Key challenges faced by molten salt thermal energy storage (TES) systems include:
1. Thermal Stability and Corrosion at High Temperatures
Traditional molten salts such as Solar Salt and Hitec Salt suffer from thermal stability issues and corrosion when operated at high temperatures required for efficient energy storage, typically up to around 565°C. This limits their operational lifespan and reliability in concentrated solar power (CSP) systems. High-temperature corrosion can degrade storage tanks and piping materials, necessitating more robust and often expensive corrosion-resistant alloys.
2. Material and Structural Challenges of Storage Tanks
Molten salt TES tanks face significant mechanical and material challenges. For example, the stainless steel commonly used (such as SS 347H) is prone to stress relaxation cracking and hot reheat cracking under operational conditions. The complexity of tank fabrication, welding, and post-weld heat treatments introduces residual stresses, increasing the risk of failures. These tank failures cause costly downtime and reduce trust in the technology.
3. High Initial Capital and Maintenance Costs
Setting up molten salt TES systems requires significant capital expenditure due to the scale of infrastructure needed—large tanks, specialized piping, heat exchangers, and corrosion-resistant materials like Hastelloy alloys. The high upfront investment and ongoing operational and maintenance expenses pose economic barriers, particularly in developing regions. Limited mass production of specialized components further drives up costs.
4. Need for High Operating Temperatures and Thermal Management
Molten salts must be kept above their melting points (often above 250–300°C) to maintain fluidity and functionality. This continuous high temperature requires substantial energy input to avoid solidification, leading to thermal losses and operational complexity. Long warm-up times before achieving operational temperatures reduce system responsiveness and flexibility.
5. Safety and Regulatory Considerations
While molten salt systems are intrinsically safe in terms of chemical hazards, the lack of standardized design codes and guidelines can lead to inconsistent safety and performance outcomes. Ensuring safe thermal storage under extreme temperatures requires careful engineering, regulatory compliance, and optimized system design.
Summary Table of Key Challenges
| Challenge | Description |
|---|---|
| Thermal stability & corrosion | Degradation of salts and materials at high operation temperatures |
| Tank material & structural issues | Susceptibility to cracking, welding, and fabrication problems causing failures |
| High costs | Large capital investment and operational expenses due to specialized materials and infrastructure |
| High operating temperatures | Need to maintain salts molten above 250–300°C, causing energy consumption and long warm-up times |
| Safety & regulatory issues | Lack of clear standards and complex safety requirements |
These challenges continue to drive research into improved molten salt formulations, advanced materials, and optimized system designs to enhance reliability, cost-effectiveness, and operational efficiency of molten salt thermal energy storage systems.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/what-are-the-key-challenges-faced-by-molten-salt-thermal-energy-storage-systems/
