 microbial fuel cells, MFCs, are devices that convert biological material into electricity. Research has increased in recent years due to their potential as a source of renewable energy. However, despite some successes with marine sediments, practical application remains limited. The main limitation is the lack of understanding of the microbiology involved. It appears that the most valuable aspect of MFC technology may not be its ability to generate electricity, but rather its capacity to degrade waste and toxins. This suggests that more attention should be paid to understanding the microbial processes involved in order to fully realize the potential of MFCs. This article was authored by Kelly P. Nevin and Ashley E. Franks.