In order to calculate the maximum extractable energy per unit volume of river water, which is the limiting reagent in this process, the Gibbs free energy of mixing is plotted with respect
to the volume of river water consumed in Figure 2b. The energy needed to mechanically exchange river water and seawater in the device is assumed to be negligible compared to the total energy
produced. For an excess of seawater reagent, the maximum energy extractable is ΔG ≈ 2.5 kJ dm3 of river water (obtained for χ ≈ 1). This means that a power plant processing 40 m3 s1 of river water could produce up to 100 MW.