1. Some Basic Concepts Related to Fuel Cells with a Focus on Microbial and Enzymatic Fuel Cells Nevin Longenecker John Adams High School

2. The PURPOSES of this investigation were to
examine and evaluate variables associated with increasing the efficiency of a microbial fuel cell .
propose and construct a prototype enzymatic fuel cell based on the previous findings.
describe in an educational science journal an inexpensive fuel cell which could be easily constructed and used in a classroom. The operation of such a cell would have diverse applications in many sciences and would integrate mathematical principles from calculus, statistics, algebra and geometry.

3. Advantages of Fuel Cells vs. Internal Combustion Engines
Unlimited supply of fuel
No reliance on foreign oil
Little or no pollutants
Much higher energy conversion %
No moving parts
No noise

4. How Does it Work? ^ V V Anode Chamber Often Platinum Catalyst
Cathode Chamber
Exposed to air
<--
Anode Chamber
Stores fuel
--> ^
Membrane - Allows for H+ passage

5. Microbial Fuel Cells

6. Procedures
A prototype microbial fuel cell was designed and built. (next slide)
Factors affecting microbial fuel cell efficiency were measured and evaluated.
Surface area of electrodes
Bacterial conc. on anode/in solution
Aerobic vs anaerobic conditions
Supplemental O2 sources
Single and mixtures of enzymes were tested in the prototype cell to compare power output.

7. Significant Factors Affecting Microbial Fuel Cell Operation
Type of electrodes
Surface area of electrodes
Use of catalysts on electrodes and PEM
Conc. of hydrocarbon in anode chamber
Agitation of hydrocarbon molecules
Rate of replacement of hydrocarbons
Types of microbes/enzymes
Conc. of microbes/enzymes

8. Examples of microbial-based fuel cells
Microbe
Substrate
Mediator
Anode
Voltage
E coli
Glucose
Methylene
Blue
Pt- C-cloth
625mV
Bacillus
subtilis
Thionine
Vitreous
Carbon
640mV
Acetate
Neutral red
Graphite
felt
250mV
Pseudomona s
methanica
Methane
1-Naphthol-2-
Sulfonate indo-
2,6 dichlorophenol
Pt-black
550mV
Proteus
vulgaris
Sucrose
Carbon rod
350mV

9. Significant Factors Affecting Microbial Fuel Cell Operation
Types of mediators
Conc. of mediators
Distance between electrode and PEM
Type of proton exchange membrane(PEM)
Surface area of PEM
Source of oxygen
Temperature effects

10. Pseudomonas sp.

12. Mediator Shuttling Electrons

13. Types of Electrodes

14. Power Output C rod vs C cloth -aerobic E coli

15. Carbon Rod and Carbon Fiber Electrodes

16. Power Output of C rod Biofilm vs C rod Solution –anaerobic Ecoli

17. Proposed Advantages of Enzyme Use
1. Immediate contact with substrate
2. Elimination of metabolism of
substrate by bacteria
3. Elimination of possible mixing of
hazardous bacterial types
4. If immobilized on electrodes, no
mediators are required.

18. Immobilized Enzyme /Cathode Interaction

19. Glucose Dehydrogenase

20. Partial Composition of PEB Enzyme Solution
Lipase
Protease
Amylase
Hydrolase
Likely-dehydrogenases, lactase, decarboxylase, invertase
Supplied by Enzyme Solutions, Inc

21. PEB EnzymeTrial –anaerobic-C rod

22. PEB Trial C rod Cathode vs Pt Cathode

23. Total Power Output in 22 hrs

24. Long Term PEB Enzyme Action

25. PEB Investigation Trends and Conclusions
1. Optimum power output developed in 2hrs
Whole Ecoli cells PEB solution
0.2 watts/m watts/m2
2. Prolonged power output at 24 hrs
0.14 watts/m watts/m2
3. Prolonged optimum power output continued for 5 days.
4. Pt. coating on the anode did not improve the efficiency of the enzymatic cell.

26. Uses for Implantable Enzymatic Fuel Cells
(To utilize arterial glucose and oxygen with immobilized enzymes on electrodes in a noncompartmentalized cell)
Micropumps-insulin, pain meds, arthritis
Current for-nerve stimulation, hearing aids
Heart pacemaker (cells in series)

27. Immobilized Enzymes on Electrodes

28. Implantable Arterial Fuel Cell

29. Additional Uses of Enzymatic Fuel Cells
Space-regeneration of human waste
Treatment of human waste in developing countries
Treatment of household wastes in place of landfills
Industry-detoxify chemical wastes
Portable units- power generation

30. Acknowledgments University of Notre Dame RET Program Dr. Alex Hahn
Dr. Robert Nerenberg
Dr. Valli Sarveswaran