development of a novel efficient solid-oxide hybrid for co ... · development of a novel efficient...

1Materials and Systems Research, Inc.

Development of a Novel Efficient SolidDevelopment of a Novel Efficient Solid--Oxide Hybrid Oxide Hybrid for Cofor Co--generation of Hydrogen and Electricity Using generation of Hydrogen and Electricity Using

Nearby Resources for Local ApplicationNearby Resources for Local Application

Greg Tao, Mike Homel, Bruce Butler, and Anil Virkar

Materials & Systems Research Inc., Salt Lake City, UT

2008 DOE Hydrogen Program Annual ReviewJune 11, 2008

Project ID#: PDP 33

This presentation does not contain any proprietary, confidential, or otherwise restricted information


OverviewOverview

• Project started: 02/10/2006• Project ends: 07/31/2009• Percent completed: 70%

• Total budget funding– DOE $2,480k– Contractor $ 620k

• Funding received in FY07– $ 1,265k

• Funding for FY08– $ 755k

Hydrogen generation by water electrolysis• G – Capital cost

– Low-cost, durable high-temperature materials development

– Lower operating temperature• H – System Efficiency• K – Electricity costs

• University of Alaska Fairbanks – anode supports fracture mechanisms and modeling of residual stresses (S. Bandopadhyay; N. Thangamani)

• University of Missouri-Rolla – cathode & seal materials development (H. Anderson; R. Brow)

• University of Utah – interconnect development (A. Virkar)

Timeline

Budget

Barriers

Partners


ObjectiveObjectiveOverall Objective

• To develop a low-cost and highly efficient 5 kW SOFC-SOFEC hybrid system co-generating both electricity and hydrogen to achieve the cost target of < $3.00/gge when modeled with a 1500 gge/day hydrogen production rate. • The project focuses on materials R&D, stack design & fabrication, and system design & verification.

2007 • 5 kW SOFC-SOFEC hybrid system development─ Materials development and application (electrodes & seals)─ Stack design and development─ Hybrid system design─ BOP components design and development

2008 • 5 kW SOFC-SOFEC hybrid system fabrication and assembly─ Cell & non-cell repeat units fabrication─ BOP components fabrication─ Stack assembly and integration─ Hybrid module evaluation─ Control system assembly & programming


MilestonesMilestonesQuarters, FY Milestone or Go/No-Go Decision1st Quarter, FY07

Go/No-Go decision: assess the appropriate load and strains that SOFC-SOFEC can withstand.

2nd Quarter, FY07

Go/No-Go decision: assess the viability of 1 kW hybrid module for cogeneration based on performance.

4th Quarter, FY07

Go/No-Go decision: finalize the cathode system for hybrid application.

3rd Quarter, FY08

Milestone: Complete the high temperature flexural tests and creep studies of SOFEC anode substrates.

4th Quarter, FY07

Milestone: Complete the design of the 5 kW system and major BOP components. Down select two “invert” glass compositions from 81 compositions that are thermal-mechanically compatible and thermal-chemically stable. Finalize the cathode system for SOFEC applications.

4th Quarter, FY08

Milestone: Complete fabrication of all cell/non-cell repeat units. Complete fabrication and pre-test of BOP components. Transfer the glass seal technology from the subcontractor to MSRI.


ApproachApproach

MSRI, UMR MSRI, UAF, UMR, UU MSRI, UU, UMR

Succ

ess

Cell / Stack /System DesignA. Stack design

B. 5kW system design

C. BOP design/dev.

D. Stresses analyses

E. Seals application

F. Economic analysis

Experimental VerificationA. Short stacks in dif. modes

B. 1 kW hybrid stack

C. Durability evaluation

D. BOP design & evaluation

E. 5 kW hybrid system development & evaluation

MaterialsDevelopmentA. Cathode materials Dev.

B. Anode optimization

C. Electrolyte optimization

D. Catalyst studies

E. Seals development

F. Fabrication Q.A.

80% complete 80% complete 50% complete

Thermocouple

Voltage leads

Thermocouple

Voltage leads

1-2 kW Stack(100 cm2/cell)


BackgroundBackgroundA Solid Oxide Fuel-Assisted Electrolysis Cell (SOFEC) directly applies the energy of a chemical fuel to replace the external electrical energy required to produce hydrogen from water/steam; decreasing the cost of energy relative to a traditional electrolysis process.

