1Materials and Systems Research, Inc.

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A Reversible Planar Solid Oxide FuelA Reversible Planar Solid Oxide Fuel--Fed Fed Electrolysis Cell and Solid Oxide Fuel Cell for Electrolysis Cell and Solid Oxide Fuel Cell for

Hydrogen and Electricity Production Operating Hydrogen and Electricity Production Operating on Natural Gas/Biogason Natural Gas/Biogas

Greg Tao, Tad Armstrong and Anil VirkarMaterials & Systems Research Inc., Salt Lake City, UT

Glendon Benson, Aker Industries, Inc., Oakland, CA

Harlan Anderson, University of Missouri-Rolla, Rolla, MO

2005 DOE Hydrogen Program Annual ReviewMay 23, 2005 Project ID#: PD2

2Materials and Systems Research, Inc.

OverviewOverview

Timeline• Project started: 09/30/2004• Project ends: 11/30/2006• Percent completed: 25%

Budget• Total budget funding

– DOE $1,200k– Industry $ 300k

• Funding received in FY04 $150k

• Funding for FY05 $690k

BarriersHydrogen generation by water electrolysis

• G – Capital cost– Low-cost, durable high-

temperature materials development

– Lower operating temperature

Subcontractors• 1. University of Missouri-Rolla:

Dr. H. Anderson, Dr. X. Zhou• 2. Aker Industries, Inc.:

Dr. G. Benson

3Materials and Systems Research, Inc.

ObjectiveObjective

To develop a composite/hybrid planar 1kW SOFEC-SOFC stack generating both hydrogen and electricity either from distributed natural gas or biogas fuel. The project will focus on material research, stack design & fabrication, and verification.

• Anode-supported cell development– Anode optimization– Electrocatalytically & chemically stable cathode in

reducing/oxidizing atmosphere

• Cell/stack design, test, & verification– Button cell– Short stack proof-of-concept– 1 kW stack demonstration

4Materials and Systems Research, Inc.

ApproachApproachTo replace the external electrical energy needed to electrolyze steam by a chemical energy directly from fuels

Fossil Energy / Renewable Energy

Electricity

Electrolysis (Hot Elly)

Hydrogen Production

SOFEC + SOFC

Electricity

222 O21HOH +↔

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400

Temperature (K)

∆H

, ∆G

, T∆s

(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)

∆H

T∆s

∆G V Nernst

∆H∆GV ocv

Electricity from Grid

Unique approach

5Materials and Systems Research, Inc.

ApproachApproach

Concept of the solid oxide fuel-fed electrolysis cell (SOFEC)*

• Cathode: Steam reductionpure H2 evolution

• Anode: Fuel oxidation depolarized, chemical energy to replace electrical energy

• Extra electrical energy is needed in order to increase hydrogen production rate

222 O21HOH +↔

2224 H7COCOOH3CH2 ++↔+

22 COO21CO ↔+ OHO

21H 222 ↔+

Anode

CathodeElectrolyte

Loa

d

−2O

−e

I

*: H.S. Spacil and C.S. Tedmon, J. Electrochem. Soc., 116, 1618 (1969)A.Q. Pham, H. Wallman, and R.S. Glass, US Patent No. 6051125 (2000)

6Materials and Systems Research, Inc.

ApproachApproach

Current flow

Steam channelCathode Electrolyte Anode

Fuel channel

Air channel Cathode Electrolyte Anode

Fuel channel

SOFEC

Hydrogen production

SOFC

Electricity generation

• Fuel, steam, air

• Pure H2 & e–

• Same fuel for SOFC & SOFEC

• SOFC provides power to SOFEC

• SOFEC generates H2

• Better thermal management

Concept of the composite/hybrid SOFC-SOFEC stack generating both hydrogen and electricity from the natural gas

7Materials and Systems Research, Inc.

Technical AccomplishmentsTechnical Accomplishments

Anode-supported cell development – anode w/ electrolyte

• Objective:Increase anode porosity and decrease thickness to minimize concentration polarizationDevelop anodes with improved mechanical and thermo-mechanical propertiesFabricate anode-supported cell with defect-free thin electrolyte layer

• Approach: Vary composition and microstructure of NiO + YSZ anodesVary pore-former to adjust porosityImprove quality controlDIR (100%) capability at 700-850 oC

• Issues:Trade-off between strength and porosity/thicknessProperty measurements at high temperatures and in reducing environment

8Materials and Systems Research, Inc.

