Sustainable water and energy for water-stressed coastal cities under future climate scenarios

The cost of water and power derived from solar thermal processes in 23 water stressed coastal cities with existing desalination infrastructure will either decline or increase depending on projected changes in annual irradiance (climate variables?) under both moderate SSP245 and high SSP585 emission scenarios through to 2099. This study uses CMIP6 projections to assess future changes in solar radiation, temperature, wind speed, seawater temperature, and salinity, combines multi-criteria geospatial screening to identify suitable coastal sites, and applies techno-economic modelling with SAM and a numerical MED framework to estimate energy and water outputs and levelized costs. The results indicate that cities such as Beirut, Biobío, and Valparaíso show significant improvements in future feasibility, with projected increases in DNI of up to 9.9%, resulting in LCOE reductions of over 1.2 USD¢/kWh. In contrast, cities like Aden and Dubai face declines in DNI of up to 4.2%, with corresponding ~6% increases in LCOE, highlighting the investment risk under high-emission scenarios. In all climate scenarios/locations, CSP-MED was demonstrated as a sustainable source of electricity and water high carbon reduction potential. For example, in Jeddah under the SSP245 near-future scenario, deploying a CSP-MED system with an annual desalination capacity of 3.28×106 m3 results in only 1.72 tonnes of CO2 emissions per year, compared to 6,630 tonnes and 20,800 tonnes annually for conventional Reverse Osmosis (RO) and MED systems, respectively. Overall, it is critical to consider the effect of future climates on the feasibility of CSP-MED to unlock solar electricity and freshwater for densely populated coastal cities.