Conversion of simulated biogas to electricity: Sequential operation of methanotrophic reactor effluents in microbial fuel cell

Abstract The utilization of the greenhouse gases (methane (CH4) and carbon dioxide (CO2)) seems a suitable alternative feed to produce biofuels and value-added products to reduce their emissions. In addition, the conversion of methanol containing methanotrophic effluents to electricity using microbial fuel cells (MFCs) is limited. The sequential operation of MFC to generate electricity has proven to be beneficial because of the increase in operational performance in comparison with single stage systems. Therefore, in the present study, the methanotrophic reactor effluents were operated in air cathode MFC for electricity generation for the first time. The methanotrophic reactor with Methylosinus sporium produced a maximum methanol concentration of 6.45 mM using simulated biogas (4:1 (v/v) CH4:CO2) with a 50% CH4 content. Maximum power densities of 235 and 270 mW/m2 were noted with methanotrophic reactor effluents from pure CH4 (MFC-1) and simulated biogas (4:1 (v/v) CH4:CO2) (MFC-2), respectively. Electrochemical impedance spectroscopy analysis revealed the presence of high charge transfer resistance as a major limitation for electricity generation. This is the first report on the sequential operation to produce methanol and electricity using simulated biogas. The system might have potential for field applications using real biogas generated through the anaerobic digestion of biowaste materials.