General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.
Users may download and print one copy of any publication from the public portal for the purpose of private study or research.
You may not further distribute the material or use it for any profit-making activity or commercial gain
You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Downloaded from orbit.dtu.dk on: May 17, 2021
SOFC and Gas Separation Membranes
Hagen, Anke; Hendriksen, Peter Vang; Søgaard, Martin
Published in:Energy solutions for CO2 emission peak and subsequent decline
Publication date:2009
Link back to DTU Orbit
Citation (APA):Hagen, A., Hendriksen, P. V., & Søgaard, M. (2009). SOFC and Gas Separation Membranes. In Energysolutions for CO2 emission peak and subsequent decline: Proceedings (pp. 153-161). Danmarks TekniskeUniversitet, Risø Nationallaboratoriet for Bæredygtig Energi. Denmark. Forskningscenter Risoe. Risoe-R No.1712(EN)
Solid Oxide Fuel Cells Solid Oxide Fuel Cells and
Gas Separation MembranesGas Separation Membranes
A H gen P V Hend ik en M Søg dA.Hagen, P.V. Hendriksen, M. SøgaardFuel Cells and Solid State Chemistry Division
Risø DTU Risø DTU
Outline
Background Motivation
Combination of Energy Conversion Technologiesgy g
Solid Oxide Fuel Cells
G S ti M bGas Separation Membranes
Summary and Outlook
16 September 20092 Risø DTU
Wind
Water Sun
BiomassWind Biomass
Energy supply
How can we satisfy our needs for energy – in the right forms and at the right times –in the right forms and at the right times
with what nature offers?
Energy need
ElectricityHeat Fuel
16 September 20093 Risø DTU
Backgroundg
Biomass
Gasification
Fuel Cells Membranes
Heat Electricity
16 September 20094 Risø DTU
Biomass: Gasification
Gasification of biomass to CO and H2
•High temperature process•High temperature process•Use of waste (wood chips, organic waste)Effi i f d f •Efficiency of wood for
electricity exceeds 25% •Potential for increase of l t i l ffi i b f
SOFCOTM
electrical efficiency by use of fuel cells and oxygen enriched gasification
! Carbon capture !
16 September 20095 Risø DTU
Viking gasifier at Risoe DTU
Combination: Gasification – SOFC-Membrane
• Increase of total efficiency:• Increase of total efficiency:– SOFC convert fuel to electricity with higher efficiency than
conventional technologies– Oxygen rich gasification gives a gas with lower nitrogen content (less – Oxygen rich gasification gives a gas with lower nitrogen content (less
diluted fuel)
• New option: Carbon capture• New option: Carbon capture
• Challenges:– Changing composition according to used biomassChanging composition according to used biomass– Load fluctuations– Impurities, minor components in gasification gas:
• Sulphur containing ammonia higher hydrocarbons etc• Sulphur containing, ammonia, higher hydrocarbons, etc.
16 September 20096 Risø DTU
Solid Oxide Fuel Cells: SOFCs
Electrical power and high value Fuel derived from conventional and sustainable sources p g
heat(e.g., methane, natural gas, hydrogen)
Solid oxide fuel cells (SOFCs)Higher efficiency than conventional power generation systems
16 September 20097 Risø DTU
Reduction of emissions and pollution (NOx, CO2, noise) Modular concept (from kW to MW)
SOFC Working Principle and Main SOFC Working Principle and Main Components
CATHODE• Catalytic activity for oxygen reduction
