Plant–microbial fuel cell for electrical generation through living plants: an internal resistance insight into the plant species used

Abstract

Abstract Climate change is a global threat, the presence of which has encouraged the development and implementation of renewable energies, including plant–microbial fuel cells, which could generate 6 629 568–33 147 840 MWh per year due to their large-scale applicability. One of the main challenges associated with microbial cells is internal resistance—a parameter whose magnitude is influenced by several factors. In the case of plant–microbial fuel cells, adding a plant positively affects the mitigation of internal resistance. However, the species employed is expected to play an important role. In the present study, the objective was to determine as a general reference the internal resistance of cells using various plant species, among which were tomato (Solanum lycopersicum), black beans (Phaseolus vulgaris), aloe vera (Aloe vera), corn (Zea mays), and moss (Dicranidae). For this purpose, an experimental procedure was carried out to compare the manual voltage measurements with a free cell concerning the voltage obtained by adding an external resistor in series. The internal resistance values were determined as a function of the measured voltage, obtaining 177, 179, 175, 324, and 233 kΩ for aloe vera, corn, tomato, black beans, and moss, respectively. From this, it was shown that the roots of the plants represent an essential addition to the internal resistance of the cell in the short term. In contrast, plants with a C4 photosynthetic metabolism are more favourable, while C3 plants can also benefit from internal resistance during a more extended period of rhizodeposition.