Technical AccomplishmentsTechnical Accomplishments

Electrolyte

Cathode Current Collector

Anode Support

Cathode Interlayer

Anode Interlayer

• Anode – nickel-zirconia cermet, -- 0.5~0.6 mm thick• Electrolyte – yttria-stabilized zirconia (YSZ), -- 10~20 µm thick• Cathode – conducting ceramic/composite, -- 40~60 µm thick

9Materials and Systems Research, Inc.

Technical AccomplishmentsTechnical AccomplishmentsAnode-supported button cell performance operating in SOFC mode

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Current density(A/cm2)

Vol

tage

(V)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Pow

er d

ensi

ty, W

/cm

2

800 oC 750 oC700 oC 650 oC

0.13 Ωcm2

0.16 Ωcm2

0.24 Ωcm2

0.45 Ωcm2

• 1” button cell

• Active area is 2cm2

• Tested @ 650 – 800 °C

• Air flow rate @ 550 ml/min

• H2 flow rate @ 140 ml/min

10Materials and Systems Research, Inc.

Technical AccomplishmentsTechnical Accomplishments

• Scaled up from button cell to 2”x2” cell w/ 32cm2 active area • 4-cell SOFC stack• Tested @ 800 °C, air and hydrogen• Fuel utilization @ 40%• Higher porosity and thinner anode decreases concentration

polarization at high current densities and high fuel utilizations

1.6”

2”x2” 16-cell

Anode Optimization

0

0.2

0.4

0.6

0.8

1

1.2

0 0.5 1 1.5 2Current density (A/cm2)

Volta

ge p

er c

ell (

V)0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Pow

er d

ensi

ty (W

/cm

2 )

Standard Anode Thin AnodeHigher Porosity Anode

S

11Materials and Systems Research, Inc.

Technical AccomplishmentsTechnical Accomplishments

• 2”x2” 5-cell stack

• Advanced anode

• Tested @ 800oC

• Air and hydrogen

• Fuel utilization @ 60%

• Oxidant utilization @ 50%

SOFC Stack Operated with Different Fuels

0

0.2

0.4

0.6

0.8

1

1.2

0 0.2 0.4 0.6 0.8 1

Current density (A/cm2)

Volta

ge p

er c

ell (

V)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Pow

er d

ensi

ty (W

/cm

2 )

H2 CPOX SyngasH2 P CPOX P S P

0.71 ~ 0.68 V

0.47 ~ 0.49 W/cm2

CPOX: 25.7% H2, 25.6% CO, balance N2

Syngas: 55.8% H2, 11.1% CO, 5.9% CO2, 27.2% H2O

12Materials and Systems Research, Inc.

Technical AccomplishmentsTechnical Accomplishments

• Scaled up to 4”x4” 10-cell stack w/ 92cm2 active area

• Tested @ 800oC

• Steam to carbon ratio @ 2:1

• Fuel utilization @ 40%

• Oxidant utilization @ 40%

SOFC Stack Operation with Methane DIR (100%)

0

2

4

6

8

10

12

0 10 20 30 40 50 60 70Stack current (A)

Stac

k vo

ltage

(V)

0

50

100

150

200

250

300

350

Stac

k po

wer

(W)

H2CH4

4”x4” 40-cell 1kW stack

13Materials and Systems Research, Inc.

Technical AccomplishmentsTechnical AccomplishmentsCathode development for SOFEC

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2

10

20

30

40

50

60

La0.70Ca0.30CrO3-δ

log(pO2)

σ (S

/cm

)

0.00

0.05

0.10

0.15

0.20

0.25

700ºC

Ce0.90Gd0.10O1.95

σ (S

/cm

)

Conductivity as a function of oxygen activity for (La,Ca)CrO3 and Ce0.9Gd0.1O1.95.

9 100.5

1

510

50100

5001100C SinteringLCCr-CSO

T (ºC)700800900

Without infiltration With infiltration

AS

R (Ω

cm

2 )

10000/T (1/K)Plot of ASR as a function of T for the composite

electrodes (LCCr – CSO) with and without infiltration.

• Cathode materials are electrocatalytically and chemically stable in both reducing and oxidizing atmospheres• Candidates: composite cathode, perovskite cathode (w or w/o infiltrated electro-active material)• Cathode functional layer optimization

14Materials and Systems Research, Inc.

