Microbial fuel cells (MFCs) use bacteria to convert chemical energy from bio-convertible substrates like glucose or acetate directly into electricity. A typical MFC consists of an anode compartment where microbes oxidize fuel and generate electrons and protons, and a cathode compartment exposed to air. A cation-specific membrane allows proton passage between compartments. MFCs offer unlimited fuel sources without pollution and can achieve higher energy conversion than other methods, with no moving parts or noise. Examples demonstrate various microbes generating voltages between 250-650mV using different substrates and mediators or mediator-less systems. Significant factors that affect MFC operation include electrode type and area, use of catalysts, substrate concentration, and types of micro