Phase change materials exhibit high latent heat and nearly isothermal phase change, which make them excellent candidates for many thermal storage as well as cooling applications. Waste generation, on the other hand, is steadily increasing, posing serious management challenges. These wastes are usually rich in chemical elements, oils, and fats and can therefore serve as raw materials for manufacturing valuable chemical products, including PCMs, encapsulations for PCMs, or thermal enhancers for improving heat transfer characteristics of PCMs. Suitable waste materials for the production of PCMs include agricultural and food-processing wastes, such as vegetable oils and fatty acid residues, as well as food-industry by-products. Industrial waste includes materials like polyethylene glycol, polymer processing waste, and industrial by-products. Municipal solid waste can be converted into energy-rich materials and PCMs by adequate thermal and chemical processes. Bio-based PCMs, usually obtained from fatty acids & esters, are derived from waste vegetable oils, animal fats, and food industry byproducts, after being chemically modified via esterification to form effective organic PCMs. Natural waxes are sourced from agricultural residues. Industrial waste-based PCMs are usually obtained from recycled plastics processed by pyrolysis or blended to create composite PCMs. By-products from polymer manufacturing and lost-wax casting wastes can serve as sources for PCMs. Waste-derived PCMs can be incorporated into building components, such as cement mortar, to improve thermal resistance and comfort. Waste-derived PCMs can be used for thermal management in electronics and battery systems to maintain a uniform and acceptable temperature within battery packs. Encapsulated PCMs can be incorporated into fabrics for flexible, medical and protective wearable applications. The continuously expanding application fields of PCMs, such as functional textiles and biomedical applications, require detailed and rigorous characterization of their thermochemical properties, including biodegradability, biosafety, and biocompatibility. This will certainly open new fronts for research and development in the area. The review’s contents can help researchers and professionals involved in waste management and in the development and production of PCMs.



