In December 2025, the National Development and Reform Commission and the National Energy Administration jointly issued the "Several Opinions on Promoting the Large-Scale Development of Concentrated Solar Power (CSP)." This document explicitly set the target of achieving a total installed capacity of 150 gigawatts (GW) for CSP by 2030 and reducing the levelized cost of electricity (LCOE) to a level comparable with coal-fired power. This policy not only injects strong momentum into the CSP industry but also paves a solid "policy runway" for the long-term development of molten salt energy storage technology.
Molten salt, in simple terms, is salt in a molten liquid state. Common types include nitrates, carbonates, and chlorides. They possess characteristics such as low cost, wide availability, high boiling point, high heat capacity, low viscosity, and good thermal stability, making them an ideal medium for heat storage and transfer. Currently, they are widely used in tower-type CSP plants and industrial heat storage systems.
In tower-type CSP plants, the most commonly used formulation is the binary molten salt mixture of 40% potassium nitrate and 60% sodium nitrate. Its operating temperature can be stably maintained between 290°C and 565°C, ensuring both system safety and heat transfer efficiency.
What role does molten salt play in CSP Plants?
Molten salt plays a dual core role in CSP plants, combining energy storage and heat transfer functions, much like a "super power bank" for the grid.
1、Heat Transfer and Storage System
Power plants typically feature two molten salt storage tanks—low-temperature and high-temperature—forming a complete thermal energy cycle system:
✔ Heat storage during the day: Molten salt from the low-temperature tank is pumped to the receiver, where it absorbs concentrated solar energy reflected by heliostats. Its temperature rises to approximately 565°C before being stored in the high-temperature tank.
✔ Power generation at night or during peak demand: High-temperature molten salt flows through a steam generator, heating water to produce high-temperature, high-pressure steam, which drives a turbine to generate electricity. After cooling, the molten salt returns to the low-temperature tank, completing a closed-loop cycle.
2、Achieving "Solar Energy ≠ Immediate Power Generation"
Molten salt energy storage enables CSP plants to overcome the limitation of relying solely on real-time sunlight. It allows excess solar energy to be stored as thermal energy on a large scale and released as stable electricity when the grid requires it, significantly enhancing the dispatchability and stability of the power system.
Flexible Peak Load Regulation
Power plants can operate at full load during peak electricity price periods to maximize revenue, while storing thermal energy or reducing output during off-peak hours. This operational flexibility significantly enhances the project's economic viability.
Long-Duration Energy Storage
The system is capable of single-cycle heat storage lasting 6 to 15 hours or even longer. This extended discharge duration provides substantial support
for grid stability, effectively smoothing out fluctuations and mitigating the intermittency challenges associated with renewable energy sources like solar and wind.
Safety and Environmental Sustainability
Molten salt is inherently safe—it is non-toxic, non-flammable, and operates at atmospheric pressure, eliminating explosion risks. The storage medium
is also recyclable, making the system an environmentally friendly choice for large-scale energy storage.
Three Major Advantages of Molten Salt Energy Storage
Flexible Peak Load Regulation
Power plants can operate at full load during peak electricity price periods to maximize revenue, while storing thermal energy or reducing output during off-peak hours. This operational flexibility significantly enhances the project's economic viability.
Long-Duration Energy Storage
The system is capable of single-cycle heat storage lasting 6 to 15 hours or even longer. This extended discharge duration provides substantial support
for grid stability, effectively smoothing out fluctuations and mitigating the intermittency challenges associated with renewable energy sources like solar and wind.
Safety and Environmental Sustainability
Molten salt is inherently safe—it is non-toxic, non-flammable, and operates at atmospheric pressure, eliminating explosion risks. The storage medium
is also recyclable, making the system an environmentally friendly choice for large-scale energy storage.
Multiple Applications of Molten Sale Energy Storage
1. Complementing Wind and Solar Power
Building a "solar thermal + photovoltaic + wind power" multi-energy complementary base to achieve 24-hour stable power supply and improve the
overall utilization efficiency of renewable energy.
2. Industrial Heating
Providing stable high-temperature heat sources for industrial processes such as chemical, textile, and food production, supporting energy
conservation and carbon reduction in the industrial sector.
3. Grid Frequency Regulation Services
Leveraging rapid response capabilities to participate in grid frequency regulation, enhancing the operational flexibility of the power system.
4.Coupling with Hydrogen Energy, Nuclear Energy, and Other Systems
In the future, it can serve as a high-temperature heat source for integrated energy systems, such as nuclear hydrogen production and thermochemical
energy storage, expanding the scope of energy services.
Breakthrough in Key Components: The Wanlong Molten Salt Valve as an Example
Breakthrough in key components
Breakthrough in Key Components: The Wanlong Molten Salt Valve as an Example. For a molten salt system to operate stably over the long term in a
high-temperature (565°C) and highly corrosive environment, each core component faces severe challenges. Among them, molten salt valves, as the
critical "switches" controlling the flow of molten salt, directly impact the safety and efficiency of the entire power plant.
The Wanlong molten salt valve is precisely designed to address these extreme operating conditions. It tackles two core challenges of molten salt systems through specialized solutions: a heating system to prevent salt crystallization in the bellows area and the scientific selection of specialized materials for high-temperature corrosive environments.
High-Temperature Corrosion Resistance: The valve body and internal components are made of specialized materials resistant to molten salt corrosion, ensuring long-term operation at 565°C without degradation and significantly extending equipment lifespan.
Solidification Prevention Design: To address the tendency of molten salt to solidify at low temperatures, the valve integrates an efficient heating system and insulation structure. This prevents localized solidification during startup, shutdown, and operation, ensuring the system remains flexible and readily available.The application of such high-performance valves is crucial for achieving long lifespan, high availability, and low maintenance costs in molten salt energy storage systems. It lays a solid industrial foundation for the scaled and commercial development of concentrated solar power plants.
Challenges and Prospects of Molten Salt Energy Storage
Despite the significant advantages of molten salt energy storage, it still faces several challenges:
◐Material Corrosion: Long-term operation under high temperatures imposes higher requirements on the materials used for pipelines and equipment.
◑Low-Temperature Anti-Solidification Measures: In cold regions, insulation and heating measures are necessary to prevent molten salt from solidifying.
◐ High Initial Investment: The costs of storage tanks, pipelines, and control systems continue to constrain its widespread adoption.
Looking ahead, with advancements in material technology, the localization and cost reduction of key components (such as valves), the realization of economies of scale, and ongoing policy support, the cost of molten salt energy storage is expected to decrease further. Its application scenarios will also expand from concentrated solar power plants to integrated energy services, district heating, industrial steam supply, and other fields, making it a crucial supporting technology for building a new-type power system.
