2000 A NNUAL P ROGRESS R EPORT

U.S. Department of Energy

Energy Efficiency and Renewable Energy

Office of Transportation Technologies

TRANSPORTATION

FUEL

CELL

POWER

SYSTEMS

TRANSPORTATION

FUEL

CELL

POWER

SYSTEMS
ACKNOWLEDGEMENT

We would like to express our sincere appreciation to Argonne National

Laboratory and Computer Systems Management, Inc., for their artistic and

technical contributions in preparing and publishing this report.

In addition, we would like to thank all our program participants for their

contributions to the programs and all the authors who prepared the 

project abstracts that comprise this report.
U.S. Department of Energy

Office of Advanced Automotive Technologies

1000 Independence Avenue, S.W.

Washington, DC 20585-0121

FY 2000

Progress Report for Fuel Cell Power Systems

Energy Efficiency and Renewable Energy

Office of Transportation Technologies

Approved by Steven Chalk Energy Conversion Team Leader

October 2000
Fuel Cell Power Systems FY 2000 Progress Report

iii

CONTENTS

Page

I. INTRODUCTION......................................................................................................................... 1

II. FUEL CELL POWER SYSTEM DEVELOPMENT ................................................................ 9

A. Atmospheric Fuel Cell Power System for Transportation ...................................................... 9

B. Pressurized Fuel Cell Power System for Transportation ........................................................ 12

C. Cost Analyses of Fuel Cell Stack/Systems ............................................................................. 16

D. Fuel Cell Systems Analysis .................................................................................................... 21

III. FUEL PROCESSING SUBSYSTEM.......................................................................................... 27

A. Advanced Fuel Processor Development for Next Millennium Fuel ProcessorTM

for Transportation Fuel Cell Power Systems .......................................................................... 27

B. Multifuel Processor for Fuel Cell Electric-Vehicle Applications ........................................... 32

C. Fuel-Flexible, UOBTM Fuel Processor System: Development and Status .............................. 36

D. Integrated Fuel Processor Development ................................................................................. 40

E. Microchannel Fuel Processor Components............................................................................. 44

F. Catalysts for Improved Fuel Processing ................................................................................. 49

G. R&D on a Novel Breadboard Device Suitable for Carbon Monoxide Remediation

in an Automotive PEM Fuel Cell Power Plant ....................................................................... 53

H. CO Clean-up Development..................................................................................................... 57

I. Evaluation of Partial Oxidation Fuel Cell Reformer Emissions ............................................. 62

J. Catalytic Autothermal Reforming........................................................................................... 65

K. Alternative Water-Gas Shift Catalyst Development............................................................... 70

IV. FUEL CELL STACK SUBSYSTEM .......................................................................................... 75

A. R&D on a 50-kW, High-Efficiency, High-Power-Density, CO-Tolerant

PEM Fuel Cell Stack System.................................................................................................. 75

B. Development of Advanced, Low-Cost PEM Fuel Cell Stack and System

Design for Operation on Reformate Used in Vehicle Power Systems.................................... 79

C. Cold-Start Dynamics of a PEM Fuel Cell Stack..................................................................... 85

D. Efficient Fuel Cell Systems .................................................................................................... 88

E. Direct Methanol Fuel Cells..................................................................................................... 91
Fuel Cell Power Systems FY 2000 Progress Report

iv

CONTENTS (Cont.)

Page

V. PEM STACK COMPONENT COST REDUCTION ................................................................ 95

A. High-Performance, Matching PEM Fuel Cell Components and

Integrated Pilot Manufacturing Process.................................................................................. 95

B. Design and Installation of a Pilot Plant for High-Volume Electrode Production ................... 100

C. Low-Cost, High Temperature, Solid-Polymer Electrolyte Membrane for Fuel Cells ............ 103

D. Development and Optimization of Porous Carbon Papers Suitable for

Gas Diffusion Electrodes ........................................................................................................ 108

E. Electrodes for PEM Operation on Reformate/Air................................................................... 111

F. New Electrocatalysts for Fuel Cells........................................................................................ 115

G. Development of a $10/kW Bipolar Separator Plate................................................................ 119

H. Layered PEM Stack Development.......................................................................................... 123

VI. AIR MANAGEMENT SUBSYSTEMS....................................................................................... 127

A. Turbocompressor for PEM Fuel Cells .................................................................................... 127

B. Development of a Scroll Compressor/Expander Module for

Pressurization of 50-kW Automotive Fuel Cell Systems........................................................ 130

C. Variable Delivery Compressor/Expander Development......................................................... 133

D. Turbocompressor for Vehicular Fuel Cell Service ................................................................. 137

E. Innovative, High-Efficiency Integrated Compressor/Expander Based on

TIVM Geometry ..................................................................................................................... 143

VII. HYDROGEN STORAGE............................................................................................................. 147

A. High-Pressure Conformable Hydrogen Storage for Fuel Cell Vehicles ................................. 147

B. Advanced Chemical Hydride Hydrogen-Generation/Storage System

for PEM Fuel Cell Vehicles.................................................................................................... 150

APPENDIX A: ACRONYMS, INITIALISMS, AND ABBREVIATIONS....................................... 157

APPENDIX B: DOE TECHNICAL TARGETS FOR FUEL CELL SYSTEMS,

SUBSYSTEMS, AND COMPONENTS .................................................................... 161
Fuel Cell Power Systems FY 2000 Progress Report

1

General Motors’ fuel-cell-powered

Precept concept vehicle.

JoAnn Milliken

Program Manager

Patrick Davis

Program Manager

Donna Lee Ho

Program Manager

Nancy Garland

Program Manager

I. INTRODUCTION

Developing Advanced PEM Fuel Cell Technologies

for Transportation

On behalf of the Department of Energy’s Office of

Transportation Technologies (OTT), we are pleased to

present the Fiscal Year (FY) 2000 Annual Progress Report

for the Transportation Fuel Cell Power Systems Program. In

this introduction, we briefly outline the nature, objectives,

and progress of the program, examine the technical barriers to

commercialization of the technology, and highlight the

program’s future directions. For additional information on

OTT’s R&D activities supporting the development of fuel

cell technology, the reader is referred to the FY 2000 Annual

Progress Reports on Fuels for Advanced CIDI Engines and

Fuel Cells, and Automotive Propulsion Materials.

