Hydrogen Utilization - Fuel Cell

Hydrogen Utilization - Fuel Cell

Shou-Shing HsiehDepartment of Mechanical and Electro-Mechanical Engineering

National Sun Yat-Sen UniversityKaohsiung,Taiwan

February 26, 2006

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. Hsiehppt. 01

What is energy ? MEMS Labs MEM Departmemt NSYSU

MEM Department NSYSUS.S. Hsieh

ppt. 02

The capacity for doing work as measured by the capability of doing work (potential energy) or the conversion of this capability to motion

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

(kinetic energy).

other means in order to accomplish tasks.

• Coal

• Oil & Natural Gas

• Nuclear

• Geothermal

• Solar

• Hydro power

• Wind

• Biomass• Fuel cells (Hydrogen Energy )

Types of Energy MEMS Labs MEM Departmemt NSYSU


ppt. 03

Energy Crisis MEMS Labs MEM Departmemt NSYSU


ppt. 04

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

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

, one thing is certain - at some point we will run out.

, influence the human ecology.

Kyoto Protocol MEMS Labs MEM Departmemt NSYSU


ppt. 05

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 loweremissions from six greenhouse gases.

Hydrogen Energy MEMS Labs MEM Departmemt NSYSU


ppt. 06

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

It is normally bound to other substances, it is colourless, odourless, non-toxic and when it burns in

extensively in many industries.

air, that reaction produces only water.

Hydrogen Energy (continued)MEMS Labs

MEM Departmemt NSYSU


ppt. 07

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 actuallygenerates electricity efficiency up to 40%~60%.

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



ppt. 08

Hydrogen Fuel Stations MEMS Labs MEM Departmemt NSYSU


ppt. 09

• Hydrogen Fuel Stations – Worldwide accumulated, sorted by region (1995-2004)

Hydrogen for Fuel Cell MEMS Labs MEM Departmemt NSYSU


ppt. 10

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 formwater.

Fuel Cell MEMS Labs MEM Departmemt NSYSU


ppt. 11

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-

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

electrode assembly (MEA).

power generation systems.

Fuel Cell ( continued )MEMS Labs



ppt. 12

• A Traditional Design of PEMFC

Fuel Cell ( continued )

• High efficiency to produce energy

(From :http://www.broadcastpapers.com/m )



ppt. 13

* LHV = lower heating

A thermodynamic term that indicates the heat needed to raise steamfrom liquid water.

value.

Fuel Cell Advantages MEMS Labs MEM Departmemt NSYSU


ppt. 14

• 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.

Types of Fuel Cell MEMS Labs MEM Departmemt NSYSU


ppt. 15

Fuel Cell Type

Electrolyte Anode Gas Cathode Gas Temperature Efficiency

Proton Exchange Membrane ( PEMFC )

solid polymer membrane

hydrogenpure or

atmospheric oxygen

75OC ( 180OF )

35-60％

Alkaline ( AFC )

potassium hydroxide

hydrogen pure oxygen below 80OC 50-70％

Direct Methanol ( DMFC )

solid polymer membrane

methanol solution in

water

atmospheric oxygen

75OC ( 180OF )

35-40％

Phosphoric Acid ( PAFC )

Phosphorous hydrogenatmospheric

oxygen200OC ( 400OF )

35-50％

Molten Carbonate ( MCFC )

Alkali - Carbonates

hydrogen, methane

atmospheric oxygen

650OC ( 1200OF )

40-55％

Solid Oxide ( SOFC )

Ceramic Oxidehydrogen, methane

atmospheric oxygen

800-1000OC ( 1500-

1800OF )45-60％

-2 2

12 2

2O H e H O

Anode Reaction

Cathode Reaction

2 2 2

1

2H O H O

Total Reaction

-2 2 2H H e

Ideal Voltage

1.23V

PEMFC MEMS Labs MEM Departmemt NSYSU


ppt. 16

( From : http://fuelcellsworks.com )

This type of fuel cell operates at low temperatures (75OC), and has a high power output density, and

PEMFC (continued)MEMS Labs



ppt. 17

It is suitable for use in light-duty vehicles, buildings, cell phones, and as replacements for small

can vary output to meet demand.

rechargeable batteries.

AFC MEMS Labs MEM Departmemt NSYSU


ppt. 18

Anode Reaction

Cathode Reaction

Total Reaction

OHeOHO 222

122

eOHOHH 222 22

OHOH 222 2

1

( From : http://www.fuelcellcontrol.com )

http://www.fuelcellcontrol.com/

AFC (continued)MEMS Labs



ppt. 19

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

OH

OH

OH

percent efficient.

