Molten Salt Thermal Energy Storage in CSP Systems
Molten salt thermal energy storage is a crucial component of Concentrated Solar Power (CSP) systems, allowing them to generate electricity even when sunlight is not available. This capability is particularly valuable as it enables CSP systems to act as dispatchable power sources, comparable to fossil fuels.
Overview of CSP Technologies
CSP systems generally use one of two main technologies:
- Tower CSP: This method involves a central tower surrounded by heliostats (mirrors) that focus sunlight onto a receiver at the top of the tower. Molten salt, typically a mixture of sodium nitrate and potassium nitrate, is used to absorb and store the heat.
- Trough CSP: Uses parabolic troughs instead of a central tower. In trough CSP, the heat is absorbed by a heat transfer fluid (HTF), usually an oil, and can be stored in molten salts as well.
Molten Salt Thermal Energy Storage Process
- Heating the Molten Salt: In tower CSP systems, the molten salt is pumped up to the receiver at the top of the tower and heated to around 565°C by concentrated sunlight. In trough CSP systems, the heat transfer fluid is heated and then transfers its heat to molten salts for storage.
- Storing Thermal Energy: The heated molten salt flows down into a storage tank, typically insulated to minimize heat loss. This stored thermal energy can be used to generate electricity by producing steam through a heat exchanger.
- Generating Electricity: When electricity is needed, the hot molten salt from the storage tank is pumped through a heat exchanger. Here, it heats water to produce steam, which drives a turbine connected to a generator to produce electricity.
- Cooling and Recycling: After transferring its heat in the heat exchanger, the molten salt returns to a “cold” tank at a lower temperature. It is then cycled back to the receiver to be reheated and stored again.
Advantages of Molten Salt Storage
- Long-Term Storage: Molten salts allow for thermal energy storage that can last for several hours or even days, making CSP systems more reliable and dispatchable.
- Reusability: Unlike fossil fuels, molten salts can be reused daily for decades, reducing operational costs and environmental impact.
Challenges and Future Developments
Despite its advantages, molten salt storage faces challenges such as corrosion and the need for large, expensive tanks. Researchers are working on improving salt chemistry and tank designs to enhance durability and efficiency.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-molten-salt-thermal-energy-storage-work-in-csp-systems/
