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

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Rationale for Direct Ammonia Fuel Cells

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Source: Norsk Hydro

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Source: Norsk Hydro

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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

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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

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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.

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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

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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.

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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