-2 2

36 6 3

2O H e H O

Anode Reaction

Cathode Reaction

Total Reaction

Ideal Voltage

1.18V

DMFC

3 2 2 2 2

33

2CH OH O H O CO H O

-3 2 2 6 6CH OH H O CO H e



ppt. 20

e-

load

Proton Exchange Membrane

CH OH3 Air (O )2

ElectrodeAnode

Cathode:Pt catalyst loading

:Pt-Ru catalyst loading

6H+

2H O and Air2 2

CH OH3

CO and H O

CH OH + H O + 1.5O3 2 2 CO + H O2 2

Direct Methaol Fuel Cell

The DMFC draws hydrogen from the methanol directly at operating temperatures of 50-100OC.

DMFC (continued)MEMS Labs



ppt. 21

It is suitable for applications such as cell phones andlaptop computers.

Anode Reaction

Cathode Reaction

Total Reaction

-2 2 2H H e

-2 2

12 2

2O H e H O

2 2 2

1

2H O H O

(From: http://www.brennstoffzelle-koeln.de/Pages)

PAFC MEMS Labs MEM Departmemt NSYSU


ppt. 22

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.

PAFC (continued)MEMS Labs



ppt. 23

Anode Reaction

Cathode Reaction

Total Reaction

- -22 2 3

12

2O CO e CO

-2 -2 3 2 2 2H CO CO H O e

2 2 2 2 2

1

2H O CO H O CO

MCFC MEMS Labs MEM Departmemt NSYSU


ppt. 24

( From : http://fuelcellsworks.com)

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.

MCFC (continued)MEMS Labs



ppt. 25

-2 -2 2 2H O H O e

- -22

12

2O e O

2 2 2

1

2H O H O

Anode Reaction

Cathode Reaction

Total Reaction

SOFC MEMS Labs MEM Departmemt NSYSU


ppt. 26

( From : http://fuelcellsworks.com )

This type of fuel cell is suitable for large, high-powerapplications such as industrial or electricity generators.

Its operating temperatures is 1000OC, and it is expected to achieve power efficiencies of 60% (85% with cogeneration).

SOFC (continued)MEMS Labs



ppt. 27

Fuel Cell Trends MEMS Labs MEM Departmemt NSYSU


ppt. 28

Fuel Cell Comparison MEMS Labs MEM Departmemt NSYSU


ppt. 29

Fuel CellType

Advantage Fault Application

PEMFC

‧ Operate at low temperatures ‧ Proven long operating ‧ Have fast starup time ‧ Have high power densities

‧ Additional humidification ‧ A platinum catalyst

is expensive

‧ Household electrical generation ‧ Light-duty

transportation

DMFC

‧ The fuel storage problems is easy ‧ Methanol is easier to

transport and supply

‧ Slow starup time ‧ Methanol crossover ‧ Expensive

‧ Cellular phones ‧ Laptops ‧ Remote power ‧ Transportation

SOFC

‧ Can make fuel with the natural gas or the methane ‧ Can make oxidizer with air

‧ Operate at high temperature

‧ Electrical generators ‧ Large power plant ‧ Industrial power

supplies

Micro Fuel Cell MEMS Labs MEM Departmemt NSYSU


ppt. 30

Distinctive, high density energy sources for portable products

Hybrid battery rechargers : separate (desktop)

Portable Electronics : radio, PDA, laptop, cellular phone, portable power source

• Applications

Micro Fuel Cell (continued)MEMS Labs



ppt. 31

Small, lightweight

Inexpensive(?)

Low (room) temperature operation

Unique multi-layer (ceramic,silicon, etc.) miniaturization possible

• Advantages of Micro PEM Fuel Cells




ppt. 32

e-

load

Proton Exchange Membrane

Air (O )2

ElectrodeAnode

Cathode:Pt catalyst loading

:Pt catalyst loading

2H+

H O and Air

Proton Exchange Membrane Fuel Cell

H2

H2

H + 0.5O2 2 H O2

2

• H2 Proton Exchange Membrane Fuel Cell (H2 PEMFC)




ppt. 33

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

• New Design




ppt. 34

• structure




ppt. 35

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.

• Advantage of new design

Serpentine Flow Field Interdigitated Flow Field Mesh Flow Field




ppt. 36

• Gasket An acrylic structure to protect and observe the fuel cell.

