SECA Solid Oxide Fuel Cell Program Presentation · Design Stack, Fuel processor BOP Components SOFC...

GE Hybrid Power Generation Systems

SECASECASolid Oxide Fuel Cell ProgramSolid Oxide Fuel Cell Program

Fourth Annual Solid State Energy Conversion Alliance MeetingApril 15-16, 2003

Seattle, WA

Copyright 2003 General Electric Company

M-4thSECA.ppt- 2



Program ObjectiveProgram Objective

• Overall objective– Demonstrate a fuel-flexible, modular 3-to-10-kW solid

oxide fuel cell (SOFC) system that can be configured to create highly efficient, cost-competitive, and reliable power plants tailored to specific markets

• Development team– GE Power Systems

Torrance, CASchenectady, NYGreenville, SC

– GE Global ResearchNiskayuna, NY

M-4thSECA.ppt- 3



SOFC System ConceptSOFC System Concept

M-4thSECA.ppt- 4



Key System FeaturesKey System Features

• SOFC– High-performance reduced-temperature cells– Operation on light hydrocarbons– Tape calendering manufacturing process

• Fuel processor– Low-cost, fuel-flexible fuel processor design– Catalytic process– Pre-reforming function

• Other subsystems– Integrated thermal management– Flexible control subsystem

M-4thSECA.ppt- 5



Program FeaturesProgram FeaturesDEMONSTRATION

OF FUEL FLEXIBLEPROTOTYPE

SYSTEM

PROTOTYPEDEMONSTRATION

TECHNOLOGY IMPROVEMENTAND COST REDUCTION

PACKAGED SYSTEMDEMONSTRATION

TECHNOLOGY ADVANCEMENTAND COST REDUCTION

FIELD TEST OFPACKAGED SYSTEM

SELECTEDAPPLICATIONFOR PHASES

II, III

DEMONSTRATIONOF PACKAGED SYSTEM

FOR SELECTEDAPPLICATION

FIELD TEST OFPACKAGED SYSTEM

FOR SELECTEDAPPLICATION

• IMPROVED PERFORMANCE, YIELDS, EFFICIENCY

• ENABLE INCREASED MANUF. AUTOMATION

• DESIGN PACKAGING

PHASE I PHASE II PHASE III

DESIGN, STACK DEVELOPMENT, FUEL PROCESSING, THERMAL MANAGEMENT, CONTROLS/SENSORS, POWER ELECTRONICS

KEY TECHNOLOGY DEVELOPMENT

• ADVANCED MATERIALS/ PROCESSES• ENABLE FULL MANUF. AUTOMATION• OPTIMIZE PACKAGING

MARKET ANALYSIS AND COST ESTIMATES

MARKET ANALYSIS AND COST ESTIMATES

COST ESTIMATES

M-4thSECA.ppt- 6



Phase I Work ElementsPhase I Work Elements

• System analysis

• Cost estimate

• Stack technology development

• Fuel processing

• Thermal management

• Control and sensor development

• Power electronics

• System prototype demonstration

M-4thSECA.ppt- 7



Development ApproachesDevelopment Approaches

• System approach– Design for Six Sigma

• Development focus to meet SECA targets– High performance– Low cost– Reliability– Modularity– Fuel flexibility

M-4thSECA.ppt- 8



System Design and Analysis ApproachSystem Design and Analysis Approach

• Propose Conceptual Design• Steady-state Model• Assume Components &Performances• Detailed Thermal/TransientSystem Model

• DesignComponents• System Analysis• Trade Studies

• Compare to Requirements• Identify Gaps

ConceptualSystem Definition

TechnologyGaps

System Definition

TechnologyDevelopment

System RequirementsTechnology Base

M-4thSECA.ppt- 9



Baseline System ConceptBaseline System Concept

Fuel Processor

Steam Generator

Natural GasDesulfurizer

P Deionizer

Fuel/AirPreheater

FUEL

WATER1 WATER2

EXHAUST

STEAM

HOTGASC

HOT GASE

ANIN

PWATER

C

AirPreheater

FCAIR

CPXAIR

AC Power

to loads

S

SOFC Stack Assembly

CAIN

C

AIR

NATGAS

Power Electronics

StartupPower

AC Power

M-4thSECA.ppt- 10



Performance EstimatesPerformance Estimates

Stationary(Baseline)

