The extractable power from the difference of salinity of river and seawater that could be obtained in many different countries around the world is summarized in Figure 2c (data from ref 10).If the energy from mixing entropy was harnessed from all these rivers, the power obtained could reach up to 2 TW, which is ∼13% of the current total global energy requirement.11 This energy can also be easily harvested at low temperatures, and is completely renewable, since the ultimate source is the solar energy which powers the water cycle.