High-temperature solar-thermal steam generation: materials, system design and application

Abstract

Solar steam technology offers an attractive way to harness abundant renewable solar energy for a broad range of applications. Compared with low-temperature vapor, high-temperature steam exceeding 100 °C has much higher energy output, stronger physical and chemical effects, and more efficient power conversion. The generation of high-temperature solar steam, however, has raised more stringent requirements on multi-level system design, and thermophysical properties of key materials. In this work, we summarize research progress in high-temperature solar steam generation through both mature concentrated solar power technology, and emerged interfacial and volumetric evaporation approaches. We introduce the working principles of these systems, emphasizing their unique optical, thermal and structural design to achieve optimum performances. We systematically analyze the key materials and components that are involved in the steam generation systems, including solar concentration scheme, solar reflectors, photothermal converters, heat transfer fluids, and micro-/macrostructural design of evaporators. By overviewing representative applications including electricity generation, sterilization, production of green chemical fuels, desalination, cleaning, underground oil extraction and food processing, we highlight the necessity in integrating the complementary advantages from these steam generation technologies to overcome their respective bottlenecks. Finally, we envision the future prospect and required research needs in gaining in-depth understanding of the high-temperature solar steam generation processes at both the system level and the material-water molecular interaction level, developing thermal functional materials, optimizing system design, and exploring more diverse applications.