Hydreogen fuel cell

1. HYDROGEN FUEL CELLS
Presented by Amit sen

2. Connections
1. Hydrogen Fuel Cells and Re-dox Reactions
2. Alkaline Fuel Cells
3. Hydrogen Fuel Cells and Electrochemistry &
thermodynamics
1. Catalyst, anodes, cathodes
4. Temperature & efficiency of Hydrogen Fuel
Cells
5. 5.4 Hydrogen Fuel Cells and the Environment
6. 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.ht
m