On the maximum electrical power efficiency of a hydroelectric nanobubble-driven cell

In recent decades, nanobubble technology has emerged as a disruptive approach with potential applications across a wide range of scientific and industrial fields. Although several theories have been proposed to explain the extraordinary longevity of nanobubbles-a behavior not predicted by classical models-this phenomenon remains the subject of active debate. Nevertheless, there is broad consensus that nanobubble stability primarily arises from strong surface electric charge associated with interfacial phenomena, leading to localized water dissociation in the vicinity of the nanobubble. The water dissociation driven by nanobubbles has prompted speculation regarding the possibility of power generation through a hydroelectric cell, potentially enabling an alternative long-term, large-scale energy storage pathway that has not yet been explored. However, despite its conceptual appeal, any quantitative estimation of the efficiency of such a system, if feasible at all, has not been established. Here, utilizing the linearized Poisson-Boltzmann (Debye-Hückel) approximation and first-order perturbations in the nanobubble surface potential, an analytical expression for the maximum efficiency of a hydroelectric nanobubble-driven cell is derived. It is shown that a maximum efficiency of  ≃ 12% can be achieved at best, with predicted current densities remaining within the same order of magnitude as those reported for conventional hydroelectric-cell systems based on nanoporous ferrites. The resulting efficiencies are sufficiently non-negligible to warrant further theoretical and experimental investigation.