Mobile MilitaryFuel Natural Gas Gasoline Diesel

Input Fuel, lb/hr Air, lb/hr Water, lb/hr

2.0 186 2.3

2.0 185 4.9

1.7 188 4.2

Power Fuel cell, kWNet, kW

5.8 5.0

4.4 3.7

3.2 2.5

EfficiencyNet, %

40

33

28

M-4thSECA.ppt- 11



Important Performance ParametersImportant Performance Parameters

SOFC STACK Average cell voltageStack voltageFuel utilizationCell temperature riseCell pressure dropAnode leakage fractionInternal Reforming fractionHeat loss

FUEL PROCESSOR Steam to carbon ratioCarbon to oxygen ratioOperating temperatureFeed TemperatureApproach to EquilibriumPressure dropHeat loss

HEAT EXCHANGERS & THERMAL MANAGEMENT Pressure dropsHeat losses

AIR DELIVERY Compressor EfficiencyCompressor pressure ratio

POWER ELECTRONICS & ELECTRICAL COMPONENTS Inverter efficiencyMotor efficiencies

M-4thSECA.ppt- 12



Stack Parameter Effects on System PerformanceStack Parameter Effects on System Performance

FUEL UTILIZATION EFFECT ON SYSTEM EFFICIENCY

25

27

2931

33

35

37

3941

43

45

0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1

Fuel Utilization

Syst

em E

ffici

ency

CELL VOLTAGE EFFECT ON SYSTEM EFFICIENCY

25

27

29

31

33

3537

39

41

43

45

0.6 0.65 0.7 0.75 0.8 0.85 0.9

Cell voltage

Syst

em E

ffici

ency

C EL L D EL T A - T EFFEC T O N S Y S T EM EFF IC IEN C Y

2 52 72 93 13 33 53 73 94 14 34 5

2 5 5 0 7 5 1 0 0 1 2 5 1 5 0 1 7 5 2 0 0 2 2 5C e ll- d e lt a T , C

Sust

em E

ffici

ency

M-4thSECA.ppt- 13



Fuel Processor Effects on System PerformanceFuel Processor Effects on System Performance

0.30

0.32

0.34

0.36

0.38

0.40

0.42

0.44

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Steam to Carbon Ratio

SYST

EM E

FFIC

IEN

CY

0.30

0.32

0.34

0.36

0.38

0.40

0.42

0.44

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Carbon to Oxygen Ratio (C/O)SY

