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Hydrogen Utilization - Fuel Cell

Hydrogen Utilization - Fuel Cell. Shou-Shing Hsieh Department of Mechanical and Electro-Mechanical Engineering National Sun Yat-Sen University Kaohsiung,Taiwan November 18, 2009. Items. What is energy ？ Kyoto Protocol Hydrogen Energy Fuel Cell Types of Fuel Cell

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Hydrogen Utilization - Fuel Cell

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  1. Hydrogen Utilization -Fuel Cell Shou-Shing Hsieh Department of Mechanical and Electro-Mechanical Engineering National Sun Yat-Sen University Kaohsiung,Taiwan November 18, 2009

  2. Items • What is energy？ • Kyoto Protocol • Hydrogen Energy • Fuel Cell • Types of Fuel Cell • Micro Fuel Cell • Experimental Results • Fuel Cell Stack Design • Micro Fuel Cell Stack Design • Bipolar Plate Fabrication • Experimental Results • Conclusions • References S.S. Hsieh ppt. 01

  3. What is energy ? The capacity for doing work as measured by the capability of doing work (potential energy) or the conversion of this capability to motion (kinetic energy). Most of the world's convertible energy comes from fossil fuels that are burned to produce heat that is then used as a transfer medium to mechanical or other means in order to accomplish tasks. S.S. Hsieh ppt. 02

  4. Types of Energy • Fuel cells(Hydrogen Energy) • Coal • Oil & Natural Gas • Nuclear • Geothermal • Solar energy • Hydro power • Wind power • Biomass S.S. Hsieh ppt. 03

  5. Energy Crisis If we continue to consume energy on such a scale , we may face a petroleum shortage in the latter half of the 21st century, according to some predictions. Though nobody is certain how much petroleum is left , one thing is certain - at some point we will run out. Because people used a large number of the fossil fuel, discharge the carbon dioxide in a large amount. These then cause global warming and, consequently , influence the human ecology. S.S. Hsieh ppt. 04

  6. Kyoto Protocol The Kyoto Protocol is a legally binding agreement under which industrialized countries will reduce their collective emissions of greenhouse gases (CO2、CH4、N2O、SF6 HFCs、PFCs) by 5.2 % compared to the year 1990 from 2008 to 2012. Their countries emissions target: EU-15 reduce 8 % US reduce 7 % Canada, Hungary, Japan, Poland reduce 6 % Croatia reduce 5 % New Zealand, Russian Federation, Ukraine reduce 0 % Norway, increase 1 % Australia, increase 8 % Iceland, increase 10 % S.S. Hsieh ppt. 05

  7. Hydrogen Energy Hydrogen is a chemical element that carries energy. It can be stored in either liquid or gaseous form. Today, hydrogen is not a substance we consciously encounter in everyday life, although it is used extensively in many industries. It is normally bound to other substances, it is colourless, odourless, non-toxic and when it burns in air, that reaction produces only water. S.S. Hsieh ppt. 06

  8. Hydrogen Energy(continued) Besides the fuel of boiler and steam turbine, the hydrogen can often be used to the fuel cell to generate electricity most directly, because it actually generates electricity efficiency up to 40%~60%. S.S. Hsieh ppt. 07

  9. Hydrogen Applications The applications of hydrogen energy are following : • As the fuel of the fuel cell • As the fuel of family • As the fuel of the vehicle engine or the energy of the electronic device • As the fuel of the aircraft • As the materials of the chemical industry • As the fuel of the boiler and steam turbine S.S. Hsieh ppt. 08

  10. Hydrogen Fuel Stations • Hydrogen Fuel Stations – Worldwide accumulated, sorted by region (1995-2009) S.S. Hsieh ppt. 09

  11. Hydrogen for Fuel Cell The electrons flow from the fuel cell's anode to cathode, thereby generating electricity. Meanwhile , the hydrogen atoms that have shed their electrons become hydrogen ions and travel through a polymer electrolyte membrane to reach the cathode side. There, with the help of a catalyst on the cathode, the hydrogen ions and electrons join with oxygen to form water. S.S. Hsieh ppt. 10

  12. Fuel Cell Fuel cell is a device that converts the chemical energy of a fuel and an oxidant directly into electricity. The principal components of a fuel cell include electrodes (anode and cathode), and membrane- electrode assembly (MEA). Fuel cell stacks available and under development are silent, produce no pollutants, have no moving parts , and have potential fuel efficiencies far beyond the most advanced reciprocating engine or gas turbine power generation systems. S.S. Hsieh ppt. 11

