Biobased phase change materials from a perspective of recycling, resources conservation and green buildings

Abstract

Implementation of thermal energy storage (TES) systems in buildings heavily relies on orthodox phase change materials (PCMs) which are derived from precious and non-renewable resources. Meanwhile, to promote recycling, pure green buildings campaign and natural resources conservation, biobased PCMs (bPCMs) are preferable over orthodox PCMs. The major characteristics of bPCMs that make them a preferred choice for TES applications include but are not limited to renewability, non-toxicity, minimal supercooling, high latent heat, thermal stability over a wider temperature range, reasonable melting/freezing temperatures, self-nucleating response, and limited flammability. Despite these advantages, there are different challenges attached to bPCMs that hinder their application on large scale i.e., biodegradability, odor generation, leakage, and demand-supply issues. However, most of these limitations are analogous to that of conventional PCMs, and promising research data is available on their solution. Further, the conventional source of bPCMs includes biobased oils and fats, most of which are of edible nature; thus, their widespread use could conflict with food security and undermine the major advantages of bPCMs. This issue can be resolved by minimizing the reliance of bPCM on conventional sources and looking for viable alternatives i.e., waste edible oils, animal fats, and genetically modified oils. Albeit strong evidence can be found in the literature about the viability of these alternatives, they are open to research. Further, life cycle assessment of different bPCMs also advocates their environment-friendliness and cost-effectiveness over conventional PCMs. Moreover, substantial technological advancements have been made referring to the incorporation of bPCMs in building envelops and TES applications; however, more studies are required on recyclable encapsulation and support materials. This paper provides a state-of-the-art review of research status and useful perspective in the paradigms of recycling, green building applications, and natural resources conservation corresponding to the bPCMs.