List Of Figures

Figure Title Page

Figure 1-1 Schematic of an Individual Fuel Cell 1-1

Figure 1-2 Simplified Fuel Cell Schematic 1-2

Figure 1-3 External Reforming and Internal Reforming MCFC System Comparison 1-6

Figure 1-4 Expanded View of a Basic Fuel Cell Repeated Unit in a Fuel Cell Stack 1-8

Figure 1-5 Fuel Cell Power Plant Major Processes 1-9

Figure 1-6 Relative Emissions of PAFC Fuel Cell Power Plants

Compared to Stringent Los Angeles Basin Requirements 1-10

Figure 1-7 PC-25 Fuel Cell 1-14

Figure 1-8 Combining the TSOFC with a Gas Turbine Engine to Improve Efficiency 1-18

Figure 1-9 Overview of Fuel Cell Activities Aimed at APU Applications 1-27

Figure 1-10 Overview of APU Applications 1-27

Figure 1-11 Overview of typical system requirements 1-28

Figure 1-12 Stage of development for fuel cells for APU applications 1-29

Figure 1-13 Overview of subsystems and components for SOFC and PEM systems 1-31

Figure 1-14 Simplified System process flow diagram of pre-reformer/SOFC system 1-32

Figure 1-15 Multilevel system modeling approach 1-33

Figure 1-16 Projected cost structure of a 5kWnet APU SOFC system. Gasoline fueled POX reformer, Fuel cell operating at 300mW/cm2, 0.7 V, 90 % fuel utilization, 500,000 units per year production volume 1-35

Figure 2-1 H2/O2 Fuel Cell Ideal Potential as a Function of Temperature 2-4

Figure 2-2 Ideal and Actual Fuel Cell Voltage/Current Characteristic 2-5

Figure 2-3 Contribution to Polarization of Anode and Cathode 2-8

Figure 2-4 Flexibility of Operating Points According to Cell Parameters 2-9

Figure 2-5 Voltage/Power Relationship 2-10

Figure 2-6 Dependence of the Initial Operating Cell Voltage of Typical Fuel Cells on Temperature 2-12

Figure 2-7 The Variation in the Reversible Cell Voltage as a Function of Reactant

Utilization 2-15

Figure 2-8 Example of a Tafel Plot 2-24

Figure 3-1 PEFC Schematic 3-4

Figure 3-2 Performance of Low Platinum Loading Electrodes 3-5

Figure 3-3 Multi-Cell Stack Performance on Dow Membrane 3-7

Figure 3-4 Effect on PEFC Performances of Bleeding Oxygen into the Anode

Compartment 3-9

Figure 3-5 Evolutionary Changes in PEFCs Performance [(a) H2/O2, (b) Reformate

Figure 3-6 Influence of O2 Pressure on PEFCs Performance (93°C, Electrode

Loadings of 2 mg/cm2 Pt, H2 Fuel at 3 Atmospheres) 3-11

Figure 3-7 Cell Performance with Carbon Monoxide in Reformed Fuel 3-12

Figure 3-8 Single Cell Direct Methanol Fuel Cell Data 3-13

Figure 4-1 Principles of Operation of Alkaline Fuel Cells (Siemens) 4-2

Figure 4-2 Evolutionary Changes in the Performance of AFC's 4-5

Figure 4-3 Reversible Voltage of The Hydrogen-Oxygen Cell 4-6

Figure 4-4 Influence of Temperature on O2, (air) Reduction in 12 N KOH 4-7

Figure 4-5 Influence of Temperature on the AFC Cell Voltage 4-8

Figure 4-6 Degradation in AFC Electrode Potential with CO2 Containing and

CO2 Free Air 4-9

Figure 4-7 iR Free Electrode Performance with O2 and Air in 9 N KOH at 55 to 60oC

Catalyzed (0.5 mg Pt/cm2 Cathode, 0.5 mg Pt-Rh/cm2 Anode) Carbon-based

Porous Electrodes 4-10

Figure 4-8 iR Free Electrode Performance with O2 and Air in 12 N KOH at 65oC 4-11

