This review delves into the application of bio-based phase change materials (PCMs) within geopolymer matrices, with a specific focus on their environmental advantages. Geopolymers, renowned for their eco-friendly characteristics as substitutes for conventional cement-based materials, have attracted considerable attention. The review covers topics such as geopolymer technology, bio-based PCMs, recent advancements, emerging trends, and the existing challenges in upscaling, durability, and standardization when integrating bio-based PCMs into geopolymer matrices. In conclusion, this review represents a valuable resource for individuals dedicated to promoting environmental sustainability in the realms of construction and materials. Bio-based geopolymer composites incorporating PCMs are poised to play a pivotal role in the pursuit of more environmentally friendly and energy-efficient building materials.
Top1. Introduction
The continuous release of carbon dioxide (CO2) and the high energy demands associated with the production of Ordinary Portland Cement (OPC) are contributing to ongoing ozone layer depletion and global warming. However, the adoption of geopolymer concrete (GPC) technology in the construction sector is promoting sustainable development and a cleaner environment by reducing environmental pollution (Alhassan et al., 2023; Kanagaraj et al., 2023). Geopolymers are advanced materials known for their eco-friendly properties and versatile applications. They are inorganic, amorphous, three-dimensional aluminosilicate networks formed through a process called geopolymerization. This process involves dissolving silicon (Si) and aluminium (Al) atoms from source materials and reorganizing precursor elements, resulting in a newly synthesized solid structure (Alhassan et al., 2023; Imtiaz et al., 2020; Kanagaraj et al., 2023; Mehrizi et al., 2023). Common aluminosilicate source materials for geopolymers include clays and clay minerals, such as kaolin, kaolinite, metakaolinite, calcined clay, and zeolite. In the context of sustainability as a substitute for Ordinary Portland Cement (OPC) composites, Geopolymer Concrete (GPC) has demonstrated remarkable strength and durability (Amran et al., 2021; L. Assi et al., 2018; L. N. Assi et al., 2020; Festus et al., 2022; G. Xu & Shi, 2018; Yu et al., 2014).
Energy and its economic implications are crucial for a nation's economic well-being. Achieving self-sufficiency in energy supply and demand can undoubtedly boost a country's economy. Among the sectors with significant energy consumption, buildings rank third, following the transport and industrial sectors (Alva et al., 2018). Buildings allocate a considerable portion of their energy use to HVAC (Heating, Ventilation, and Air Conditioning) systems, primarily for ensuring occupant and equipment comfort. The utilization of energy storage systems provides an effective way to bridge the gap between energy supply and demand (Abdallah et al., 2016; Ahmed, 2014).
One such energy storage system is Latent Heat Thermal Energy Storage (LHTES) employing Phase Change Materials (PCMs). These systems are widely used in various domains, including solar thermal power plants, nuclear power facilities, and building thermal management, thanks to their isothermal properties, substantial thermal energy storage (TES) capacity, and phase change occurring within a narrow temperature range. Unlike power generation facilities, buildings using Phase Change Materials (PCMs) can store surplus solar energy during the day, reducing heat ingress into the building, and releasing it at night when temperatures drop below the PCM's melting point, making PCMs promising for thermal management in buildings (Arivazhagan et al., 2020; Sharshir et al., 2023).
Phase Change Materials (PCMs) are substances that can absorb and release substantial amounts of energy during phase transitions, depending on their specific temperature range and threshold values. To fully harness PCM capabilities, certain criteria related to thermal, physical, chemical, and kinetic attributes must be met, alongside economic feasibility and material availability. Essential chemical requirements for PCMs include non-toxicity, non-flammability, and low risk of explosion (Navarro et al., 2019; A. Sharma et al., 2009).