State-of-the-art review on sediment microbial fuel cells: evolution, innovations, challenges, scalability, and policy implications for sustainable development

Sediment microbial fuel cells or SMFCs are innovative bio-electrochemical systems that address the interconnected global issues of energy scarcity, wastewater pollution, and sediment contamination. This comprehensive review examines the progression from early 20th-century microbial fuel cells to contemporary SMFCs, emphasizing significant developments including mediator-less electron transfer in the 1990s and in-situ sediment applications in the 2000s. Advancements in electrode materials, such as biochar modifications and nanostructured carbons, have increased power densities to 3.31 W/m 2 in laboratory settings and improved remediation efficiencies, resulting in over 97 % COD removal, 93 % Cr(VI) reduction, and notable mitigation of nutrients and heavy metals. Lab-to-field transitions highlight enduring challenges such as environmental variability and scaling difficulties, which can be addressed through AI-optimized designs, synthetic biology for improved biofilms, and hybrid systems such as constructed wetland-SMFCs. Projections suggest that field outputs will consistently reach or exceed 1 W/m 2 by 2050, facilitating significant energy recovery and enabling an annual avoidance of 0.4–0.9 Gt of CO 2 emissions through global implementation. Policy implications correspond with UN SDGs 6, 7, 9, and 13, promoting incentives for commercialization to facilitate net-zero transitions. Despite achieving TRL 5–6 maturity, addressing internal resistance and longevity challenges is essential for mainstream integration, thereby establishing SMFCs as an important asset for sustainable development.