Some Basic ConceptsSome Basic ConceptsRelated to Fuel CellsRelated to Fuel Cells

with a Focuswith a Focuson Microbial and Enzymaticon Microbial and Enzymatic

Fuel CellsFuel Cells

Nevin LongeneckerNevin LongeneckerJohn Adams High SchoolJohn Adams High School

The PURPOSES of this The PURPOSES of this investigation were toinvestigation were to

examine and evaluate variables associated with examine and evaluate variables associated with increasing the efficiency of a microbial fuel cell .increasing the efficiency of a microbial fuel cell .

propose and construct a prototype enzymatic fuel propose and construct a prototype enzymatic fuel cell based on the previous findings.cell based on the previous findings.

describe in an educational science journal an describe in an educational science journal an inexpensive fuel cell which could be easily inexpensive fuel cell which could be easily constructed and used in a classroom. The constructed and used in a classroom. The operation of such a cell would have diverse operation of such a cell would have diverse applications in many sciences and would applications in many sciences and would integrate mathematical principles from calculus, integrate mathematical principles from calculus, statistics, algebra and geometry.statistics, algebra and geometry.

Advantages of Fuel CellsAdvantages of Fuel Cellsvs.vs.

Internal Combustion EnginesInternal Combustion Engines

Unlimited supply of fuelUnlimited supply of fuel No reliance on foreign oilNo reliance on foreign oil Little or no pollutantsLittle or no pollutants Much higher energy conversion %Much higher energy conversion % No moving partsNo moving parts No noiseNo noise

How does it work?How does it work?

Anode ChamberAnode Chamber– Stores fuelStores fuel

-->

Cathode ChamberCathode Chamber– Exposed to airExposed to air

<--

Membrane - Membrane - Allows for HAllows for H++ passage passage^

Often Platinum Often Platinum CatalystCatalyst

V V

Microbial Fuel CellsMicrobial Fuel Cells

ProceduresProcedures

A prototype microbial fuel cell was A prototype microbial fuel cell was designed and built. (next slide)designed and built. (next slide)

Factors affecting microbial fuel cell Factors affecting microbial fuel cell efficiency were measured and evaluated.efficiency were measured and evaluated.– Surface area of electrodesSurface area of electrodes– Bacterial conc. on anode/in solutionBacterial conc. on anode/in solution– Aerobic vs anaerobic conditionsAerobic vs anaerobic conditions– Supplemental O2 sources Supplemental O2 sources Single and mixtures of enzymes were tested in Single and mixtures of enzymes were tested in

the prototype cell to compare power output. the prototype cell to compare power output.

Significant Factors AffectingSignificant Factors AffectingMicrobial Fuel Cell Operation Microbial Fuel Cell Operation

Type of electrodesType of electrodes Surface area of electrodesSurface area of electrodes Use of catalysts on electrodes and PEMUse of catalysts on electrodes and PEM Conc. of hydrocarbon in anode chamberConc. of hydrocarbon in anode chamber Agitation of hydrocarbon moleculesAgitation of hydrocarbon molecules Rate of replacement of hydrocarbonsRate of replacement of hydrocarbons Types of microbes/enzymesTypes of microbes/enzymes Conc. of microbes/enzymesConc. of microbes/enzymes

Examples of microbial-based fuel cellsExamples of microbial-based fuel cells

MicrobeMicrobe SubstrateSubstrate MediatorMediator AnodeAnode VoltageVoltage

E coliE coli GlucoseGlucose MethyleneMethylene

BlueBluePt- C-clothPt- C-cloth 625mV625mV

BacillusBacillus

subtilissubtilisGlucoseGlucose ThionineThionine VitreousVitreous

CarbonCarbon640mV640mV

E coliE coli AcetateAcetate Neutral redNeutral red GraphiteGraphite

feltfelt250mV250mV

PseudomonPseudomonasas

methanicamethanica

MethaneMethane 1-Naphthol-2-1-Naphthol-2-

Sulfonate indo-Sulfonate indo-

2,6 2,6 dichlorophenoldichlorophenol

Pt-blackPt-black 550mV550mV

ProteusProteus

vulgarisvulgarisSucroseSucrose ThionineThionine Carbon rodCarbon rod 350mV350mV

Significant Factors AffectingSignificant Factors AffectingMicrobial Fuel Cell OperationMicrobial Fuel Cell Operation

Types of mediatorsTypes of mediators Conc. of mediatorsConc. of mediators Distance between electrode and PEMDistance between electrode and PEM Type of proton exchange Type of proton exchange

membrane(PEM)membrane(PEM) Surface area of PEMSurface area of PEM Source of oxygenSource of oxygen Temperature effectsTemperature effects

Pseudomonas sp.Pseudomonas sp.

