Solar heat localization: concept and emerging applications

Recently, the solar heat localization concept has provided an appealing route for efficient utilization of solar thermal energy. This concept has shown remarkable promise in power generation, desalination, distillation, water splitting, sterilization, oil spill cleanup, electricity generation from salinity and also CO2 capture. In this concept, a material paradigm localizes the solar irradiation forming a hot spot in the material and minimizes the energy losses to the surrounding environment. In most applications, the localized thermal energy is used for liquid-vapor phase change in which the material wicks the liquid into the hot spot to generate hot steam. In contrast to conventional steam generation systems, thermal losses are reduced significantly, thereby offering high evaporation efficiencies. In this comprehensive review, the physics of solar heat localization is elaborated and a roadmap on necessary material properties is provided to achieve superior performance through this concept. The current advancements in the synthesis of new materials for solar heat localization are discussed in detail. Various applications of this concept are explored individually and the figures of merit for each application are elucidated. A comparative analysis is conducted for these figures of merit on a wide range of studies and key takeaways are highlighted. Finally, the current challenges and future prospects for technological implementation of this concept are reviewed. As solar energy is the most abundant renewable energy resource on earth, this concept could provide a path to significantly reduce the carbon footprint of electricity and water generation in the world.