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

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 for multi-level system design and the thermophysical properties of key materials. In this work, we summarize the research progress in high-temperature solar steam generation through both mature concentrated solar power technology and the emerging interfacial and volumetric evaporation approaches. We introduce the working principles of these systems, emphasizing their unique optical, thermal and structural designs to achieve optimum performances. We systematically analyze the key materials and components that are involved in the steam generation systems, including the solar concentration scheme, solar reflectors, photothermal converters, heat transfer fluids, and micro-/macrostructural design of evaporators. By giving an overview of representative applications, including electricity generation, sterilization, production of green chemical fuels, desalination, industrial degreasing, underground oil extraction and food processing, we highlight the necessity of integrating the complementary advantages from these steam generation technologies to overcome their respective bottlenecks. Finally, we envision the future prospects and required research needs to gain an in-depth understanding of the high-temperature solar steam generation processes at both the system level and the material-water molecular interaction level to develop thermal functional materials, optimize system design, and explore more diverse applications.