Global site selection for hybrid solar thermal desalination: advancing the energy-water nexus with open-source tools

Solar desalination leverages renewable energy to advance SDG 6 (Clean Water and Sanitation) and SDG 7 (Affordable and Clean Energy), addressing energy consumption and water scarcity challenges. However, collocating large-scale concentrated solar power (CSP) with multi-effect distillation (MED) necessitates balancing resource demands such as climate, market dynamics, land topography, water availability, infrastructure, land use, and increased frequency of disaster risk due to global warming. This work develops an open-source multi-dimensional tool that integrates Geographic Information Systems (GIS) data, the System Advisor Model (SAM), an in-house techno-economic model, and multi-criteria decision-making (MCDM) to assess site feasibility at resolutions from 0.5 to 50 km. Simulations under current climate conditions identified 61 countries with suitable locations for CSP-MED plants, with 67.3% of the sites located in Australia, the United States, Mexico, South Africa, Egypt, Spain, and Namibia, where typical payback periods are 15–21 years. Optimal sites are characterised by direct normal irradiance (DNI) greater than 5 kWh/m²/day, moderate elevation, and limited distance to seawater, thereby avoiding high-altitude and far-inland locations. Dynamic simulations under different carbon emissions scenarios (low, medium, and high) for 2030 and 2050 demonstrate that climate change will only minimally impact the feasibility of CSP-MED processes, with payback periods increasing by a maximum of 6 months under high carbon emission scenarios. Overall, it is expected that the developed tool can be used to assist with national and state/provincial-level strategic planning for deploying large-scale solar-desalination projects.