Comparative Estimation of Bioelectrical Performance in Plant Microbial Fuel Cells using Aquatic and Semi-Aquatic Species under Controlled and Solar Environments

Abstract

Plant Microbial Fuel Cells (PMFCs) offers a sustainable approach for bioelectricity generation by exploiting interactions between plant roots, exudates, and electrochemically active microorganisms. However, system performance relies heavily on plant species selection and ambient light dynamics. This study evaluated the bioelectricity output of three aquatic and semi-aquatic species, which are water lettuce (Pistia stratiotes), caladium (Caladium bicolour), and hydrilla (Hydrilla verticillata), in dual-column PMFC systems. The experiment consisted of two sequential 10-day phases (20 days in total). Phase 1 was under controlled laboratory conditions, and phase 2 was under natural direct sunlight exposure. Aluminium rods and graphite rods were supplied as the anode and cathode, separated by a poly(vinylidene fluoride)-co-poly(vinylimidazole) (PVDF-co-PVIm) ion exchange membrane. Electrical parameters were measured across a fixed external load resistor. In laboratory settings, power density increased linearly over time. Water lettuce achieved the highest output (105 mW), followed by caladium (75 mW) and hydrilla (56 mW). Sunlight exposure in phase 2 significantly enhanced output, yielding peak power outputs of 308 mW (water lettuce), 300 mW (caladium), and 228 mW (hydrilla). Highly branched root systems provided superior surface area for microbial colonisation and exudate transport. These findings highlight species selection and ambient solar radiation as crucial factors for optimising PMFC performance.