Worldwide interest in fuel cell technology for a wide range of

applications remains very strong. The major automotive and

fuel cell companies are announcing technology

breakthroughs, development vehicles, partnerships, and new

initiatives with increasing frequency. Major energy providers

have emerged to begin addressing important fuel

infrastructure issues. The U.S. Department of Energy (DOE)

remains committed to contributing to this progress in a

significant way by supporting R&D activities that address the

most critical barriers to the introduction of commercially

viable polymer-electrolyte-membrane (PEM) fuel cell

systems.

The mission of the Transportation Fuel Cell Power Systems Program is to develop highly efficient, low- or

zero-emission automotive fuel cell propulsion systems. DOE has selected the PEM fuel cell as its leading

technology candidate because of its high power density, quick start-up capability, and simplicity of

construction.

The Program supports the Partnership for a New

Generation of Vehicles (PNGV), a cooperative research

and development partnership between the federal

government and the U.S. Council for Automotive

Research, which comprises Ford, General Motors, and

DaimlerChrysler. One of the major objectives of PNGV is

to develop a mid-size passenger vehicle capable of

achieving a gasoline-equivalent fuel economy of 80 miles

per gallon (mpg) while adhering to anticipated future

emissions standards and maintaining such attributes as

performance, comfort, and affordability. PNGV has
Fuel Cell Power Systems FY 2000 Progress Report

2

targeted PEM fuel cell power systems as one of the promising

technologies for achieving this objective.

The primary purpose of this report is to document the progress

made by the DOE Transportation Fuel Cell Power Systems

R&D Program during FY 2000 against the R&D barriers and

tasks identified in the Office of Advanced Automotive

Technologies R&D Plan. We would be remiss, however, if we

neglected to note the advances in fuel cell technology being

made through other private and public initiatives throughout the

year. In January 2000, General Motors introduced the Precept,

its second fuel-cell-powered concept vehicle. Designed to

operate on hydrogen stored aboard the vehicle as a chemical

hydride, the Precept has a projected fuel economy in excess of 100 mpg (gasoline equivalent) and a range of

500 miles. In the fall of 1999, Ford unveiled the FC5 fuel cell vehicle, designed — unlike their previously

introduced P2000 — to operate on hydrogen extracted from methanol by means of an onboard fuel processor.

The California Fuel Cell Partnership, a program announced last year, is continuing to generate a high level of

interest by industry and governments to accelerate the development of fuel cell vehicles. The Partnership

plans to put about 70 fuel cell vehicles — cars and buses — on the road between 2000 and 2003. Over the

past year, several new members have joined the Partnership, including DOE and the U.S. Department of

Transportation (DOT). Membership now includes six auto companies (DaimlerChrysler, Ford, Honda,

Hyundai, Nissan, and Volkswagen); two technology developers (Ballard and International Fuel Cells); seven

fuel and fuel infrastructure interests (BP, Shell Hydrogen, Texaco, Air Products, Linde AG, Methanex, and

Praxair); two transit agencies (AC Transit and SunLine), and five government agencies (California Energy

Commission, California Air Resources Board, South Coast Air Quality Management District, DOE, and

DOT). A 55,000-square-foot fuel cell vehicle headquarters and hydrogen refueling facility in West

Sacramento, California, is expected to open in the fall of 2000. Initially, up to 18 fuel cell vehicles will be

regularly driven throughout the Sacramento area to gain "real world" road experience and increase public

awareness.

The DOE Transportation Fuel Cell Power Systems Program is implemented through cost-shared contracts

with automotive suppliers and fuel cell and component developers. Furthermore, DOE national laboratories

and universities throughout the United States conduct R&D activities to increase the knowledge base and

develop enabling technologies for PEM fuel cells.

The Ford FC5 fuel cell concept vehicle.
Fuel Cell Power Systems FY 2000 Progress Report

3

Technical and Economic Challenges

The adjacent chart illustrates the shortfall in meeting the year 2000 transportation fuel cell power system

technical and cost targets. These ambitious targets were originally established in 1994 to meet the PNGV

timeframe for production prototype vehicles in 2004. However, fuel cells are the long-term technology for

PNGV, and a great deal has been learned since the original targets were established. Therefore, DOE is

currently in the process of revising the

targets (including extension of the

timeframe) to better reflect the status of the

technology and an improved understanding

of fuel cell systems, anticipated progress,

and future PNGV fuel cell vehicle

requirements.

On the technical side are such challenging

issues as reducing component and system

costs, reducing platinum usage,

demonstrating component and system

durability, reducing system start-up time,

the availability of high-efficiency air

management subsystems, and the

availability of a suitable fuel infrastructure.

On the economic side are the issues of fuel

cell manufacturing capitalization, cost of a

new fuel infrastructure, and competition

from other technologies.

Cost ($/kW)

50

Durability (hrs)

Transient Response

(sec) Start-Up to Full Power

(min)

Energy Efficiency @

25% Peak Power

(%)

Emissions

Power Density

(W/l)

Specific Power

(W/kg)

300

300

5000

48

1 0.5

15*

120*

120*

3 1

300* 2000

1000*

6*

<Tier II*

Inner Circle 2000 Targets

Outer Circle 2004 Targets

 Status indicated by asterisk *

40

250

250

150

34*

Projected status (pending validation in system deliverables) vs.

technical and cost targets for a 50-kw fuel-flexible fuel cell

system operating on gasoline.
Fuel Cell Power Systems FY 2000 Progress Report

4

System and Component Costs. The Arthur D. Little projection of the high-volume manufacturing cost of the

fuel cell system based on the current status of the technology ($300 per kW) is six times higher than that

needed ($50 per kW) to be competitive with the internal combustion engine. To meet the challenges of

lowering system costs, the Transportation Fuel Cell Power Systems Program strives to develop components

with lower-cost materials, more advanced manufacturing processes, and higher operating efficiency.

Platinum Cost And Supply. A preliminary analysis done by Arthur D. Little for DOE indicates that the

current platinum requirement of a fuel cell system is too high to support market penetration. The platinum

alone for a 50-kW system is currently estimated to cost $57/kW, which is higher than the DOE year 2004 cost

target for the entire fuel cell system of $50/kW. Even a 10% market penetration at the current system

platinum content would exceed current world platinum-production levels. Attainment of the year 2004 goals

for platinum use in fuel cell systems will enable large market penetration and ensure adequate world platinum

reserves. A more comprehensive study on platinum supply and cost is planned to investigate this critical

issue.

