Microbial Fuel Cells: A Comprehensive Overview of Performance Boundaries, Material Innovations and Pathways to Broader Applications

The increasing global demand for sustainable wastewater treatment has intensified interest in bio‐electrochemical systems (BES), particularly microbial fuel cells (MFCs), which can simultaneously remove organic pollutants and recover bioelectricity. Despite extensive laboratory investigations, progress toward scalable and commercially viable MFC technologies remains fragmented, with inconsistent reporting formats and limited cross‐study comparability. This review synthesizes more than two decades of experimental, analytical, and techno‐economic evidence to clarify the performance boundaries, governing mechanisms, and deployment potential of MFCs. A quantitative meta‐synthesis of different datasets reveals reproducible operational optima at pH 6.5, 20–30°C, and moderate substrate strength (COD ≈ 400 mg L −1 ), with typical energy yields of 0.4–0.6 V cell −1 and 25–150 W m −3 . Carbon‐based anodes and PGM‐free cathodes (Fe–N–C, Mn/Co composites) show the most consistent electrochemical performance and cost advantage, while AEMs provide superior proton transport and Coulombic efficiency (CE) relative to PEMs and CEMs. Ceramic and membrane‐less architectures demonstrate strong promise for sanitation and decentralized wastewater treatment, supported by field‐scale demonstrations ranging from 100 to 1500 L. Technology readiness analysis places current MFC configurations at TRL 4–6, constrained by cathode kinetics, scale‐dependent Ohmic losses, membrane fouling, and long‐term biological instability. Commercial and techno‐economic assessments (TEAs) indicate that integrated systems (CW‐MFC, AD‐MFC) can outperform conventional aerobic processes in niche scenarios, particularly where aeration energy dominates OPEX. Overall, this review consolidates performance determinants, technological maturity, and economic feasibility into a unified framework, providing a roadmap for future research toward scalable, low‐cost, and field‐deployable MFC technologies.