Mediator Shuttling ElectronsMediator Shuttling Electrons

Types of ElectrodesTypes of Electrodes

Power Output C rod vs Power Output C rod vs C cloth -aerobic E coliC cloth -aerobic E coli

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 5 10 15 20 25

Time Hrs

mW

atts

/cm

2

Cloth Elec

C Rod Elec

Carbon Rod and Carbon Fiber Carbon Rod and Carbon Fiber ElectrodesElectrodes

Power Output of C rod Biofilm vs Power Output of C rod Biofilm vs C rod Solution –anaerobic EcoliC rod Solution –anaerobic Ecoli

0

20

40

60

80

100

120

140

160

180

0 5 10 15 20 25

Time(hrs)

mW

att

s/c

m2

C rod biofilm

Solution Bacti

Proposed Advantages of Enzyme UseProposed Advantages of Enzyme Use

1. Immediate contact with substrate1. Immediate contact with substrate

2. Elimination of metabolism of 2. Elimination of metabolism of substrate by bacteriasubstrate by bacteria

3. Elimination of possible mixing of 3. Elimination of possible mixing of hazardous bacterial typeshazardous bacterial types

4. If immobilized on electrodes, no4. If immobilized on electrodes, no mediators are required.mediators are required.

Immobilized Enzyme /Cathode Immobilized Enzyme /Cathode InteractionInteraction

Glucose DehydrogenaseGlucose Dehydrogenase

Partial Composition of PEB Partial Composition of PEB Enzyme SolutionEnzyme Solution

LipaseLipase ProteaseProtease AmylaseAmylase HydrolaseHydrolase Likely-dehydrogenases, lactase, Likely-dehydrogenases, lactase,

decarboxylase, invertasedecarboxylase, invertase Supplied by Enzyme Solutions, Inc Supplied by Enzyme Solutions, Inc

PEB PEB EnzymeTrialEnzymeTrial –anaerobic-C rod –anaerobic-C rod

0

0.5

1

1.5

2

2.5

3

0 10 20 30 40 50 60 70

Time(hrs)

wat

ts/m

2

PEB Trial C rod Cathode vs Pt CathodePEB Trial C rod Cathode vs Pt Cathode

0

0.5

1

1.5

2

2.5

3

0 10 20 30 40 50 60 70 80 90 100

Time Hrs

Wat

ts/m

2

Trial #1 C Rod

Trial #2 Pt

Total Power Output in 22 hrsTotal Power Output in 22 hrs

0

500

1000

1500

2000

2500

0.56 1.11 2.22 4.44 8.89

PEB conc. pph anode solution

Wat

ts (

met

er2)

Long Term PEB Enzyme ActionLong Term PEB Enzyme Action

0

0.5

1

1.5

2

2.5

3

3.5

4

0 20 40 60 80 100 120

Time -Hrs

Wat

ts/m

2

Watts/m2

PEB Investigation Trends and PEB Investigation Trends and ConclusionsConclusions

1. Optimum power output developed in 2hrs1. Optimum power output developed in 2hrs Whole Ecoli cellsWhole Ecoli cells PEB solutionPEB solution

0.2 watts/m20.2 watts/m2 2.1 watts/m2 2.1 watts/m2

2. Prolonged power output at 24 hrs2. Prolonged power output at 24 hrs 0.14 watts/m20.14 watts/m2 2.05 watts/m22.05 watts/m2

3. Prolonged optimum power output continued for 5 3. Prolonged optimum power output continued for 5 days.days.

4. Pt. coating on the anode did not improve the 4. Pt. coating on the anode did not improve the efficiency of the enzymatic cell.efficiency of the enzymatic cell.

Uses forUses forImplantable Enzymatic Fuel CellsImplantable Enzymatic Fuel Cells

(To utilize arterial glucose and oxygen with (To utilize arterial glucose and oxygen with immobilized enzymes on electrodes in a immobilized enzymes on electrodes in a noncompartmentalized cell)noncompartmentalized cell)

Micropumps-insulin, pain meds, arthritisMicropumps-insulin, pain meds, arthritis

Current for-nerve stimulation, hearing aidsCurrent for-nerve stimulation, hearing aids

Heart pacemaker (cells in series)Heart pacemaker (cells in series)

Immobilized Enzymes on Immobilized Enzymes on ElectrodesElectrodes

Implantable Arterial Fuel CellImplantable Arterial Fuel Cell

Space-regeneration of human wasteSpace-regeneration of human waste Treatment of human waste in Treatment of human waste in

developing countriesdeveloping countries Treatment of household wastes in Treatment of household wastes in

place of landfillsplace of landfills Industry-detoxify chemical wastesIndustry-detoxify chemical wastes Portable units- power generationPortable units- power generation

Additional Uses of Additional Uses of Enzymatic Fuel CellsEnzymatic Fuel Cells

AcknowledgmentsAcknowledgments

University of Notre DameUniversity of Notre Dame RET ProgramRET Program Dr. Alex HahnDr. Alex Hahn Dr. Robert NerenbergDr. Robert Nerenberg Dr. Valli SarveswaranDr. Valli Sarveswaran