1. Fuel Cells and the Hydrogen Economy
July 2012
Sustainable Energy Workshop for Science and Technology Teachers (SEWFSTT)
Module 2
Fuel Cells and the Hydrogen Economy
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2. Module 02: Fuel Cells - Outline
Definition and Overview
PEM Fuel Cells
Teaching about Fuel Cells
Cellular Structure – Batteries Relationship
The Hydrogen Economy
Challenges and Advantages

3. Fuel Cells
July 2012
Section 01: Definition and Overview Goal: Understand basic structure of a fuel cell
Basic definition of a fuel cell
Central chemistry of fuel cells
Overview of types of fuel cells
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4. Fuel Cells Fuel Cells July 2012
Top:
Lower Left:
Middle Top:
Middle Bottom:
Upper Right:
Lower Right: Pictures from Kettering Sustainable Energy Event, Sept. 2006:
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5. Discussion: Prior Exposure with Fuel Cells
July 2012
Discussion: Prior Exposure with Fuel Cells
(outside of the automotive industry)
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6. Fuel Cells come in all shapes and sizes
July 2012
Fuel Cells come in all shapes and sizes 2 6 8 7 4 7
1) Pictures from Kettering Sustainable Energy Event, Sept. 2006: 2)
3) Toshiba MP3 4) 5)
6) KeelyNet
7) Pictures from Kettering Sustainable Energy Event, Sept. 2006: 8)
9) Pictures from Kettering Sustainable Energy Event, Sept. 2006: 3 5
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7. Basic Definition of a Fuel Cell
Fuel Cells
Basic Definition of a Fuel Cell
July 2012
Electrochemical Energy Conversion Device
Key difference – fuel cells will have ‘flow through’ properties
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8. Different Kinds of Fuel Cells
July 2012
What makes them different? Electrolyte, Operating Temperature … (Application)
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9. Section 02: PEM Fuel Cells Goal: Detailed understanding of operation of PEM fuel cells
Central Chemistry - Redox
General Process in Fuel Cell
Structure/Parts of a Fuel Cell
Step-by-Step Operations

10. Energy Conversion: PEM Fuel Cell
Fuel Cells
Energy Conversion: PEM Fuel Cell
July 2012
Hydrogen and oxygen are combined in a non-combustion process
Electricity, heat and water are produced
Reduction-Oxidation Rxn (redox)
Oxidation refers to the loss of electrons, while reduction refers to the gain of electrons.
The anode is the electrode where oxidation occurs and mass is lost where as the cathode is the electrode where reduction occurs and mass is gained.
Anode Half-Reaction
Cathode Half-Reaction
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11. Electric Potential Developed
Fuel Cells
July 2012
Electric Potential Developed
Redox potential is a measure of a substance’s electronegativity (affinity for electrons)
“Downhill” in Energy Diagram -- Free energy
Don’t have oxidation reaction without reduction reaction present at same time (matched set)
Nernst Equation
Calculation of electric potential in “non-ideal” circumstances
Oxidation Half-Reaction
V(SHE) = Standard Hydrogen Electrode  defined as zero for Hydrogen (uses Hydrogen as reference point)  4.4V
1.23 V is open-circuit potential
Reduction Half-Reaction
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12. Proton Exchange Membrane Fuel Cell
Fuel Cells
July 2012
Proton Exchange Membrane Fuel Cell
(Polymer Electrolyte Membrane)
Oxidation reaction facilitated by a catalyst - typically Pt ($$$)
Between the reduction and oxidation stages, the electrons are routed through a circuit
Hydrogen ions (protons) permeate through the electrolyte membrane
Reduction reaction
1.23 V
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13. Power Produced – Watts/m2
Activation Loss
potential difference above the equilibrium value required to produce a current (depends on activation energy of the reaction)
energy is lost as heat
Ohmic Loss
voltage drop due to resistance of the cell components and interconnects
Mass Transport Loss
depletion of reactants at catalyst sites under high loads

14. PEM (Polymer Electrolyte Membrane)
Polymers such as polyphenylenes, Nafion are used
Water is a crucial participant in the process
absorption of water increases the proton conductivity
membrane is confined – not free to swell – pushes electrodes