Figure 5-1 Improvement in the Performance of H2-Rich Fuel/Air PAFCs 5-4

Figure 5-2 Advanced Water-Cooled PAFC Performance 5-6

Figure 5-3 Effect of Temperature: Ultra-High Surface Area Pt Catalyst. Fuel:

H2, H2 + 200 ppm H2S and Simulated Coal Gas 5-12

Figure 5-4 Polarization at Cathode (0.52 mg Pt/cm ) as a Function of O2 Utilization, which is Increased by Decreasing the Flow Rate of the Oxidant at

Atmospheric Pressure 100% H3PO4, 191°C, 300 mA/cm2, 1 atm 5-13

Figure 5-5 Influence of CO and Fuel Gas Composition on the Performance of

Pt Anodes in 100% H3PO4 at 180°C. 10% Pt Supported on Vulcan XC-72, 0.5 mg Pt/cm2. Dew Point, 57°. Curve 1, 100% H2; Curves 2-6,

70% H2 and CO2/CO Contents (mol%) Specified 5-16

Figure 5-6 Effect of H2S Concentration: Ultra-High Surface Area Pt Catalyst 5-17

Figure 5-7 Reference Performances at 8.2 atm and Ambient Pressure 5-20

Figure 6-1 Dynamic Equilibrium in Porous MCFC Cell Elements (Porous electrodes are depicted with pores covered by a thin film of electrolyte) 6-3

Figure 6-2 Progress in the Generic Performance of MCFCs on Reformate

Gas and Air 6-5

Figure 6-3 Effect of Oxidant Gas Composition on MCFC Cathode Performance at 650°C, (Curve 1, 12.6% 02/18.4% C02/69.0% N2; Curve 2, 33% O2/

Figure 6-4 Voltage and Power Output of a 1.0/m2 19 cell MCFC Stack after 960 Hours at 965°C and 1 atm, Fuel Utilization, 75% 6-13

Figure 6-5 Influence of Cell Pressure on the Performance of a 70.5 cm2 MCFC at 650°C (anode gas, not specified; cathode gases, 23.2% O2/3.2% CO2/66.3% N2/7.3% H2O and 9.2% 02/18.2% CO2/65.3% N2/7.3%

H2O; 50% CO2, utilization at 215 mA/cm2) 6-16

Figure 6-6 Influence of Pressure on Voltage Gain 6-17

Figure 6-7 Effect of CO2/O2 Ratio on Cathode Performance in an MCFC, Oxygen

Pressure is 0.15 atm 6-20

Figure 6-8 Influence of Reactant Gas Utilization on the Average Cell Voltage of an MCFC Stack 6-21

Figure 6-9 Dependence of Cell Voltage on Fuel Utilization 6-23

Figure 6-10 Influence of 5 ppm H2S on the Performance of a Bench Scale MCFC

(10 cm x 10 cm) at 650°C, Fuel Gas (10% H2/5% C02/10% H2O/75% He)

at 25% H2 Utilization 6-27

Figure 6-11 IIR/DIR Operating Concept, Molten Carbonate Fuel Cell Design 6-29

Figure 6-12 CH4 Conversion as a Function of Fuel Utilization in a DIR Fuel Cell (MCFC at 650°C and 1 atm, steam/carbon ratio = 2.0, >99% methane conversion achieved with fuel utilization > 65%) 6-31

Figure 6-13 Voltage Current Characteristics of a 3kW, Five Cell DIR Stack with

5,016 cm2 Cells Operating on 80/20% H2/CO2 and Methane 6-31

Figure 6-14 Performance Data of a 0.37m2 2 kW Internally Reformed MCFC

Stack at 650°C and 1 atm 6-32

Figure 6-15 Average Cell Voltage of a 0.37m2 2 kW Internally Reformed MCFC Stack at 650°C and 1 atm. Fuel, 100% CH4, Oxidant, 12% CO2/9%

