Pathways and challenges for efficient solar-thermal desalination

Abstract

Solar-thermal desalination (STD) is a potentially low-cost, sustainable approach for providing high-quality fresh water in the absence of water and energy infrastructures. Despite recent efforts to advance STD by improving heat-absorbing materials and system designs, the best strategies for maximizing STD performance remain uncertain. To address this problem, we identify three major steps in distillation-based STD: (i) light-to-heat energy conversion, (ii) thermal vapor generation, and (iii) conversion of vapor to water via condensation. Using specific water productivity as a quantitative metric for energy efficiency, we show that efficient recovery of the latent heat of condensation is critical for STD performance enhancement, because solar vapor generation has already been pushed toward its performance limit. We also demonstrate that STD cannot compete with photovoltaic reverse osmosis desalination in energy efficiency. We conclude by emphasizing the importance of factors other than energy efficiency, including cost, ease of maintenance, and applicability to hypersaline waters.

Bioinspired Temperature Regulation in Interfacial Evaporation

“…Such design also separated the bulk water from the water inside the interfacial film to ensure the interfacial evaporation process . 5,36,37…”

The relative insignificance of advanced materials in enhancing the energy efficiency of desalination technologies

“…The optimization of solar thermal desalination (STD) systems and the application of solar-based heating for membrane distillation (MD) have become prominent areas of investigation. [7][8][9] In contrast to thermal-driven processes, electro-driven technologies are most practical in the desalination of brackish and low-salinity waters, with the advantage of circumventing the use of high pressures or temperatures. Capacitive deionization (CDI), founded on the principle of storing salt ions in electrodes, has experienced a surge in research efforts, becoming the most investigated electro-driven desalination technology over recent years.…”

Structure Architecting for Salt‐Rejecting Solar Interfacial Desalination to Achieve High‐Performance Evaporation With In Situ Energy Generation

“…In a recent report led by Lin and co‐workers, more insights on the specific water productivity of solar thermal systems was provided. [ 7 ] Their analysis has disclosed that PV–driven reverse osmosis can yield substantially more water per solar radiation area compared to the current solar‐driven desalination, and it also suggests that water productivity of solar desalination system could be effectively enhanced by maximizing latent heat recovery. As we already mentioned above, this approach has indeed exhibited great competence to enhance steam generation.…”

“…The need for low‐cost methods to produce clean water from seawater with minimum infrastructure and energy requirement has given rise to research thrusts being focused on the development of solar‐driven evaporation based desalination technologies. [ 4–7 ]…”