Component Durability. The durability of key components, such as membrane/electrode assemblies and fuel

processing catalysts, has not been demonstrated to 5,000 hours. Some of these components, including

automotive-type sensors and valves, are not even available yet for durability testing. Durability testing of

these components in the harsh automotive environment is critically needed. Test fleets, such as those

proposed by the California Fuel Cell Partnership, are also needed to identify component failure modes for

future development and to help establish vehicle warranties that mitigate the manufacturer’s risk.

Start-Up Time. The current start-up time for fuel cell systems, which is controlled by the fuel processor, is in

the range of 6 to 20 minutes. This does not compete well with current production vehicles and would be

unacceptable to consumers. Lengthy start-up times also have major implications for the fuel cell vehicle’s

fuel economy and emissions. Batteries could be used with the fuel cell to permit immediate operation of the

fuel cell vehicle, but the energy demand on the battery could be large (5 kWh).

Air Management. Fuel cell systems require air to operate, but the current compressors are not very efficient

in supplying air to the fuel cell, and the fuel cell is not very efficient in using it. The inefficient use of air

results in an oversupply of air delivered to the fuel cell, placing an added burden on the air compressor,

lowering the overall system efficiency, and increasing the stack size, weight, and cost. A peer review of the

technology determined that no off-the-shelf compressor technology available today comes close to matching

the DOE technical requirements for the fuel cell system. Advances in the activity of the cathode catalyst are

also needed to effectively reduce the air-supply burden on the air management subsystem.

Fuel Infrastructure. Methanol and hydrogen would be good fuels for the automotive fuel cell, as evidenced

by the use of these fuels in the early fuel cell concept cars under test by the automakers. For these and other

alternative fuels such as ethanol, significant capital investments in infrastructure will be required. Such

investments are unlikely, however, until fuel cell vehicles achieve a market penetration that can support the

investment. Petroleum-based fuels, for which an infrastructure already exists, will require the use of a fuel

processor, and may require the development of a compatible specialized fuel blend with very low sulfur and

reduced aromatics.

R&D Highlights

Researchers supporting the Transportation Fuel Cell Power Systems R&D Program continued to make

significant progress in meeting these challenges during FY 2000. Notable advances were achieved in systems

development, fuel cell and fuel-processing subsystems technology, air compressor technology, and the

development of low-cost, high-volume manufacturing processes for key components. The summaries that

follow are selected highlights of the progress made under the program.
Fuel Cell Power Systems FY 2000 Progress Report

5

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

1.4 1.6 1.8 2.0 2.2 2.4

1000/Reactor Temp. (1000/°K)

ln (rate constant, min-1)

n.-p. metal/mixed oxide inc. temp.

n.-p. metal/mixed oxide after 400°C

0.14 wt% Pt/Mixed Oxide/Alumina

400°C 180°C

Activity of ANL nonprecious-metal/mixed oxide

catalyst compared to that of Pt/mixed oxide/alumina.

Honeywell 50-kW CO-tolerant

PEMFC stack system design.

Atmospheric Fuel Cell Power System. During

FY 2000, International Fuel Cells (IFC) successfully

delivered a 50-kW (net) gasoline-fueled power plant

configured for system verification testing. The

laboratory power plant, designed to operate at nearambient pressure, consists of a fully tested 50-kWequivalent fuel-flexible fuel processing system (FPS)

and a 50-kW PEM stack assembly. The FPS was

tested at steady state throughout the required fuel flow

range, as well as during start/stop and transient cycles.

Demonstrated fuel conversion was 98%, with overall

fuel processor efficiency exceeding 83%. CO levels in

the reformate were consistent with required low

levels. Separate testing of the 50-kW stack

demonstrated a gross power output of ~67 kW dc at a

stack voltage of approximately 280 V dc and a current

density of ~650 mA/cm2

. Assembly and installation of the integrated power plant in the IFC test stand is

complete. Verification testing of the system will be performed once the planned checkout procedure is

complete.

Fuel Processor CO Clean-up Catalysts. In a major

breakthrough, Argonne National Laboratory (ANL) has

identified a nonprecious-metal/mixed oxide water-gas

shift (WGS) catalyst that does not lose activity at

temperatures up to 400°C and is air-stable. The cost of

this catalyst is comparable to the current low

temperature WGS catalyst, copper/zinc oxide. Although

noble metal catalysts have desirable air and temperature

stability, their high cost may limit their acceptability for

transportation applications. The nonpreciousmetal/mixed oxide catalyst has WGS activity

comparable with that of the platinum/mixed oxide at a

fraction of the cost. Although the nonprecious

metal/mixed oxide catalyst is not as active as

copper/zinc oxide, it does not lose its activity after

exposure to air at 230°C as does the copper/zinc oxide

catalyst.

CO-Tolerant PEM Fuel Cell Stack System. During

FY 2000, Honeywell (formerly AlliedSignal) made

significant advances in the development of a 50-kW

CO-tolerant fuel cell stack system. Design of the 50-kW

brassboard system, which includes the PEM stack and

the supporting gas-, thermal-, and water-management

subsystems, has been completed. The projected nominal

efficiency of the brassboard system is 45%. In

supporting stack development activities, Honeywell has

demonstrated that its cells can tolerate greater than

200-ppm CO contamination in the anode fuel gas

without appreciable performance loss; an 82-cell stack

IFC 50-kW gasoline-fueled, PEM fuel cell power plant

ready for verification testing.
Fuel Cell Power Systems FY 2000 Progress Report

6

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 250 500 750 1000 1250 1500 1750 2000

Current density (mA/cm2

)

Cell potential (V)

cell1

cell2

cell3

cell4

Compression-molded

plates

Injection-molded

Active area(cm2) :292

H2/Air stoich.:1.5/2.5

Temp. (deg. C):60

Pressure (kPa):308

Characteristic cell performance of Energy Partners’ injection

vs. compression molded plates.

was successfully operated for 250 hours on CO-containing reformate. A subscale stack was also subjected to

several freeze-thaw cycles to -40oC without damage. A 10-kW (112-cell) class stack containing composite

bipolar plates with a new flowfield design demonstrated lower stoichiometry capability, a 13% increase in

active cell area, and substantial improvements in weight (specific power of 0.87 kW/kg), volume (power

density of 1.6 kW/L), and manufacturability.

