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This paper presents a detailed review of shell materials that have the potential to be used for high temperature thermal energy storage (TES) applications, particularly in conjunction with concentrated solar power (CSP) plants. This paper considers shell materials that are thermally stable at more than 300 °C and have successfully been used to encapsulate a phase change material (PCM). The current review does not consider the thermal performance of the shell material and PCM combinations that have been studied. Using these constraints several feasible materials were identified including: steel (carbon and stainless), nickel (and nickel alloy), sodium silicate, silicon dioxide, calcium carbonate and titanium dioxide. These materials have the potential to encapsulate high temperature PCMs and thus provide a suitable method of high temperature TES. [ABSTRACT FROM AUTHOR]

According to the SunShot initiative, one sixth of the levelized cost of electricity for Concentrated Solar Thermal Power is thermal energy storage. For this power generation paradigm to be successful, the cost of every sub-system must be dramatically reduced. However, the search space for possible storage mediums is too large for a brute force experimental search to be feasible. Thus, a more refined approach is necessary. In this paper, eutectic salt combinations are considered as storage medium. The state of the selection process for these eutectics is discussed. Various methods to predict the important thermophysical properties are reported and applied to eutectics whose physical properties are known. Based on single salt properties, the density of molten salt eutectics can be predicted, around their melting point, to within 5%. Prediction of the melting point and composition is accurate to within 7%. However, the estimation of latent heat for multi-component eutectics is not always accurate, and requires more work. Finally, the thermal conductivity of multi-component eutectics has not been well studied; further research is required to corroborate the predictions. [ABSTRACT FROM AUTHOR]

Abstract: Designing a cost-effective phase change thermal storage system involves two challenging aspects: one is to select a suitable storage material and the other is to increase the heat transfer between the storage material and the heat transfer fluid as the performance of the system is limited by the poor thermal conductivity of the latent heat storage material. When used for storing energy in concentrated solar thermal power plants, the solar field operation temperature will determine the PCM melting temperature selection. This paper reviews concentrated solar thermal power plants that are currently operating and under construction. It also reviews phase change materials with melting temperatures above 300°C, which potentially can be used as energy storage media in these plants. In addition, various techniques employed to enhance the thermal performance of high temperature phase change thermal storage systems have been reviewed and discussed. This review aims to provide the necessary information for further research in the development of cost-effective high temperature phase change thermal storage systems. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Demand for high temperature storage is on a high rise, particularly with the advancement of circular economy as a solution to reduce global warming effects. Thermal energy storage can be used in concentrated solar power plants, waste heat recovery and conventional power plants to improve the thermal efficiency. Latent thermal energy storage systems using phase change materials are highly thought for such applications due to their high energy density as compared to their sensible heat counterparts. This review, therefore, gives a summary of major factors that need to be assessed before an integration of the latent thermal energy system is undertaken. In addition, challenges faced when constructing and experimenting with the storage systems are mentioned. Finally, an insight on the cost analysis and the general performance metrics of the latent thermal energy storage systems is provided before conclusions are drawn. • High temperature phase change materials for CSP thermal energy storage. • Phase change materials in CSP plants. • Challenges in building LTES systems. • TES sizing and effectiveness. [ABSTRACT FROM AUTHOR]

Latent heat thermal energy storage, by using phase change materials (PCMs), is considered as a promising technology that can be integrated into concentrated solar power (CSP) applications to mitigate the load and electricity supply. Multiple PCMs connected in series has attracted considerable research attention as this configuration has the potential to improve the thermal performance compared to single PCM storage. However, this technology has not yet been deployed in commercial CSP plants. One of the major restrictions is the lack of reliable thermophysical property data for high temperature PCMs. This study gives a broad review of the experimentally verified PCMs with melting temperatures from approximately 500 °C–700 °C, applicable to CSP systems. A further twelve PCM candidates, containing low-cost sodium and/or potassium salts, were identified in this study and their thermophysical properties were experimentally evaluated. It was found that nine of the new candidates can be used as PCMs. • Experimentally verified PCMs with melting points of 500 °C–700 °C were reviewed. • 12 potentially low-cost PCM candidates were identified from the literature. • PCMs were experimentally characterised by using the DSC and TGA. • 9 out of 12 candidates are suitable as PCMs. • The measured weight loss by TGA is in proportion to the estimated vapor pressure. [ABSTRACT FROM AUTHOR]