Coffee and turmeric bio-based shape-stabilized composite PCMs for thermal and solar energy storage applications

Bio-based shape-stabilized composite phase change materials (ss-PCMs) are emerging as sustainable solutions for thermal and solar energy harvesting. However, typical shape-stability issues, poor thermal/optical properties, and complex synthesis methods hinder the use of such materials at large scale. This study reports the design of nanofiller-loaded bio-based composite PCMs with enhanced thermo-optical and mechanical properties (shape-stability). Incorporating a 25 wt% biomass-derived porous matrix (coffee/turmeric powder) significantly enhanced the material's structural integrity by effectively controlling PCM leakage while achieving a high latent thermal energy storage (TES) capacity of ~130 J/g. Graphene-loaded ss-composite PCMs demonstrated a significant photothermal conversion efficiency enhancement (106 %) and effective thermal management (TM) potential (superheat degree reduced by ~10 deg C) compared to pristine PCM, due to the improved photo-thermal properties and power density. Thermal cycling (up to 500 cycles) and load-bearing capacity tests (~212,566 and ~31,242 N/m2 across the phase transition zone) confirm the high reliability of the proposed novel ss-composite PCMs in terms of thermal and shape stability. These results highlight their strong potential for long-term TES applications, with stable performance even under adverse environmental conditions such as humidity and wetting. This research contributes to the design of bio-compatible (possibly edible) substance-based strategies for creating cost-effective composite PCMs with enhanced thermo-optical and shape stability characteristics, offering significant advancement for latent TES systems and TM technologies.