Biofilms: Potential forBiofilms: Potential for Energy Productiongy

OEST 740OEST 740022208

OutlineOutline

Introduce fuel cellsIntroduce fuel cells

Enzyme Fuel Cells

Mi bi l F l C llMicrobial Fuel Cells

New Improvements to MFC

Comparison

SummarySummary

Fuel Cells

Francis Bacon 1932Francis Bacon - 1932

Enzyme Fuel Cellsy

- +

e-

- +

e-

Ethanol

ADHNAD+ H2O

H+Ethanol

ADHNAD+ H2O

H+H+

2e-Acetaldehyde NADH

H+

P t

½ O2

Anode Cathode

2 H+2e-2e-Acetaldehyde NADH

H+

P t

½ O2

Anode Cathode

2 H+

Proton ConductiveMembrane

Anode Proton ConductiveMembrane

Anode

Microbial Fuel Cells

“The disintegration of organic compounds by g g p ymicroorganisms is accompanied by the liberation of electrical energy” M.C. Potter, 1911H b id f bi l i l d l t h i l tHybrid of biological and electrochemical reactors

Why Biofilms?Why Biofilms?

Sometimes it is good to be so bad!Sometimes it is good to be so bad!Resistant to many toxic chemicalsPhysically robustPhysically robustLong-term stabilityA l ti f EPSAccumulation of EPS

Opportunity for continuous long-termMFC

Indirect Microbial Fuel CellIndirect Microbial Fuel Cell

Mediator-driven Microbial Fuel Cell

Direct Electron TransferDirect Electron Transfer

2-Chambered Microbial Fuel Cell

Self-generated mediatorsSelf generated mediators

Electron shuttlesElectron shuttlesGeothrix ferementansPsuedomonas sppPsuedomonas spp.

Energy expensiveMust be recycled

Competitive disadvantage in open environments

Microbial NanowiresMicrobial Nanowires

Electricigens – novel microbial respirationElectricigens novel microbial respirationGeobacteraceae

GeobacterGeobacterDesulfuromonas

Shewanella sppShewanella spp.Pili

Seek outSeek out and establish

t tcontact

.he

Microbial NanowiresMicrobial Nanowires

Electrically Conductive PiliElectrically Conductive Pili

Geobacter sulfurreducensGeobacter sulfurreducens

Pathway for Anaerobic oxidation of OM

Sediment Microbial Fuel CellSediment Microbial Fuel Cell

SRB – Helping handsSRB Helping hands

ComparisonComparison

F l C ll E F l C ll Mi bi l F l C llFuel Cell Enzyme Fuel Cell Microbial Fuel Cell

Expensive catalysts Only harvest small percentage of electrons

Catalyze fuels inside cell

Operate at high temperature Better developed technology Room temperature

Fuels – highly explosive or toxic

Good power/size ratio Diverse range of ‘dirty’ fuels

Highly purified Possibility of 90%extraction

Complex highly regulated di ib i

Self sustaining and renewingdistribution systems

50 W/m3 cell

SummaryyMicrobial Fuel Cells- offer a safe and stainable

f l i i d imeans for electricity productionBiofilms can enhance MFC increasing longevity and efficiency Electicigens – possibility of efficiently g p y yconverting organic compounds into electricity in self-sustaining systems with long term g y gstability

Oxidize OM with electrode as electron acceptor pwhile conserving energy for growth