Technical and environmental perspectives on solar-driven seawater desalination: A case study of multi-effect distillation

There is growing interest in enhancing the energy sustainability of seawater desalination processes given the increasing reliance on this technology in water-stressed regions. In this paper, we present the design and modelling of an energy-efficient thermal desalination plant (using low-pressure multi-effect distillation) powered by a solar linear Fresnel collector. A steady-state computer model was developed in engineering equation solver (EES) using energy, mass, and salt balance equations. The EES model was used to evaluate the annual performance of the plant and to calculate its equivalent mechanical energy consumption. We also assessed environmental impacts using the life-cycle assessment (LCA) methodology. The equivalent mechanical energy of the optimized desalination plant was 8 kWh/m3, which is 59% lower than that of conventional thermal desalination plants. This significant reduction in equivalent energy consumption reduces the required solar field size by 25%. The environmental assessment showed that the operation phase accounted for approximately 80% of the plant’s climate change impact. Our integrated solar desalination plant can potentially reduce CO2 emissions by 10 kg per 1 m3 of freshwater produced, and can reduce human toxicity impacts three fold. Chemical usage in the desalination process has a significant impact on ozone depletion based on the consumption of antifoaming agents that contain many ozone-depleting substances.