Solar-Driven Multi-Effect Distillation: A Technical, Economic, and an Environmental Study

Freshwater scarcity is a critical issue in Qatar. Current groundwater reserves are limited and the country relies on seawater desalination for 99% of its municipal water consumption. Although seawater desalination is the only viable solution, this technology is very energy intensive and significantly impacts the environment and the economy. Using solar energy to power thermal desalination opens numerous possibilities and challenges that this research addresses. Therefore, this research proposes an optimized solar-driven desalination process using low-pressure multi-effect distillation powered with solar thermal energy. The objective of this work is to simulate the performance of a solar-driven desalination plant under Qatar’s climate, optimize the overall process and plant configuration, investigate the potential environmental impacts of the plant using life cycle assessment, and investigate the economic feasibility and market commercialization barriers. A steady-state computer model was developed using the Engineering Equation Solver software and was validated using real data. Simulations of the plant performance showed that 1 m² of the solar linear Fresnel collector (with a concentration ratio of 78) produces 8.6 m³ of freshwater per year under Qatar’s climate. The equivalent mechanical energy of the optimized process was 8 kWh/m³ which is 59% lower than multi-effect distillation plants with thermal vapor compression. The optimized configuration also resulted in reducing the solar field size by 25%. The environmental assessment indicated that the operation phase of the plant accounts for 80% of the climate change impact. Solar-driven desalination reduces the climate change impact by 10 kg of CO₂ per m³ of freshwater as compared to desalination powered by combined-cycle natural gas power plants. The economic study revealed that the levelized cost of water for solar-driven thermal desalination is in the range $2.89-4.31 per m³. The research also provides several policy recommendations on solar-driven desalination.