PEM DIFEREN

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intensys H2NET September 2001

An Overview Of Fuel Cell Technology


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The Main Types Of Fuel Cell.

Alkaline (AFC)

Solid Polymer (SPFC, PEM or PEFC)

Direct Methanol (DMFC)

Phosphoric Acid (PAFC)

Molten Carbonate (MCFC)

Solid Oxide (SOFC)


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Large utility,

small APU,

residential

45 – 55%800 - 1000CeramicSOFC

Can use

unreformed fuel,slow start up &

response

Large utility50 – 60%650Molten Carbonate

Salt

MCFC

In use. Doubts

over cost

Medium

stationary

35 – 45%180 - 210H3PO4PAFC

First use by

NASA.

Required pure

reactants

Military,

aerospace,

automotive

40 - 50%80 - 120KOHAFC

Battery

replacement, portable

30 – 40%50 - 60Solid Polymer DMFC

Significant

investment, close

to market

Transport,

small/medium

stationary,

portable

35 – 50%70 - 80Solid Polymer PEM

CommentsUseEfficiencyApprox

Operating Temp(oC)

ElectrolyteType

Comparison Of Types


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Electrochemical Reactions


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AnodeCathodeElectrolyte

(ion conductor)

e-

SOFCH2

H2O

O2-O2 T = 900oC

PAFC

& SPFC

H2 H+

O2

H2O

T = 200oC (PAFC)

T = 80oC (SPFC)

Fuel in Oxidant in

Depleted oxidant& products out

Depleted fuel

& products

out

MCFCH2

CO2

O2

CO2CO3

2- T = 650oC

T = 80oCAFC

H2

H2O

O2OH-


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0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 200 400 600 800 1000 1200

Current Density (mA/cm2)

C

e l l P o t e n t i a l ( V )

Fuel Cell Polarisation Curve

Regioncontrolled

by activation

polarisation

Region controlled by ohmic polarisation

Region controlled by

concentration polarisation


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0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

0 200 400 600 800 1000 1200 1400 1600 1800

Temperature (oC)

E f f i c i e n c y

Carnot Cycle

PEMFC System

PAFC System

MCFC System

SOFC+CCGT

Gas Turbine

Combined Cycle GT & Steam

Hydrogen Natural Gas

Efficiency Comparison


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Candidate Fuels

MilitaryDiesel

TransportGasoline

Stationary Natural Gas

Transport & PortableMethanol

Transport, Stationary & PortableHydrogen

ApplicationType


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Cumulative Emissions Reduction from the

use of FCVs for the period 2010-2030

(Assumes 24% penetration by 2030)

05

10

15

20

25

30

35

40

MeOH H2 MeOH H2 MeOH H2

NMOG NOx CO

M i l l i o n

M e t r i c T o n s

R e d u c t i o n

Cumulative Emissions Reduction from the

use of FCVs for the period 2010-2030

(Assumes 24% penetration by 2030)

22802285

229022952300230523102315

2320232523302335

MeOH H2

CO2

M i l l i o

n M e t r i c T o n s

R e d u c t i o n

F o r C O 2

Potential Emissions Reductions (US) Gained

From The Use Of FCVs (US DoE Figures)


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The Solid Polymer Fuel Cell System


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1989 – 100 Watts/Litre



September 2001 – GM announce 1750 Watts/Litre

Increases In Stack Power Density


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Building Blocks Of A Fuel Cell System

Fuel Cell Stack

Fuel Delivery

Air Delivery

Power Conditioning

Thermal Management Water Management

Control System


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Hydrogen Store

Power Conditioner

Fan or

Compressor

Elements Of A Hydrogen Fuelled System


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Autothermal System Arrangement

Separator

Separator

F u e l C e l

l S t a c k s

Water Reservoir

Fresh Water

Sea Water

Air

Cathode OffgasFuel

Reformate

Anode Offgas

Condensate

Exhaust

Electrical Output

Air Humidity,

Temperature

& Pressure.

Cooling System.

SELOX

Separator

Combuster

LTS

HTS

Autothermal Reactor

Pre-processor

Power

Conditioner


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Gasoline

Autothermal

Methanol Steam

Reforming

Hydrogen Gas 5000

psi

Fuel Consumption Rate (mpg) 60.06 37.31 75.3

Fuel Consumption Rate (litre/100 km) 4.64 7.48 121.2

Fuel Volume (litres) 28.8 46.27 175.3

Fuel Mass (kg) 21.1 36.6 5.05

Fuel Tank Volume (litres) 30.30 48.71 260

Total Mass With Tank (kg) 26.00 44.39 75.4

Fuel Storage Requirement

Medium Basic Car

380 Mile (612 km) Range


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Vehicle Fuelling Issues

No current

infrastructure

problems.

Security of supply.

Seen as transitional

fuel.

Best optionDifficult processing.

Emissions issues.

Lowest efficiency

Gasoline

No current

infrastructure.

Seen as transitional

fuel.

Reasonable.Easiest processing

option.

Methanol

Localised

infrastructure in near

term.Cost of mass

infrastructure.

Volume problems for

gas.

Weight problems for hydrides.

Simplest option.

Lowest cost.

Good Efficiency

Hydrogen

InfrastructureStorageSystemFuel


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Necar 4 (Liquid Hydrogen)


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Efficiency of Prime Movers

0

10

20

30

40

0 20 40 60 80 100 120

Percentage Maximum Rated Load

E f f i c i

e n c y ( % )

Constant Speed Diesel

Road Load Diesel

Fuel Cell System


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Res earch & Technology

1999 NECAR 4

1997 NEBUS

1996 NECAR II

1994 NECAR I

Hydrogen FC-Vehicles - DevelopmentProgress


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Research & Technology

Necar 4 Efficiency in NEDC

Target: 40-45 %Target: 40-45 %

37,7 %37,7 %


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Future Development Requirements

0,4

0,5

0,6

0,7

0,8

0,9

1

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

Current Density (A/cm²)

C e

l l V o l t a g e

Cell Voltage (V) Today

Cell Voltage (V) Future

MEA Properties:

Today Future

Max. Temperature: 80 °C 90-110 °C

Pt-loading: < 1 mg/cm2

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