Science Buddies: "Ask an Expert"

Good day!

I am Em, a student who is currently conducting research about Comparing the Power Output of Different Soil Types Through a Microbial Fuel Cell Experiment. My research group has based on your MudWatt vessel in doing our DIY MudWatt set up using:

1. DIY Graphite Disk using mixed clay soil, crushed charcoal, and water (Graphite is not available in our country)
2. 1500ml round plastic container
3. OHM Resistors
4. Bread Board
5. 3 Mud Types: Loam, Vermicast, Clay
6. Insulated Copper Wires
7. Multimeter and Alligator Wires

I'm reaching out to ask for assistance or any suggestions you can provide on how we can conduct our own DIY MudWatt set-up using our student budget-friendly and feasible materials. As I watched the procedure on how to do a MFC, a green hacker board is needed. Is there a way on how we can maximize our materials?

Hello!

Yes. Your project is doable with budget materials, and you do not need the “green hacker board” to run a microbial fuel cell (it mainly makes measuring/charging easier). The most important parts are a carbon-based anode buried in the mud (low oxygen), a carbon-based cathode exposed to air (high oxygen), solid electrical connections, and a consistent way to measure voltage/current across a known resistor. Your charcoal–clay “graphite disk” can work as a carbon electrode, but performance improves if you maximize surface area (thin, porous, larger disks or multiple pieces) and keep the anode completely buried while the cathode stays near the top with good air access. Use the same container size, soil mass, moisture level, electrode size, depth, and resistor value for each soil type, and let cells run for several days because power often increases as the microbial community stabilizes. For measurements, connect the electrodes through a resistor on the breadboard and use the multimeter to record voltage across the resistor; then compute current and power using I=V/R and P=V^2/R, which allows fair comparisons between loam, vermicast, and clay. If you can, test a few resistor values (e.g., 100 Ω, 1 kΩ, 10 kΩ) to find which gives the highest power output, and run replicates to improve reliability.