Introduction to fuel cell systems
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Introduction to Fuel Cell Systems. Conventional Current. e -. e -. e -. Anode (-) for fuel cell Electrons flow FROM anode H 2 is OXIDIZED. Cathode (+) for fuel cell Electrons flow TO cathode O 2 is REDUCED. H 2. 1/2O 2. 2H +. 3-phase region Reactant (O 2 ) Electrode (e - )

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Introduction to Fuel Cell Systems

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Introduction to fuel cell systems

Introduction to Fuel Cell Systems


Fuel cell basics

Conventional Current

e-

e-

e-

Anode

(-) for fuel cell

Electrons flow FROM anode

H2 is OXIDIZED

Cathode

(+) for fuel cell

Electrons flow TO cathode

O2 is REDUCED

H2

1/2O2

2H+

3-phase region

Reactant (O2)

Electrode (e-)

Electrolyte (H+)

Electrolyte

Conducts ions

Impermeable to reactants

Does not conduct e-

H2O

Fuel Cell Basics


Fuel cell types

Electrical load

e-

Fuel in

Oxidant in

+ Ions

Anode gas channel

Cathode gas channel

Porous anode

Porous cathode

- Ions

Electrolyte

Depleted fuel out

Product gas out

(MCFC, SOFC)

Fuel Cell Types

Depleted oxidant out

Product gas out (PEMFC, PAFC)

Fuel cell typeElectrolyte (Mobile Ion)

Proton exchange membrane fuel cell (PEMFC)Sulfonated polymer (H+)

Direct methanol fuel cell (DMFC)Sulfonated polymer (H+)

Phosphoric acid fuel cell (PAFC)Phosphoric acid (H+)

Molten carbonate fuel cell (MCFC)Molten carbonate (CO32-)

Solid oxide fuel cell (SOFC)Solid YSZ (O2-)


Proton exchange membrane fuel cells pemfc

Proton Exchange Membrane Fuel Cells (PEMFC)

  • Low temperature 60-80C (140–180F)

  • High power density

  • Potential for low cost

  • Attractive for transportation and small-scale CHP

  • 5 – 250 kWe

Polymer membrane

H2 - Rich Fuel

Humid Air

Anode: Pt supported on carbon

Gas diffusion layers - porous carbon paper

Flow channels cut in collector plate

Cathode: Pt supported on carbon

Cathode collector plate

Anode collector plate

Unused Fuel

Depleted Air and Product Water (Vapor and Liquid)


Direct methanol fuel cells dmfc

Direct Methanol Fuel Cells (DMFC)

  • Low temperature 20-90C (70–190F)

  • Low power density

  • High energy density (when fuel is considered)

  • Simplified fuel requirements

  • Attractive as an alternative to Li-ion batteries in portable electronics

  • Size: ~ Watts

Polymer membrane

CH3OH+H2O

Humid Air

Anode: Pt /Ru supported on carbon

Backing layers - porous carbon paper

Flow channels cut in collector plate

Cathode: Pt supported on carbon

Cathode collector plate

Anode collector plate

Unused Fuel, H2O & CO2

Depleted Air and Product Water (Vapor and Liquid)


Phosphoric acid fuel cells pafc

Phosphoric Acid Fuel Cells (PAFC)

Phosphoric acid in

Porous matrix

  • Op. temperature 200 C (390 F)

  • Commercially available

  • 200 kWe @ 40% electrical efficiency

  • Hundreds of demo stacks installed

  • Current cost is $5000/kWe

H2 - Rich Fuel

Air

Anode: Pt supported on carbon

Gas diffusion layers - porous carbon paper

Flow channels cut in collector plate

Cathode: Pt supported on carbon

Cathode collector plate

Anode collector plate

Unused Fuel

Depleted Air and Product Water (Vapor and Liquid)


Molten carbonate fuel cells mcfc

Molten Carbonate Fuel Cells (MCFC)

Molten carbonate in

porous matrix

  • High temperature 650 C (1200 F)

  • No precious metal catalysts

  • Inexpensive materials

  • Internal reforming of simple fuels

  • Compatible with bottoming cycles

  • Size range: 250–2000 kWe

Humid Air and CO2

H2 - Rich Fuel

Anode – Ni alloy

Cathode - NiO

Corrugated stainless steel collector plates

Depleted Air

Unused Fuel,

Water, and CO2


Solid oxide fuel cells sofc

Solid Oxide Fuel Cells (SOFC)

  • High temperature 1000 C (1800 F)

  • No precious metal catalysts

  • Internal reforming of simple fuels

  • Compatible with bottoming cycles

  • 5 – 2000 kWe

Materials of construction

Air electrode (cathode): Lanthanum manganite

Electrolyte: YSZ

Fuel electrode (anode): Cermet – Nickel/YSZ


Summary of fuel cell characteristics

Summary of Fuel Cell Characteristics


Fuel cell stack

Fuel cell stack


Fuel cell systems

Fuel Cell Systems

Source

Fuel

Fuel

Processor

Fuel in

Electrical

Power Out

FUEL CELL STACK

Power

Conditioner

Exh

Water

Water

Mgmt

Heat

Air

Heat Out

Thermal

Mgmt

Air

Mgmt

Exhaust Out


Fuel cell system performance

Fuel Cell System Performance


Fuel processing

Fuel Processing

Exhaust

Compressed Air

Spent Fuel From Anode

LTS

Water

Natural Gas Feed (CH4)

