Technical Challenges and Material Stability Issues of KNO₃–NaNO₃ (Solar Salt) for Concentrated Solar Power Thermal Energy Storage

BIKRAM KESHORI DANDAPAT

Technical Challenges and Material Stability Issues of KNO₃–NaNO₃ (Solar Salt) for Concentrated Solar Power Thermal Energy Storage

Author(s)	Dr. BIKRAM KESHORI DANDAPAT
Country	India
Abstract	Concentrated Solar Power (CSP) plants depend extensively on high-temperature thermal energy storage (TES) technologies to maintain reliable electricity generation and enhance grid dispatchability. Among the various storage materials available, the eutectic mixture of sodium nitrate (NaNO₃) and potassium nitrate (KNO₃), widely known as solar salt, has become the most commonly utilized molten salt in CSP facilities. Its widespread application is mainly attributed to its favorable thermophysical characteristics, comparatively low cost, and good chemical stability at elevated temperatures. In most commercial TES systems, solar salt is employed in a typical composition of 60% NaNO₃ and 40% KNO₃ and operates within a temperature range of approximately 290–565 °C in two-tank molten salt storage configurations. Despite these advantages, the practical implementation of solar salt presents several technical and operational challenges. Major issues include its relatively high melting temperature, thermal decomposition at very high operating temperatures, corrosion of storage and piping materials, and relatively low thermal conductivity that limits heat transfer efficiency. These challenges can negatively influence the reliability, operational efficiency, and economic viability of CSP power plants. This study examines the key technical challenges associated with the use of KNO₃–NaNO₃ molten salt mixtures in thermal energy storage systems. Particular attention is given to thermal stability, corrosion behaviour, compatibility with structural materials, and operational limitations encountered in CSP applications. In addition, potential mitigation strategies—including modification of salt compositions, development of corrosion-resistant materials, and enhancement of heat transfer performance—are discussed. The outcomes of this study provide useful insights for improving the performance of molten salt TES systems and outline future research directions for the development of advanced high-temperature energy storage materials.
Keywords	Thermal energy storage, molten salts, solar salt, concentrated solar power, corrosion, material stability.
Field	Engineering
Published In	Volume 7, Issue 2, March-April 2026
Published On	2026-03-19

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Technical Challenges and Material Stability Issues of KNO₃–NaNO₃ (Solar Salt) for Concentrated Solar Power Thermal Energy Storage

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