Figure 6-16 Model Predicted and Constant Flow Polarization Data Comparison 6-35

Figure 8-1 Solid Oxide Fuel Cell Designs at the Cathode 8-1

Figure 8-2 Solid Oxide Fuel Cell Operating Principle 8-2

Figure 8-3 Cross Section (in the Axial Direction of the +) of an Early Tubular

Configuration for SOFCs 8-8

Figure 8-4 Cross Section (in the Axial Direction of the Series-Connected Cells)

of an Early "Bell and Spigot" Configuration for SOFCs 8-8

Figure 8-5 Cross Section of Present Tubular Configuration for SOFCs 8-9

Figure 8-6 Gas-Manifold Design for a Tubular SOFC 8-9

Figure 8-7 Cell-to-Cell Connections Among Tubular SOFCs 8-10

Figure 8-8 Effect of Pressure on AES Cell Performance at 1000°C 8-14

Figure 8-9 Two Cell Stack Performance with 67% H2 + 22% CO + 11% H2O/Air 8-15

Figure 8-10 Two Cell Stack Performance with 97% H2 and 3% H2O/Air 8-16

Figure 8-17 Cell Performance at 1000°C with Pure Oxygen (o) and Air (A) Both at

25% Utilization (Fuel (67% H2/22% CO/11%H2O) Utilization is 85%) 8-17

Figure 8-12 Influence of Gas Composition of the Theoretical Open-Circuit Potential of

SOFC at 1000°C 8-18

Figure 8-13 Variation in Cell Voltage as a Function of Fuel Utilization and Temperature (Oxidant (o - Pure O2; A - Air) Utilization is 25%. Currently Density is

160 mA/cm2 at 800, 900 and 1000°C and 79 mA/cm2 at 700°C) 8-19

Figure 8-14 SOFC Performance at 1000°C and 350 mA/cm,2 85% Fuel Utilization and 25% Air Utilization (Fuel = Simulated Air-Blown Coal Gas Containing

Figure 8-15 Voltage-Current Characteristics of an AES Cell (1.56 cm Diameter,

50 cm Active Length) 8-21

Figure 9-1 A Rudimentary Fuel Cell Power System Schematic 9-1

Figure 9-2 Representative Fuel Processor Major Componentsa & Temperatures 9-3

Figure 9-3 "Well-to Wheel" Efficiency for Various Vehicle Scenarios 9-8

Figure 9-4 Carbon Deposition Mapping of Methane (CH4) (Carbon-Free

Region to the Right and Above the Curve) 9-23

Figure 9-5 Carbon Deposition Mapping of Octane (C8H18) (Carbon-Free

Region to the Right and Above the Curve) 9-24

Figure 9-6 Optimization Flexibility in a Fuel Cell Power System 9-35

Figure 9-7 Natural Gas Fueled PEFC Power Plant 9-40

Figure 9-8 Natural Gas fueled PAFC Power System 9-42

Figure 9-9 Natural Gas Fueled MCFC Power System 9-44

Figure 9-10 Schematic for a 4.5 MW Pressurized SOFC 9-46

Figure 9-11 Schematic for a 4 MW Solid State Fuel Cell System 9-51

Figure 9-12 Schematic for a 500 MW Class Coal Fueled Pressurized SOFC 9-54

Figure 9-13 Regenerative Brayton Cycle Fuel Cell Power System 9-59

Figure 9-14 Combined Brayton-Rankine Cycle Fuel Cell Power Generation System 9-62

Figure 9-15 Combined Brayton-Rankine Cycle Thermodynamics 9-63

Figure 9-16 T-Q Plot for Heat Recovery Steam Generator (Brayton-Rankine) 9-64

Figure 9-17 Fuel Cell Rankine Cycle Arrangement 9-65

Figure 9-18 T-Q Plot of Heat Recovery from Hot Exhaust Gas 9-66

Figure 9-19 MCFC System Designs 9-71

Figure 9-20 Stacks in Series Approach Reversibility 9-72

Figure 9-21 MCFC Network 9-75

Figure 9-22 Estimated performance of Power Generation Systems 9-78

Figure 9-23 Diagram of a Proposed Siemens-Westinghouse Hybrid System 9-79

Figure11-1 Equilibrium Constants (Partial Pressures in MPa) for (a) Water Gas Shift, (b) Methane Formation, (c) Carbon Deposition (Boudouard Reaction), and (d) Methane Decomposition (J.R. Rostrup-Nielsen, in Catalysis Science and Technology, Edited by J.R. Anderson and M. Boudart, Springer-Verlag, Berlin GDR, p.1, 1984.) 11-2

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