PROX

Fuel to Anode

(H2,CO2,H2O)

HTS

REF

MS

Desulfurizer

Reformer

CH4 + H2O + HEAT  3H2 + CO

Shift Converters

CO + H2O  H2 + CO2 + HEAT


Fuel cell systems for buildings

Fuel Cell Systems for Buildings


Combined heat power chp for building applications

Combined Heat & Power (CHP)For Building Applications

Simultaneous production of heat and power for useful purposes

0.67

0.33

1

Conventional Electric Power Generation

0.2

0.4

1

0.4

Combined Heat and Power


Fuel cell systems for chp applications in buildings

Fuel Cell Systems for CHP Applications in Buildings

  • Wide size range

  • Excellent full and part load performance

  • Minimal environmental impact

  • Simple maintenance

  • Site friendly


Fc system integration for buildings

FC System Integration for Buildings

Typical 200kWe/200kWt PAFC System

Exhaust

18%

Thermal Energy

40 – 80 C (100 – 175 F)

40%

Heat Recovery

40%

42%

100%

85%

Fuel Cell Stack Air & Thermal Management

Fuel Processor

Power Conditioning

Fuel

Power

2%

Heat


5 kwe 9kwt residential pemfc system

5 kWe/9kWt Residential PEMFC System


Commercially available 200 kwe pafc system

Commercially Available 200 kWe PAFC System


Prototype 100 kwe sofc system

Prototype 100 kWe SOFC System


Fuel cell chp system economics

Fuel Cell CHP System Economics

  • Cost of electricity ($/kWh)

Maint

0.01-0.03

Net cost

0.05–0.17

Capital

0.01–0.08

=

Fuel

0.06

+

+

HR Credit

0 – 0.03

-

Basis:CC = $500 – $3000/kW

r = 10%LF = 0.5FC = $8/MCF

E= 45% T= 40% A= 80%


Fcchp economics commercial bldgs

FCCHP Economics: Commercial Bldgs

Basis:LF = 0. 5 F1 = 0.3 r = 12% N = 20years

E=0.4 T=0.4A=0.8 MC = $0.01/kWh


Economic energy environmental performance of fcchp

Economic/Energy/EnvironmentalPerformance of FCCHP

  • 2,500 ft2 residence

  • Atlanta, GA

  • Alternatives:

    • Elec AC/Elec Ht (EAC-EH)

    • Elec AC/Gas Ht (EAC-GH)

    • Fuel cell CHP (FCCHP)

WH

HT

FC

HP

AC

ELEC


Potential driving factors for fuel cells in buildings

Potential Driving Factors forFuel Cells in Buildings

  • REDUCED FIRST COST

  • Increased energy costs

  • Increased valuation of environmental benefits

  • Enhanced concern for power quality (e.g. Hospitals, data processing, security)

  • Integration with hydrogen infrastructure


Fuel cell systems for transportation

Fuel Cell Systems for Transportation


Comparison of fuel cell vehicles and conventional ic engine vehicles

Comparison of Fuel Cell Vehicles and Conventional IC Engine Vehicles

  • Primary energy use

    • Gasoline ICEV: 5 MJ/mile

    • FCV using cH2 – onsite NG SR: 2.3 MJ/mile

  • Emissions (GHG,regulated)

    • Gasoline ICEV: 410 g-CO2/mile

    • FCV using cH2 – onsite NG SR: 250 g-CO2/mile

  • Alternative/Renewable/Domestic fuels


Efficiency of conventional and alternative engines

Efficiency of Conventional and Alternative Engines


Automotive fuel cell system

Automotive Fuel Cell System

Water Vapor Condenser

Air Humidifier

Fuel

Fuel System

Air

Air System

De-ionized Water

Thermal System

From Hydrogen

Storage Tanks

H2 Humidifier

Dome-Loaded

Pressure Regulator

Air In

Water Injection

Pump

Air

Compressor

Humidification

Water Reservoir

Fuel Cell Stack

H2 Inlet

Air in

Air out

Thermostat

Bypass

Main Thermal Pump

Radiator

Reservoir


Fuel cell engine

Fuel Cell Engine


On board versus off board reforming

On-Board versus Off-Board Reforming

1. On-Board Reforming

Fuel Cell

Fuel Tank

Gasoline

Methanol

Other Hydrocarbon

Fuel Processor

2. Direct Hydrogen: (Reforming off the Vehicle)

Fuel Processing Station

(reforming + purification + storage)

Fuel Cell

Hydrogen Tank

Natural Gas

Other Hydrocarbon

Hydrogen

Ref: SAE 2000-01-0001


Fuel selection challenges

Fuel Selection Challenges


Well to wheel energy use for conventional and alternative systems

Well to Wheel Energy Use for Conventional and Alternative Systems


Well to wheels ghg emissions

Well-to-wheels GHG Emissions


Keys to fcv commercialization

Keys to FCV Commercialization

  • Affordability, plus people must want them (conventional vehicles are very good, and improving)

  • Hydrogen fuel storage and range (or on-board fuel processing?)

  • Infrastructure for hydrogen energy carrier; feedstock diversity to get to renewables


Future h2 energy system configurations

Future H2 Energy System Configurations

Hydrogen Storage and Dispensing

Hydrogen Vehicle

Electricity

Heat

Natural Gas

Hydrogen

Fuel processor

Electrolyzer


Possible cost timeline for fuel cells

Possible Cost “Timeline” for Fuel Cells


Questions

Questions???


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