Optimized Electrodes for Reformate/Air Stacks. Los Alamos National Laboratory (LANL) is working on

electrode optimization to achieve maximum performance in PEM fuel cells under conditions appropriate for

reformate/air operation. One very important aspect of this work is the identification of new catalysts and

operating conditions that improve the tolerance of the PEM fuel cell to CO in reformate fuel from a fuel

processor. During FY 2000, a 500-hour life test

of a 50-cm2 cell demonstrated tolerance to 100

ppm CO. Stable cell performance with 500

ppm CO in reformate was also achieved in a

100-hour test with an advanced PtRu catalyst.

Significant progress was also made towards the

R&D goal of improved performance at high

cell voltages. LANL demonstrated that stable

performance of 0.4 A/cm2

 at 0.8 V could be

achieved with neat hydrogen as a fuel.

Although there is still a need to lower the

required catalyst loading and operate on the

reformate, this does represent a substantial first

step on the road to simultaneously achieving

acceptable performance and high-voltage

efficiency.

High-Volume Electrode Production. During FY 2000, Southwest Research Institute (SwRI) teamed up with

W. L. Gore and Associates, a leading supplier of MEAs for PEM fuel cells, to develop a high-volume pilot

manufacturing process for electrode material, a crucial (and currently costly) element in the high-volume

production of fuel cell MEAs. The key component of this process is a vacuum coating unit with the capability

to produce millions of square feet of high

performance, ultra-low-Pt loaded electrodes per

year. SwRI is acquiring electrode substrate

materials, membranes, and reference MEAs that

utilize technology from W.L. Gore and

Associates; these items will be used by SwRI for

MEA assembly and benchmarking. The

objective of the project is to demonstrate the

production levels necessary to achieve MEA

production costs below $10/kW. Specific power

values approaching 5 kW/g of platinum on

hydrogen have been achieved by utilizing the

new technology, represents progress toward the

DOE year 2004 performance target of 5 kW/g of

platinum for operation on gasoline reformate.

Ultra-low loadings as low as 0.001 mg/cm2

 have

been demonstrated in the laboratory with catalyst

uniformity within 5% achieved across 15-cm

widths of material. Work continues to further

100 ppm CO in Reformate + 4% Air

Anode: 0.5mg Pt/cm2, Reconfigured Anode

Cathode: 0.3 mg Pt/cm2

, Single-Sided E-TEK V2.22

0

10

20

30

40

50

0 200 400 600

Time /Hours

Cell Current /Amps

500 hrs.

H2 @ 1.5 stoich

N1135, 50cm2

Cell Temp: 80 oC

Pressure:30/30 PSIG

Life test of cell with reconfigured anode exposed to

100 ppm CO in simulated reformate (4% air bleed).
Fuel Cell Power Systems FY 2000 Progress Report

7

optimize catalyst composition and reduce precious metal content, with a target of less than 0.10 mg/cm2

thought to be achievable.

Low-Cost Bipolar Plate Development. Research at Energy Partners is contributing to a reduction in stack

component costs through the development of a high-speed injection molding process (patents pending) for

composite graphite bipolar plates. Composite bipolar plates are currently injection-molded, with cycle times

of less than 20 seconds; with proper tool design, the projected cycle time is reduced to about 10 seconds.

Energy Partners’ thermoplastic technology has the potential to greatly reduce cycle time and processing cost

(<$10/kW), improve hydrolytic stability and corrosion resistance, and allow for material recycling. Injectionmolded blank plates (500 cm2

) with machined flow fields were evaluated in a fuel cell stack and compared

with the performance of cells containing Energy Partners’ compression-molded plates (performance similar to

that of cells using POCO graphite plates). Although the polarization curves for a four-cell stack were slightly

lower for the injection-molded plates than for the compression molded plates (corresponding to the higher

conductivity of the compression-molded plates), work in progress at Energy Partners indicates that

optimization of the formulation and compounding process will improve the conductivity of the injectionmolded plates.

Future Directions

Although substantial progress was made during FY 2000 toward meeting the technical targets for fuel cell

systems for light-duty vehicles, significant technical and economic challenges remain before fuel cell vehicles

will achieve significant market penetration. As we move forward, we will continue to work with our

government and industry partners to address these challenges. We will also increase our cooperation with

DOE’s PEM Fuel Cells for Buildings and Hydrogen Programs to maximize the synergy with these programs.

In developing our future R&D plans, we will put less emphasis on system integration and full-scale stack

development because industry has the capability to carry this effort forward. Our future R&D will focus on

addressing the most critical issues of cost, durability, and performance of materials, components, and

enabling technologies. This is expected to include new work on high-temperature membranes and MEAs with

higher activity cathodes and CO-tolerant anodes; advanced fuel processors and water-gas shift catalysts that

represent a significant improvement over the state-of-the-art; new compressor/expander technologies; and

advanced components including sensors for fuel cell power systems (both chemical and physical), heat

exchangers, and devices to enrich the oxygen and hydrogen content in on-board fuel cell feed streams. During

FY 2000 we held two workshops to define R&D needs and technical targets: sensor needs for CIDI engines

and fuel cells, and basic and applied research needs for PEM fuel cells. The proceedings of these workshops

can be found on the World Wide Web at http://www.ott.doe.gov/oaat/library.html.

During FY 2001, researchers at Pacific Northwest National Laboratory will continue to develop microchannel

fuel processor technology, which has the potential to substantially reduce the cost, size, and weight of this

critical subsystem. Southwest Research Institute and 3M will continue the development of low-cost

automated industrial processes for the manufacture of PEM electrode and membrane/electrode assemblies.

