Modern World = Electrical World
• Can you list TEN items in your home
that are operated by electricity?
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Learning Objectives
1. History of Fuel Cells
2. Operation of Fuel Cells
3. Comparison between Fuel cells and
Batteries
4. Applications of Fuel Cells
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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)
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1. Fossil Fuel (化石燃料)
•
•
•
•
Coal (煤)
Natural gas (天然氣)
Oil (石油)
Tar sands (焦油沙)
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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）
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Electrical Cells
Electrical cell – device for generating
electricity
1. Solar cell
2. Chemical cell
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1. Solar Cell
- A device for converting the sun’s energy to
electricity
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2. Chemical Cell
- A device for converting chemical energy into
electrical energy
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Classification of Chemical Cells
a.
b.
c.
d.
Simple chemical cells
Dry cells/batteries
Wet cells
Fuel cells
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Simple chemical cells
e.g. Mg/Cu cell
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Dry Cells
- A portable source of electricity
2 classes of dry cells
1. Primary cells - non-rechargeable batteries
2. Secondary cells - rechargeable batteries
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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
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Secondary Cell (蓄電池)
e.g. Nickel-cadmium cells 鎳鎘蓄電池
e.g. Lead acid battery (car battery)
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Worksheet 2
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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.
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Dry Cells Disposal Problems
• Environmental pollution環境污染
• Toxic有毒
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Worksheet 3
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Specific Energy (Watt-hr/kg)
Specific Energy of Batteries and FuelCells
3500
3000
3000
2500
Nominal
2000
High
1500
1000
500
0
250
30 100
100
NiMH
Alkaline
600
450
150
100
Zn/Air
Li-Ion
Cell Type
600
100
300
Li Polymer Methanol
FC
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Fuel Cells
e.g. Alkaline fuel cell was used in spacecraft
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Fuel Cell（燃料電池）
An Alternative Energy
Source for the Future
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Fuel Cell
The ultimate clean machine for
generating electricity
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Brief History of Fuel Cells
1839
1950
Late 1950
1960 – 70
1970s
Demonstrated operating principle
Demonstrated the operation of a fuel cell stack
NASA choose AFC to provide power for spaceship
Alkaline fuel cell (AFC) went to the moon
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
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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
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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
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An Alkaline Fuel Cell
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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.
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Demonstration on Reversible Operation of
Fuel Cell – Electrolysis
Cardboard
硬咭紙
Anode
陽極
H2
O2
氫氣
氧氣
Water
Cathode
陰極
水
Beaker 燒 杯
6 volt Battery 電 池
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Applications for Fuel Cells
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•
•
•
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）
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Comparison between Fuel Cell and Battery
Fuel Cell
Battery
Energy from chemical energy
Energy from chemical energy
Electrodes separated by electrolyte
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 density
Low power density
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Worksheet 4
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POROUS NICKEL ELECTRODE
多孔性鎳電極
3
FUEL
Anode Electrode
陽 極
-
Cathode Electrode
陰 極
+
氫氣 H2
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OXIDANT
O2 氧氣
1
2
ELECTROLYTE
電解質
5
H2O
H2O 6
水
水
Electrical Load
電流強度
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Electric Motor
馬達
FUEL CELL OPERATION DIAGRAM
燃料電池示意圖
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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）
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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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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
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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
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Demonstration on Operation of Fuel Cell
Chemical energy of a bio-fuel-methanol converts to
Electrical energy
1.
2.
3.
4.
5.
Mix 1.5 mL of methanol (fuel) into 25 mL 1M KOH
solution(electrolyte) in a beaker.
Stir for a few minutes with a glass rod.
Pour the mixed fuel and electrolyte into the Fuel Cell and
wait for 5 minutes.
Put the top cover onto the cell body.
The fan will turn! Electricity produced by the fuel cell turns
the fan.
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Reversible Operation of Fuel Cell - Electrolyis
1.
2.
3.
4.
5.
6.
Fill the beaker with about 400 mL of tap water.
Add a few drops of dilute sulphuric acid.
Cut 2 small slits into the card board paper to serve as a
holder and insulator for the lead strip electrodes.
Place the lead strips into the water
Connect the leads to the battery terminals as illustrated
in the diagram.
Bubbles of hydrogen and oxygen gas will be observed
after a few minutes indicating that the electrolysis is on
progress.
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