15. PEM (Polymer Electrolyte Membrane)
Fuel Cells
July 2012
PEM (Polymer Electrolyte Membrane)
Thickness of the membrane and catalyst in the PEM can vary …
Example: catalyst layers containing about 0.15 milligrams (mg) Pt/cm2
thickness of the catalyst layer is close to 10 micrometers
yields a MEA with a total thickness of about 200μm (or 0.2 mm or 20 sheets of paper)
generates more than half an ampere of current per cm2 at a voltage of 0.7 volts
Platinum needs to be placed to maximize surface area
Needs to be encased in engineered components
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16. Design Goals: Limited Overview
Deliver Hydrogen
Deliver Oxygen
Chemical reaction – what can influence rate of reaction
Water Management
Maintain hydration levels
Remove water by-product
Efficient path for electrons to ‘migrate’ to electrodes
Thermal management

17. Parts of a Fuel Cell Bipolar Plates Anode Cathode
Fuel Cells
July 2012
Bipolar Plates
Serpentine channels for hydrogen and oxygen to flow through device
Acts as a current collector – electrons enter and exit cell through the plate
Anode
Conducts electrons away from catalyst to external circuit
Channels to supply H2 evenly to the surface of the catalyst
Cathode
Channels to supply O2 evenly to the surface of the catalyst
Conducts electrons back to catalyst for recombining
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18. Parts of a PEM Fuel Cell Membrane Electrode Assembly Anode Cathode
Fuel Cells
Parts of a PEM Fuel Cell
July 2012
Membrane Electrode Assembly
Anode
Cathode
PEM (Polymer Electrolyte Membrane)
conducts only positively charged ions
blocks electrons and other substances
Catalyst
thin coat of platinum powder applied to carbon paper or cloth
maximizes surface area
Backing Layers
porous carbon cloth conducts electrons away from catalyst to external circuit
allows right amount of water vapor to enter/exit
too much blocks the pores
membrane needs to be humidified
Bottom:
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19. Schematic of Fuel Cell Operation
Fuel Cells
July 2012
Schematic of Fuel Cell Operation
1.2 V = theoretical maximum voltage generated by this reaction
Typical output = 0.7V – 0.9V ….. (1 W per cm2)
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20. Schematic of Fuel Cell Operation
Fuel Cells
July 2012
Schematic of Fuel Cell Operation
Anode
Hydrogen gas is circulated through ‘serpentine’ channels
Hydrogen from channels passes through porous medium
(gas diffusion backing)
Electron is stripped from Hydrogen as it makes contact with Pt catalyst which is embedded in a carbon nanoparticle
Hydrogen nucleus (proton) passes through PEM membrane to cathode
Electron conducted away through circuit
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21. Schematic of Fuel Cell Operation
Fuel Cells
July 2012
Schematic of Fuel Cell Operation
Cathode
Oxygen gas is circulated through ‘serpentine’ channels
Oxygen from channels passes through porous medium
(gas diffusion backing)
Electrons from circuit come in to contact with Oxygen atom and Protons (Hydrogen nuclei) passing through the PEM membrane
Hydrogen and Oxygen recombine to form water & exit
Excess Oxygen exits the fuel cell
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22. Activity: PEM Fuel Cell Car (Pairs)
Fuel Cells
July 2012
Activity: PEM Fuel Cell Car (Pairs)
Outline:
Produce hydrogen and oxygen via electrolysis
Use stored H2 and O2 to generate electricity and drive motor
Educational Objectives for this Activity:
Recognize H2 and O2 as portable fuels: same role as gasoline in an IC engine
Recognize that a separate process is required to produce hydrogen
Observation of the relationship between the volumes of displaced water in the hydrogen and oxygen tanks (and relationship to redox equations)
Recognize that the hydrogen and oxygen produced came from initial injection of water
Discussion of extension activities
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23. Parts Identification Battery components Chassis Fuel Cell
Battery pack
2 AA Batteries
Connection Cable
Add batteries to battery pack
Chassis
Fuel Cell
Identify Hydrogen and Oxygen side
Incredibly important!
H2 and O2 Storage Tanks
Two cylinders + 2 cup-like caps w/ long hoses attached
… but wait … there’s more …

24. Parts Identification Hydration Components Syringe
Two short, narrow tubes with black and red caps
Short length of wide tubing
90mL of distilled water + cup
Very important - needs to be distilled water (NOT Purified water)
Why?
If you do not ALSO have a short length of wide tubing, you’re OK – just remove the black plug and use the narrow tube

25. Hydrate Fuel Cell
Fill the syringe with distilled water and (gently) inject a small amount in to the LOWER nozzle on the HYDROGEN side
You will see the water fill in the fuel cell – you can go all the way until the water pours out the top nozzle.
GENTLY
Remove the syringe and insert the tube with the black cap in the LOWER nozzle