Gas transport (porosity)• Electron- (ion-) conducting
CATHODE• Catalytic activity for oxygen reduction
Gas transport (porosity)• Electron- (ion-) conducting
O2
O2 + 4e- → 2O2-
Electron (ion ) conducting
O2
ELECTROLYTE• Gas tight
• (Oxygen) ion
O2
O2 + 4e- → 2O2-
Electron (ion ) conducting
O2
ELECTROLYTE• Gas tight
• (Oxygen) ion
ANODE
2H2 + 2O2- → 2H2O + 4e-
H2
O2-• (Oxygen) ion conducting
• Electronic isolator e-
ANODE
2H2 + 2O2- → 2H2O + 4e-
H2
O2-• (Oxygen) ion conducting
• Electronic isolator e-
ANODE• Catalytic activity for fuel oxidation
• Gas transport (porosity)• Electron- (ion-) conductingGENERAL
ANODE• Catalytic activity for fuel oxidation
• Gas transport (porosity)• Electron- (ion-) conductingGENERAL
• Chemical inertness• Thermal compatibility
• Mechanical strength and flexibility
• Chemical inertness• Thermal compatibility
• Mechanical strength and flexibilityGasification gas
16 September 20098 Risø DTU
SOFCs at Risoe DTU: Generation G2
•Risoe DTU has developed several SOFC generations based on ceramic materials, which are tailored for different operating conditionswhich are tailored for different operating conditions•A pre-pilot manufacture line was established using scale-able and economically competitive processes
16 September 20099 Risø DTU
Durability of SOFCs – Generation G2y
• Good initial performance• Good initial performance• Good durability over thousands of hours in different fuels:
– Hydrogen, synthesis gas (CO + H2), methane + steam
0.8
1m
2
Durability tests on 2G, synthesis gas, 75% fuel utilization
0.6
ity in
W/c
m
850 oC750 oC0.4
ower
den
si 850 oC750 oC
0
0.2Po
16 September 200910 Risø DTU
0 500 1000 1500 2000Time under current in h
Durability of SOFCs – Generation G2:H2S ImpuritiesH2S Impurities
800cell B CH4/H2O/H2O
700
V
H2/H2O
600tage
in m
V
1 A/cm2H2SH2S
CH4/H2O/H2O
500
Cel
l vol
cell A
850 oC 1 A/cm22G cell
400H2S
850 C, 1 A/cm
• Tolerance of 2G SOFCs towards H S impurities in a fuel mainly containing
4000 500 1000 1500 2000
Time under current in h
16 September 200911 Risø DTU
• Tolerance of 2G SOFCs towards H2S impurities in a fuel mainly containing hydrogen and also hydrocarbons (methane) and steam not sufficient
SOFC: Improvement of Anode of 2G Cellp
Impedance analysis, 750 oC, 20% H2O
0.15
0.20
2 ]
FitCat IAno I
Cell AElectro-
Convs.Diff.
Impedance analysis, 750 oC, 20% H2O
0.15
0.20
2 ]
FitCat IAno I
Cell AElectro-
Convs.Diff. Electro-
Convs.Diff. Electro-
Convs.Diff.
(2G)
56,000 Hz10,000 Hz
790 Hz
110 Hz19 Hz
0 00
0.05
0.10
-Z''
[ Ω c
m
Ano ICat IIDiffusionConversionCell #A
Cathode
Anode lyte 56,000 Hz
10,000 Hz790 Hz
110 Hz19 Hz
0 00
0.05
0.10
-Z''
[ Ω c
m
Ano ICat IIDiffusionConversionCell #A
Cathode
Anode lyte
Cathode
Anode lyte
Cathode
Anode lyte
0.000.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80
Z' [Ω cm2]
0.15
0.20
FitCat I
Cell B
Cathode
Electro-l t
Convs.Diff
0.000.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80
Z' [Ω cm2]
0.15
0.20
FitCat I
Cell B
CathodeCathodeCathode
Electro-l t
Convs.Diff
Electro-l t
Convs.Diff
Electro-l t
Convs.Diff
43,000 Hz5,500 Hz 680 Hz
56 Hz18 Hz0.05
0.10
-Z''
[ Ω c
m2 ]
Cat IAno ICat IIDiffusionConversionCell #B Cathode
AnodelyteDiff.
43,000 Hz5,500 Hz 680 Hz
56 Hz18 Hz0.05
0.10
-Z''
[ Ω c
m2 ]
Cat IAno ICat IIDiffusionConversionCell #B Cathode
AnodelyteDiff.
CathodeAnode
lyteDiff.
CathodeAnode
lyteDiff.
