1 / 54

Hydrogen Utilization - Fuel Cell

MEMS Labs MEM Departmemt NSYSU. MEM Department NSYSU. Hydrogen Utilization - Fuel Cell. Shou-Shing Hsieh Department of Mechanical and Electro-Mechanical Engineering National Sun Yat-Sen University Kaohsiung,Taiwan February 26, 2006. MEMS Labs MEM Departmemt NSYSU. MEM Department NSYSU.

tacey
Download Presentation

Hydrogen Utilization - Fuel Cell

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Hydrogen Utilization -Fuel Cell Shou-Shing Hsieh Department of Mechanical and Electro-Mechanical Engineering National Sun Yat-Sen University Kaohsiung,Taiwan February 26, 2006

  2. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Items • What is energy？ • Kyoto Protocol • Hydrogen Energy • Fuel Cell • Types of Fuel Cell • Micro Fuel Cell • Experimental Results • Fuel Cell Stack Design • Conclusions • References S.S. Hsieh ppt. 01

  3. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Types of Energy • Coal • Oil & Natural Gas • Nuclear • Geothermal • Solar • Hydropower • Wind • Biomass • Fuel cells(Hydrogen Energy ) S.S. Hsieh ppt. 03

  5. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Kyoto Protocol The Kyoto Protocol is a legally binding agreement under which industrialized countries will reduce their collective emissions of greenhouse gases by 5.2% compared to the year 1990. The goal is to lower emissions from six greenhouse gases. S.S. Hsieh ppt. 05

  7. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Hydrogen Fuel Stations • Hydrogen Fuel Stations – Worldwide accumulated, sorted by region (1995-2004) S.S. Hsieh ppt. 09

  11. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Fuel Cell ( continued ) • A Traditional Design of PEMFC S.S. Hsieh ppt. 12

  14. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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) S.S. Hsieh ppt. 13

  15. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Types of Fuel Cell S.S. Hsieh ppt. 15

  17. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU PEMFC Anode Reaction Cathode Reaction Total Reaction Ideal Voltage 1.23V ( From :http://fuelcellsworks.com) S.S. Hsieh ppt. 16

  18. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU PEMFC (continued) This type of fuel cell operates at low temperatures (75OC), 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU AFC Anode Reaction Cathode Reaction Total Reaction ( From :http://www.fuelcellcontrol.com) S.S. Hsieh ppt. 18

  20. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU AFC (continued) Alkali fuel cells (AFC) use a concentrated solution of potassium hydroxide (KOH) in water as an electrolyte. Hydroxyl ions ( ) migrate from the cathode to the anode in these fuel cells. Hydrogen gas supplied to the anode reacts with the 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU DMFC Anode Reaction Cathode Reaction Total Reaction Ideal Voltage 1.18V S.S. Hsieh ppt. 20

  22. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU PAFC Anode Reaction Cathode Reaction Total Reaction (From: http://www.brennstoffzelle-koeln.de/Pages) S.S. Hsieh ppt. 22

  24. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU MCFC Anode Reaction Cathode Reaction Total Reaction ( From :http://fuelcellsworks.com) S.S. Hsieh ppt. 24

  26. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU SOFC Anode Reaction Cathode Reaction Total Reaction ( From :http://fuelcellsworks.com) S.S. Hsieh ppt. 26

  28. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Fuel Cell Trends S.S. Hsieh ppt. 28

  30. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Fuel Cell Comparison S.S. Hsieh ppt. 29

  31. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. 30

  32. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. 31

  33. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Micro Fuel Cell (continued) • H2 Proton Exchange Membrane Fuel Cell (H2 PEMFC) S.S. Hsieh ppt. 32

  34. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. 33

  35. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Micro Fuel Cell (continued) • structure S.S. Hsieh ppt. 34

  36. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. 35

  37. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. 36

  38. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. 37

  39. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. 38

  40. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Micro Fuel Cell flow-field plate fuel cell S.S. Hsieh ppt. 39

  41. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Experiments lamp H2 in Air in H2 out S.S. Hsieh ppt. 40

  42. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. 41

  43. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU 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. 42

  44. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Experimental Results S.S. Hsieh ppt. 43

  45. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Experimental Results (continued) S.S. Hsieh ppt. 44

  46. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Stack Design Methods Fuel cell stack using series is a conventional method for commercialization, because we can get high voltage and low current to drive devices in our life. The methods of series are following : Conventional Vertical Stack Planar Flip-Flop Stack Banded Stack S.S. Hsieh ppt. 45

  47. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Stack Design Methods (Continued) • Conventional Vertical Stack The conventional vertical stack is a simple design method to construct a fuel cell stack, because its principle and experiment test loop are easier and simpler. But, its volume is huger than the other design methods. • Planar Flip-Flop Stack and Banded Stack The planar flip-flop and banded stack are advanced methods to construct fuel cell stacks, because they use conductor to connect other neighbor single cell. Its advantages are small volume and packaging flexibility, but using interconnected conductor methods will cause potentially higher ohmic loss and difficulty of ensuring equal reactant distribution to muiltiple cells in a plane. S.S. Hsieh ppt. 46

  48. MEMS Labs MEM Departmemt NSYSU H2 input Conductor MEM Department NSYSU Stack Design Methods (Continued) Fuel cell stack connected in parallel is not useful for micro fuel cell, because we can not get high voltage and low current to drive devices in our life (The parallel method gets low voltage and high current). The volume of parallel stack is larger than the series, and the method is difficulty of ensuring equal reactant distribution to muiltiple cells. The method of parallel is following : Surface to Surface Stack S.S. Hsieh ppt. 47

  49. MEMS Labs MEM Departmemt NSYSU Anode Cathode Membrane i i MEM Department NSYSU Stack Design Methods (Continued) In spite of the above-statements in the high power rate fuel cell using for the power plant, SOFC, the method is very suitable. Because the parallel method can avoid short circuit when there are fuel cells not working in the system. The method of parallel Is following : The power plant used in parallel and series fuel cell stack system S.S. Hsieh ppt. 48

  50. MEMS Labs MEM Departmemt NSYSU MEM Department NSYSU Stack Design Goals • Low resistance connection between cells Because the force from nut and bolt will increase the contact resistance in stack fabrication, we should take care of the effect in fuel cell design. • Interconnect must accurately control and distribute air and • fuel flows If the hydrogen and oxygen don’t distribute equally in each cells, it will cause higher concentration resistance and decrease stack performance. So we should take extreme caution in fuel cell design. • Fuel losses must be controlled for high fuel utilization Fuel loss will cause the performance decrease, so we can use UV glue or other packaged materials to prevent the effect. S.S. Hsieh ppt. 49

More Related