*A Review on Phase Change Materials for Sustainability Applications by Leveraging Machine… DOI: http://dx.doi.org/10.5772/intechopen.114380*

energy, in particular, has gained global traction due to its universal availability and potential in power production, drying, and space heating [58–62]. Enhancements in Solar Air Heaters (SAH) efficiency through ribbed heating surfaces and PCM [63–65], alongside the development of computational and mathematical models for PCM and nanofluids [66–69], mark significant progress. Yet solar power systems face challenges such as irregular energy supply, efficiency fluctuations [70], and nighttime power generation gaps. Concentrated Solar Power (CSP) systems, which concentrate sunlight to heat a transfer fluid for power generation or storage in TES systems, offer solutions to extend operational hours and improve efficiency. Despite these advancements, residential solar thermal applications encounter distinct challenges, further explored in subsequent sections. The integration of TES in CSP, illustrated in the System Advisor Model (SAM) for a parabolic trough plant, is a step toward addressing these limitations, enhancing efficiency, and reducing costs (**Figure 6**).

Traditional TE systems use molten salts for sensible heat storage, preferred for their high operating temperature ranges and low vapor pressures. Innovations in molten salt formulations are being explored to extend these temperature ranges, aiming for cost reduction and enhanced thermal efficiency. Research by Robak et al. on using PCMs in CSP applications showed that a PCM-based system employing heat pipes could significantly reduce the volume and overall system cost by 65 and 15%, respectively, compared to traditional two-tank models [72]. Nithyanandam and Pitchumani supported this, finding an 11% cost reduction in electricity production with PCMs over conventional sensible heat storage. The adoption of PCMs in TES could lead to substantial savings, though challenges like limited high-temperature PCM availability, phase segregation, and low thermal conductivity need addressing [73].

**Figure 6.** *System Advisor Model (SAM) sketch of a parabolic trough plant. Credit NREL/SAM [71].*
