1 Modern World = Electrical World Can you list TEN items in your home that are operated by electricity?

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3 Learning Objectives 1. History of Fuel Cells 2. Operation of Fuel Cells 3. Comparison between Fuel cells and Batteries 4. Applications of Fuel Cells

4 Two types of Energy Supplies 1. Fossil Fuel ( 化石燃料 )/ Non-renewable energy ( 非再生能源 ). 2. Renewable Energy Source ( 可再生能源 )

5 1. Fossil Fuel ( 化石燃料 ) Coal ( 煤 ) Natural gas ( 天然氣 ) Oil ( 石油 ) Tar sands ( 焦油沙 )

6 2.Renewable Energy Source ( 可再生能源 ) Hydroelectric power （水力發電） solar power （太陽能） wind power （風力發電） wave and tidal power （潮汐發電） geothermal power （地熱能源）

7 Electrical Cells Electrical cell – device for generating electricity 1.Solar cell 2.Chemical cell

8 1.Solar Cell - A device for converting the sun’s energy to electricity

9 2.Chemical Cell - A device for converting chemical energy into electrical energy

10 Classification of Chemical Cells a.Simple chemical cells b.Dry cells/batteries c.Wet cells d.Fuel cells

11 Simple chemical cells e.g. Mg/Cu cell

12 Dry Cells - A portable source of electricity 2 classes of dry cells 1. Primary cells - non-rechargeable batteries 2. Secondary cells - rechargeable batteries

13 Dry Cells Common Primary Dry Cells 原電池 1.Zinc-carbon cells 鋅碳電池 2.Alkaline manganese cells 鹼性錳電池 3.Silver oxide cells 氧化銀電池 4.Mercury cells 水銀電池 5.Lithium cells 鋰電池

14 Secondary Cell ( 蓄電池 ) e.g. Nickel-cadmium cells 鎳鎘蓄電池 e.g. Lead acid battery (car battery)

15 Worksheet 2

16 Expected Answers for Worksheet 2 1.Hearing aids are small and they need very small batteries. Silver oxide batteries shaped like a button and satisfied this purpose. 2.Silver and its compounds (e.g. silver oxide) are expensive.

17 Dry Cells Disposal Problems Environmental pollution 環境污染 Toxic 有毒

18 Worksheet 3

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21 Fuel Cells e.g. Alkaline fuel cell was used in spacecraft

22 Fuel Cell （燃料電池） An Alternative Energy Source for the Future

23 Fuel Cell The ultimate clean machine for generating electricity

24 Brief History of Fuel Cells 1839 Demonstrated operating principle 1950 Demonstrated the operation of a fuel cell stack Late 1950 NASA choose AFC to provide power for spaceship 1960 – 70 Alkaline fuel cell (AFC) went to the moon 1970s Fuel cell extended – Phosphoric Acid, Solid Oxide, Molten Carbonate, Proton Exchange Membrane Late 1970s Fuel cell as s stationary power generation source The Hydrogen economy concept proposed Late 1980s Fuel cell car appeared Late 1990s Small fuel cell replaced battery, Iceland plan to use geothermal energy and hydroelectric power for hydrogen economy

25 What is a Fuel Cell ? A device that generates electricity without combustion Chemical energy is converted directly into electrical energy Similar to a battery but much better

26 How Fuel Cell Works There are two electrodes Electrolyte must be placed between the electrodes Fuel is supplied to anode Oxidant is supplied to cathode The reaction between fuel and oxidant in the fuel cell generates electrical current

27 An Alkaline Fuel Cell

28 Hydrogen Economy An economic model where hydrogen is used as the main fuel. –The economic development requires an unlimited supply of energy. –Fossil fuel are polluting the environment. First proposed in the late 1970s Iceland may be the first country to fully implement the hydrogen economy concept.