  13. (1) Air outlet • End plate • Current collector • Flowfield plate • Gasket • MEA (2) (3) Air inlet (4) (5) (4) (3) (2) (1) H2 inlet H2 outlet Fuel Cell ( continued ) • A Traditional Design of PEMFC S.S. Hsieh ppt. 12

  14. Fuel Cell ( continued ) • High efficiency to produce energy * LHV = lower heating value. * A thermodynamic term that indicates the heat needed to raise steam from liquid water. (From :http://www.broadcastpapers.com/m 20091019) S.S. Hsieh ppt. 13

  15. Fuel Cell Advantages • Working time is longer than the traditional batteries • It can offer energy for a long time when the hydrogen supply with. • Short time in supplement fuel process • After the fuel is used up, then it can run once again if we supply • the hydrogen constantly. • Clean in the energy production process • The products are only water and heat. S.S. Hsieh ppt. 14

  16. Types of Fuel Cell S.S. Hsieh ppt. 15

  17. PEMFC Anode Reaction Cathode Reaction Total Reaction Ideal Voltage 1.23V ( From : http://fuelcellsworks.com 20091019) S.S. Hsieh ppt. 16

  18. PEMFC (continued) This type of fuel cell operates at low temperatures (25OC), and has a high power output density, and can vary output to meet demand. It is suitable for use in light-duty vehicles, buildings , cell phones, and as replacements for small rechargeablebatteries. S.S. Hsieh ppt. 17

  19. AFC Anode Reaction Cathode Reaction Total Reaction ( From : http://www.fctec.com/fctec_types_afc.asp20091019) S.S. Hsieh ppt. 18

  20. AFC (continued) Alkali fuel cells (AFC) use a concentrated solution of potassium hydroxide (KOH) in water as an electrolyte. Hydroxyl ions (OH-) migrate from the cathode to the anode in these fuel cells. Hydrogen gas supplied to the anode reacts with the OH- ions to produce water. The reaction releases electrons, which provide the electrical power. And AFC are 60 percent efficient. S.S. Hsieh ppt. 19

  21. DMFC Anode Reaction Cathode Reaction Total Reaction Ideal Voltage 1.18V S.S. Hsieh ppt. 20

  22. DMFC (continued) The DMFC draws hydrogen from the methanol directly at operating temperatures of 50-100OC. It is suitable for applications such as cell phones and laptop computers. S.S. Hsieh ppt. 21

  23. PAFC Anode Reaction Cathode Reaction Total Reaction (From: http://www.fctec.com/fctec_types_pafc.asp20091019) S.S. Hsieh ppt. 22

  24. PAFC (continued) This type of fuel cell operates at high temperatures (150 ~ 200OC) to maintain the ionic conductivity of phosphoric acid. It generates electricity at 40% efficiency (80% if the steam produced is used for cogeneration) and can use impure hydrogen as fuel. S.S. Hsieh ppt. 23

  25. MCFC Anode Reaction Cathode Reaction Total Reaction ( From : http://fuelcellsworks.com 20091019) S.S. Hsieh ppt. 24

  26. MCFC (continued) MCFC are expected to achieve power efficiencies of 60% (85% with cogeneration) and operate at very high temperatures (650OC) to maintain electrolyte conductivity. This type of fuel cell is suitable for large electric utility applications. S.S. Hsieh ppt. 25

  27. SOFC Anode Reaction Cathode Reaction Total Reaction ( From : http://fuelcellsworks.com 20091019 ) S.S. Hsieh ppt. 26

  28. SOFC (continued) This type of fuel cell is suitable for large, high-power applications such as industrial or electricity generators. Its operating temperatures is 1000OC, and it is expected to achieve power efficiencies of 60% (85% with cogeneration). S.S. Hsieh ppt. 27

  29. Fuel Cell Comparison S.S. Hsieh ppt. 28

  30. Micro Fuel Cell • Applications Distinctive, high density energy sources for portable products Hybrid battery rechargers : separate (desktop) Portable Electronics : radio, PDA, laptop, cellular phone, portable power source S.S. Hsieh ppt. 29

  31. Micro Fuel Cell (continued) • Advantages of Micro PEM Fuel Cells Small, lightweight Inexpensive(?) Low (room) temperature operation Unique multi-layer (ceramic, silicon, etc.) miniaturization possible S.S. Hsieh ppt. 30

