Microfluidic membraneless microbial fuel cells: new protocols for record power densities

Area of Science:

• Microbial electrochemistry
• Bioelectrochemical systems
• Renewable energy technologies

Background:

• Membraneless microbial fuel cells (MFCs) face challenges with low electrode area-normalized power, hindering their scalability.
• Power densities in microfluidic MFCs have stagnated for years, creating a gap compared to larger systems.

Purpose of the Study:

• To enhance microfluidic MFC performance by improving technology and establishing record power densities.
• To introduce novel normalization methods for comparing MFC performance across different scales.

Main Methods:

• Developed a new membraneless MFC design incorporating technological improvements.
• Utilized a pure-culture *Geobacter sulfurreducens* electroactive biofilm (EAB) for optimal anode colonization.
• Applied new power normalization methods, including normalization by wetted cross-section area and flow rate.

Main Results:

• Achieved a record electrode areal power density of 3.88 W m^-2 (24.37 kW m^-3) for microfluidic MFCs.
• Demonstrated power densities of 8.08 W m^-2 when normalized by the wetted cross-section area.
• Obtained normalized energy recovery values of 0.025 kW h m^-3 when normalized by flow rate.

Conclusions:

• The developed strategy successfully closed the performance gap between micro- and macroscale MFCs.
• The study presents a roadmap for advancing microfluidic MFC technology.
• Novel normalization methods facilitate more accurate comparisons of MFC performance across diverse scales.