Progress in research and development of phase change materials for thermal energy storage in concentrated solar power

Concentrated solar power (CSP) technologies are seen to be one of the most promising ways to generate electric power in coming decades. However, due to unstable and intermittent nature of solar energy availability, one of the key factors that determine the development of CSP technology is the integration of efficient and cost-effective thermal energy storage (TES) systems. Sensible heat TES system is the most widespread technology in commercial CSP plants, however, due to the requirement of high specific heat of the storage material, large size and bigger temperature difference between the heat transfer fluid and the storage material, sensible energy storage systems suffer from a low energy density and temperature degradation during discharging. In this context, over the past ten years, interest in phase change materials (PCM) has resurfaced considerably, mainly motivated for the deployment of latent heat TES system for CSP application that utilizes PCM. Though there have been some review studies on the application of PCM in CSP plants, however these are either over 5 years old or give a general overview of PCM application in CSP plants. To bridge this gap, this work presents a comprehensive review on the actual state of all major components of cutting-edge PCM based TES technologies for CSP application and condenses all the available information and categorizes them considering the main functional parts and remarking the current research progress in each part as well as the future challenging issues. It intends to understand and explain the foundations of the innovative concepts, future research directions and strategies developed over the past 10 years to tune the engineering and thermal sciences of PCM based TES systems. Insight into classes of PCM TES storage materials with details like their geometrical configurations, design parameters, physical properties, operational issues, cost, technology readiness level, suitability to CSP application and comparative assessment of various PCM based TES systems is provided.