PEM Plates will continue the development of a bipolar plate compression molding process to substantially

reduce cost. Argonne National Laboratory will continue to develop fuel processing and water-gas shift

catalysts to improve the performance of fuel-flexible fuel processors. Los Alamos National Laboratory will

continue to develop improved electrodes for reformate/air fuel cells, as well as CO cleanup technology for

fuel processors. We are also looking forward to the testing of stack subsystems from Energy Partners and

AlliedSignal and integrated systems from Plug Power and International Fuel Cells. Through these efforts and

other related projects, researchers in the Transportation Fuel Cell Power Systems R&D Program will continue

to achieve improvements in cost, durability, efficiency, and overall system performance, allowing us to move

closer to the commercial availability of fuel cell vehicles.
Fuel Cell Power Systems FY 2000 Progress Report

8

The remainder of this report presents project abstracts that highlight progress achieved during FY 2000 under

the Transportation Fuel Cell Power Systems Program. The abstracts summarize both industry and national

laboratory projects, providing an overview of the work being conducted to overcome the technical barriers

associated with the development of fuel cell power systems. Each project abstract identifies the related

barriers in the Office of Advanced Automotive Technologies R&D Plan.

Patrick Davis JoAnn Milliken

Donna Lee Ho Nancy Garland

Program Managers

Energy Conversion Team

Office of Advanced Automotive Technologies

Office of Transportation Technologies
Fuel Cell Power Systems FY 2000 Progress Report

9

II. FUEL CELL POWER SYSTEM DEVELOPMENT1

A. Atmospheric Fuel Cell Power System for Transportation

Murdo J. Smith

International Fuel Cells

195 Governor’s Highway

South Windsor, CT 06074

(860) 727-2269, fax: (860) 727-2399, e-mail: smithmu@ifc.utc.com

DOE Program Manager: Patrick Davis

(202) 586-8061, fax: (202) 586-9811, e-mail: patrick.davis@ee.doe.gov

ANL Technical Advisor: Walter Podolski

(630) 252-7558, fax: (630) 972-4430, e-mail: podolski@cmt.anl.gov

Contractor: International Fuel Cells, South Windsor, Connecticut

Prime Contract No. DE-AC02-99EE50567, October 1999-November 2002

Objective

The objective of this contract is to deliver to the U.S. Department of Energy (DOE) a 50-kW-equivalent gasoline

fuel processing system and a fully integrated, gasoline-fueled, 50-kW polymer electrolyte membrane (PEM) power

plant for functional demonstration testing. The fuel processing system will utilize fuel-flexible reforming technology

that can be modified to accommodate such fuels as methanol, ethanol, and natural gas. Demonstration testing of

each of the units will be performed at International Fuel Cells (IFC). After IFC’s testing, the PEM power plant will

be delivered to Argonne National Laboratory (ANL) for additional operational tests by DOE.

OAAT R&D Plan: Tasks 5, 8, and 11; Barrier J

Approach

• Build and test autothermal fuel processor.

• Build and test an ambient-pressure integrated power plant.

Accomplishments

• Delivered and tested a 50-kW-equivalent gasoline fuel processing system.

• Delivered and tested a 50-kW PEM cell stack assembly for incorporation into the integrated power plant.

• Delivered a 50-kW integrated power plant configured for system verification testing.

Future Directions

• Complete verification testing of the 50-kW PEM power plant at IFC.

• Deliver the power plant to DOE for follow-on testing at ANL.

 

1

 The DOE technical targets for integrated fuel cell power systems can be found in Table 1, Appendix B.
Fuel Cell Power Systems FY 2000 Progress Report

10

Introduction

International Fuel Cells is committed to the

commercialization of PEM fuel cell power plants for

transportation applications. We have in place a

program that addresses technology development and

verification for each of the necessary components

and subsystems, and ultimately for the fully

integrated power plant itself. The focus of IFC’s

program is an ambient-pressure PEM power plant

system operating on gasoline fuel and delivering

50-kW net direct-current (dc) power to the

automotive electrical system.

Project Deliverables

Under the contract, IFC will deliver to DOE a

50-kW-equivalent gasoline fuel processing system

(FPS) and a 50-kW PEM power plant.

Planned Approach

Fuel Processing System

Assembly of the gasoline fuel processing system

(FPS) deliverable was completed in December 1999.

The FPS consists of a fuel desulfurizer, an

autothermal fuel reformer, a shift converter, a

selective oxidizer, and the balance-of-plant

equipment and controls necessary to operate the

system. The FPS is sized to provide sufficient

hydrogen to meet the requirements of the PEM fuel

cell for generating 50 kW of dc electrical power. The

objective of the FPS test program was to verify that

the operation of the integrated FPS system met the

power-plant requirements.

Figures 1 and 2 are photographs of the delivered

FPS test article. The locations of the major FPS

components are identified.

The FPS was tested against a specific test plan,

using gasoline with the characteristics of California

reformulated gasoline (RFG) II. The program

included steady-state performance demonstrations

throughout the required fuel flow range, from idle to

rated power conditions, as well as start/stop and

transient cycles. Figure 3 illustrates steady-state

hydrogen production as a function of gasoline flow.

Demonstrated fuel conversion was 98%, with overall

fuel processor efficiency exceeding 83%. The FPS

efficiency is the ratio of energy delivered by the FPS

in the form of hydrogen (LHV 51,574 Btu/lb) to the

energy delivered to the FPS in the form of gasoline

CA-0421

SHIFT CONVERTER

DESULFURIZER

AUTOTHERMAL

REFORMER

Figure 1. Fuel processing system, showing location of

the desulfurizer, autothermal reformer, and

shift converter.

CA-0422

SHIFT

CONVERTER

SELECTIVE

OXIDIZER

FC42012

990912

Figure 2. Location of FPS shift converter and selective

oxidizer.

1

2

3

4

5

6

7

8

9

10

11

4 8 12 16 20 24 28 32 36 40

Gasoline Flow (pph)

Hydrogen Production (pph)

Lines with hollow markers indicate design

 goal, solid markers indicate test data

Figure 3. FPS steady-state hydrogen production.
Fuel Cell Power Systems FY 2000 Progress Report

11

(LHV 18,900 Btu/lb). Exit CO levels were

consistent with required levels.

50-kW Power Plant

Figure 4 provides a schematic of the gasoline

fuel cell power plant. The major subsystems include

the fuel processing subsystem, the power subsystem,

and the balance-of-plant. The balance-of-plant

includes the thermal management subsystem, the air

and water subsystems, and the controller and

associated electrical equipment.

The 50-kW power subsystem was assembled

and acceptance tested as a separate component.

Figure 5 is a photograph of the power subsystem

after successful completion of the acceptance test.

As shown, the power subsystem comprises two

25-kW PEM ambient-pressure cell stack assemblies.

