Sedimentary Based Microbial Fuel Cells Evaluated by Power DensityZachary GilstrapAlston LoperMatthew Wieters

Problem SpecificsTo design and implement a sediment based microbial fuel. $20 budget Produce 1Watt/m3 of power

Definition of ProblemSpecifics(1) C6H12O6 + 6H20 6CO2+24H++24e-

The oxidation or loss of electrons

(2) 24e- + 24H+ 12H2O The reduction of gain of electrons

Overall ReactionC6H12O6 + 6O2 6CO2 + 6H2O

Aerobic Respiration

Definition of ProblemSpecifics

V=IR Ohm’s Law

P=IV Power Equation

Power Density=P/V Power Density Equation

GoalsProcess Compatibility with environment Aerobic environment for cathode

Structural General well being Wiring connectivity Stability

Mechanical Simplistic design

ConstraintsEquipment 75% of design from natural or recycled resources

Budget $20 limit for the total amount of materials used in design

Skills Not particularly efficient engineers

Time Two lab periods for fabrication and implementation

ConsiderationsSafety Weather Tools

Ethical Requisitioning resources Impact on location population

Environmental Cold weather, less prolific bacteria

Life cycle/Use/Sustainability Long-term functionality Not recommended for professional use Sustainable

MFC Overview

Relevant Designs• Sediment MFC easily

modified to fit the design goal.

• Mirrored our structural design off sediment MFC shown with slight modifications

• Simplistic design required very little mechanical aspect

Relevant Designs• Larger surface area to

volume ratio was decided to be beneficial

• Referenced design achieved 3300Watts/m3 using 100mL anode volume

• Modifying this principle and aforementioned structural design, we fabricated our own MFC

Analysis of DesignSimplistic design

Easily implemented Modified for design goal

Larger SA:V principle Crushed graphite anode Smaller anode volume

Synthesis of DesignCrushed graphite had an experimentally observed density of 0.365g/mL

Anode volume chosen to be 5g or 13.68mL

Synthesis of DesignUsing this and a simplistic ratio with our second source and a chosen anode volume of 13.68cm3, the wattage produced would hypothetically be .45watts/13.68cm3 for our MFC Article design more efficient*

Materials and CostMaterials: Costs2ft Bamboo N/A 5ft Copper Wire $3.2910g Crushed Graphite (5g anode & cathode) $5.38Window Screen 2.5in x 2.5in (2) $1.76Electric Tape $0.85ZipLoc Bag $0.09

Total $11.37

Description of Design 2ft bamboo

structural support Crushed graphite

anode and cathode Free floating

cathode Anode buried 3in

within the sediment Copper wiring

Description of AlternativesBamboo could have been replaced with PVC Additional cost and environmental impact

Light blue thread could have been replaced with purple thread Stylistic

Potentiometer chosen over bread board Potential convenience

4.00E-05 5.00E-05 6.00E-05 7.00E-05 8.00E-05 9.00E-05 1.00E-040

0.050.1

0.150.2

0.250.3

f(x) = − 4138.1527928818 x + 0.451781674843524R² = 0.950994259408842

Polarization Curve

Current (I) [A]

Vol

tage

(V

) [V

]

Initial Polarization CurveResistance (R)[Ω] Voltage (V) [V] Current (I) [A]

2.8 0.00 0.00E+00300 0.00 0.00E+00660 0.06 9.09E-052090 0.16 7.66E-053650 0.21 5.75E-054820 0.24 4.98E-05

Initial Power Curve

4.00E-05 5.00E-05 6.00E-05 7.00E-05 8.00E-05 9.00E-05 1.00E-040.00E+002.00E-064.00E-066.00E-068.00E-061.00E-051.20E-051.40E-05

Initial Power Curve

Current (I) [A]Pow

er (

P) [

wat

ts]

Resistance (R) [Ω] Voltage (V) [V] Current (I) [A] Power (P) [watts]2.8 0 0.00E+00 0.00E+00660 0.06 9.09E-05 5.45E-062090 0.16 7.66E-05 1.22E-053650 0.21 5.75E-05 1.21E-054820 0.24 4.98E-05 1.20E-05

Final Polarization Curve

2.00E-05 4.00E-05 6.00E-05 8.00E-05 1.00E-04 1.20E-04 1.40E-040

0.050.1

0.150.2

0.25f(x) = − 2148.65878861686 x + 0.330746448997114R² = 0.991652938552688

Final Polarization Curve

Current (I) [A]Vol

tage

(V

) [V

]

Resistance (R) [Ω] Voltage (V) [V] Current (I) [A]4.2 0 0635 0.075 1.18E-041700 0.145 8.53E-052600 0.186 7.15E-053800 0.212 5.58E-054900 0.226 4.61E-05

Final Power CurveResistance (R) [Ω] Voltage (V) [V] Current (I) [A] Power (P) [watts]

4.2 0 0 0635 0.075 1.18E-04 8.86E-061700 0.145 8.53E-05 1.24E-052600 0.186 7.15E-05 1.33E-053800 0.212 5.58E-05 1.18E-054900 0.226 4.61E-05 1.04E-05

0.00E+00 5.00E-05 1.00E-04 1.50E-040.00E+002.00E-064.00E-066.00E-068.00E-061.00E-051.20E-051.40E-05

Final Power Curve

Current (I) [A]

Pow

er (

P) [

wat

ts]

Power Density vs TimeTime [days] Voltage [mV] Power (watts) Voltage (V) [V] Current (I) [A] Power Density [watts/m3]

1 280 1.89E-05 0.28 6.76E-05 1.382 320 2.47E-05 0.32 7.73E-05 1.813 252 1.53E-05 0.252 6.09E-05 1.124 240 1.39E-05 0.24 5.80E-05 1.025 210 1.07E-05 0.21 5.07E-05 0.786 251 1.52E-05 0.251 6.06E-05 1.117 120 3.48E-06 0.12 2.90E-05 0.258 314 2.38E-05 0.314 7.58E-05 1.749 116 3.25E-06 0.116 2.80E-05 0.2410 289 2.02E-05 0.289 6.98E-05 1.4711 220 1.17E-05 0.22 5.31E-05 0.85

Volume [cm3] Volume [m3] Resistance (R) [Ω]13.68 0.00001368 4140

Constants

Conclusions

1 2 3 4 5 6 7 8 9 10 110.00

0.50

1.00

1.50

2.00

Power Density vs Time

Time [days]Pow

er D

ensi

ty [

wat

ts/m

3]

Sediment MFC design successfully achieved an average power density of 1.07 watts/m3

Appendices

Appendices

Appendices

Literature Cited

http://www.nature.com/nrmicro/journal/v4/n7/fig_tab/nrmicro1442_F3.html

http://www.ncbi.nlm.nih.gov/pubmed/24956566