XX

1. Microbial Fuel Cell Lab
Devon Beesley
Logan Gammon
Nick Tuttle

2. Introduction to a MFC
The main goal of an MFC is to mimic biology in order to create usable energy.
As the world population continues to grow and develop more and more
power is needed for modern conveniences. The MFC allows for power to be
produced without any harm to the environment. This becomes a powerful
asset in creating green energy that can be used for the foreseeable future.
Even though this is a way to create power the scale at which it creates is very
small, the most powerful MFC’s create about 10V of energy, which is not
enough to power much of anything other that small hand tools. The
furthering of this technology can lead to a renewable source of energy that
can handle our electric needs, this device can change the way we produce
energy.

4. Researched Microbial Fuel Cells
The research for MFC’s was done mostly in a homework assignment where
we had to find a research article on an MFC and analyze it for the key points.
This lead our group to find three different MFC’s to help us form an idea for
our own. The three articles that we found were defined experiments, one
using a typical integrated mfc design comparing anode materials, one done
with an air cathode used to remediate water, one comparing the power
density of air cathode MFCs in the presence of a PEM and in the absence of
a PEM. From this we found how a MFC should work and what the necessary
parts of an MFC are. We then moved on to designing our own MFC.

5. Literature Review
● Air Cathode MFC designed to sit in sediment
● Conductive Paint/ ORR catalyst
● Canvas Cloth, Water-Proof coating, Carbon Felt Anode
● Highest Power Density 107.1 +- 8.6 mW/m^2

6. Governing Equations of an MFC
There are several equations used when measuring an MFC’s production they
are:
● V=IR
● P=VI
● Power Density=P/m^3

7. Analysis of Information
For a MFC to be functional the system must have a cathode and cathode
chamber along with an anode and an anode chamber. Between the cathode
and anode chamber there must be some divider that allows for protons to
go from anode to cathode and prevent electrons from moving from either
chamber. The MFC must also have wiring that allows for electrons to move
from the anode to the cathode creating a current.

8. Process Goals
● 1.25 W/m^3
● Materials must be biologically compatible with cultures of bacteria and
algae in water

9. Structural Goals
Our main structural goal for this project was to make an air cathode. This
goal requires other structural goals. These were to have a waterproof
interior chamber, having airways for interaction between the cathode and
anode, and being able to connect the anode and cathode to the
potentiometer effectively.
These goals had to be addressed during our production and multiple
solutions were used in order to achieve them. Some examples of this is that
creating a “roof” on the MFC out of a piece of rubber, using waterproof
carbon cloth and creating holes at the top of the MFC to help allow air to
enter the MFC.
75% of material should be natural and/or biodegradable

10. Mechanical Goals
● No moving parts
● Must have airflow

11. Constraints
● $10 budget
● Time
○ MFC’s meant to be implemented during class Wednesday 11/15
○ Time given on Friday to implement, Our MFC flooded, had to be resealed
○ Absolutely needed to be implemented Before Thanksgiving Break

12. Considerations
When designing the MFC many factors were taken into account. The main
one being how creating current in a pool of sitting water could affect the
water's condition. When designing the device we used mostly recycled
materials such as our bamboo frame and rubber top. The nature of these
materials make them incredibly safe to be in the water. Also the use of
electrical tape to insulate the wire made the MFC safe to place in the water.
The life cycle of the MFC is hard to calculate because many factors could
limit that life cycle. The main consideration is the sealant and the wires both
of which could be chewed through or degrade.

13. Design
Our initial design featured an air cathode located inside a bamboo chute, on
the outside of the bamboo was a graphite pouch, this functioned as the
cathode. Outside of the graphite pouch was waterproof carbon cloth which
acted as the anode, our anode chamber is the entire aquaculture. The two
wires connected to the graphite pouch and the carbon cloth, the wires were
insulated with electric tape. To allow for air to enter the MFC four air holes
were drilled near the top and a rubber cover was added to keep rainwater
from entering. Finally a hole was drilled at roughly a 45 degree angle to hold
the potentiometer in place, one wire was run through the middle of the MFC
the other was run on the outside of the MFC.

14. CAD

16. Redesign Part 1
For our first redesign of our MFC we used a bath caulk sealant and CEM
paper instead of duct taping the carbon cloth to the bamboo the general
design was the same. One wire was connected to the CEM paper and the
other was connected to the carbon cloth.

