Geobacter Sulfurreducens might be a promising energy source

Geobacter Sulfurreducens is a species that is found in sediments & found in anaerobic conditions. This species have the ability to ‘breathe electrons'. They can transfer electrons to an elecron acceptor such as iron oxide by making nanowires to form a biofilm. Then voltage can be collected by completing the circuit , which is by making a cathode .