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Solid Oxide Fuel Cells:cell and stack technology
August 23, 2011
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
Solid Oxide Fuel Cells:cell and stack technology
contents
requirementsapplicationsstack design
cell configurationscharge transportmass transportheat management
some examplestubularplanarindustrial developments
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: cell and stack requirements
are governed by the system requirements,which, in turn, are governed by the application:
size demand for kWeoperation dynamic load-following vs. stationary base-load
operation time vs. degradation ratefuel availability
in the end, however, it will all come down to
cost of investmentcost of operation
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: systems applications and sizes
mobilehand held < 1kWpersonal power e.g. military applicationμ-CHP 1-5 kWrecreational, camper
APUcars 5-10 kWstationary heating, onboard electronicstrucks 5-50 kWidling reduction, refrigerationplanes 50 kWnoise reduction, water generatorships 10-250 kWport power
stationaryμ-CHP 1-5 kWsingle housesCHP 10-250 kWhospitals, distributed power power plant > 1 MWcentralized power production
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: systems applications and operation
stationary μ-CHP for single housing
(1-5 kW)
APUfor cars
(5-10 kW)
operation time 40.000 hours 5.000 hours
degradation < 1% in 1000 hours
< 10% in 1000 hours
cycling > 50 (thermal) > 250 (thermal)> 250 (red-ox)
start up 4-5 hours < 10 minutes
cost $ 100/kW for stack $ 50/kW for stack
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
+
-
SOFC: stack design
fuelH2, CO, CH4, CO2, H2O
coolantwarm
oxidantO2
exhaustH2, CO2, H2O
coolanthot
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
+
-
SOFC: stack design
fuelH2, CO, CH4, CO2, H2O
coolantwarm
oxidantO2
exhaustH2, CO2, H2O
coolanthot
anode inter-connect
electrolyte
cathode sealing
distributorfuel gas
distri-butoroxidant
heatexchanger
collectorexhaust
is solving the puzzle
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: stack design
taking into accountthe materials used for the componentsthe manufacturing technologies usedthe cell configuration selectedthe processes for
charge transport short current paths, no short-circuiting good electrical contacts and sufficient contact area
mass transport no gas leakages, no cross-leakages uniform distribution of reactants, not only across thearea of each cell but also to each cell of the stack
heat transport appropriate gas flow configurations for stack cooling,more uniform temperature distribution during operation
mechanical/structural integrity adequate mechanical strength for assembly, handling and during operationminimise mechanical and thermal stresses
is solving the puzzle
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: cell configurations
electrolyte =
supporting component
tubular
planar
electrolyte anode
cathode
high mechanical strengthno high-temperature seals
low(er) power densityhigh(er) manufacturing costs
limited mechanical strengthhigh-temperature seals require
high(er) power densitylow(er) manufacturing costs
advantages disadvantages
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: cell configurations
electrolyte anode
cathode
inertceramic
tubular
planar
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: cell configurations
electrolyte anode
cathode
inertceramic
metal
tubular
planar
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: cell configurations
electrolyte anode
cathode
inertceramic
metal
tubular
planar
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: cell configurations
planar
flattenedtubular
tubular
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: stack design and charge transport
electrical connection of cells:
in series and in series in parallel
A
A'
A - A'
interconnectorinterconnector
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: stack design and charge transport
electrical connection of cells:
in series
interconnector
contact elementsmaller conducting cross sectionlonger distance between contact pointssmaller contact area
larger conducting cross sectionshorter distance between contact pointslarger contact area
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: stack design and mass transport
fuel and air supply:to all cells in a stack manifolding (Z- or U-type)
externalinternal (integrated)
over the cell (electrode) area flow fieldparallelserpentine (meander)radialspiral
in the (porous) electrode tothe electrode/electrolyte interfacee.g. the reaction sites not directly relevant for stack design
fuel vs. air flow configurationco-flow in same directioncounter-flow in opposite directionscross-flow in directions usually differing 90°
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: stack design and mass transport
fuel and air supply:to all cells in a stack manifolding (Z- or U-type)
externalinternal (integrated)
U-type flow
0 0.25 0.5 0.75 1
rel. position of cell in stack