STEM

EFF

ICIE

NC

Y

M-4thSECA.ppt- 14



Schematic of Method for Cost EstimationSchematic of Method for Cost Estimation

Define SystemIdentify Components

Establish Performance Specifications

Size Components

Identify BOP Suppliers/Manufacturers

Calculate Costs

Solicit Cost Information

Perform System Cost Estimation

Map Manufacturing Process

Design Stack, Fuel processor

SOFC Stack and Fuel ProcessorBOP Components

Determine Production Rates

Raw Materials CostEquipment CostLabor CostFacilities/Utilities Cost

Vendors

Engineering Judgment

Assembly Costs

M-4thSECA.ppt- 15



Stack Material Cost EstimatesStack Material Cost Estimates

Cell Material

Costs

Cell Design

Cell Size

Number of Cells per System

Cell Cost References

CostsSystem Power

Cell Voltage

Stack Size

Polarization Curve

Number of Cells per Stack

CellMaterial

Costs

Cell Design

Cell Size

Number of Cells per System

Cell Cost References

Stack MaterialCosts

System Power

Cell Voltage

Stack Size

Polarization Curve

Number of Cells per Stack

SECA Baseline Manufacturing

Plan

Costs

Stack Equipment

Costs

SECA Baseline Manufacturing

Plan

Stack LaborCosts

StackEquipment

Costs

Stack Facility Costs

Stack FacilityCosts

Production Volume

Ancillary Parts Cost References Ancillaries

MaterialCosts

Production Volume

Ancillary Parts Cost References Ancillaries

MaterialCosts

Stack Material

Cell CompositionCell Composition

Layers Characteristics

Layers Characteristics

Manufacturing Yield

Manufacturing Yield

M-4thSECA.ppt- 16



Stack Manufacturing Cost EstimatesStack Manufacturing Cost Estimates

Manufacturing Plan

Manufacturing Processes

Manufacturing Actions

Work Load per Action

Stack Equipment Costs

Stack Labor Costs

Equipment Item Costs

Equipment List

Cost per Employee

Equipment Requirements

Plant Size Requirement

Land and Building Costs

Amortization and Maintenance

Amortization and Maintenance

Plant & Utilities Costs

Utilities Costs

Plant Operation

Real Estate Data

Manufacturing Plan

Manufacturing Processes

Manufacturing Actions

Work Loadper Action

Stack EquipmentCosts

Stack LaborCosts

EquipmentItem Costs

Equipment List

Cost perEmployee

Equipment Requirements

Plant SizeRequirement

Land andBuilding Costs

Amortization andMaintenance

Amortization andMaintenance

Plant & UtilitiesCosts

UtilitiesCosts

PlantOperation

Real EstateData

Stack Labor Costs

Stack Equipment Costs

Plant & Utilities Costs

M-4thSECA.ppt- 17



Stack Cost : Monte Carlo Simulation ExamplesStack Cost : Monte Carlo Simulation Examples

16.50 20.64 24.79 28.93 33.07

$/kgFrequency Chart

$ / kW

.000

.008

.015

.023

.030

0

3.75

7.5

11.25

15

$235.2 $262.2 $289.2 $316.2 $343.2

500 Trials 496 Displayed

Forecast: Total

$16.50 $20.64 $24.79 $28.93 $33.07

$/kgFrequency Chart

$ / kW

.000

.006

.011

.017

.022

0

2.75

5.5

8.25

11

$210.3 $241.7 $273.2 $304.6 $336.0

500 Trials 499 Displayed

Forecast: Total

M-4thSECA.ppt- 18



Cost EstimatesCost Estimates

Overall System Cost Allocations

BOP63%

Overall System Cost Allocations

Stack23%

Fuel Processor5%

Thermal Management9%

BOP63%

M-4thSECA.ppt- 19



Controls Analysis and Design ProcessControls Analysis and Design Process

Control Requirements Definition•Model Development•Subsystem Analysis•Control Loop Analysis•Cell Monitoring

“Design for Control”

Preliminary Control Design•Simulation Based Design•Assume Component Performance•Controllability of System Addressed

Control Evaluation and Development•Control Design Trade Studies•Focus Control Design for Application•Built-In Test and Health Monitoring•Final Control Design for Phase I•Develop Sensor Requirements•Develop Actuator Requirements

Sensor and Actuator Evaluation•Sensor Trade Studies•Sensor Testing•Actuator Trade Studies•Actuator Testing

Sensor and Actuator Development•Sensor Development•Actuator Development

Control System Integration•Rapid Prototyping System Implementation of Control Strategy•Hardware Selection and Procurement•Software Development•Hardware/Software Implementation

System Design-FMEA-Event

Ledger...

M-4thSECA.ppt- 20



Control & Sensing ApproachControl & Sensing Approach

PlantSensors

Feedback

Feedforward

Estimation

Controls

– GE Fuel Cell Dynamic Component LibraryDynamic Component ModelsDynamic Subsystem ModelsDynamic System ModelsControl System DesignSimulation Trade Studies

– Rapid Prototyping of Control SystemsRapid Test DevelopmentHardware-in-the-Loop Simulations and TestsAutomatic Code Generation

– Hardware Implementation and Validation of most Promising Control System Design

Rapid Prototyping

This approach allows for low-cost investigation of advanced control techniques which provide significant system cost and performance breakthroughs

This approach allows for low-cost investigation of advanced control techniques which provide significant system cost and performance breakthroughs

M-4thSECA.ppt- 21



StartupStartup

• Four start-up strategies have been identified

• Simulation based trade studies are currently being conducted to optimize start-up strategy

• Control Requirements– Performance– Cost– Reliability– Safety

YES

Set reactant flows to warm-upconditions

System heating

SteamAvailable?

Start Reformer

StackWarm?