Stack performance on reformate is presented in

Figure 6, which shows stack voltage and power

output as a function of current density.

Figure 7 is a photograph of the fully integrated

power plant in the process and control (PAC) test

configuration. In this configuration, the power-plant

system is complete, with the exception of the power

subsystem (which is not included). Initial testing is

performed without the power subsystem to allow

tuning the controls and components without

affecting the cell stacks. Assembly of the unit, which

weighs 1,550 lb and has a volume of 30 ft3

, was

completed in May 2000. It has been installed in the

test stand at IFC and is undergoing a planned

checkout procedure. When the procedure is

completed, the power subsystem will be installed

and verification testing of the complete power plant

FUEL

FUEL PROCESSOR SUBSYSTEM POWER SUBSYSTEM

FPS Fuel Processor System

CSA Cell Stack Assembly

BOP Balance of Plant

FPS CSA

BOP

DESULFURIZER

CELL STACK

CELL STACK

INTEGRATED FUEL PROCESSOR SYSTEM

(IFPS)

CONTROLLER

TEMPERATURE SHIFT

CONVERTER

LOW AUTOTHERMAL

REFORMER

FC41748

R000205

THERMAL

MANAGEMENT

SUBSYSTEM SUBSYSTEM

AIR

&

WATER

REFORMATE TO

INVERTER

DC

POWER OXIDIZER

SELECTIVE

Figure 4. Power-plant schematic.

Figure 5. 50-kW power subsystem.

0

50

100

150

200

250

300

350

400

0 100 200 300 400 500 600 700

Current Density - mA/cm2

Stack Voltage - V dc

0

10

20

30

40

50

60

70

80

Stack Power - kW dc

Stack Voltage

Stack Power

Figure 6. Power subsystem performance.
Fuel Cell Power Systems FY 2000 Progress Report

12

will be performed. The efficiency of the power plant

will be determined during the testing program.

Figure 7. 50-kW gasoline-fueled power plant.

Conclusions

IFC is committed to the commercialization of

PEM fuel cell power plants for transportation

applications. The focus of IFC’s program is an

ambient-pressure PEM power plant system operating

on gasoline fuel. The assembly and testing of a

50-kW equivalent fuel processing system was

completed. The test results confirmed that the

operation of the FPS system met the power-plant

requirements. A 50-kW power subsystem was also

assembled and acceptance tested as a separate

component. The fully integrated power plant

configured for system verification is now

undergoing testing. Following the verification test,

the power subsystem will be installed and

verification testing of the complete power plant will

be performed.

B. Pressurized Fuel Cell Power System for Transportation

William D. Ernst

Plug Power, LLC

Latham, NY 12110

(518) 782-7700, fax: (518) 782-7914, e-mail: William_Ernst@plugpower.com

DOE Program Manager: Donna Lee Ho

(202) 586-8000, fax: (202) 586-9811, e-mail: donna.ho@ee.doe.gov

DOE Program Support: Larry Blair

(202) 586-0626, fax: (202) 586-9811, e-mail: larry.blair@ee.doe.gov

ANL Technical Advisor: Walter Podolski

(630) 252-7558, fax: (630) 972-4430, e-mail: podolski@cmt.anl.gov

Contractor: Plug Power, Inc., Latham, New York 12110

Prime Contract No. DE-FC02-97EE50472, September 30, 1997-December 31, 2000

Major Subcontractor: Nuvera Fuel Cells, Cambridge, Massachusetts 02140

Objectives

• Research and develop a fully integrated fuel cell system that operates on common transportation fuels (gasoline,

methanol, ethanol, and natural gas) for automotive applications.

• Deliver a fully integrated, 50-kWe (net) system consisting of a polymer electrolyte membrane (PEM) fuel cell

stack, with balance-of-plant components, and a 50-kWe (net) fuel-flexible reformer.
Fuel Cell Power Systems FY 2000 Progress Report

13

OAAT R&D Plan: Tasks 5, 8, and 11; Barriers A-H and J

Approach

The integrated fuel cell system is being pursued in four phases:

• Phase I: Define overall system; build and demonstrate a 10-kWe system.

• Phase II: Develop components for 50-kWe system.

• Phase III: Integrate all components into 50-kWe brassboard system.

• Phase IV: Build and test integrated 50-kWe power system in a test stand.

Accomplishments

• Built 50-kWe (net) brassboard fuel cell power subsystem, using commercially available components.

• Achieved functional operation with simulated reformate.

• 50-kWe (net) fuel cell and fuel processing subsystems are built, characterized, and ready to be integrated with

each other.

Fuel Cell Power System

(including fuel processor, stack and auxiliaries; excluding gasoline tank and DC-DC converter)

Characteristic Status DOE Technical Target

Net Power (kWe) 50 50

Energy Efficiency @ 25% Peak Power (%) 40 (predicted) 40

Power Density (W/L) 250 (predicted) 250

Specific Power (W/kg) 250 (predicted) 250

Durability (hours) 2000 (predicted) 2000

Future Directions

• Integrate fuel cell subsystem with fuel processor subsystem.

• During integration, gain experience with compressor/motor/expander unit (CMEU) integration, water balance,

system control strategy, and power distribution.

• On the basis of integration experience, develop an integrated system with increased fuel cell and fuel processor

efficiency and improve overall system power density.

• Design, build, and test a highly integrated, 50-kWe gasoline-powered fuel cell system (Phase IV).

Introduction

The goal of Phase I of this program is to develop

fundamental knowledge about the individual

components in the fuel cell system, culminating in

the integration of a 10-kWe (net) PEM fuel cell stack

with a partial oxidation fuel processor. Phase II is

the development of components at the 50-kWe level,

followed by brassboard system integration of the

various components in Phase III. Phase IV will

consist of building a fully integrated, compact

50-kWe system that incorporates the results of

Phase III testing; this system will be used for

performance and emissions testing.

