The main materials used in molten salt energy storage are typically mixtures of inorganic salts, prominently including sodium nitrate, potassium nitrate, and calcium nitrate. These salts are chosen for their thermal properties, such as melting point, thermal stability, heat capacity, and conductivity. For example, a common eutectic mixture melts around 131 °C and can be heated up to about 565 °C for energy storage and release cycles.
Main Materials
- Sodium nitrate (NaNO3)
- Potassium nitrate (KNO3)
- Calcium nitrate (Ca(NO3)2)
These are often combined in eutectic mixtures tailored to optimize melting point and heat capacity for specific applications.
How These Materials Affect the Environment
- Abundance and low cost: These salts are abundant and inexpensive, which minimizes environmental pressures related to raw material extraction and cost barriers to adoption.
- Thermal stability and recyclability: Molten salts do not undergo chemical changes during heating and cooling cycles, which means they have a long service life and don’t generate waste products during normal operations.
- Non-toxic and relatively safe: While nitrates must be handled carefully to avoid environmental contamination, they are generally less toxic and hazardous than many alternative energy storage chemicals or fossil fuels.
- Potential environmental risks: Improper handling or accidental release of nitrate salts could lead to localized soil or water pollution, since nitrates can contribute to eutrophication in water bodies.
- Material requirements for containment: Stainless steels (e.g., austenitic stainless steel) are used for tanks and piping to withstand high temperatures (>400 °C) and resist corrosion from molten salts, helping prevent leaks and minimizing environmental contamination risks from equipment failure.
Overall, molten salt energy storage uses widely available inorganic salt mixtures that provide efficient, stable, and reusable heat storage with relatively benign environmental impact compared to fossil fuels or toxic chemical storage media. However, proper engineering controls are necessary to manage nitrate salt containment and prevent environmental pollution.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/what-are-the-main-materials-used-in-molten-salt-energy-storage-and-how-do-they-affect-the-environment/