Technical AccomplishmentsTechnical Accomplishments

N2

H2

CH4

Anode

Cathode

Heating tapeN2

AirH2

T Controller

Split furnace

Rotameter

3-way valve

Humidifier

Rotameter

Humidifier

T Controller

sample

Heating tape

Deplete Deplete

Sampling tubeDehumidifier

To GC

N2

H2

CH4

Anode

Cathode

Heating tapeN2

AirH2

T Controller

Split furnace

Rotameter

3-way valve

Humidifier

Rotameter

Humidifier

T Controller

sample

Heating tape

Deplete Deplete

Sampling tubeDehumidifier

To GC

SOFC/SOFEC test rig setup diagramCapable of operating in both the SOFC and SOFEC modes under various fuel condition

15Materials and Systems Research, Inc.

Technical AccomplishmentsTechnical AccomplishmentsButton cell SOFC/SOFEC test verification

Fixture exploded view Test rig setup

16Materials and Systems Research, Inc.

Technical AccomplishmentsTechnical Accomplishments• Button cell

• Anode-supported

• Active area: 2cm2

• Tested @ 800oC

Cell Operation in SOFC & SOFEC Mode

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

-1.5 -1 -0.5 0 0.5 1 1.5

Current density (A/cm2)

Cel

l vol

tage

(V)

SOFC H2 SOFEC H2 SOFC Syngas SOFEC Syngas SOFC CH4 SOFEC CH4

SOFCSOFEC

0.65 Ωcm2

0.59 Ωcm20.58 Ωcm2

0.76 Ωcm2

0.75 Ωcm2

0.89 Ωcm2

H2 generation (cc/min-cm2) H2 (fuel) consumption (cc/min-cm2)

11.3 7.5 3.8 0.0 3.8 7.5 11.3

Cell Operation in SOFC & SOFEC Mode

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

-1.5 -1 -0.5 0 0.5 1 1.5

Current density (A/cm2)

Cel

l vol

tage

(V)

SOFC H2 SOFEC H2 SOFC Syngas SOFEC Syngas SOFC CH4 SOFEC CH4

SOFCSOFEC

0.65 Ωcm2

0.59 Ωcm20.58 Ωcm2

0.76 Ωcm2

0.75 Ωcm2

0.89 Ωcm2

H2 generation (cc/min-cm2) H2 (fuel) consumption (cc/min-cm2)

11.3 7.5 3.8 0.0 3.8 7.5 11.3

H2 generation (cc/min-cm2) H2 (fuel) consumption (cc/min-cm2)

11.3 7.5 3.8 0.0 3.8 7.5 11.3

• In the optimized SOFC, MSRI successfully reduced the ASR to less than 0.2Ωcm2

• Efforts will be devoted to develop materials/microstructures so that the ASR is low in both SOFC and SOFEC modes

17Materials and Systems Research, Inc.

Technical AccomplishmentsTechnical AccomplishmentsCathode improvement – operation in SOFEC mode

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 0.2 0.4 0.6 0.8 1

Current density (A/cm2)

Cel

l vol

tage

(V)

0 1 2 3 4 5 6 7 8H2 production rate (SCCM/cm2)

C1 H2 C1 CH4 C2 H2 C2 CH4 C3 H2 C3 CH4C4 H2 C4 CH4

• Button cell

• Anode-supported

• Active area: 2cm2

• Tested @ 800oC

18Materials and Systems Research, Inc.

Future WorkFuture Work

• Remainder of FY05• Further implementation of quality assurance in cell fabrication• Newly developed cathode verification on single cell level• Cell improvement (reduce ASR)• Single cell reliability testing (long-term, SOFEC/SOFC oscillation)• Stack design and machining• Short stack testing – proof-of-concept

• FY06• BOP cost analysis• Stack modeling to optimize fluid flow and thermal management• Stack design optimization• Long-term and degradation test• Thermal cycling test in short stack• 1 kW stack testing

19Materials and Systems Research, Inc.

AcknowledgementAcknowledgement

Department of Energy

• DOE Golden Field Office: David Peterson• DOE EERE: Matthew Kauffman

Pete Devlin

20Materials and Systems Research, Inc.

Hydrogen SafetyHydrogen Safety

• The most significant hydrogen hazard associated with this project is:

• having a leak from the hydrogen storage tanks or from the testing setup that may cause an explosion.

• Our approach to deal with this hazard is:• all of the hydrogen that is on site is stored in qualified pressure

vessels and is located in a secluded area away from ignition sources, oxidants and other chemicals. All of the hydrogen pipelines have been leak tested and are rated for the operating pressures. All testing setups are located under ventilation hoods that are rated at 3000 CFM.