Drawtest loadStand-by for service

NO

YES

NO

Start-up Desired

BrainstormStrategies

Optimized Start-up StrategyApproach Modeling

M-4thSECA.ppt- 22



Transient OperationTransient Operation1

OFF

1

Off

1

Off

2

STARTUP

1Startup

3

SETPOINT

1

Idle

1Maintain

1Maintain

4

IncreasePower

1Increase

5

DecreasePower

2Decrease

6

SHUTDOWN

3

Shutdown or Fault

2

Fault

2

Fault

2 Shutdown or Fault

7

Emergency

1Fault

8

Normal

2Shutdown

• Transients seen during start-up and shut-down– Temperature ramp rates on all

components will be maintained– Component limitations accounted

for explicitly in control system

• Transients seen during normal operation– Components maintained

isothermally– Efficiency traded for system

stability Fuel Cell Warm Up

Test Load and Standby

-20

-10

0

10

20

30

40

50

60

70

80

90

100

0 30 60 90 120 150 180

Time, Minutes

Pow

er, %

of F

ull L

oad

Fuel Processor & BOPWarm Up

M-4thSECA.ppt- 23



SECA Dynamic System Model SECA Dynamic System Model -- Ramp ResultsRamp Results

• Ramp increase in power from 0% to 75% load in 10 seconds

• SOFC temperature too low resulting in poor performance

– Anode inlet temperature low

– Cathode inlet temperature low

• Direct ramping of system seems promising, but further analysis is needed

Preliminary ResultsPreliminary Results

M-4thSECA.ppt- 24



SECA Dynamic System Model SECA Dynamic System Model -- Step ResultsStep Results

• ~0.5 kW steps

• SOFC temperature control very sensitive

– Steam-to-carbon – Air utilization

• Fuel cell performance low

– High current density– High fuel utilization

• Stepping of power shows some stability benefits

Preliminary ResultsPreliminary Results

M-4thSECA.ppt- 25



Tape Tape Calendering Calendering Process Process

Fracture SurfaceLaMnO3Cathode

ZrO2Electrolyte

NiO/ZrO2Anode

Tape Forming Rolling Rolling

Electrolyte

SupportElectrode

SupportElectrode

BilayerBilayer

Thin Electrolyteon SupportElectrode Layer

M-12569.ppt

ElectrodeApplication Firing Cutting

M-4thSECA.ppt- 26



NDE Inspection of Green TapesNDE Inspection of Green Tapes

• X-Ray inspection of three tapes in various stages of processing, the radiographs show indications of higher and lower density regions

M-4thSECA.ppt- 27



NDE Inspection of Sintered BilayersNDE Inspection of Sintered Bilayers

Ultrasonic ImageX-Ray ImageOptical Image

• Both X-Ray and ultrasonic imaging are being evaluated for fired bilayers

• Density variations can be observed with both techniques• Ultrasonic more sensitive of surface features

M-4thSECA.ppt- 28



Footprint ScaleFootprint Scale--UpUp

• Effects and issues related to foot-print scale-up are being explored

• 8” diameter cells and interconnects have been fabricated and tested

M-4thSECA.ppt- 29



8”8”––Cell Stack PerformanceCell Stack Performance

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.000 0.200 0.400 0.600 0.800

Current Density (A/cm2)

Cel

l Vol

tage

(V)

% F

uel U

tiliz

atio

n

0.000

0.080

0.160

0.240

0.320

0.400

0.480

Pow

er D

ensi

ty (W

/cm

2 )

8''-V4.375''-V4.375''-FU8''-FU8''-PD4.375''-PD

M-4thSECA.ppt- 30



Cathode Materials and Microstructure DevelopmentCathode Materials and Microstructure Development

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 1 2 3Current Density, A/cm2

Cel

l Vol

tage

, V

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Pow

er D

ensi

ty, W

/cm2800C

660C

Oxidant: airFuel: Hydrogen

0.40.50.60.70.80.9

11.11.2

0 20 40 60 80Time, Hours

Cel

l Vol

tage

, V

600

620

640

660

680

700

Tem

pera

ture

, C

take polarization

Oxidant: AirFuel: H2, 67cc/minJ=1.19A/cm2

High Performance Cathode

Engineered Structures

Engineered porosityTPB LengthInterfacial properties

High conductivityHigh catalytic activity

Compatibility-low reactivityInterlayer development

New Materials

M-4thSECA.ppt- 31



Fuel Concentration and UtilizationFuel Concentration and Utilization64% H2 Balanced with N2