  32. Micro Fuel Cell (continued) • H2 Proton Exchange Membrane Fuel Cell (H2 PEMFC) S.S. Hsieh ppt. 31

  33. Micro Fuel Cell (continued) • New Design Three to one layer design: combine current collector , flow filed plate and backing layer Microstructure by MEMS fabrication: (a) thin film deposited and layer growth with surface mount technology (b) microflow channel by excimer laser processing S.S. Hsieh ppt. 32

  34. (1) Air outlet (2) Air inlet (3) (4) (3) (2) (1) • End plate (2000 µm) • Flowfield plate (200 µm) • Gasket (200 µm) • MEA (include GDL) (650 µm) H2 inlet H2 outlet Micro Fuel Cell (continued) • Structure S.S. Hsieh ppt. 33

  35. Micro Fuel Cell (continued) • Advantage of New Design Minimized fuel cells and reduce its weight. Catalyst (Pt) loading reduced as low as 0.15mg/cm2 (traditional design is 0.4mg/cm2). Flow field plate have a large effective flow passage even up 20% increase in contact area. S.S. Hsieh ppt. 34

  36. Micro Fuel Cell (continued) • Gasket • An acrylic structure to protect and observe the fuel cell. • Flow Field Plate、Current Collector Serpentine Flow Field Interdigitated Flow Field Mesh Flow Field S.S. Hsieh ppt. 35

  37. Micro Fuel Cell (continued) • Membrane-electrode assembly (MEA) An assembly consisting of an anode, and electrolyte, and a cathode (3 layer MEA), and may include gas diffusion layers. S.S. Hsieh ppt. 36

  38. MEA Morphology SEM image showing the morphological condition of thin platinum sputtered on AFM image showing the morphological condition on thin platinum (200x200nm2) Nafion 117 (1.5x1.2μm2) S.S. Hsieh ppt. 37

  39. Micro Fuel Cell flow-field plate fuel cell S.S. Hsieh ppt. 38

  40. Experiments lamp H2 in Air in H2 out S.S. Hsieh ppt. 39

  41. Fuel Cell Polarization As the fuel cell is operating, the cell potential decreases from its reversible (ideal) value for the sake of the irreversible losses. These losses are often referred as polarization , which include activation polarization, concentration polarization, ohmic polarization. S.S. Hsieh ppt. 40

  42. Fuel Cell Polarization(continued) • Activation Polarization It happens in the delayed phenomenon of reactive speed when fuel cells start the electric chemical reaction on the electrode surface. • Ohmic Polarization It happens on the move of ion in the electrolyte and the impedance of electron move. • Concentration Polarization It happens when the fuel cells don’t maintain the proper concentration of reactant on the electrode surface. S.S. Hsieh ppt. 41

  43. Experimental Results S.S. Hsieh ppt. 42

  44. Experimental Results (continued) power density(mW/cm2) S.S. Hsieh ppt. 43

  45. Micro Fuel Cell Stack Design Air Air Air H2 H2 H2 Gasket: 5000μm Air In H2 In End plate:450μm H2 Out Air Out Bipolar plate: 650μm MEA(include GDLs): 750μm Total thickness of 2-cell stack (not include Gasket): 3.05 mm Total thickness of 7-cell stacks (not include Gasket): 10.05 mm S.S. Hsieh ppt. 44

  46. 1. Clean Cu film (50μm) 200μm Mask Heating Heating Cu film SU-8 Cu electroforming 200μm 200μm Bipolar Plate Fabrication 3. Soft bake 4. Exposure 2. Spin coating SU-8 Substrate 5. Post exposure bake 6. Development 7. Electroforming 200μm 8. Remove photoresist 9. Redo 1-8 processes S.S. Hsieh ppt. 45

  47. 650μm Bipolar Plate Fabrication (continued) 3-D image of electroforming bipolar plate S.S. Hsieh ppt. 46

  48. Experimental Results (PEMFC) The performance test for 2-cell stack at fixed anode P=97kPa and different cell temperature S.S. Hsieh ppt. 47

  49. Experimental Results (PEMFC)(continued) The performance test for 7-cell stack at fixed anode P=97kPa and different cell temperature S.S. Hsieh ppt. 48

  50. Experimental Results (PEMFC)(continued) (a) Image for 7-cell stack during operation (b) Lateral image of 7-cell stack S.S. Hsieh ppt. 49

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