A concentrating solar power (CSP) system converts sunlight into a heat source which can be used to drive a conventional power plant. Thermal energy storage (TES) improves the dispatchability of a CSP plant. Heat can be stored in either sensible, latent or thermochemical storage. Commercial deployment of CSP systems have been achieved in recent years with the two-tank sensible storage system using molten salt as the storage medium. Considerable research effort has been conducted to improve the efficiency of the CSP system and make the cost of electricity comparable to that of the conventional fossil-fuel power plant. This paper provides a comprehensive summary of CSP plants both in operation and under construction. It covers the available technologies for the receiver, thermal storage, power block and heat transfer fluid. This paper also reviews developments in high temperature TES over the past decade with a focus on sensible and latent heat storage. High temperature corrosion and economic aspects of these systems are also discussed.

Review on concentrating solar power plants and new developments in high temperature thermal energy storage technologies

Heat transfer fluids for concentrating solar power systems – A review

Thermochemical energy storage of concentrated solar power by integration of the calcium looping process and a CO2 power cycle

Mainstreaming commercial CSP systems: A technology review

Molten salts as engineering fluids – A review

The preparation and properties of multi-component molten salts

This paper focuses on thermal stability of molten salts consisting of potassium nitrate, sodium nitrite, sodium nitrate and one kind of additives such as A, B and C at a high temperature. The multi-component molten salts were prepared by mixing the pure salts, heating statically to the melting state and then cooling to room temperature to form the mixed molten salts. The stability experiments were carried out at 500 and 550°C, and the experiment found that the molten salt with 5% additive A performed better high-temperature thermal stability and its optimum operating temperature was increased to 550 from 500°C. XRD and DSC analyses indicated that the molten salt with 5% additive A had a lower freezing point and a higher phase change latent heat. Besides, the concentration of NO 2 anion in the molten salt was analyzed and the results showed that the main reaction for the molten salts in air was nitrite thermal oxidation at 500 and 550°C. In addition, the energy used for the oxidation of nitrite would be increased with an increase in additives and the prolonging of reaction time at the same time.

High-temperature thermal stability of molten salt materials

Heat transfer medium in solar thermal power stations are used by molten salts materials. Quaternary molten salts which were composed of potassium nitrate, sodium nitrite, sodium nitrate when adding 5%, 10%, 15% additive A, additive B, additive C respectively were prepared. Thermal stability and thermal cycling analysis of molten salts, XRD and DSC tests showed molten salt with 5% additive A had higher thermal stability. Its optimum operating temperature would be increased to 550°C from 500°C. This kind of heat transfer medium had high phase change latent heat and low melting point. So it could reduce the size of system and requirement for energy. The efficiency of its using energy was higher and the effect of energy saving was better. Besides, this kind of molten salt may also supply theoretical prediction for molten salts synthesis and basic method for project application.

Qiang Peng

Papers

The preparation and properties of multi-component molten salts

High-temperature thermal stability of molten salt materials

Performance of Molten Salts Phase Change Materials