Anisotropic hemp-stem-derived biochar supported phase change materials with efficient solar-thermal energy conversion and storage

Abstract As cheap and renewable sources, the exploitation of biomass resources was great value in phase change energy storage. In this study, hemp stems were converted into biochars with three-dimensional multi-level anisotropic pores through a temperature-controlled charring process, which used as supports for polyethylene glycol (PEG6000) to form shape-stable composite materials (ss-CPCMs). It is shown that ss-CPCMs using hemp-stem-derived biochar obtained at carbonization temperature 900 °C support has high PEG6000 loading rate (88.62wt%), large latent heat (170.44 J/g) favorable thermal stability owning its surface area hierarchical pores. The biochar-based ss-CPCM also good light absorption ability maximum solar-thermal conversion efficiency 97.70%. addition, different conductivities transverse longitudinal directions reflect unique structure. This work can not only improve high-value utilization biochars, but provide excellent performance storage systems. Graphical