29 Demonstration on Reversible Operation of Fuel Cell – Electrolysis

30 Applications for Fuel Cells Space program （太空計劃） Power Generation （發電） Transportation （運輸） Landfill/Wastewater Treatment( 廢物堆填 及廢水處理） Portable power （可攜式電源）

31 Comparison between Fuel Cell and Battery Fuel CellBattery Energy from chemical energy Electrodes separated by electrolyte No electrode consumed during reaction At least one electrode consumed during reaction Outside sources supply reactants continuously Reactants stores inside battery Reaction product remove from the cell continuously Reaction product stored inside the battery Precious metal as catalyst, least pollution problem Contain heavy metal, cause pollution High power densityLow power density

32 Worksheet 4

33 FUEL CELL OPERATION DIAGRAM 燃 料 電 池 示 意 圖 FUEL CELL OPERATION DIAGRAM 燃 料 電 池 示 意 圖 Electrical Load 電 流 強 度 氫氣 H 2 O 2 氧氣 ELECTROLYTE 電 解 質 FUEL OXIDANT H2O水H2O水 H2O水H2O水 H2O水H2O水 H2O水H2O水 POROUS NICKEL ELECTRODE 多 孔 性 鎳 電 極 Anode Electrode 陽 極 Cathode Electrode 陰 極 Electric Motor 馬 達 Electric Motor 馬 達

34 Advantages of Fuel Cells 1.Less Pollution （減輕污染） 2.High Efficiency （高效能） 3.High Power Quality and Reliability （電 源品質好和可靠性高） 4.Distributed Power Supply （分散供電） 5.High Power Density （能源密度高）

35 Problems with Fuel Cell Technologies 1. Fuel cells require catalyst （催化劑） : - expensive catalyst - problem of catalyst poisoning 2. Specialty materials to withstand corrosive （侵蝕） environment of alkaline solution at high temperature 3. Hydrogen : flammable （易燃） and explosive （爆炸）

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38 Fuel Cell Terminology Anode( 陽極 ) – the negative electrode Cathode( 陰極 ) – the positive electrode Electrochemical( 電子學的 ) – convert chemical energy to electrical energy Electricity( 電、電流 ) – flow of electrons in a circuit Electrolysis( 電解 ) – a process of chemical changes by passing an electric current through a solution resulting in a transfer of electrons to the electrode Electrolyte( 電解質 ) – a chemical means in the transfer of ions from one medium to another Fuel cell( 燃料電池 ) – an electrochemical/self generating power source

39 Fuel Cell Terminology Hydrogen( 氫 ) – chemical fuel of a fuel cell flowing through the anode Membrane( 薄膜 ) – substance allowing hydrogen and oxygen to pass through Oxygen( 氧 ) – chemical fuel flowing through the cathode PEM( 質子交換膜 ) – proton exchange membrane Stacking( 堆疊 ) – method of adding fuel cells to increase voltage output Voltage( 伏特 ) – a measure of electrical potential of an electrical circuit or device ZEV( 零排放車輛 ) – zero emission vehicle

40 Demonstration on Operation of Fuel Cell Chemical energy of a bio-fuel-methanol converts to Electrical energy 1.Mix 1.5 mL of methanol (fuel) into 25 mL 1M KOH solution(electrolyte) in a beaker. 2.Stir for a few minutes with a glass rod. 3.Pour the mixed fuel and electrolyte into the Fuel Cell and wait for 5 minutes. 4.Put the top cover onto the cell body. 5.The fan will turn! Electricity produced by the fuel cell turns the fan.

41 Reversible Operation of Fuel Cell - Electrolyis 1.Fill the beaker with about 400 mL of tap water. 2.Add a few drops of dilute sulphuric acid. 3.Cut 2 small slits into the card board paper to serve as a holder and insulator for the lead strip electrodes. 4.Place the lead strips into the water 5.Connect the leads to the battery terminals as illustrated in the diagram. 6.Bubbles of hydrogen and oxygen gas will be observed after a few minutes indicating that the electrolysis is on progress.