0.0

0.2

0.4

0.6

0.8

1.0

0 0.2 0.4 0.6 0.8

Current Density, A/cm2

Cell

Volta

ge, V

&

Pow

er D

ensi

ty, W

/cm2 80%

70%60%50%

33% H2 Balanced with N2

0.0

0.2

0.4

0.6

0.8

1.0

0 0.2 0.4 0.6 0.8


Cell

Volta

ge, V

&

Pow

er D

ensi

ty, W

/cm

2

80%70%60%50%

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 0.2 0.4 0.6 0.8


Cel

l Vol

tage

, V &

Pow

er D

ensi

ty, W

/cm

2

33% H2

64% H2

Mass transfer is a major issue for anode-supported SOFCs

il = - nFDT PH2

δ

M-4thSECA.ppt- 32



Anode Microstructure DevelopmentAnode Microstructure Development

Enhanced catalytic activitiesInternal reforming capability

Sulfur tolerance

Engineered PorosityReduced thickness

Low cost materialsToughed support structures

Enhanced catalytic activitiesInternal reforming capability

Sulfur tolerance

Engineered PorosityReduced thickness

Low cost materialsToughed support structures

0.5

0.6

0.7

0.8

0.9

0 0.2 0.4 0.6 0.8


Cel

l Vol

tage

, VV, 50%FUV, 60% FUV, 70% FUV, 80% FU

64%H2 balance N2

SECA Target(80% Utilization, 075V)

M-4thSECA.ppt- 33



LongLong--Term TestingTerm Testing

• Stacks tested up to 3000 hours• Performance degradation (much higher than

target) observed• Potential causes for performance losses being

investigated

M-4thSECA.ppt- 34



SIMS Results on 3000SIMS Results on 3000--hours Stackhours Stack

78.1 micron

Cathode

Elec

troly

te

Mn red, Cr green

78.1 micron

Cathode

Elec

troly

te

Mn red, Cr green• Chromium builds up at

cathode-electrolyte interface

• Chromium is associated with manganese, not with lanthanum

• TEM underway to look at phases that are present

M-4thSECA.ppt- 35



SOFC Operation on Hydrocarbon FuelsSOFC Operation on Hydrocarbon Fuels

Direct-OxidationSOFCFuel

CH4, H2, COFuel

CompleteReformer

Internal ReformingSOFC

Fuel SOFC

Pre-reformer

H2, CO

M-4thSECA.ppt- 36



CPOX for Processing Hydrocarbon FuelsCPOX for Processing Hydrocarbon Fuels

• Fuels: propane, butane, octane, JP-8, and diesel

• Duration: 700 hours to date

• Thermal cycles: 10

• Sulfur tolerance: 1000 ppm dibenzothiophene in JP-8

• Fuels: propane, butane, octane, JP-8, and diesel

• Duration: 700 hours to date

• Thermal cycles: 10

• Sulfur tolerance: 1000 ppm dibenzothiophene in JP-8

0%

20%

40%

60%

80%

100%

0 40 80 120 160 200 240 280 320

Time (Hours)

Perc

ent Y

ield

%

H2

COThermal Cycle

M-4thSECA.ppt- 37



PrePre--Reforming EvaluationReforming Evaluation

• CPOX as a baseline

• Evaluation of CPOX catalysts under ATR conditions

• Preliminary results indicate feasibility of operating CPOX as ATR

M-4thSECA.ppt- 38



SOFC Operation on Hydrocarbon Containing FuelsSOFC Operation on Hydrocarbon Containing Fuels

0.0

0.2

0.4

0.6

0.8

1.0

0.000 0.100 0.200 0.300 0.400 0.500


Cel

l Vol

tage

, V

33% H2 + 200 ml H2O22% H2 + 200 ml H2O +4% CH413% H2 +200 ml H2O + 9% CH40% H2 + 200 ml H2O + 11% CH4

M-4thSECA.ppt- 39



Concluding RemarksConcluding Remarks

• SECA system concept has been developed

• Current development efforts focus on resolving key technical issues concerning key system components

• Significant technical progress has been achieved in several technical areas

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