Engineering of thermal energy storage: An experimental study of organic/silver and organic/silver-coconut shell biochar composite phase change materials

• Ecofriendly carbon-based nanoparticle is synthesized from coconut shell. • Composite PCM’s optical absorbance spike by 105 % and transmissibility fall by 76.68 % • Composite PCM showed higher thermal conductivity and melting enthalpy. • Composite PCM exhibits high reliability after repeated heating and cooling cycles. • Generated higher voltage in TEG using A49-Ag-CSB0.1 composite PCM. The focus on producing and using renewable materials has become increasingly important in the quest for carbon neutrality and lower carbon emissions, playing a crucial role in fostering sustainable society. Although Phase Change Materials (PCMs) are considered a promising approach for energy storage, they often encounter issues with thermal conductivity, thermal stability, and optical attributes, highlighting the need for solid supporting structures. To address this issue, various concentrations of binary silver (Ag) and coconut shell biochar (CSB) particles enhanced A46 PCM composite synthesized by two step method and characterized the thermophysical properties. Resulting the binary nanocomposite demonstrated a remarkable 102.15 % increase in thermal conductivity, rising from 0.23 W/(m·K) to 0.465 W/(m·K). There was an increase in energy storage potential from 158.6 J/g to 167.8 J/g, and the optical absorbance of the binary nanocomposite showed an enhancement of 2.05 times compared to the base PCM. The composites exhibited minimal changes in their thermophysical properties after 500 thermal cycles, confirming the durability of the developed binary nanoparticle-enhanced phase change materials. Moreover, the hybrid nanocomposite incorporated in the thermoelectric generator achieved a voltage increment of 7.98 % compared to the base PCM. These results indicate that the synthesized nanocomposite holds a great potential as a thermal energy storage material, particularly for applications within the 44–48 °C temperature range.