Microbial fuel cell performance with a pressurized cathode chamber

Area of Science:

• Electrochemistry
• Renewable Energy Technologies
• Biotechnology

Background:

• Microbial fuel cells (MFCs) offer a promising avenue for sustainable energy generation.
• Power output in MFCs is frequently limited by the slow oxygen reduction reaction (ORR) at the cathode.
• Low oxygen solubility in cathode electrolytes causes mass transport limitations, hindering ORR efficiency.

Purpose of the Study:

• To investigate the impact of elevated cathode air pressure on MFC performance.
• To compare the efficacy of anion-exchange membranes (AEMs) versus cation-exchange membranes (CEMs) under varying pressures.
• To elucidate the mechanisms behind pressure-dependent MFC power enhancement.

Main Methods:

• MFCs utilizing AEMs and CEMs were operated at atmospheric, +17.24 kPa, and +34.48 kPa cathode air pressures.
• Cell potential and power density were measured at a constant external resistance (100 Ω).
• Comparative analysis of AEM and CEM performance under identical conditions.

Main Results:

• Increasing cathode air pressure from atmospheric to 17.24 kPa boosted cell potential from 0.423 V to 0.553 V in AEM-based MFCs.
• This pressure increase led to a 70% rise in power density (4.29 to 7.29 W/m³).
• AEM-based MFCs consistently outperformed CEM-based MFCs, yielding 66-108% more power.

Conclusions:

• Elevated cathode air pressure is an effective strategy to enhance oxygen availability and MFC power density.
• AEMs demonstrate superior performance compared to CEMs in MFCs, particularly under increased pressure.
• Controlling oxygen diffusion across the membrane to the anode is crucial for optimizing pressure-enhanced MFC operation.