Dynamic electrical reconfiguration for improved capacitor charging in microbial fuel cell stacks

•4 electrical configurations were examined using a stack of 8 MFCs.•A novel switch box enabled rapid switching between electrical configurations.•Each fixed configuration only performed optimally within a specific voltage range.•By dynamically switching configurations, capacitor charge speed increased 2-fold.•Rate of charging improvement by 99%.

A microbial fuel cell (MFC) is a bioelectrochemical device that uses anaerobic bacteria to convert chemical energy locked in biomass into small amounts of electricity. One viable way of increasing energy extraction is by stacking multiple MFC units and exploiting the available electrical configurations for increasing the current or stepping up the voltage. The present study illustrates how a real-time electrical reconfiguration of MFCs in a stack, halves the time required to charge a capacitor (load) and achieves 35% higher current generation compared to a fixed electrical configuration. This is accomplished by progressively switching in-parallel elements to in-series units in the stack, thus maintaining an optimum potential difference between the stack and the capacitor, which in turn allows for a higher energy transfer.