Post on 01-Jan-2016
description
University of Notre Dame Civil Engineering and Geological Sciences
Department
Microbial Fuel Cells for Renewable Energy - Characterization Study
Presented by:
Jesus M Garcia FigueroaUniversity of Puerto Rico at Mayaguez
Mentor: Susan Dahlheimer Advisor: Dr. Robert Nerenberg P.E.
IntroductionIntroduction
90% of world’s energy is supplied by fossil 90% of world’s energy is supplied by fossil fuelsfuelsNon-sustainableNon-sustainableNegative environmental impacts Negative environmental impacts
Need sustainable, environmentally-friendly Need sustainable, environmentally-friendly energy sourcesenergy sources
Fuel cells are a promising technologyFuel cells are a promising technology
Hydrogen Fuel CellHydrogen Fuel Cell
H2 O2
M
H2O
Chemical Reaction:
H2 2H+ + 2e-
½ O2 + 2H+ + 2e- H2O
2H2 + O2 → 2H2O
2e-→ 2e- ↓
H2
2H+ + 2e- ½O2 + 2H+ + 2e-2H+
Alternative Fuel CellsAlternative Fuel Cells
HH22 is not readily available is not readily available Organic wastes also contain energy:Organic wastes also contain energy:
Common catalysts not effectiveCommon catalysts not effective Bacteria can catalyze electron transfer to anodeBacteria can catalyze electron transfer to anode
Chemical Reaction:
Wastewater + H2O nH+ + yCO2 + ne-
½ O2 + 2H+ + 2e- H2O
Wastewater + O2 → 2H2O + CO2
Our Experimental SetupOur Experimental SetupVoltmeter
O2 Pumping
R Load
AnodeCathode
Proton Exchange Membrane
(PEM)
ObjectivesObjectives
MFC Qualitative Characterization
Cathode Chamber Characterization
Proton Exchange Membrane (PEM) Characterization
Anode Chamber Characterization
Cathode Characterization Cathode Characterization ExperimentsExperiments
Cathode Electrode Characterization
Surface Area Size
Surface Area Form
Cathode Material
1. Original (6x10)cm2
2. Double
3. Half
Electrode Thickness
1. Original (Thin)
2. Thick Electrode
1. Original (Planar Electrode)
2. Rod Electrode
1. Original (Carbon)
2. Platinum
Cathode Oxidant
1. Original (Oxygen)
2. Ferricyanide solution
Cathode Characterization DetailsCathode Characterization Details
Experiments included loads of 10 Experiments included loads of 10 ΩΩ, 100 , 100 ΩΩ, 1 k, 1 kΩΩ, 10 k, 10 kΩΩ, 100 k, 100 kΩΩ and 1 M and 1 MΩΩ
A data logger recorded VA data logger recorded VWith V and R, current and power were With V and R, current and power were
calculated using Ohm’s (V = IR) and calculated using Ohm’s (V = IR) and Watt’s (P = VI) Laws.Watt’s (P = VI) Laws.
Proton Exchange Membrane Proton Exchange Membrane CharacterizationCharacterization
Proton Exchange Membrane (PEM) Characterization
Nafion PEM
Ultrex PEM
PEM Characterization DetailsPEM Characterization Details
Both chambers of the MFC contained a Both chambers of the MFC contained a buffer solution, one chamber had no Obuffer solution, one chamber had no O22, ,
other was saturated with Oother was saturated with O22..
Monitored OMonitored O22 diffusion across two diffusion across two
membranes with a dissolved Omembranes with a dissolved O22 probe. probe.
Compared how OCompared how O22 concentration changed concentration changed
as a function of time for two membranes.as a function of time for two membranes.
Anode Chamber CharacterizationAnode Chamber Characterization
Anode and Anode Electrode Characterization
Suspended BacteriaAttached Bacteria
Anode Characterization DetailsAnode Characterization Details
Anode with biofilm was removed from Anode with biofilm was removed from operating MFC and placed in new MFC.operating MFC and placed in new MFC.
Fresh electrode placed in operating MFC Fresh electrode placed in operating MFC with suspended growthwith suspended growth
Compared the two systems.Compared the two systems.
