MFCs make use of wastewater treatment, although not commercially available yet, they could provide the solution for 100% Renewable Energy fuel cells. MFCs use electrochemically-active bacteria grown on an electrode which are able to directly produce electricity from biomass in residential and industrial wastewater streams. These special bacteria have evolved a way to force electrons from their cells, enabling them to transfer those electrons to a metal surface when they break down the waste.
If MFCs can be installed at water-intensive applications, then the energy potential is cumulatively very large. For instance they could be used in manufacturing plants that utilize water for their manufacturing processes. Also, if they prove viable they could be used in water treatment facilities. The amount of wastewater in our cities is immense. Harnessing the wastewater to produce clean energy would be an amazing achievement.
Taking into account MFCs is geared toward a very specific application in a sector that is flooded with inefficiencies. There is ten times more energy in wastewater than in the process of treating it. If MFCs come out as reliable and durable, then fuel cell technology will be back on track.