Fossil Energy / Renewable Energy

Electricity

Electrolyzer

Hydrogen Production

SOFEC + SOFC

Electricity

Unique process

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400

Temperature (K)

ΔH

, ΔG

, TΔs

(kJ/

mol

)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

VN

erns

t (V)

ΔH

TΔs

ΔG V Nernst

ΔHΔGV ocv

Electricity from GridCo-generationCH4-assisted SOFEC Reaction Electrochemical Process

4H2O + 8e’ 4H2 + 4O2- at cathode4O2- + CH4 CO2 + 2H2O + 8e’ at anodeCH4 + 2H2O CO2 +4H2Pure H2 formed. No need for H2 separation membranes. Lower electricity requirement.


Concept of Hybrid SOFCConcept of Hybrid SOFC--SOFEC Integral SystemSOFEC Integral System

• Pure H2 & electricity co-production from feedstock: hydrocarbon fuel, steam, and air

• Hybrid comprised of SOFCs and SOFECs

• SOFECs produce pure H2 and SOFCs generate electricity for a high H2 production rate

• Thermal integration improves system efficiency

Technical Challenges and SolutionsCost of Hydrogen

SOFC-SOFECperformance

Systemefficiency

Long-termdurability

cathode materials:composition,microstructure,catalyticcharacterisitcs;anode material:porosity, tortuosity,composition;low operatingtemperature:inexpensivematerials, non-precious metalcatalysts;manufacturability.

SOFC-SOFEChybridarchitecture;thermalintegration;co-generationconcept.

"invert" seal materialthermalmechanicalcompatibility andthermalchemicalstability;anode mechanicalstrength.


SOFEC Cathode Materials Development SOFEC Cathode Materials Development LSCM Redox Stability StudyLSCM Redox Stability Study

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.20.0

-0.2

-0.4

-0.6

-0.8

-1.0

-1.2

Z"

Z'

1st (air/wetH2) at 800oC

2nd (air/wetH2) at 800oC

3rd (air/wetH2) at 800oC

4th (air/wetH2) at 800oC



• Previous studies show that (La,Sr)(Cr,Mn)O3-based cathode material is electrocatalytically and chemically stable in both reducing and oxidizing atmospheres

• Previous long-term tests show degradation rate < 1% per 1000hrs over a 4500 hrs continuous test in the SOFC mode.

• Redox stability is desired for reversible applications


SOFCSOFC--SOFEC Anode Substrate Development SOFEC Anode Substrate Development

NiO-YSZ

Reduction

• Fracture Mechanism• Reliability• Optimization of processing conditions

Microstructure and porosity studiesNi-YSZ

Effect of porosity, composition, temperature and thermal shock on Young’s Modulus, biaxial strength

and toughness in reducing environments at High TemperatureCharacterization

Effects of Residual/Chemical/Applied Stresses on Mechanical IntegrityEffects of Residual/Chemical/Applied Stresses on Mechanical Integrity


Reduction of HalfReduction of Half--cells cells

8YSZ

Ni

pore

8YSZNiO

• Porosity

• Triple phase boundary (TPB)

Unreduced

Reduced

NiO (s) + H2 (g) Ni (s) + H2O (g)

• Density

• Mechanical properties

Reduced

Unreduced


Effect of Reduction on Phases & MicrostructureEffect of Reduction on Phases & Microstructure

As-sintered 10min 30min 2 hr 8 hr

0 100 200 300 400 5000

10

20

30

40

50 Porosity Density

Time of reduction (min)

Por

osity

(%)

4.6

4.8

5.0

5.2

5.4

5.6

20 40 60 80 100

Inte

nsity

Diffraction angle 2θ (degree)

