This document discusses hydrogen fuel cells, including their history, types, and connections to electrochemistry and thermodynamics. It describes how hydrogen fuel cells work through redox reactions, with hydrogen oxidizing at the anode to produce protons and electrons, and oxygen being reduced at the cathode by protons and electrons to produce water. Two main types are alkaline fuel cells, which use an alkaline electrolyte, and proton exchange membrane (PEM) fuel cells, which are more efficient and used in vehicles. Fuel cells can be more efficient than combustion engines and produce only water, making them more environmentally friendly than gasoline-powered vehicles. They may be powered by hydrogen produced through electrolysis using renewable energy.

1. HYDROGEN FUEL CELLS
Karen Wang
Joey Liu

2. Connections
1. Hydrogen Fuel Cells and Re-dox Reactions
2. Alkaline Fuel Cells
3. Hydrogen Fuel Cells and Electrochemistry &
thermodynamics
– Catalyst, anodes, cathodes
• Temperature & efficiency of Hydrogen Fuel
Cells
• 5.4 Hydrogen Fuel Cells and the Environment
• Applications of Hydrogen Fuel Cells– nuclear
energy

3. INTRODUCTION
Fuel Cell Overview

4. Historical Overview
• 1838: discovered by German scientist
Christian Friedrich Schöenbein
• 1839: Demonstrated by Welsh scientist Sir
William Robert Grove

5. What are Fuel Cells?
• Battery that produces electricity
• overall reaction: oxidation of a fuel by oxygen
• 2H2(g) + O2(g)  2H2O(l)
(Hydrogen) Fuel + oxygen  water
• Unlimited fuel supply:
reactants continuously
supplied from an external
source (open system)
• Also known as flow battery
• Used as a stack

6. Types of Fuel Cells
• Molten carbonate cells
• Solid oxide cells
• Direct methanol and other non-hydrogen
cells
• Biofuel cells
• Phosphoric Acid
• Proton Exchange Membrane
• Acid and alkaline cells

7. How Do Fuel Cells Work?
HYDROGEN FUEL CELLS
& ELECTROCHEMISTRY

8. Connection 1: FUEL CELLS
& REDOX REACTION
• oxidation
• Anode (negative electrode): e- leave the cell
• H2  2H+
+ 2e-
• reduction
• Cathode (positive electrode): e- enter the cell
• 4H+
+ 4e-
+ O2  2H2O

9. Connection 2: FUEL CELLS
& CATALYSTS (rate of reaction)
• the splitting of H2 into p+ and e- at the anode is typically
speeded up by the presence of a catalyst (typically metal
placed on the anode, or the electrode itself)
• Platinum film is often used

10. • Electrolyte – permit only appropriate ions to pass
between anode and cathode; otherwise the chemical
reaction may be disrupted
• End product: water = drained

11. Types of Fuel Cells
Connection 3
HYDROGEN FUEL CELLS
ALKALINE & PEM FUEL CELLS

12. TYPES OF HYDROGEN FUEL CELLS
Alkaline Fuel Cells
• Aka: Bacon fuel cell
• Used in NASA since
mid-1960s (Appollo)
• Efficiency – 70%
• hydrogen + oxygen 
water, heat, electricity
PEM Fuel Cells
• Proton Exchange
Membrane (or Proton
Electrolyte Membrane)
• Transport applications
and stationary fuel cell
applications
• Lower temp./pressure
ranges (50-100 )
℃

13. Alkaline Fuel Cells
1. Hydrogen
2. Electron flow
3. Load
4. Oxygen
5. Cathode
6. Electrolyte
7. Anode
8. Water
9. Hydroxyl ions

14. How Hydrogen Fuel Cells Work – PEM
• Proton exchange membrane cells
• A fuel cell produced electricity by combining Hydrogen
and Oxygen atoms electrochemically rather than through
combustion
• Hydrogen = fuel  electrolysis – stored as a compressed
gas/liquid/metal compound
• A single fuel cell consists of an anode and a cathode with
an electrolyte in between
• Hydrogen molecules enter the anode  react with
catalysts (1)  split into H+ & e-  H+ pass through
electrolyte, e- directed through an external circuit =
electrical current
• Oxygen molecules enter at the cathode + H+
+ e- 
water & heat
• Individual fuel cells placed in a series = fuel cell stack 
power vehicle

17. HYDROGEN FUEL CELLS
& REDOX REACTION
Alkaline Fuel Cells
@ Anode, H2 is oxidized:
H2 + 2OH-
 2H2O + 2e-
H2  2H+
+ 2e-
Electrons flow through an external circuit and return to the cathode, reducing
oxygen:
O2 + 2H2O + 4e-
 4OH-
4H+
+ 4e-
+ O2  2H2O
PEM Fuel Cells

18. HYDROGEN FUEL CELLS
AS AN ENERGY SOURCE

19. Connection 4: HYDROGEN FUEL CELLS
& EFFICIENCY and
THERMODYNAMICS
• Automobile internal combustion engines
• inefficient – 25%
• Rechargeable batteries (modified lead-acid, nickel-
cadmium batteries)
• Run down quickly – 250 Km
• Recharged from external electrical source
• Takes hours
• Fuel cells
• Efficient – 80%

20. Connection 4: HYDROGEN FUEL CELLS
& EFFICIENCY and
THERMODYNAMICS
• Fuel cells create electricity chemically; ,
unlike combustion
are not subject to thermodynamic laws
• ∴ fuel cells are more efficient
• Some waste heat can also be harnessed

21. Connection 5: HYDROGEN FUEL CELLS
& THE ENVIRONMENT
• Automobile engines: gasoline = pollutants
• CO2, Nox, VOCs
• health & environmental problems: smog, greenhouse
effect
• Electric cars: hydrogen fuel cells = pollution free
• Cleaner, quieter, more efficient
• Product: water vapour

22. Connection 5: HYDROGEN FUEL CELLS
& THE ENVIRONMENT
• Production of hydrogen fuel – unnatural resource
• Hydrocarbon fuels (petroleum, methane) = pollution
• Electrolysis of water powered by solar energy or
hydroelectricity = low pollution
• Renewable energy source

23. systems
• Fuel cell powered cars
• http://www.youtube.com/watch?v
=oy8dzOB-Ykg
• Efficiency, pollution-free

24. Connection 6: HYDROGEN FUEL CELLS
AS AN ENERGY SOURCE
• Production of hydrogen fuel – unnatural resource
• Hydrocarbon fuels (petroleum, methane) = pollution
• Electrolysis of water powered by solar energy or
hydroelectricity = low pollution

25. Connection 6: HYDROGEN FUEL CELLS
& NUCLEAR ENERGY
• Implementation scenarios
• Fossil
• nuclear

26. References
• (Sørensen), B. S. (2005).Hydrogen and Fuel Cells: Emerging
Technologies and Applications (Sustainable World). Toronto:
Academic Press.
• Harkin, T., & Hoffmann, P. (2001). Tomorrow's Energy:
Hydrogen, Fuel Cells, and the Prospects for a Cleaner Planet.
London: The Mit Press.
• Holland, G., & Provenzano, J. (2007). Hydrogen Age, The.
Layton: Gibbs Smith, Publisher.
• ollecting the History of Proton Exchange Membrane Fuel
Cells. (n.d.). National Museum of American History. Retrieved
April 20, 2010, from
http://americanhistory.si.edu/fuelcells/basics.htm