Phase I was completed during fiscal year (FY)

1998, and Phase II was completed during FY 1999;

Phase III, currently in progress, will conclude with

the integration of Plug Power’s 50-kW (net)

brassboard system with a 50-kWe (net) fuel

processor brassboard system developed and built by

Nuvera Fuel Cells (formerly known as ADL/Epyx).
Fuel Cell Power Systems FY 2000 Progress Report

14

Approach

Components developed during Phases I and II

have been integrated into a 50-kWe brassboard

system, but the system has not run in an integrated

mode. In Phase III, the fuel cell subsystem and fuel

processor subsystem, built on individual skids, will

be connected together. The interface points between

the fuel cell stack subsystem and the Nuvera fuel

processor subsystem have been identified for the

integrated system design. At each interface point, the

necessary fluid state, flow, and thermal conditions

have been defined. The overall system operating

strategy has also been established. The key points

are that (1) the operating pressure varies from

3.1 atm at maximum power to 2.2 atm at one-fourth

power, (2) the closed-loop water management

system will be simulated by totaling water generated

and water consumed, and (3) fully saturated

reformate will be provided to the fuel cell stack. The

net effects of these conditions are maintenance of

water balance within the system and improved

power density.

The philosophy in building the Phase III

brassboard system was functionality first, efficiency

and emissions second. Size and weight were not as

high of a priority in the design. A conservative

design approach was taken, and additional hardware

(valves, instrumentation, and filtration) was included

in the Phase III design to facilitate thorough

characterization of the system. The additional items

increase the pressure drop of the entire system,

leading to a higher parasitic load from the CMEU.

(See Figures 1 and 2.)

Figure 1. Phase III brassboard fuel cell system, photo.

Figure 2. Phase III brassboard fuel cell system,

schematic.

Results

Stand-alone operation of the fuel cell brassboard

system has been achieved with simulated reformate.

(See Figure 3.) Operation of auxiliary systems and

components by direct-current (dc) power from the

stack has been demonstrated. A battery charging and

regulation system is incorporated into the brassboard

system to provide independent start-up capability.

Due to the power requirements of the CMEU, startup power for the unit (during fuel processor warmup) will be provided by a lab power supply.

The control system utilizes a dc-powered,

embedded computer to carry out control functions

and an integrated, but separable, PC to provide

operator interface. Closed-loop flow control is

provided by either user-entered flow rates or by

system power demand (load following). The fuel

processor controls reformate flow on the basis of

fuel cell demand. CMEU speed determines air flow

Figure 3. Performance of two Phase III stacks with

simulated reformate.
Fuel Cell Power Systems FY 2000 Progress Report

15

for the entire system. The fuel processor

independently controls air flow to its system by

taking the air that it needs from the CMEU supply.

Stack operating pressure is set by expander

operation, in conjunction with back-pressure control

valves (used to provide balancing adjustments).

The CMEU has offered its own set of

challenges. Foremost, the unit’s power consumption

is greater than originally planned, primarily because

of the increased system pressure drop caused by the

addition of filters, control valves, check valves, and

instrumentation. To overcome these pressure drops,

Plug Power had to retrofit the CMEU with a larger

motor and associated controller and power supply.

Corrosion of the aluminum components within the

CMEU was overcome by choosing different coatings

for the internal components.

Improvements to stack hardware were made to

better meet the requirements of the PRDA system

for Phase IV. Notable improvements include an

increase in the active area by 30%, simplification of

the endplate and closure mechanism, elimination of

contact between the collector plates and the fluid

streams, and incorporation of improved alignment

features. The net results of these hardware

modifications include an increase in power density

by 20% at the full power operating point, a 10%

increase in plate utilization, a 15-kg reduction in

stack weight, shorter stack assembly time, and

reduced stack cost.

Conclusions and Future Work

The remainder of this program will focus

primarily on systems integration and operation.

During the integrated testing, we plan to

quantify the effects of reformate saturation level,

pressure, and temperature on system performance.

The relationship between water balance and

operating pressure will be evaluated. Once an

effective operating strategy has been developed,

control valves will be eliminated from the system.

(We expect to control flows and back pressures

entirely with the CMEU, thereby enabling the

elimination of valves.) An important goal is to

reduce system pressure drop by 50%.

Upon completion of Phase III testing, Phase IV

design and development will commence. Test results

from Phase III will be used to optimize selection of

the components to be used in Phase IV. The Phase

IV system will utilize a single design (one set of

schematics) and will be built on one compact skid.

Upon completion of qualification testing at Plug

Power, the Phase IV system will be delivered to

Argonne National Laboratory.

References

1. W.D. Ernst, “Plug Power Fuel Cell

Development Program,” DOE Automotive

Technology Development Customers’

Coordination Meeting, Dearborn, Mich.,

Oct. 27-30, 1997.

2. W. Ernst, J. Law, J. Chen, and W. Acker, “PEM

Fuel Cell Power Systems for Automotive

Applications,” Fuel Cell Seminar, Palm Springs,

Calif., Nov. 1998.

3. W.D. Ernst, “Reformate-Fueled PEM Fuel

Cells,” SAE Fuel Cells for Transportation

TOPTEC, Cambridge, Mass., March 18-19,

1998.

FY 2000 Publications/Presentations

• W.D. Ernst, J.R. Boyer, D.L. Ho, and

W.F. Podolski, “Fuel-Flexible Automotive Fuel

Cell Power System,” SAE Paper 00FCC-3,

presented at Future Car Congress, Washington,

D.C., April 3, 2000.
Fuel Cell Power Systems FY 2000 Progress Report

16

C. Cost Analyses of Fuel Cell Stack/Systems

Eric J. Carlson (primary contact) and Stephen A. Mariano

Arthur D. Little, Inc.

Acorn Park

Cambridge, MA 02140-2390

(617) 498-5903, fax: (617) 498-7012, e-mail: carlson.e@adlittle.com

FY2000 DOE Program Manager: Donna Lee Ho

(202) 586-8000, fax: (202) 586-9811, e-mail: donna.ho@ee.doe.gov

FY2001 DOE Program Manager: Nancy L. Garland

(202) 586-5673, fax: (202) 586-9811, e-mail: nancy.garland@ee.doe.gov

DOE Program Support: Larry S. Blair

(202) 586-0626, fax: (202) 586-9811, e-mail: larry.blair@ee.doe.gov

ANL Technical Advisor: Robert D. Sutton

(630) 252-4321, fax: (630) 252-4176, e-mail: sutton@cmt.anl.gov

Contractor: Nuvera Fuel Cells, Cambridge, Massachusetts

Prime Contract No. DE-FC02-99EE50587, May 1999-March 2004

Objective

To develop an independent cost model for polymer electrolyte membrane (PEM) fuel cell systems for transportation

applications and to assess cost reduction strategies for year 2000 to 2004 development programs.

