One of the main issues of long duration autonomous robots is their energy source and energy generation. NASA tries to circumvent this using solar energy, which is still far from optimal because there are still times that the robot has to stop and recharge. Now scientists at the Bristol Robotics Laboratory in the UK have discovered a new novel solution: fuel cells full of living bacteria. The team recently developed Row-bot, a swimming robot with Microbial Fuel Cells (MFCs) that directly harvests energy from the water it swims in. The Row-bot is modeled after a water beetle. It has two side paddles to move, stabilizers to keep it from drowning, and the MFCs at its core. It has a mouth where the water (the fuel source) can enter and an outflow port where it can exit.
Microbial Fuel Cells
The MFCs generate electricity by “electrons mobilized by the redox reaction that takes place in electrogenic bacterial anabolism.” The biomass in the water functions both as the inoculant for the bacteria and the anolyte that fuels the reactions. The result is an “environmentally biocompatible means of electricity generation.” The MFCs can operate in freshwater, seawater, and even waste water, which is actually cleaned as the Row-bot goes. The energy generated by the MFCs is stored in a capacitor, and only uses 1.8 joules per cycle (opening its mouth, swimming 10 strokes forward at just under 1 stroke per second and then closing its mouth).
Research is still ongoing on how to further optimize the Row-bot and make it more efficient. Potential applications of the Row-bot are environmental monitoring, cleanups, and maybe even space exploration.