A two-staged system to generate electricity in microbial fuel cells using methane

Abstract

Methane is an abundant and inexpensive feedstock that is available as natural gas and renewable biogas. However, methane has not been regarded as a good substrate for microbial fuel cells (MFCs) due to low power densities. To increase power, a two-step strategy was used based on conversion of methane into methanol, followed by electricity generation using methanol as the substrate in the MFC. To produce methanol, a methaneoxidizing culture was grown in a high phosphate buffer resulting in the accumulation of 350 ± 42 mg/L of methanol. The methanol-fed MFC produced a maximum power density of 426 ± 17 mW/m 2. It was also shown that the methanol-rich medium produced from the first step can directly be supplied to the MFCs, removing the need for purification of methanol. Analysis of the microbial community suggests that acetogens first converts methanol into acetate, which is then consumed by exoelectrogens for power generation.

Microbial Electrosynthesis of Bioalcohols through Reduction of High Concentrations of Volatile Fatty Acids

“…Methanol production from acetic acid and butyric acid reduction in MES has been reported previously, but production pathways by mixed cultures were not clearly understood. , The possible conversion of formic acid to methanol by formaldehyde dehydrogenase and alcohol dehydrogenase was reported as the known pathway of reduction in microbial metabolism . Furthermore, bioelectrochemical reduction of carbon dioxide to methanol has been demonstrated using formate dehydrogenase, methanol dehydrogenase, and carbonic anhydrase (CO 2 + 6H + + 6e – → CH 3 OH + H 2 O at 0.016 V vs SHE). − Methanol production from methane can be achieved by methanotrophs, which convert methane to methanol using methane monooxygenase enzymes . Planktonic production of methanol, which does not rely on the biofilm, could also be considered .…”

“…36−38 Methanol production from methane can be achieved by methanotrophs, which convert methane to methanol using methane monooxygenase enzymes. 39 Planktonic production of methanol, which does not rely on the biofilm, could also be considered. 38 Ethanol was detected as the second major product with a maximum production of 1.13 ± 0.13 mM under 4.0 g-COD/L VFAs.…”

Electroactive microorganisms in bioelectrochemical systems

“…and methanogens grew on the anode, and thus both were likely needed for current production 61 . Direct evidence for methanol being an intermediate in power generation from methane was shown in a two-stage process where methane was converted to methanol by methanogens in the first stage, and power was produced in a second-stage MFC likely from methanol oxidation to acetate 62 . Another study genetically engineered the methanogen Methanosarcina acetivorans to produce current in an MFC from methane, but other known exoelectrogens identified in the biofilm were thought to be responsible for current generation 63 .…”

Enhanced Electricity Generation and H2O2 Production in a Photocatalytic Fuel Cell and Fenton Hybrid System Assisted with Reverse Electrodialysis

“…In this system, bacteria in the anode chamber could oxidize the substrates to generate electrons, which are transported through an external resistor to the cathode chamber, thereby forming H 2 O 2 via the reduction of dissolved oxygen. 2,3…”