(111) YSZ

(200

) YS

Z

(111) Ni

(111

) NiO

(220

) YS

Z(2

00) N

i

(200

) NiO

(311

) YS

Z(2

20) N

iO(2

22) Y

SZ

(222

) YS

Z

(400

) YS

Z(3

11) N

iO(2

20) N

i(2

22) N

iO(3

31) Y

SZ

(420

) YSZ

(311

) Ni

(422

) YS

Z

(222

) Ni

As received NiO-8YSZ

10 min

30 min

2 h

8 h

NiNiO

10 min

30 min

2 h

8 h

As-sintered NiO-YSZ

20 40 60 80 100

Inte

nsity


(111) YSZ

(200

) YS

Z

(111) Ni

(111

) NiO

(220

) YS

Z(2

00) N

i

(200

) NiO

(311

) YS

Z(2

20) N

iO(2

22) Y

SZ

(222

) YS

Z

(400

) YS

Z(3

11) N

iO(2

20) N

i(2

22) N

iO(3

31) Y

SZ

(420

) YSZ

(311

) Ni

(422

) YS

Z

(222

) Ni


10 min

30 min

2 h

8 h

NiNiO

20 40 60 80 100

Inte

nsity


(111) YSZ

(200

) YS

Z

(111) Ni

(111

) NiO

(220

) YS

Z(2

00) N

i

(200

) NiO

(311

) YS

Z(2

20) N

iO(2

22) Y

SZ

(222

) YS

Z

(400

) YS

Z(3

11) N

iO(2

20) N

i(2

22) N

iO(3

31) Y

SZ

(420

) YSZ

(311

) Ni

(422

) YS

Z

(222

) Ni


10 min

30 min

2 h

8 h

20 40 60 80 100

Inte

nsity


(111) YSZ

(200

) YS

Z

(111) Ni

(111

) NiO

(220

) YS

Z(2

00) N

i

(200

) NiO

(311

) YS

Z(2

20) N

iO(2

22) Y

SZ

(222

) YS

Z

(400

) YS

Z(3

11) N

iO(2

20) N

i(2

22) N

iO(3

31) Y

SZ

(420

) YSZ

(311

) Ni

(422

) YS

Z

(222

) Ni


10 min

30 min

2 h

8 h

NiNiO

10 min

30 min

2 h

8 h

As-sintered NiO-YSZ


Effect of Reduction on Mechanical PropertiesEffect of Reduction on Mechanical Properties

0 200 400 600 800 100040

60

80

100

120

140

You

ng's

Mod

ulus

(GP

a)

Temperature (oC)

As-sintered 10min 30min 2h 8h

600 μm thick half-cells

0 200 400 600 800 100030

40

50

60

70

80Ni-8YSZ half cell in 5% H2-Ar atmosphere (600 μm)

You

ng's

Mod

ulus

(GP

a)Temperature (oC)

Half-cells that have NiO:

• Higher initial E and a peak in E at 300°C due to rhombohedral to cubic transition

Half-cells that have no or negligible NiO:

• No structural transition assisted change in E; Oxidation of Ni increases E

• Scattering of E at high temperatures due to thermodynamic instability of c-ZrO2


Events Affecting ‘E’ at Elevated TemperaturesEvents Affecting ‘E’ at Elevated Temperatures

200 400 600 800 1000-40

-20

0

20

40

60

80

100 As-sintered & reduced NiO-8YSZ half cells

Hea

t Flo

w

Temperature (OC)

As-sintered 10 min 30 min 2 hrs 8 hrs

Structural transition of NiO

Oxidation of Ni

0 200 400 600 800 10004

6

8

10

12

14

16 TEC of NiO-8YSZ Thermal Expansion

0 100 200 300 4000

10

20

30

40

50

60

Heating

Ther

mal

Exp

ansi

on (μ

m)

Temperature (OC)

Cooling

Temperature (OC)TE

C x

10-6

K-1

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

DL/L

O

0 200 400 600 800 10004

6

8

10

12

14

16 TEC of NiO-8YSZ Thermal Expansion

0 100 200 300 4000

10

20

30

40

50

60

Heating

Ther

mal

Exp

ansi

on (μ

m)

Temperature (OC)

Cooling

Temperature (OC)TE

C x

10-6

K-1

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

DL/L

O

• Rhombohedral to cubic transition of NiO that affects the thermal expansion and Young’s modulus @ ~ 300°C

• Oxidation of Ni @ ~ 500°C


Hermetic Seals Development Hermetic Seals Development

“Invert” silicate:Glasses with SiO2<45 mole%

Compositions based on:Pyrosilicate and Orthosilicate

Evaluated More Than 81 ‘Invert’ Glass CompositionsEvaluated More Than 81 ‘Invert’ Glass CompositionsEvaluated More Than 81 ‘Invert’ Glass Compositions

650 700 750 800 850 9006

8

10

12

14

YSZ

430SS

G#81

G#50

Coe

f. Th

erm

al E

xpan

sion

(10-6

/ o C)

Softening temperature ( oC )


Electrical Conductivity in Air and Forming GasElectrical Conductivity in Air and Forming Gas

0 5 1 0 1 5 2 0 2 5 3 0 3 5

-7 .0

-6 .8

-6 .6

-6 .4

-6 .2

-6 .0

-5 .8

5 0 S iO 2-3 0 B a O -2 0 Z n O

Con

duct

ivity

log(

S/cm

), in

air

t im e (d ays )

