Abstract
Seawater desalination is an important process to alleviate the freshwater crisis. However, traditional desalination techniques are typically energy-intensive and significantly contribute to the worldwide release of carbon dioxide. Additionally, desalination using fluctuating renewable energy, such as wind and solar power, heavily relies on external weather. In this context, harnessing ocean thermal gradient for desalination emerges as a promising alternative for achieving sustainable desalination. Because it is a natural thermal energy source with a continuous and stable supply, and is widely available in tropical regions where freshwater shortages are most pressing. Nowadays, ocean thermal desalination has been proven technically feasible, however traditional configurations face obstacles such as high-power consumption and low-performance ratio as narrow temperature differences. Therefore, this review comprehensively discusses optimization approaches for ocean thermal desalination in terms of structural enhancement and multi-energy complementarity to identify the direction of future development of the technology. The present state, impediments, and future outlook pertaining to ocean thermal desalination are also presented. Finally, the performance and cost-effectiveness of reviewed ocean thermal desalination processes are examined and compared with other desalination processes. This review highlights the potential of desalination using ocean thermal gradient and emphasizes that optimization strategies from multiple perspectives can significantly enhance system performance and enable sustainable desalination.