Fuel Cells

1
Fuel Cells

• Presented By
• -Taylor Morton
• -Chris Irvine

2
Overview

• Not self contained
• Reactants enter cell
• Products leave cell
• Use combustion to produce electricity
• E- transferred
• through external
• circuit

Source http//www.aerospaceweb.org/question/propu
lsion/jet/combustion.gif
3
PEM(Proton Exchange Membrane)

• A.K.A. Hydrogen Fuel Cell
• Operating temp. 80ºC
• Requires electrocatalyst
• Electrodes
• Platinum based
• Graphite
• Sulfonated perfluroethylene

4
PEM continued

• Anode 2H2(g) ---gt 4H(aq) 4e-
• Cathode O2(g) 4H(aq) 4e- ----gt 2H2O(g)
• Overall 2H2(g) O2(g) ----gt 2H2O(g)
• Process
• 2 H2 absorbed
• 2 e- from each H2 travel externally
• 2H hydrate and migrate
• O2 absorbs e-
• O2- receives H
• H20 formed

Source http//physics.nist.gov/MajResFac/NIF/Imag
es/FuelCellBasic.gif
5
Efficiency

• No Pollutants
• Other environmental impact
• How is H2 obtained?
• Viability
• PEM 75
• Coal-fired 40
• Petroleum in ICE 25

6
Microbial Fuel Cells

• Using microorganisms to generate energy

7
What it is!

• Converts chemical energy to electrical energy by
  the catalytic reaction of microorganisms
• Exact same principle as a voltaic cell, only
  using the respiration of bacteria to generate
  electricity

8
Mediated

• Methylene Blue, thionine, or humic acid
• Mediator acts as electrolyte
• Facilitates e- transfer from microbial cells to
  the electrode
• Mediator is necessary because most microbes are
  electrochemically inactive

9
Its just science

• mediator crosses the outer membrane
• Accepts e- that would normally be taken up by O2
• e- laden mediator exits cell and transports e- to
  anode
• after e- deposition, mediator returns to original
  oxidized state

10
Mediator-less S. putrefaciens

• Electrochemically active bacteria usually have
  cytochromes (or other redox enzyme) in their
  outer membranes that can transfer e-
• e- are carried directly to the anode

11
(No Transcript)
12
C12H22O11 13H2O ---gt 12CO2 48H 48e-

• The biofilm is attached to the anode
• Anaerobic conditions force bacteria to respire
  anaerobically (duh)

13
Now what?

• Waste Water Plants
• Power stations based on plants/algae