stat
icpr
essu
re
distributor manifold
collectormanifold
inlet
outlet
Z-type flow
0 0.25 0.5 0.75 1
rel. position of cell in stack
stat
icpr
essu
re
distributor manifold
collectormanifold
inlet
outlet
source: Th. Wüster, Ph.D. Thesis, RWTH Aachen
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: stack design and mass transport
fuel and air supply:to all cells in a stack manifolding (Z- or U-type)
externalinternal (integrated)
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: stack design and mass transport
fuel and air supply:to all cells in a stack manifolding (Z- or U-type)
externalinternal (integrated)
over the cell (electrode) area flow fieldparallelserpentine (meander)radialspiral
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: stack design and mass transport
fuel and air supply:fuel vs. air flow configuration
co-flow in same directioncounter-flow in opposite directionscross-flow in directions usually differing 90°
co-flow counter-flow cross-flow
cell length x / cm10 201550
0
5
10
15
20
cell width y / cm
cell length x / cm10 201550
0
5
10
15
20
cell width y / cm
cell length x / cm10 201550
0
5
10
15
20
cell width y / cm
air
fuelfuel fuel
air
air
750 800 850 900 950 1000
temperature / °C
air
has direct effect on current and temperature distribution
heat management
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: stack design and mass and heat transport
heat productionelectrochemical reactions (T S)current (I²R)
coolingair mass flow (stoichiometry > 2)internal reforming of methane (endothermic)
co-flow counter-flow
cell length x / cm10 201550
0
5
10
15
20
cell width y / cm
cell length x / cm10 201550
0
5
10
15
20
cell width y / cmfuel fuel
air
air
750
800
850
900
950
1000
temperature / °C
cell length x / cm10 201550
0
5
10
15
20
cell width y / cm
cell length x / cm10 201550
0
5
10
15
20
cell width y / cmfuel fuel
air
air
30%pre-reformedmethane
100%pre-reformedmethane
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: some examples of stack concepts
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC macro tubular cells / stacks
cathode supported tubes with one cell per tubeanode supported tubes with one cell per tubeinert supported tubes with multiple cells
advantages:low degradationrelatively easy sealingpressurized operationfor multiple cells: high output voltage
disadvantages:high temperature 900-1000°Clow power density < 0.3 W/cm²low heating rates
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: micro tubular cells / stacks
electrolyte supported
anode supported
advantages:high heating ratesmoderate power density ~0.5 W/cm²(low degradation?)
disadvantages:high temperature ~900°Clow power per cellcomplex manifolding and sealing
advantages:moderate power density ~0.5 W/cm²medium temperatures 700-800°C
disadvantages:low power per cellcomplex manifolding and sealingredox instable
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: micro tubular cells / stacks
micro tubular anode supported
monolithic
advantages:low temperature 500-600°Chigh power density > 1
W/cm²(high heating rates)
disadvantages:low power per cellcomplex manifolding and sealing cooling problems
advantages:low temperature 600-700°C
disadvantages:low power density < 0.4 W/cm²(complex manifolding and sealing)
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: planar cells / stacks
electrolyte supportedwith ceramic interconnect
advantages:low degradation
disadvantages:high temperature ~900°Clow power density < 0.3 W/cm²complex sealing geometrycomplex manufacturing
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: planar cells / stacks
electrolyte supportedwith metallic interconnect
anode supportedwith metallic interconnect
light-weight APU
advantages:red-ox stable?
round cells: simple sealing geometry
disadvantages:high temperature >900°Clow power density < 0.3 W/cm²degradationcomplex sealing geometrylow heating rates
advantages:high power density 1.0 W/cm²medium temperatures 700-800°C(pressurized operation)
disadvantages:degradationcomplex sealing geometrynot red-ox stable(low heating rates)
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: Siemens Westinghouse Power Co
FuelFlow
Interconnection
FuelElectrode
AirElectrode
ElectrolyteNickel Felt
e-+
e--
AirFlow
FuelFlow
AirElectrode
Electrolyte
Interconnection
FuelElectrode
Nickel-Felt Interconnector
Electrolyte
Anode
Cathode
e-
e-
+
-
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: Siemens Westinghouse Power Co
CHP 125 / SFC-200
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: Rolls Royce Fuel Cell Ltd
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: HEXIS
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
SOFC: Versa Power Systems
Institute of Energy and Climate Research:Fundamentals of Electrochemistry (IEF-9)
1st Joint European Summer School on Fuel Cell and Hydrogen TechnologyAug 22 – Sep 2, 2011, Viterbo, Italy
SOFC: cell and stack technology
Thanks for your attention
Questions anyone?
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