Our Approach

The power output of a benthic bacterial cell is dependent on the effective area of the electrode and the power per unit area. It follows then that any improvements in each of those factors would multiply into a larger power output.

Increasing the surface area can be done in the macro-world by simply building bigger cells with more surface of the same type. However, this approach would make the power station be physically bigger and more expensive. It would also be a bigger target and more easily detectible. So, this is not a desirable pathway.

An alternative solution is to inbuild more area in the same volume, e.g. through microstructures arrayed into large arrays reaching macroscopic size. This approach makes basic physical sense, since the individual production unit is a benthic bacterium, which is in itself microscopic. Then the same physical size in terms of overall volume may contain many times the effective area, through components miniaturization and arraying.

Miniaturization also means that the distance between a bacterium and the nearest electrode can be significantly shrunk, compared to macro-electrode systems. Our hypothesis was that this shortening would have a strong positive effect on the power output. The argument is that an emitted electron has a certain probability to be recombined in the water before it can reach the electrode. The overall probability should be dependent on the overall distance to the nearest electrode. Hence, the capture efficiency of the electrode, defined as its ability to capture emitted electrons, should be strongly dependent on geometry and distances. Hence, miniaturizing the electrode should increase the capture efficiency and the overall power output, independently of overall area size.

Both lines of thinking are thus pointing towards miniaturization of benthic bacterial biofuel cells. The expertise of the lab in microfluidics thus lent itself very well to important advances in benthic bacterial biofuel cells.