High-Efficiency Photo-Thermo-Electric System with Waste Heat Utilization and Energy Storage.

In a photo-thermo-electric system, solar energy is first converted into heat and then into electrical energy, which has attracted much attention. However, the heat of the cold side of a thermoelectric generator (TEG) is generally removed by an air-cooling or water-cooling technology without being fully utilized, resulting in a low solar energy utilization efficiency. Here, we designed an integrated system composed of a photo-thermo-electric conversion part and a waste energy collection part. In this system, one carbon foam (CF) doped with PPy and PEG is used as a layer for photothermal conversion and energy storage, and the other CF─where one side was hydrophobically modified─is used for the storage of cooling water and the recovery of waste heat. The two CF layers contact the hot and cold sides of TEG, respectively. With the system, solar energy can be converted into heat and then electricity for TEG. On the other hand, waste heat can be utilized for seawater desalination by the process of water evaporation. In addition, the integrated system can work sustainably under intermittent light conditions. With the recovery of waste heat, the solar energy utilization efficiency in this system is greatly increased to as much as 86%.