2. Introduction to MFCs
● Biological Reactor
○ Electrons from microbial metabolism
intercepted to provide usable electricity
● Aerobic vs. Anaerobic
○ Microorganisms oxidize organic matter in
anode
○ Cathode chamber contains electron
acceptor (O2)
● External Circuit
○ Electrons flow from anode to cathode
creating electrical current
3. What’s the Big Deal?
● CLIMATE CHANGE
○ Almost 2/3rds of our GHG’s are linked to burning of
fossil fuels
● Renewable Energy
○ Law of Conservation of Energy
○ Microbial life is guaranteed
● Production of electrical power
○ Transforming biological energy into electrical energy
https://physicsworld.com/a/global-energy-in-2050-can-
renewables-supply-it-all/
4. ★ GOAL
○ Process goal: produce 1
W/m^3 of power
★ Constraints
○ Minimal electrical and bioprocessing knowledge
○ Household materials
○ Virtual environment for instruction/communication
○ ~2 weeks of research
○ STINKIN Resistor!?
★ Considerations
○ Low electrical current = safe to perform
○ Using processes in nature for electrical benefit
○ All materials used can be reused or recycled
5. Literature Review/Theory
● Sediment MFC in BE 2120
○ Lab 5 Worksheet
■ Hands on experience of how to measure
resistance, voltage
● Homework 3 - peer reviewed
journal article on MFC
○ Plant Microbial Fuel Cell
(PMFC)
■ Used potted
plants in
compost/soil to
produce electrical
current
6. Design
Materials:
● 1 L Plastic Container
● Sifted Compost
● Crushed Coal
● Window Screen
● Copper Wire
● Pencil Resistor*
● Water
● Gardner Bender
Multimeter
● Staples
● Wooden skewers
● Sand*
*improvements over time
7.
8. Reaching Goal
V = IR -> V=1481(I) ---(1)
● 1 W/m^3 requires power
output equivalent to anode
volume:
○ 2 oz = 5.915E-5 m^3
○ 5.915E-5 W/5.915E-5 m^3
= 1 W/m^3
P = IV -> 5.915E-5 = IV ---(2)
Solving for I and V in (1) and (2) to
determine voltage and current
needed to reach goal:
I = 1.998E-4 A V = 0.29597 V
9. Results and Discussion
● First Design (Compost Tea)
○ Possibly completely anaerobic
○ Resistance too low
● Redesign
○ sand/gravel separate anode/cathode
chambers
○ 1481 Ω resistor from old circuit board
10. Results
● Current:
○ V = IR -> I = V/R
● Power:
○ P = IV
● Power Density:
○ Pd = P/V
➔ 1481 Ω resistor
➔ 5.915E-5 m^3 anode volume
➔ Voltage measured daily in mV using
multimeter
➔ Highest power density recorded on day 14
◆ 0.0237 W/m^3 anode volume
Time (Days) Voltage (V) Current (A) Power (W) Power Density
(W/m^3)
1-9 0 0 0 0
10 0.0305 2.059E-5 6.281E-7 0.0106
11 0.0337 2.275E-5 7.668E-7 0.0130
12 0.0440 2.971E-5 1.307E-6 0.0221
13 0.0395 2.667E-5 1.053E-6 0.0178
14 0.0456 3.079E-5 1.404E-6 0.0237
15 0.0448 3.025E-5 1.355E-6 0.0229
Table 1. Power production of compost MFC over 15 days
11. Discoveries and Possible Improvements
● Current fluctuated depending on time of day and
temperature outside
● Decrease in water volume = decrease in voltage
Time Temperature (℃) Voltage (mV)
7:45 am 5 5.5
9:30 am 16 7.5
11:30 am 18 12.8
1:30 pm 22 20.7
8:15 pm 19 14.9
Table 2. DIfference in voltage output with respect to time and
temperature
● Future improvements:
○ Larger cathode chamber
■ More O2 as electron acceptors
○ Better contact with wire and electrode
surface area
■ Higher electron flow
○ Determine peak power
■ Polarization curve to determine internal
resistance
● Peak power produced when
external resistance = internal
resistance
12. Conclusions
● Compost Sediment MFC did not meet project goal power production of 1 W/m^3
anode volume
○ Highest power density 0.0237 W/m^3
● Power output of my design ~1.0E-6 W using 5.915E-5 m^3 anode
● Scale up to power 60 W light bulb using power density ratio
○ (60 W)/(? m^3 )= (~1.0E-6 W)/(5.915E-5 m^3)
○ Requires anode volume of 3549 m^3
○ Would require very large container, amount of compost, and amount of water.
In conclusion, this project achieved the production of power using biological processes, but
failed to meet project goal due to lack of proper synthesis of design. MFC was simply put
together using an idea, instead of using precisely calculated size and shape requirements to
meet goal.
13. References
M.A. Moqsud et al. Nov. 2014. Compost in plant microbial fuel cell for bioelectricity generation. Waste
Management. Elsevier. https://www.sciencedirect.com/science/article/pii/S0956053X14005200?via%3Dihub
Drapcho, C. 2020. BE 2120 Lab 5. Unpublished course notes, Clemson University.
Fengying Ma et al. Jan. 2019. Start Up Process Modelling of Sediment Microbial Fuel Cells. Mathematical
Theories and Applications for Nonlinear Control Systems. Hindawi.
https://www.hindawi.com/journals/mpe/2019/7403732/#references
Introduction (10 pts) – Introduce basic background information of your project(don’t discuss the specifics of your project)
Recognition of Problem/Need–– What is the big picture problem that you are trying to solve? (For projects this year global climate change is the big problem which leads to the need to develop carbon capture systems or renewable, non-fossil fuel energy sources)
Define Specific Need that your project will address
~ What is the specific need that your project is addressing? (ie producing electrical power, heating water without using fossil fuels or capturing carbon)
~Define specific Goals: Process, Structural, Mechanical (What specific goals do the projects have this year? Which category do they fall under?)
Literature Review/Theory (10 pts)
Description of other designs that you found in literature (not your specific design)
Information from research articles; Past Experience, Heuristics
Alternatives I could have chosen:
Graphite (Electrodes)
Different media (soil, clay, sand, etc)
Results and Discussion (25 pts)
Testing and evaluation of your design prototype
Show equations used for calculations; show data in table and figures
Redesign (if used) or suggestions for future improvements
