Anisotropic reed-stem-derived hierarchical porous biochars supported paraffin wax for efficient solar-thermal energy conversion and storage

Abstract

It is valuable to develop and utilize cheap and widely available biowaste for phase change energy storage with high value applications. In this work, by removing lignin and hydrolyzing cellulose with cellulase enzymes, the macropore channels of reed stems were made to be connected via rich micropores on the carbon wall during high-temperature carbonization process. By loading paraffin wax by vacuum impregnation, shape-stable composite phase change materials (CPCMs) with a three-dimensional multi-level pore structure were obtained. The CPCMs have high loading rate (93.45 wt%), high energy storage capacity (141.47 J/g) and good heat transfer performance. The anisotropic reed-stem-derived hierarchical porous biochars supported CPCMs has good solar absorption ability, and as high as 92.28 % solar-thermal conversion efficiency. The good thermal stability as well as cyclic thermal stability are beneficial for practical applications. In addition, this work can achieve the purpose of energy saving and carbon emission reduction via increasing the value utilization of biowaste.