Effects of anode materials in electricity generation of microalgal-biophotovoltaic system – part II: Free-floating microalgae in aeration mode

A biophotovoltaic (BPV) system is a developing renewable energy technology that promises carbon-free electricity generation from solar energy, by utilizing photosynthetic exoelectrogenic microorganisms. The electrical power production of BPV devices, on the other hand, is relatively low, and this has become a significant challenge for this new technology. Sufficient supply would require large-scale BPV farms for megawatt applications, which may not be economically viable. A possible solution is to acquire bioelectricity from algae cultivation medium, as it benefits the system in terms of volume. Moreover, it enables combination with an algae pool or floating photobioreactor. One technical concern is that previous studies focused on the absorption of electrons from cultivated biofilm, whereas bioelectricity generation by aerated algae cultivation medium under different anode materials still has research value. Hence, cell performance by well-mixed anodic algae cultivation medium under different anode materials is a crucial decision-making factor of BPV device in aeration mode. In this study, the experiments were repeated three times to compare the performances of various anode-based devices. In the experiments, indium tin oxide (ITO)-coated glass-based BPV device produced a steady power output, comparable to those of graphite- and ITO-coated plastic-based BPV devices. Maximum power densities of 0.659 mW/m², 0.437 mW/m², and 0.059 mW/m², respectively, were obtained in each repeated condition. The findings are expected to contribute to further understanding on the correlation of these parameters, with regards to power generation of the BPV devices.