DC

430SS substrates

Glass pasteTest conditions:800oC in air and forming gas

Glass #50

0 1 2 2 4 3 6 4 8-8 .0

-7 .5

-7 .0

-6 .5

-6 .0

F o rm in g g a s

A ir

'A s s e a le d G # 8 1 ' a t 8 0 0 oC

Con

dutc

ivity

log

(S/c

m)

t im e (h rs )


Thermal Cycle Effects on SealsThermal Cycle Effects on Seals

(Samples held at pressure for 24 hours at 800°C; tested for leaks using a 4 psig differential in the testing gas)

Sealing materials Test conditions Notes

430SS/G501 (45µm)/Ni-YSZ

wet forming gas Failed after 20 cycles; Ni-YSZ fracture

430SS/G501(45µm)/YSZ air Failed after 60 cycles; YSZ fracture


forming gas 10 cycles; Ni-YSZ fracture


forming gas Failed after 30 cycles; Ni-YSZ fracture

430SS/G812(25µm)/Ni-YSZ

forming gas 32 cycles without failure

1 Glass prepared by a commercial vendor (MO-Sci)2 Glass prepared at UMR

Hermetic Seals After Initial Multiple Thermal CyclesHermetic Seals After Initial Multiple Thermal Cycles


HermeticityHermeticity and Materials Compatibility and Materials Compatibility

Little Evidence for Significant Reactions @ Seal InterfacesLittle Evidence for Significant Reactions @ Seal Interfaces

SS430

G#50

4.0 4.5 5.0 5.5 6.00

50

100

150

200

250

300

ba

Cr peak

coun

ts p

er s

econ

d

energy (ev)

a

b

Ten days in wet forming gas at 800oC


Cathode Characteristics in SOFC/SOEC/SOFEC ModesCathode Characteristics in SOFC/SOEC/SOFEC Modes

-1

-0.5

0

0.5

1

1.5

2

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

Current density (A/cm2)

Cel

l vol

tage

(V)

15 11 7.5 3.8 0 3.8 7.5 11 15

Fuel consumption (SCCM/cm2)Hydrogen production (SCCM/cm2)

Ele

ctri

city

savi

ng

• Cells: 2cm2 active area• Reversible CA, LSCrM• 800oC• Cell was tested in three

modes: SOFC; SOEC; SOFEC

I – SOFC modeII – SOEC mode

I/IV – SOFEC modeI/IV – H2 generation @ Ca

II – H2 generation @ An

-1

-0.5

0

0.5

1

1.5

2

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

Current density (A/cm2)

Cel

l vol

tage

(V)

15 11 7.5 3.8 0 3.8 7.5 11 1515 11 7.5 3.8 0 3.8 7.5 11 15

Fuel consumption (SCCM/cm2)Hydrogen production (SCCM/cm2)

Ele

ctri

city

savi

ng

• Cells: 2cm2 active area• Reversible CA, LSCrM• 800oC• Cell was tested in three

modes: SOFC; SOEC; SOFEC

I – SOFC modeII – SOEC mode

I/IV – SOFEC modeI/IV – H2 generation @ Ca

II – H2 generation @ An

−− +=+ 222 OHe2OH

−− += e2O21O 2

2

Anode – Ni

CathodeElectrolyte

SOEC mode

H2 +H2O (H2O ~ 10% to 100%)

I

−e2 P.S.

Loa

d

+

-

+-

Air

−− +=+ 222 OHe2OH

−− += e2O21O 2

2

Anode – Ni

CathodeElectrolyte

SOEC mode

H2 +H2O (H2O ~ 10% to 100%)

I

−e2 P.S.

Loa

d

+

-

+-

I

−e2 −e2 P.S.

Loa

d

+

-

+-

Air

SOFC mode

Anode – Ni

CathodeElectrolyte

−− +=+ e2OHOH 22

2

−− =+ 22 Oe2O

21

Syngas & CH4

H2 +H2O (H2O ~ 0% to 90%)

I

−e2

Loa

d

+

-

Air

SOFC mode

Anode – Ni

CathodeElectrolyte

−− +=+ e2OHOH 22

2

−− =+ 22 Oe2O

21

Syngas & CH4

H2 +H2O (H2O ~ 0% to 90%)

I

−e2 −e2

Loa

d

+

-

Air

Anode – Ni

CathodeElectrolyte

SOFEC mode

−− +=+ 222 OHe2OH

Syngas & CH4

−− +=+ e2OHOH 22

2

H2 +H2O (H2O ~ 10% to 100%)

Loa

d

I

−e2 +- P.S.

+

-Anode – Ni

CathodeElectrolyte

SOFEC mode

−− +=+ 222 OHe2OH

Syngas & CH4

−− +=+ e2OHOH 22

2

H2 +H2O (H2O ~ 10% to 100%)

Loa

d

I

−e2 +- P.S.

