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Hydrogen Fuel Cells

Hydrogen Fuel Cells. Trends in the Use of Fuel. 19 th century: steam engine. 20 th century: internal combustion engine. 21 st century: fuel cells. The History of Fuel Cells. Electrolyser. Grove’s Gas Battery. (first fuel cell, 1839). (after Larminie and Dicks, 2000).

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Hydrogen Fuel Cells

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  1. Hydrogen Fuel Cells Heliocentris: Science education through fuel cells 1

  2. Trends in the Use of Fuel

  3. 19th century: steam engine 20th century: internal combustion engine 21st century: fuel cells

  4. The History of Fuel Cells Electrolyser Grove’s Gas Battery (first fuel cell, 1839) (after Larminie and Dicks, 2000)

  5. Photo courtesy of University of Cambridge Bacon’s laboratory in 1955

  6. Photo courtesy of NASA NASA Space Shuttle fuel cell

  7. Applications for Fuel Cells Transportation vehicles Photo courtesy of DaimlerChrysler NECAR 5

  8. Applications for Fuel Cells Distributed power stations Photo courtesy of Ballard Power Systems 250 kW distributed cogeneration power plant

  9. Applications for Fuel Cells Home power Photo courtesy of Plug Power 7 kW home cogeneration power plant

  10. Applications for Fuel Cells Portable power 50 W portable fuel cell with metal hydride storage

  11. The Science of Fuel Cells Alkaline(AFC) Polymer Electrolyte Membrane (PEMFC) Phosphoric Acid(PAFC) Polymer Electrolyte Membrane(PEMFC) Types of Fuel Cells Molten Carbonate(MCFC) Direct Methanol (DMFC) Direct Methanol(DMFC) Solid Oxide(SOFC) Solid Oxide (SOFC)

  12. PEM Fuel Cell Electrochemical Reactions Anode: H2 2H+ + 2e- (oxidation) Cathode: 1/2 O2 + 2e- + 2H+ H2O (l) (reduction) Overall Reaction: H2 + 1/2 02 H2O (l) ΔH = - 285.8 kJ/mole

  13. A Simple PEM Fuel Cell Hydrogen + Oxygen  Electricity + Water Water

  14. Membrane Electrode Assembly (MEA) C a t a l y s i s Oxidation - 4 e Platinum- catalyst T r a n s p o r t H 2 2 H + 2 4 H R e s i s t a n c e N a f i o n O 2 H O 2 Reduction Platinum- catalyst + H Anode K Cathode - - 4 4 e e O O Polymer electrolyte (i.e. Nafion) 2 2 N a f i o n + + Carbon cloth Carbon cloth 4 4 H H 2 2 H H O O 2 2 N N a a f f i i o o n n 2

  15. Polymer Electrolyte Membrane Polytetrafluoroethylene (PTFE) chains Water collects around the clusters of hydrophylic sulphonate side chains Sulphonic Acid 50-175 microns (2-7 sheets of paper) (after Larminie and Dicks, 2000)

  16. Thermodynamics of PEM Fuel Cells Change in enthalpy (ΔH) = - 285,800 J/mole Gibb’s free energy (ΔG) = ΔH - TΔS ΔG at 25° C: = - 285,800 J - (298K)(-163.2J/K) = - 237,200 J Ideal cell voltage (Δ E) = - ΔG/(nF) ΔE at 25º C = - [-237,200 J/((2)(96,487 J/V))] = 1.23 V ΔG at operating temperature (80º C): = - 285,800 J - (353K)(163.2 J/K) = - 228,200 J ΔE at 80º C = - [-228,200 J/((2)(96,487 J/V))] = 1.18 V

  17. Characteristic Curve Power Curve activation losses + internal currents 1.2 MPP 2.5 ohmic losses 1 x concentration losses 2 0.8 1.5 P V 0.6 1 0.4 0.5 0.2 0 0 0 1 2 3 4 0 1 2 3 4 5 I I • Factors Affecting Curve: • activation losses • fuel crossover and internal currents • ohmic losses • mass transport or concentration losses Max Power Point (MPP):

  18. Hydrogen Storage 56 L 14 L 9.9 L Compressed gas (200 bar) Liquid hydrogen MgH2metal hydride Liters to store 1 kg hydrogen

  19. H2 H2 H2 H2 H2 H2 Fuel tank Reformer Hydrogen bottles Hydrogen bottles Hydrogen bottles Electrolyser Solar panel Algae Hydrogen: Energy Forever

  20. Renewable Energy Sources As long as the sun shines, the wind blows, or the rivers flow, there can be clean, safe, and sustainable electrical power, where and when required, with a solar hydrogen energy system

  21. The Benefits of Fuel Cells Clean Modular Quiet Benefits of Fuel Cells Safe Sustainable Efficient

  22. Our Fragile Planet. We have the responsibility to mind the planet so that the extraordinary natural beauty of the Earth is preserved for generations to come. Heliocentris: Science education through fuel cells 22 Photo courtesy of NASA

  23. Presentation courtesy of Heliocentris

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