQM

SQM produces Thermo-Solar salts from two natural resources found in northern Chile:

• Caliche: extracted from the Atacama Desert. Products such as Sodium Nitrate and Iodine are obtained from it.
• Brines from the Atacama Salt Flats: pumped from underground wells and evaporated in the sun to concentrate minerals.

From these raw materials, SQM obtains a wide range of derivative products:

• Sodium nitrate
• Potassium nitrate
• Potassium chloride
• Magnesium chloride hexahydrate
• Boric acid
• Potassium sulfate
• Lithium salts

Process for obtaining Sodium and Potassium Nitrate

1. The caliche is crushed and undergoes a leaching process with water.
2. Sodium Nitrate is obtained through crystallization.
3. This nitrate is combined with Potassium Chloride from the Atacama Salt Flat.
4. The mixture undergoes ion exchange, crystallization, and drying processes.
5. The result is high-purity Potassium Nitrate, essential for Thermo-Solar salts.

Strict control of stoichiometry at each stage allows for a perfect mixture of Sodium Nitrate and Potassium Nitrate, ensuring stable thermal properties for CSP solar plants.

Advantages of SQM’s Thermo-Solar Salts

• 24/7 operation: solar energy storage for use at night or on cloudy days.
• Greater efficiency: more stable heat transfer than thermal oils.
• Reliable supply: thanks to SQM’s extensive experience in mining and chemical processes.
• Scalability: applicable in large-scale solar projects.