0.000.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80
Z' [Ω cm2]
0.000.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80
Z' [Ω cm2]
Smaller resistance from anode and smaller electrolyte resistance
16 September 200912 Risø DTU
Smaller resistance from anode and smaller electrolyte resistance= Better performing cell
Durability of SOFCs – Generation G2.X with Improved Anode: H2S Impurities
800cell B CH4/H2O/H2O
Improved Anode: H2S Impurities
800cell B CH4/H2O/H2O
700
V
H2/H2O700
V
H2/H2O
600tage
in m
V
1 A/cm2H2SH2S
CH4/H2O/H2O600tage
in m
V
1 A/cm2H2SH2S
CH4/H2O/H2O
500
Cel
l vol
cell A
850 oC 1 A/cm22G cell
500
Cel
l vol
cell A2G cell850 oC 1 A/cm2
400H2S
850 C, 1 A/cm
400H2S
850 C, 1 A/cm
4000 500 1000 1500 2000
Time under current in h• Tolerance of 2G SOFCs towards H S impurities in a fuel mainly containing
4000 500 1000 1500 2000
Time under current in h• Significantly improved tolerance of improved 2G SOFCs towards H S
16 September 200913 Risø DTU
• Tolerance of 2G SOFCs towards H2S impurities in a fuel mainly containing hydrogen and also hydrocarbons (methane) and steam not sufficient
• Significantly improved tolerance of improved 2G SOFCs towards H2S impurities in the fuel
From Solid Oxide Fuel Cells – Oxygen From Solid Oxide Fuel Cells Oxygen Transfer Membranes
CATHODE• Catalytic activity for oxygen reduction
Gas transport (porosity)• Electron- (ion-) conducting
CATHODE• Catalytic activity for oxygen reduction
Gas transport (porosity)• Electron- (ion-) conducting
O2
O2 + 4e- → 2O2-
Electron (ion ) conducting
O2
ELECTROLYTE• Gas tight
• (Oxygen) ion
O2
O2 + 4e- → 2O2-
Electron (ion ) conducting
O2
ELECTROLYTE• Gas tight
• (Oxygen) ionO2 + 4e- → 2O2-
O2O2 + 4e- → 2O2-
O2
ANODE
2H2 + 2O2- → 2H2O + 4e-
H2
O2-• (Oxygen) ion conducting
• Electronic isolator e-
ANODE
2H2 + 2O2- → 2H2O + 4e-
H2
O2-• (Oxygen) ion conducting
• Electronic isolator e-2H 2O2 2H O 4O2-
2H 2O2 2H O 4O2-
ANODE• Catalytic activity for fuel oxidation
• Gas transport (porosity)• Electron- (ion-) conductingGENERAL
ANODE• Catalytic activity for fuel oxidation
• Gas transport (porosity)• Electron- (ion-) conductingGENERAL
• Chemical inertness• Thermal compatibility
• Mechanical strength and flexibility
• Chemical inertness• Thermal compatibility
• Mechanical strength and flexibility
16 September 200914 Risø DTU
Oxygen Transfer Membranes (OTMs)yg ( )
Oxygen is separated from air, transported through a membrane and transported through a membrane and supplied to partial oxidation of methane
Cross section SEM picture of a ceria Cross section SEM picture of a ceria based membrane
16 September 200915 Risø DTU
OTMs: Performance (Flux)( )
MeasurementsEconomical feasibility
CalculationsEconomical feasibility
101
102
cm-2
]
100
[ ml O
2 min
-1 c
T = 600CT = 700C
100 101 102 10310-2
10-1
Vf /
[
T = 800C T = 900C T = 1000C
Flux
Flux
Hydrogen
10 10 10 10 lEly / [ μm ]
0.02 atm O2
Membrane thickness
Air
y g30 µm thick CGO
10 atm air
2
CGO
16 September 200916 Risø DTU
Summary Outlooky
Combination of biomass gasification and SOFC:
• Potential electric efficiency of +50% through use of a SOFC • Potential electric efficiency of +50% through use of a SOFC
• By using intelligent heat management, high total efficiencies ~ 90% possible
• Well performing and durable SOFCs developed and demonstrated for several fuels, even in presence of H2S impurities
– Challenge: Tolerance towards other impurities
Combination of biomass gasification and OTM:
Increase of overall efficiency due to gasification gas with higher • Increase of overall efficiency due to gasification gas with higher energy density (less diluted)
• Know-how developed for SOFCs can be utilized
• Promising results regarding performance (flux) and economic feasibility
– Challenge: Increase of flux and durability
16 September 200917 Risø DTU
g y
Acknowledgementsg
W t f ll k l d t f •We gratefully acknowledge support from our sponsors:
•Topsoe Fuel Cell A/S•Topsoe Fuel Cell A/S•Danish Energy Authority•Energinet.dkg•EU Framework Programmes•Danish National Advanced Technology Foundation •Danish Research Councils•DONG Energy•Areva
16 September 200918 Risø DTU