Results and Results and DiscussionDiscussion
Cathode Size Comparison
0.0E+00
2.0E-03
4.0E-03
6.0E-03
8.0E-03
1.0E-02
1.2E-02
1.4E-02
1.6E-02
1 10 100 1000 10000 100000 1000000
Resistance (Ohms)
Pow
er (m
W)
Original (6x10)cm 2̂
Double Electrode
Half Electrode
Instability Region
Cathode Comparison
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
1 10 100 1000 10000 100000 1000000
Resistance (Ohms)
Pow
er (
mW
)
Original (Carbon Electrode + Oxygen)
Pt Electrode
Cathode Comparison
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
1 10 100 1000 10000 100000 1000000
Resistance (Ohms)
Pow
er (
mW
)
Original (Carbon Electrode + Oxygen)
Ferricyanide Solution
Pt Electrode
General Results and DiscussionGeneral Results and Discussion
Open circuit voltage was not stable in all Open circuit voltage was not stable in all experiments.experiments.
Higher resistances resulted in unstable Higher resistances resulted in unstable voltages, therefore the mid-range voltages, therefore the mid-range resistance of 10K Ohms is used for resistance of 10K Ohms is used for comparisons as it resulted in large power comparisons as it resulted in large power production in all experiments.production in all experiments.
Voltage and current characterization show Voltage and current characterization show consistence with power characterization consistence with power characterization for all experimental comparison.for all experimental comparison.
Cathode ResultsCathode Results
Size:Size: Double surface area better than half better Double surface area better than half better than original.than original.
Thickness:Thickness: Thin is ~1.25x better than thick Thin is ~1.25x better than thick electrode.electrode.
Surface Area Form:Surface Area Form: Rod increased power ~1.1x Rod increased power ~1.1x greater the planar electrode surface.greater the planar electrode surface.
Material:Material: Pt electrode increased power ~5.5x. Pt electrode increased power ~5.5x. Oxidant:Oxidant: Performance with ferricyanide ~12.6x Performance with ferricyanide ~12.6x
better than with oxygen.better than with oxygen.
PEM Diffusion Test Comparison
0
1
2
3
4
5
6
7
0 10000 20000 30000 40000 50000 60000 70000 80000
Time (s)
O2
(mg/
L)
Nafion PEM
Ultrex PEM
Suspended vs. Attached Bacteria Comparison
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.020
10 100 1000 10000 100000 1000000
Resistance (Ohms)
Pow
er (
mW
)
Attached Bacteria
Suspended Bacteria
ConclusionConclusionCathode parameters affect power Cathode parameters affect power
productionproductionUltrex has lower OUltrex has lower O2 2 diffusion than Nafiondiffusion than NafionBoth attached and suspended growth Both attached and suspended growth
contribute to electron transfercontribute to electron transferMFC technology a promising alternative MFC technology a promising alternative
energy sourceenergy source
Lab PicturesLab Pictures
Future WorkFuture Work
Make Anode MFC Experiments (such like Make Anode MFC Experiments (such like Glucose and wastewater instead as a Glucose and wastewater instead as a acetate feed) and more.acetate feed) and more.
See other things such as bacteria growth See other things such as bacteria growth and PEM Oxygen and Hydrogen diffusion and PEM Oxygen and Hydrogen diffusion coefficients.coefficients.
Try to discover and explain how MFC Try to discover and explain how MFC Single Chamber works.Single Chamber works.
AcknowledgementsAcknowledgements
Thanks for:Thanks for: Susan Dahlheimer, Dr. Roberto Nerenberg P.E. and his Susan Dahlheimer, Dr. Roberto Nerenberg P.E. and his
Graduate studentsGraduate students Dr. Valli Sarveswaran, Jennifer Forsythe and EMSI-REU Dr. Valli Sarveswaran, Jennifer Forsythe and EMSI-REU
ProgramProgram University of Puerto Rico at MayaguezUniversity of Puerto Rico at Mayaguez
-Dr. Jose A. Colucci Rios P.E.-Dr. Jose A. Colucci Rios P.E.
-Monica Ospinal Jimenez-Monica Ospinal Jimenez
-Juan Carlos Flores-Juan Carlos Flores Bryan AndersonBryan Anderson