Global warming enhances salinity gradient energy potential through hydroclimatic change

Global energy demand continues to rise, increasing the need for reliable renewable energy resources. Salinity gradient energy, generated by freshwater–seawater mixing, is an emerging renewable energy resource that remains insufficiently understood in estuarine and coastal regions. As this resource depends on climate-sensitive river discharge, water temperature, and salinity contrasts, its future evolution remains uncertain. Here, using state-of-the-art climate simulations, we quantify the projected changes in the global theoretical salinity gradient energy resource under global warming. The simulations consistently show an overall increase in this theoretical resource, with large regional heterogeneity. Enhanced river discharge associated with increased precipitation minus evapotranspiration is the dominant contributor, while higher mixed-water temperature further increases the resource and altered ocean–river salinity contrasts partly offset these effects. These results indicate that global warming may expand the global theoretical resource base of salinity gradient energy, providing a basis for assessing its potential contribution to future renewable energy portfolios. Global theoretical salinity gradient energy is projected to increase overall under greenhouse warming, with rising river discharge as the primary driver and warmer mixed-water temperatures providing additional enhancement, according to state-of-the-art climate simulations.