Towards sustainable water resources: A critical review of evaluating traditional and solar-based desalination technologies and innovations

Scarcity of water is a universal problem affecting more than 2 billion individuals, with about 785 million having no access to basic drinking water. Spurred by the population growth, urbanization, and global climate change, meeting this challenge coheres with the UN's Sustainable Development Goal 6 to make water available by 2030. Desalination, which transforms saline water that constitutes approximately 97 % of the global resources of water into fresh water, is progressively critical, particularly in dry and coastal areas. Of the various desalination processes, Reverse Osmosis (RO) stands out due to its energy requirement of 3–10 kWh/m³ and quality of fresh water. Thermal technologies like Multi-Stage Flashing (MSF) and Multi-Effect Distillation (MED) are also utilized but are usually more energy-intensive. The integration of renewable energy sources, including solar, has improved sustainability, with hybrid solar desalination systems minimizing the energy intake by up to 30 %. Recent progress in solar still technologies, such as ceramic magnets and black powder-coated crushed granite for heat storage, has increased productivity by 28 %, attained energy efficiencies of 30.5 %, and reduced payback periods to less than four months. This article overviews solar desalination processes solar thermal, photovoltaic-driven RO (PV-RO), and CSP hybrid systems focusing on technological developments like nanomaterial and advanced membranes. Comparative evaluation of these technologies against traditional technologies weighs technical viability, cost-effectiveness, scalability, and environmental considerations. Case studies from water-scarce locations inform practical experience and issues. The article concludes by reviewing future opportunities, emphasizing innovative technologies and facilitating policy regimes to ensure sustainable, energy-efficient desalination solutions worldwide.