19. Redesign Part 2: The Return
On 11/29, a reading of 0 mV was measured at 5.06 kΩ. The sealant around
the top part of the anode turned to mush and the air cathode chamber
flooded. The MFC was drained and wrapped with electrical tape near the top
of the anode over the sealant. A new polarization curve was generated from
this redesign.

20. Materials and Costs
● Original-16-gauge wire, 4 ft total, $0.88
Waterproof Carbon Felt, 38in^2, ($79.68, 89% Depreciation), $9.00
Window Screen, 38in^2, $0.07
Crushed Graphite- 5 grams, $0.05
Total Cost- $10 (Convenient)
● After Repairs- 16-gauge wire, 4 ft total, $0.88
Waterproof Carbon Felt, 38in^2, ($79.68, 89% Depreciation), $9.00
Cation Exchange Membrane (CEM), 36in^2, $1.84
Kwik Seal Adhesive Caulk, $3.50
Total Cost- $15.22

21. Alternatives
Drill more holes to achieve optimal air flow
Use PVC for main structure, easier to secure CEM and waterproof carbon felt
Use of epoxy sealant instead of silicone

22. First Polarization Curve (Dismiss)

23. Polarization Curve Fixed

24. Power Calculation Vs. Time

25. Conclusions
● Internal Resistance - 2937 Ohms
● Max Power - 7.69 E-03 mW
● Max Power Density 3.14 W/m^3 (3.14 E-04 W/m^2)
● Average Power Density .57 W/m^3 (.57 E-04 W/m^2)
Power density = Power/(volume of anode) = (7.69 e-6)W / (2.45 e -6) m^3

26. References
Mercer, Justin. “Microbial Fuel Cells: Generating Power from Waste.” Illumin,
University of Southern California. May, 4, 2010. http://illumin.usc.edu/134/microbial-fuel-cells-generating-
power-from-waste/
Yuan, Yong. “A new Approach to in situ sediment remediation based on
air-cathode microbial fuel cells.” May, 2010. https://search-proquest-
com.libproxy.clemson.edu/asfa/docview/753819485/A8C79559A8DF43EEPQ/1?accountid=6167
Class Notes, Fundamentals of Biosystems Engineering 2120, Dr. Caye Drapcho,
Clemson University

27. References
Hong, Liu, and Logan Bruce. “Electricity Generation Using an Air-Cathode Single Chamber Microbial Fuel Cell in the
Presence and Absence of a Proton Exchange Membrane.”
ACS Publications, 2004
pubs.acs.org/doi/pdf/10.1021/es0499344.
Hou, Huijie. “Microfabricated Fuel Cell Arrays Reveal Electrochemically Active Microbes.” PLOS. August, 2009.
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0006570

28. Appendices

29. Polarization Curve (Dismiss)
Date Voltage (mV) Resistance (kOhms) Current (mAmps) Water Temp [C]
11/19/2017
0.08 5.06 1.58E-05
14.2
0.06 3.99 1.50E-05
0.04 2.27 1.76E-05
R for max power (Ohms)
10298

30. Data Using Internal Resistance From First
Polarization Curve Data
Date Voltage [mV] Resistance [kOhms] Current [mA] Water Temp [C] Power [mW]
11/19 0.06 5.06 1.50E-05 14.2 9.02E-10
11/25 12 5.06 3.55E-03 10.7 4.26E-05
11/26 5 5.06 1.48E-03 11.7 7.40E-06
11/27 1 5.06 2.96E-04 12.3 2.96E-07
11/28/2017 9 5.06 2.66E-03 12.9 2.40E-05

31. Polarization Curve Fixed Data
Voltage (V) Resistance (Ohm) Current (A) Temp (C)
0.038 4000 0.0000095
11.9
0.051 5030 0.00001013916501
0.008 370 0.00002162162162
0.021 1330 0.00001578947368
0.019 980 0.0000193877551
0.032 2290 0.00001397379913
R for max power (Ohms)
2937

32. Data Collected Using Internal Resistance From
Second Polarization Curve
Date Voltage [mV] Resistance [kOhms] Current [mA] Water Temp [C] Power [mW]
11/29 *NEW POLAR CURVE
11/29 17 3.01 5.79E-03 11.9
9.60E-05
11/30 9 3.03 2.97E-03 13.7 2.67E-05
12/1 53 2.99 1.77E-02 13.3 9.39E-04
12/2/2017 107 2.97 3.60E-02 13.6 3.85E-03
12/3/2017 148 2.85 5.19E-02 13.8 7.69E-03