26. Hydrate Fuel Cell
Fill the syringe with distilled water and (gently) inject a small amount in to the LOWER nozzle on the OXYGEN side
You will see the water fill in the fuel cell – you can go all the way until the water pours out the top nozzle.
Remove the syringe and insert the tube (red cap) in the LOWER nozzle
GENTLY O2

27. Prepare to Generate Hydrogen and Oxygen
Insert the cup-like caps in to the Hydrogen and Oxygen tanks
0 mL
Align the notch in the cap with the gap in the tank
we want to allow trapped air to escape when we fill the tanks with water
Fill the tanks to the zero (0) mL mark with distilled water
Suggestion: Use the syringe (each will take about 30mL)

28. Prepare to Generate Hydrogen and Oxygen
Connect the tank hoses to the upper nozzles on their respective sides (i.e. Hydrogen tank to Hydrogen nozzle)
Don’t forget to connect the Oxygen side too!

29. Prepare to Generate Hydrogen and Oxygen
Make sure battery pack is turned off
Connect battery pack to connector
Connect banana plugs to fuel cell (black to black, red to red)
Don’t turn it on yet …..

30. (Black-to-Black, Red-to-Red)
Double -Check
Double check connections
(Black-to-Black, Red-to-Red)
Turn on the battery pack and observe the production of H2 and O2

31. Disconnect Battery Pack
You now have a full ‘gas tank’ and a flow-through battery
Need a DC motor and wheels to drive a car

32. Transfer Assembly to Car and Connect Motor
As a unit, transfer the gas tanks and the fuel cell to the car chassis
Connect the banana plugs from the motor to the fuel cell (black-to-black) to begin operation
Be careful moving the tanks – a leak at this stage means you are “out of gas”!

33. Comments
Fuel cells need to be hydrated in order to run properly, if a fuel cell has been sitting un-used for a long time it may need a soaking rest to re-hydrate.
Running the car is the least of the objectives of this exploration
Since the fuel cell is used for the electrolysis of water, many people get confused and think that a perpetual motion machine can be created by taking the water waste from the cell and using the electricity generated by the fuel cell to generate more Hydrogen.

34. Reflection Amount of hydrogen and oxygen produced during electrolysis
Source for all this power – the original fuel?
Moving the gas tanks to the car – Production of H2? Where?

35. Activity: Construct a PEM Fuel Cell
Fuel Cells
July 2012
Activity: Construct a PEM Fuel Cell
A small, single cell, PEM fuel cell can easily be constructed
Source of hydrogen needed
Chemical reaction
Fuel cell production + storage
Kits:
Helpful hint: accordion
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36. Activity

37. Comments
Fuel cells need to be hydrated in order to run properly, if a fuel cell has been sitting un-used for a long time it may need a soaking rest to re-hydrate. Try placing it in a plastic bag with a wet towel for a few hours

38. Section 03: Teaching about Fuel Cells Goal: Exploration of techniques and methods for instruction
Curricular Objectives
Available Animations
Survey of available resources
Critique based on current understanding
Energy Chain for Fuel Cells
Identification of energy input for electrolysis
Motivation for Hydrogen economy
Available Levels of Instruction

39. Educational Objectives – Curricular Connections

40. Discussion: Available Animations

41. Energy Chain for Fuel Cells
Are there associated societal issues associated with fuel cells (power generation &/or propulsion?)
Something is missing here ….

42. Energy Chain for Fuel Cells?!

43. Multiple Instructional Levels
Exposure/Exploration
Process understanding
Chemical Reaction
Rate of reaction: dependence on pressure, temperature, etc.
Load Impact on Cell Efficiency
High voltage vs. low voltage applications
Activation energy

44. Activity: Fuel Cell Stack
July 2012
Activity: Fuel Cell Stack
Exploration of a pressurized fuel cell stack
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45. Activity

46. Comments

47. Section 04: Cellular Structure (Batteries) Goal: Relationship between fuel cells & common batteries
Battery Construction
Battery Chemistry
Comparison
Fuel Cell as a Stationary Power Generator
Fuel Cell: Propulsion Application

