Response of stacked microbial fuel cells with serpentine flow fields to variable operating conditions

The stacked microbial fuel cell (MFC) is a potential pathway for future applications, and its response to variable operating conditions is important for practical operation. In this study, a stacked MFC with serpentine flow field was constructed to investigate the stack performance and response to cell number, connection type, variable loads and electrolyte flow rates. The results showed that the highest maximal power (22.2 mW) was observed in a series connection, which was 12.1% and 29.1% higher than the maximal power in the parallel and hybrid connection, respectively. With the increasing number of cells, a gradually decreasing increase in the voltage output was found in the parallel stack and series stack at a high load, while the series stack showed first an increase and later a decrease in the voltage output at low load. Voltage reversal was observed when switching to a series connection or decreasing the load, resulting in a decreased stack voltage. The performance of the stack could be improved to an extent by increasing the electrolyte flow rates.