Building a Battery Out of Mud
Written by: Pranav Mahableshwarkar ‘25
Edited by: Melinda Li ‘22
A few weeks ago, I walked down to India Point Park, sat down by the mossy rocks and scooped silt and mud into numerous plastic containers. An hour later, with the help of my friend, we were able to generate electricity from the bacteria hidden within what we had collected. All it took was a resistor (1 for $0.04), two alligator clips, some nylon cloth, a plastic container and some fresh, locally sourced mud and we were able to make our own - albeit small - microbial fuel cell!
For some context, microbial fuels cells (MFCs) utilize the energy produced by bacteria in metabolic processes and convert it into electrical energy. Metabolic processes are sets of chemical reactions that occur within cells to sustain life and development. For humans, this includes glycolysis and the Krebs or citric acid cycle, key in the production of ATP (energy). The beauty of the MFCs is that they are self-sustaining! As long as a continuous source of food is provided to the bacteria, they will be able to reproduce and continue to generate electricity. The “food” for these bacteria can even include sewage and other common waste products .
The potential applications of MFCs are endless. Unlike the electrochemical batteries that we see around the world today, MFCs do not have a limited lifetime. Because of their self-renewable design, these batteries have a super long lifespan and have been implemented in monitoring sensors in remote areas or the ocean. These biosensors can track levels of compounds like nitrates or phosphates in water. Even NASA has looked at using MFCs to power small aircrafts due to their ability to generate power over a long period of time . As we look to develop new sources of clean energy, MFCs not only have no carbon footprint but can also help to reduce pollution. MFCs have the potential to “produce hydrogen for fuel cells, desalinate sea water, and produce sustainable energy sources for remote areas” .
The microbial fuel cell includes components including an anode and cathode, a resistor, the electrodes, and energy sources (food wastes or sewage). The electrodes are connected by a wire where the anode, or the negative electrode, has bacteria growing on it. The model above represents a simplified version of the MFC. Industrial versions of the MFC are slightly more complex but follow the same general structure .
Now that we have shared a little bit about these complex yet simple systems, let’s show you how to make your own MFC! You can follow this tutorial online from Oregon State University. As you read, you can follow this video tutorial made by Brown Science Prep .
The end of the video references some simple experimentation that can be done with the fuel cell. We recommend that you try and see for yourself what impacts vinegar and hand sanitizer each have on your MFCs energy potential. (Hint: Vinegar contains acetic acid!)
It is crazy to believe that when you flush your toilet, you could be powering a battery somewhere down the street. But that is the beauty of the microbial fuel cell: taking what we might consider to be waste and generating electricity!
 Anon. 2022. “NASA - Waste Not.” Nasa.gov. Retrieved May 2, 2022 (https://www.nasa.gov/vision/earth/technologies/18may_wastenot.html).
 Mercer, Justin. 2010. “Microbial Fuel Cells: Generating Power from Waste – USC Viterbi School of Engineering.” Usc.edu. Retrieved May 2, 2022 (https://illumin.usc.edu/microbial-fuel-cells-generating-power-from-waste/).
 Microbial Fuel Cells! Brown Science Prep - Brown University (Video: Lisa Duan ‘25, Pranav Mahableshwarkar ‘25)
 Oregon State University. n.d. Microbial Fuel Cells & Bacterial Power Levels: Grades 9-12 Content Areas.
[Image Citation] Anon. 2022. “India Point Park 201 India St Providence, RI Parks - MapQuest.” Mapquest.com. Retrieved May 2, 2022 (https://www.mapquest.com/us/rhode-island/india-point-park-360174257).
[Image Citation] Wikipedia Contributors. 2022. “Microbial Fuel Cell.” Wikipedia. Retrieved May 2, 2022 (https://en.wikipedia.org/wiki/Microbial_fuel_cell).