Abstract: Polyethylene glycol (PEG) is an excellent phase change material with high phase change enthalpy, biodegradability, non toxicity and corrosion resistance. However, the easy leakage and poor thermal conductivity hinder its large-scale application. Therefore, with wheat flour as the matrix, a biomass carbon foam composite SCF-X-Y reinforced by sepiolite, where X represents the amount of sepiolite added and Y represents the carbonization temperature) was prepared as the efficient carrier of PEG phase change material by using microbial foaming and high temperature carbonization technology. The experimental results show that the compressive strength of SCF-10-800 can reach 5.42 MPa. The thermal conductivity of SCF-5-1000@PEG reaches 0.39 W/(m·K), and its melting enthalpy and solidification enthalpy are 123.4 J·g⁻¹ and 106.6 J·g⁻¹, respectively. Meanwhile, it has excellent leakage resistance. Using SCF-5-1000@PEG as an optical absorption source, a light driven thermoelectric conversion system was assembled, which showed a light to heat conversion efficiency of 63.2% and could achieve a stable current output for more than 400 s, demonstrating its application potential in the light-thermal-electric energy conversion system.