Direct solar steam generation system for clean water production

The social development, economic growth and booming population have caused aggravated water pollution, making clean water shortage an urgent issue to be solved. In recent decades, researchers have aroused upsurge studies of direct solar steam generation (DSSG) system for the production of clean water, in which solar thermal conversion materials (STCM) can strongly transform absorbed solar light into thermal energy, tremendously speeding the evaporation of water under sunlight irradiation. DSSG system has been considered an efficient, sustainable, low-cost and environment-friendly way to solve water shortage crisis of practical importance. In this review, we will provide a comprehensive summary of the recent development of DSSG system for clean water production. The introduction about categories of DSSG, principle of solar thermal conversion on STCM and efficiency calculation in DSSG system will first demonstrate the fast water evaporation mechanism. Then strategies for high performance water evaporation in DSSG are detailed including sunlight absorption regulation on STCM for efficient light utilization, system optimization of DSSC for minimizing the heat loss, water transport adjustment for adequate water supply and so on. Benefiting from the basic understanding and effective strategies of DSSG system, the quality of produced clean water, pollutants disposal in remaining water body and various designs of solar stills for high clean water productivity are further presented. Finally, we outline the current challenges and crucial issues of recent DSSG system, aiming to provide guidances and pointers to speed the development of DSSG in clean water production for practical applications.