Renewable Energy, 5th Edition

Figure 4.109 Schematic picture of dialytic battery.

Inserting the numerical values given in section 3.7.2, and T=300 K, the cell electromotive force becomes ϕ≈0.05 V. The actual value of the external potential, Δϕ_ext, may be reduced as a result of various losses, as described in section 4.5.1 (e.g., Fig. 4.105). ϕ is also altered if the “fresh” water has a finite amount of ions or if ions other than Na⁺ and Cl⁻ are present.

If the load resistance is R_ext, the power delivered by the cell is given by the current I=Δϕ_ext R_ext⁻¹,

$E=I\mathrm{\Delta }{\varphi }_{ext},$

and, ...