Some Basic Concepts Related to Fuel Cells with a Focus on Microbial and Enzymatic Fuel Cells Nevin L

1
Some Basic ConceptsRelated to Fuel
Cellswith a Focuson Microbial and
EnzymaticFuel CellsNevin LongeneckerJohn
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 Cellsvs.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?
How Does it Work?

• Often Platinum Catalyst

V V

• Cathode Chamber
• Exposed to air

lt--

• Anode Chamber
• Stores fuel

--gt

• 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 AffectingMicrobial 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
9
Significant Factors AffectingMicrobial 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.
11
(No Transcript)
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/m2 2.1 watts/m2
• 2. Prolonged power output at 24 hrs
• 0.14 watts/m2 2.05 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 forImplantable 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