+

-

Loa

d

I

−e2 −e2 +- P.S.

+

-

Transpose to SOEC direction


SOFEC Stability TestSOFEC Stability TestSingleSingle--cell Stack with 100 cmcell Stack with 100 cm22 PerPer--cell Active Areascell Active Areas

Per cell production rate: 13.92 standard liters of H2 per hour, or 27.54 grams per day


SOFCSOFC--SOFEC Hybrid Power & HSOFEC Hybrid Power & H22 CogenerationCogeneration

13-SOFC in power generation

20-SOFEC in H2 production

Power & H2 cogeneration

Co-Production rate: Net power output @ 130 Watts and 270 standard liters of H2 per hour (or 0.534 kg/day) CoCo--Production rate: Net power output @ 130 Watts and 270 standard lProduction rate: Net power output @ 130 Watts and 270 standard liters of Hiters of H22 per hour (or 0.534 kg/day) per hour (or 0.534 kg/day)

SOFC (13-cell) + SOFEC (20-cell) Hybrid Stack for a Continuous H2 ProductionTemperature @ 780oC, AN: Syngas; CA1: air; CA2: H2O; Uf/Uair/Usteam=50/60/40 --> 50/50/40

-10

-5

0

5

10

15

20

25

0 10 20 30 40 50 60 70 80

Time (hr)

Volta

ge (V

)

0

5

10

15

20

25

30

35

Hyb

rid s

tack

cur

rent

(A)

SOFEC voltage SOFC voltage Stack current

Stack currentOvernight H2 ProductionH2 Production

lower Uair to 50%


Next Generation Stack Design for the 5 kW SystemNext Generation Stack Design for the 5 kW System

• Larger stacks (60+ cells per stack)• Thermal and flow management

Novel flow geometry for in-stack temperature and flow optimization

• Improved sealing• Design for assembly

Stack components have been minimized to reduce stacking time and errorImproved reliability

• Reduced pressure drop over previous designs


Balance of Plant HardwareBalance of Plant Hardware

• Combustors, reformers and steam generators are being fabricated and tested prior to system integration.

• Catalytic combustors ensure minimal noxious byproducts.

Catalytic combustor


Control SystemControl System

• Design of electronic control algorithm for the SOFC-SOFEC hybrid system.

• Autonomous operation enables to perform all stacks at maximum fuel efficiency and producing hydrogen from excess capacity.

• Multiple stacks in parallel operation to increase reliability and disrupt failure cascades.

• Acquisition of electronic control hardware and integration with system software.

• Pre-test of power electronics and load leveling systems before beingintegrated into the overall system.


Future Work (FY 08 Future Work (FY 08 –– FY 09)FY 09)FY 08FY 08

• Materials DevelopmentExploring an advanced cathode materialContinuous investigation of anode substrates: equi-biaxial test and flexural strength under both air and H2 at working temperatures; effect of thermal cycles on strength

• 5 kW Hybrid System FabricationBOP components fabricationStack assembly, integration and burn-inImplementation and optimization of system controls

FY 09FY 09• 5 kW Hybrid System Assembly and Evaluation

5 kW hybrid system assemblySystem testing and evaluationHydrogen production cost analysis using H2A model


Project SummaryProject SummaryRelevance: Investigate an alternative approach to provide low-cost and highly efficient

distributed electricity and hydrogen

Approach: Develop a 5 kW SOFC-SOFEC hybrid system based on innovative materials development and system design research to co-generate hydrogen and electricity

Materials development: - Evaluated redox stability and long-term stability of the promising cathode material for SOFEC applications. - Finalized two promising “invert” glass compositions from 81 candidates. Seals survived after 30+ thermal cycles in reducing/oxidizing atmospheres. - Investigated effects of reduction on microstructure development and phase formation, elastic properties as a function of temperature, and effects of porosity, composition & microstructure on strength. 5 kW hybrid system development: - Evaluated long-term stability tests of hydrogen production to reduce cost. –Finalized the design of hybrid modules with improved thermal management and flow optimization. – Designed and fabricated major BOP components. –Designed hybrid system control algorithm and acquired control hardware.

Proposed Future Continue implementing mechanical/thermal analyses of anode supports; fabricate and evaluate BOP components and optimize hybrid system controls; implement 5 kW system experimental evaluation and perform cost analyses using DOE H2A model.

Technologies Accomplishments and Progresses:

Research:

development of a novel efficient solid-oxide hybrid for co ... · development of a novel efficient...

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