• Flow Field Plate 、 Current Collector

• Membrane-electrode assembly (MEA)

An assembly consisting of an anode, and electrolyte, and a cathode (3 layer MEA), and may include gas diffusion layers.




ppt. 37

MEA Morphology MEMS Labs MEM Departmemt NSYSU


ppt. 38

SEM image showing the morphologicalcondition of thin platinum sputtered on

AFM image showing the morphologicalcondition on thin platinum (200x200nm2)

Nafion 117 (1.5x1.2μm2)

Micro Fuel Cell MEMS Labs MEM Departmemt NSYSU


ppt. 39

flow-field plate fuel cell

Experiments

lamp

Air in

H2 in

H2 out



ppt. 40

Fuel Cell Polarization MEMS Labs MEM Departmemt NSYSU


ppt. 41

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.

Fuel Cell Polarization (continued)MEMS Labs



ppt. 42

• Activation Polarization

It happens in the delayed phenomenon of reactive speed when fuel cells start the electric chemical reaction on the electrode surface.

• Ohmic PolarizationIt happens on the move of ion in the electrolyte and the impedance of electron move.

• Concentration PolarizationIt happens when the fuel cells don’t maintain the proper concentration of reactant on the electrode surface.

Experimental Results

0 50 100 150 200 250 3000.0

0.2

0.4

0.6

0.8

1.0

1.2 @P=153kPa@T=50oC

volta

ge

(V)

current density(mA/cm2)

interdigitated serpentine mesh



ppt. 43

Experimental Results (continued)

0 50 100 150 200 250 3000

20

40

60

80

100@P=153kPa@T=50oC

Pe

rfo

rma

nce

(mW

/cm

2 )

current density(mA/cm2)

interdigitated serpentine mesh



ppt. 44

Stack Design Methods MEMS Labs MEM Departmemt NSYSU


ppt. 45

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



ppt. 46

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.



ppt. 47


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 :

H2 input

Conductor

Surface to Surface Stack



ppt. 48


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 :

i i

Anode Cathode Membrane

The power plant used in parallel and series fuel cell stack system



ppt. 49

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.

• Notebook

Fuel Cell Applications

Samsung 2004 presents new DMFC notebook. It can work more than 10



ppt. 50

• Transportation vehicle

( From : http://www.fuelcelltoday.com )

hours without recharging.

Honda’s 2005 FCX fuel cell vehicle – it is powered by a Honda designed and manufactured fuel cell stack.

( From : http:// www.motorcities.com )

http://www.fuelcelltoday.com/

http://www.motorcities.com/

Conclusions MEMS Labs MEM Departmemt NSYSU


ppt. 51

No matter in food, clothing, lives, transportation, education, amusement, the energy is closely linked with our life. So on the premise of no pollution for the environment, it is a good choice to use the fuel cell togenerate electricity.

We can believe that under the regulation of Kyoto Protocol, it will be sure to have brighter prospects touse the fuel cell to generate electricity in the future.

References

• S.-S. Hsieh, J.-K. Kuo, C.-F. Hwang, and H.-H Tasi, “A Novel Design and Microfabrication for a Micro PEMFC,” Microsystem Technologies ,Vol.10, 2004,pp. 121-126.

• S.-S. Hsieh, C.-F. Huang, J.-K. Kuo, H.-H Tasi, and S.-H. Yang, “SU-8 Flow Field Plates for a Micro PEMFC,” Journal of Solid State Electrochemistry, Vol.9,2005,121-131.

• Fabrication and Testing of a Two Cell PEM Fuel Cell Stack, Table of Contents (2003)

• Dr. Hazem Tawfik, Hydrogen Economy & (PEM) Fuel Cells

• Life Style Publications ( http://www.lifestyle-movement.org.uk/str1/publicns.htm )

• Introduction to hydrogen ( http://europa.eu.int/comm/research/energy/nn/nn_rt/nn_rt_hy/article_1142_en.htm )

• Energy and Environment ( http://www.toyota.co.jp/en/tech/environment/fchv/fchv02.html )



ppt. 52

http://www.lifestyle-movement.org.uk/str1/publicns.htm




http://europa.eu.int/comm/research/energy/nn/nn_rt/nn_rt_hy/article_1142_en.htm

http://www.toyota.co.jp/en/tech/environment/fchv/fchv02.html

Thanks for Your Attention !



Hydrogen Utilization - Fuel Cell

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