48. Different From a Battery?
Fuel Cells
July 2012
Redox (Oxidation-Reduction Reaction)
Left:
Middle:
Right:
Baghdad Battery – 250 BC
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49. Lead-Acid Batteries e.g. car batteries, deep-cycle batteries
Fuel Cells
Lead-Acid Batteries
July 2012
(2V per cell)
e.g. car batteries, deep-cycle batteries
Energy-to-weight ratio very low
Energy-to-volume ratio: low
But ….Power-to-Weight ratio: LARGE
Left:
Right:
RECHARGABLE
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50. NiMH (Nickel-metal hydride) Batteries
Fuel Cells
July 2012
NiMH (Nickel-metal hydride) Batteries
RECHARGABLE
e.g. hybrid vehicles
Top Left:
Bottom Left;
Bottom Right:
Lithium-ion batteries are also an option for hybrids
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51. Regenerative Braking – Hybrid Vehicles
Fuel Cells
July 2012
Regenerative Braking – Hybrid Vehicles
Friction brakes dissipate car’s kinetic energy as heat
eCorner. The wheel rim (1) remains the same. Beneath is the wheel hub motor (2). Braking is via electronic wedge brake (3). The active suspension (4), like the electronic steering (5), replaces the conventional hydraulic system.
Apply the brake ----
Car’s electronics switch Electric Traction Motor to
a generator
Wheel spins – load applied (generates electricity to
charge battery)
Reverse torque applied to wheels – slowing the car down
Left:
Middle Top:
Top Right:
Middle Bottom:
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52. Similarities and Differences
Chemical potential energy converted in to Electric potential energy
Cellular structure
Redox reactions
Differences
Passage of H2 and O2 thru vs. storage of chemicals in battery
Flow battery

53. Cellular Structure of Fuel Cells
July 2012
Cellular Structure of Fuel Cells
Batteries in series
Left: (c Johnson Matthey)
Middle:
Right:
Can do all of the series/parallel experiments that one does with batteries
Fuel cells are essentially flow-through batteries
Challenge is getting H2 and O2 uniformly to all of the cells
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54. Stationary Power Facility: Stacks
Fuel Cells
July 2012
Stationary Power Facility: Stacks
5 kW Fuel Cell System, Manufactured by PlugPower, Installed at a USDOD Facility
5 PC 25TM Fuel Cells sited in Anchorage, Alaska (International Fuel Cells, LLC)
Top Left:
Bottom Left:
Right:
200-kW ,000 BTU heat
PAFC (Phosphoric Acid Fuel Cells)
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55. Parts of a PEM Fuel Cell System
July 2012
Propulsion System
Left:
Right: VW’s HTFC
Automotive Application
Volkswagen’s HTFC
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56. Section 06: The Hydrogen Economy Goal: Understand infrastructure issues with fuel cells
Definition: Hydrogen Economy
Infrastructure Planning
Hydrogen Production Methods
Hydrogen Delivery Methods
Hydrogen Safety Issues

57. The Hydrogen Economy Hydrogen as a storage medium for energy
Fuel Cells
July 2012
Hydrogen as a storage medium for energy
Problem: Hydrogen does not occur naturally in nature as H2
Left:
Right:
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58. The Hydrogen Economy Infrastructure
Fuel Cells
July 2012
Infrastructure
How does one go about developing a production, delivery and use system for an energy storage medium that is only in its infancy
Right:
Left:
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59. Hydrogen Production and Delivery
Fuel Cells
July 2012
Hydrogen Production and Delivery
Advantage: Hydrogen is storage medium – Production from a variety of sources
Currently: Steam Reforming of Natural Gas
Biological Water Splitting
Photoelectrochemical Water Splitting
Reforming of Biomass and Wastes
Solar Thermal Water Splitting
Renewable Electrolysis
Community Adoption – Priming the Pump
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60. Fuel Cells
July 2012
Hydrogen Storage
Hydrogen is not an ‘energy dense’ fuel (need lots to go anywhere)
Pressurized Steel and Composite Tanks
Hydrogen can cause metals to become brittle (not good!)
Metal Hydride
H2 is locked in another chemical
Chemical reaction releases that metal
Micropore Storage
Buckyballs & nanoscale methods
Left:
Metal Decorated Nanostructures
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61. The Hydrogen Safety Movie
Fuel Cells
The Hydrogen Safety Movie
July 2012
It’s not what you may think
Left:
Right:
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62. Section 07: Challenges and Advantages Goal: Listing of Future Directions

63. Discussion: Synthesis of Fuel Cell

64. Challenges for PEM Fuel Cells
July 2012
Platinum: reduction of amt of material used = reduced cost
Wikipedia: cost was $1,000 per kW
Water management
Too little --- membrane dries up
Too much --- pores blocked, efficiency drops
Steady Fuel Supply
Controlling amount of incoming gas + pressure
Poisoning of the anode by carbon monoxide
Temperature control
This technology is coming out of its infancy …..
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