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Direct Ammonia Fuel Cells for DistributedPower Generation and CHPAndrew McFarlan, Nicola Maffei, Luc Pelletier
Presented at:
“Ammonia – The Key to a Hydrogen Economy”
Argonne National Laboratories
Oct 13-14, 2005
2
Rationale for Direct Ammonia Fuel Cells
3
Source: Norsk Hydro
4
Source: Norsk Hydro
5
Overall Efficiency and CO2 Emissions During Productionand Distribution of Hydrogen Energy Carriers
• CO2 capture and sequestration contributes only slightly to the losses
in the full hydrogen value chain
• Central hydrogen and ammonia production seem to be the most
efficient way to produce CO2-free energy carriers
• Ammonia infrastructure development is easier because truck
transport is possible – supply and demand will be in balance
through time
• On site natural gas reforming and methanol steam reforming have
highest CO2 emissions
(H. Anderson, World Hydrogen Energy Conference, Montreal, 2002)
Conclusions drawn from studies done by Norsk Hydro:
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How does ammonia measure up as a fuel for fuel cells?
Fuel property Ammonia Methanol
Energy consumed to make, GJ/m.t. 27-28 28-31Energy density, MJ/Kg (HHV) 22.5 22.7Hydrogen content, % by weight 17.8 12.6CO2 emissions, Kg/Kg 0 1.38
Hazards nonflammable flammabletoxic toxic
corrosive noncorrosiveTransport/Storage liquified gas liquid
126 psia@20°CVolume equiv. to 50L gasoline 137 101
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Solid Electrolyte Ammonia Fuel Cell
What is the concept?
• Ammonia is catalytically decomposedto N2 + H2 at anode
• high temperature, low pressure favourequilibrium limited decomposition
• Protons transport across a solid protonconducting electrolyte.
• Removal of hydrogen at the anodedrives decomposition reaction tocompletion.
• H2/air oxidation at the cathode provideschemical driving force for the fuel cellAND provides the heat of reaction forammonia decomposition.
• Products of the fuel cell are nitrogen,water, electric power and heat.
Solid Electrolyte
Anode
Cathode
H+
Load
Air
NH3
N2
H2
catalyst
O2, N2, H2O
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6 H+ + 3 O2- 3 H2O + heat
3 H2 6 H+ + 6 e
Electrochemical Reactions in a Direct Ammonia Fuel Cell
Using Proton Conducting Electrolyte
ANODE(fuel side)
CATHODE(air side)
OVERALL
2 NH3 + heat 3 H2 + N2
3/2 O2 + 6 e 3 O2-
2 NH3 + 3/2 O2 N2 + 3 H2O
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What is the ammonia fuel cell energy balance?
“Ammonia Cracking”:
2 NH3 N2 + 3 H2 H = 92.4 kJ/mol
= 2.72 MJ/kg NH3
-22.5MJ/kg-h H=2.7 MJ/kg-h
Solid Electrolyte
Anode
Cathode
H+
Load
Air
NH3
N2
H2
catalyst
10.8 MJ/kg-h
3.0 kWe
~55% eff.
9.0 MJ/kg-h
2.5 kW thermal
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The historical market price of anhydrous ammonia in thepast decade has been about $150/ton:
At $150/ton, the fuel cost of electricity is: $0.05/KWHAt $300/ton… $0.10/KWH
In Q4 2003, Ontario wholesale spot market for electricity(NGCC power at $7MMBtu/MWH) was around $0.05/KWH.Renewable “Green” power traded at around $0.09-$0.10/KWH.
A CO2 emissions penalty of $150/ton for electricity
generation is equivalent to about $0.05/KWH (NGCC).
Relative Cost of Ammonia as Fuel for “Green” Electricity
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Fuel Cell Materials R&D Activities
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BaCe0.8Gd 0.2O3-* Electrolyte
Powder XRD patterns of BCG calcined at 1350°C (a), sintered at
1500°C (b), 1550°C (c), 1600°C (d), 1650°C (e).
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Pt/BCG/Pt Ammonia Single Cell Fuel Cell
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 10 20 30 40 50 60 70 80
Current Density (mA/cm2)
Vo
lta
ge
(V
)
H2_50
NH3_40
NH3_25
NH3_15
NH3_10
J. Electrochemical Society, 2004, 151(6), A930
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Pt/BCG/Pt Ammonia Single Cell Fuel Cell
0
5
10
15
20
25
30
35
0 10 20 30 40 50 60 70 80 90
Current Density (mA/cm2)
Po
we
r D
en
sit
y (
mW
/cm
2)
H2_50
NH3_40
NH3_25
NH3_15
NH3_10
J. Electrochemical Society, 2004, 151(6), A930
15
N1= NiO-BCG/BCG/Pt
N2=NiO-BCG/BCG/LSC
N3=NiO-BCG/BCG/LCFC
Cathode Performance Characteristics for Series of Cells
J. Power Sources 2004, 136, 24
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0
10
20
30
40
50
0 50 100 150 200
Current density (mA/cm2)
Po
we
r d
en
sity (
mW
/cm2) BCGP - Hydrogen
BCGP - Ammonia
BCG - Hydrogen
BCG - Ammonia
Doubly-doped BaCe0.8Gd0.19 Pr0.01O3-* Electrolyte
J. Power Sources 2005, 140, 264
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A green 2” dia BCGP discformed by tape casting
2” and 1” dia. BCGP discsafter sintering
Tape Casting of BCGP Electrolyte Materials
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R&D Activities Using Commercially AvailableConventional SOFC Materials
19
Direct Ammonia Fuel Cell UsingCommercial O2- Conducting Electrolyte
0
10
20
30
40
50
60
0 50 100 150 200
Current density (mA/cm2)
Po
we
r d
en
sity (
mW
/cm2 )
Hydrogen
Ammonia
700°C
800°C
750°C
Performance is stable at agiven operating temperatureregardless of fuel.
Power densities are similarwhether with ammonia orhydrogen.
20
0
5
10
15
20
25
30
35
40
45
0 50 100 150 200
Current density (mA/cm2)
Po
we
r d
en
sity (
mW
/cm2)
1
1
1
BCG – H+
BCGP – H+
NextCellTM – O2-
Compares proton conducting(in-house) and oxygen ionconducting (commercial)materials at 700°C inammonia.
Due to their higherconductivity, protonconducting electrolytematerials can operate atlower temperatures than O2-
conducting materials.
Proton Conducting vs O2- conducting Electrolytes for SOFC
21
Commercial Opportunities for Direct Ammonia Fuel Cells
In stationary distributed power generation:
UPS for Critical Ammonia Refrigeration:• Experienced in handling ammonia• Market is expanding due to shift to environmentally
friendly refrigerants• Insatiable power requirement• High overall efficiency in CHP cycles• Requirement for uninterruptible power
In transportation:Railway Locomotives?
We are currently talking to a Canadian fuel cellmanufacturer and ammonia producers about doing acollaborative field trial.
22
Acknowledgements
Our R&D team:
CANMET Materials Technology LaboratoriesDr. Nicola Maffei
National Research Council – ICPETMr. Yeong Yoo
CANMET Energy Technology CentreMr. Luc PelletierDr. A. McFarlanDr. J.P. CharlandMr. Rob Brandon
Financial support from:NRCan - Office of Energy Research and Development
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Thank You