A Reversible Planar Solid Oxide Fuel-Fed Electrolysis Cell ...
Transcript of A Reversible Planar Solid Oxide Fuel-Fed Electrolysis Cell ...
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
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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
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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
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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)
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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
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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
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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
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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
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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
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0 0.5 1 1.5 2Current density (A/cm2)
Volta
ge p
er c
ell (
V)0
0.1
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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
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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
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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
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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
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0 10 20 30 40 50 60 70Stack current (A)
Stac
k vo
ltage
(V)
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350
Stac
k po
wer
(W)
H2CH4
4”x4” 40-cell 1kW stack
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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
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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
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Technical AccomplishmentsTechnical AccomplishmentsButton cell SOFC/SOFEC test verification
Fixture exploded view Test rig setup
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Technical AccomplishmentsTechnical Accomplishments• Button cell
• Anode-supported
• Active area: 2cm2
• Tested @ 800oC
Cell Operation in SOFC & SOFEC Mode
-0.6
-0.4
-0.2
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-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
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-0.4
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-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
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Technical AccomplishmentsTechnical AccomplishmentsCathode improvement – operation in SOFEC mode
-0.4
-0.2
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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
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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.