Development of a module of stacks of air-breathing microbial fuel cells to light-up a strip of LEDs

This work focuses on scaling-up of the microbial fuel cells technology according to the principle of miniaturization and multiplication. Seven stacks of 16 mini-MFCs (electrodic area of 0.866 cm2) were built up leading to a big module of 112 MFCs. The electrical connection among the MFCs in the stacks and among the stacks into the modules was optimized in order to implement this technology. Results show that 1 MFC generates 1.22 mW while the optimization of the electric connection in order to achieve the maximum power results in 6.62 mW compared to the theoretical 182 mW, indicating the existence of large energy losses in the system. However, to light a LED there is not a threshold power but there are input voltage (2.6 V) and input current (0.020 mA) requirements. For this reason, another optimization of the electrical configuration was carried out to satisfy the threshold values of voltage and current and a strip of 220 LEDs was illuminated for several days. Furthermore, robustness of the MFC technology was confirmed after operating simultaneously 112 MFCs with reproducible performance for 30 days