OAAT R&D Plan: Task 8; Barrier J

Approach

• In the first year, develop a baseline system configuration and cost estimate based on best available and projected

technology and manufacturing practices.

• In the second year, assess the impact of potential technology developments on system cost reduction.

• In the subsequent four years, update the baseline cost model and system scenarios annually, based on

assessments of developments in PEM fuel cell (PEMFC) system technologies and manufacturing processes.

Accomplishments

• Baseline system configuration developed, in conjunction with Argonne National Laboratory.

• Baseline cost model and cost projection of $300/kW at high volume production developed and report prepared

for distribution to the fuel cell community.

• Results of study presented to National Research Council (NRC) review committee, Partnership for a New

Generation of Vehicles (PNGV) Fuel Cell Technical Committee, and technical conferences, including the

Future Car Congress. Constructive feedback on revisions to the model have been obtained through these

discussions about basic assumptions and system performance targets.
Fuel Cell Power Systems FY 2000 Progress Report

17

Future Directions

Develop projections of future system performance and cost on the basis of continued industry feedback and

projected technology developments. Projections of future system performance and cost include, at a minimum, the

following scenarios:

• An increase in ambient temperature to 120°F resulting in an increase in the size and weight of heat exchangers.

• A stack optimized for high power output (higher current density, but lower cell voltage) resulting in a less

efficient but smaller and less costly stack system.

• System hybridization (fuel cell/battery) and the subsequent dependence of system cost ($/kW) on rated power.

• Effect of total pressure on system cost to determine if technical targets can be met at an operating pressure of 2

or 2.5 atm.

• Effect of a high temperature membrane (150°C) on system design and cost.

Introduction

A baseline cost estimate for a 50-kW PEM fuel

cell system for passenger vehicles was developed on

the basis of technology available in the year 2000,

but using a high production volume scenario

(i.e., 500,000 units per year). The baseline system

cost estimate presented here is the first step in a

multiyear program to assess the impact of

technology advances on system cost and to monitor

progress over the next four years. In 2000, we will

be soliciting feedback from system developers and

original equipment manufacturers (OEMs), as well

as identifying cost reduction opportunities.

Approach

The first step in the construction of the baseline

cost analysis was to conduct a technology

assessment to define a plausible configuration and

realistic operating parameters. Table 1 shows how

the various components were allocated to the fuel

processing and fuel cell subsystems, as well as

miscellaneous components. To meet the PNGV

goals, an overall system efficiency above 35% and

water self-sufficiency were required; these

conditions strongly influenced the design and

specification of the system, as shown in Figure 1.

System efficiency was the major driver in specifying

and developing the system parameters shown in

Table 2.

Table 1. Allocation of components between subsystems.

Fuel Processor Subsystem Fuel Cell Subsystem Balance-of-Plant

Reformate Generator

• Autothermal Reformer (ATR)

• High-Temperature Shift (HTS)

• Sulfur Removal

• Low-Temperature Shift (LTS)

• Steam Generator

• Air Preheater

• Steam Superheater

• Reformate Humidifer

Reformate Conditioner

• NH3, Removal

• PROX

• Anode Gas Cooler

• Economizers (2)

• Anode Inlet Knockout Drum

Fuel Supply

• Fuel Pump

• Fuel Vaporizer

Water Supply

• Water Separators (2)

• Heat Exchanger

• Steam Drum

• Process Water

Reservoir

• Fuel Cell Stack (Unit Cells)

• Stack Hardware

• Fuel Cell Heat Exchanger

• Compressor/Expander

• Anode Tailgas Burner

• Sensors and Control Valves

• Start-up Battery

• System Controller

• System Packaging

• Electrical

• Safety

• Sensors and Control Valves for each section
Fuel Cell Power Systems FY 2000 Progress Report

18

Figure 1. Block diagram of overall system.

Table 2. Important system parameters and design goals.

System Requirements

• Fuel Flexible (gasoline)

• System Efficiency >35%

• Water self-sufficiency

• 3-atm operation

• Turbocompressor/Expander

Fuel Cell Module

• 50-kW (net)

❏ 300 V @ full power

• 80°C

• Reformate fuel

Fuel Cell Stack

• 0.8 V per cell

❏ 310 mA/cm2

 current density

❏ One cooling plate per cell

❏ Total power, 56 kWe

• 85% H2, utilization

• Specified by DOE ❏ Established during technology assessment

The factory cost estimate of the fuel cell system

and components presented in this paper includes

fixed and variable manufacturing costs, but it

excludes corporate expenses (e.g., research and

development, sales, marketing, general and

administrative) and profits. A bottom-up

manufacturing model, identifying critical

manufacturing operations, was used to estimate the

cost of major fuel processor and fuel cell

components. The cost of the balance of the system

components (e.g. heat exchangers, control valves,

sensors) is based on discussions with potential

suppliers. However, many of the components needed

in the system (such as valves and sensors) are not

readily available and will have to be developed.

Others are available but will likely require redesign

for high-volume manufacturing. In those cases, the

costs in the model are based on Arthur D. Little’s

best estimates.

Results

The model results indicate that the overall

system cost for the baseline year 2000 is $14,700 (or

$294/kW). As shown in Table 3, the cost of the fuel

cell subsystem represents 60% of the overall system

cost; the fuel processor subsystem, about 30%; and

the balance-of-plant and assembly, the remaining

10%.

The fuel cell stack represents approximately

80% of the fuel cell subsystem cost, while the

integrated tailgas burner ($460), compressed air

supply ($860), and stack cooling system 
Fuel Cell Power Systems FY 2000 Progress Report

19

Table 3. Breakdown of cost by major subsystems (50-kWe net, 500,000 units/year).

Cost ($/kW)

PNGV Goals

Subsystem

Factory Cost

($)

Percent Total

(%)

Baseline

Model Year 2000 Year 2004

Fuel Cell 8,850 60 177 100 35

Fuel Processor 4,310 29 86 30 10

Balance-of-Plant 500 3 10

Assembly 1,040 8 21

Not listed separately in

PNGV goals

Total 14,700 294 150 50

($480) make up the balance. Within the fuel cell

stack (Table 4), the precious metal content in the

membrane electrode assemblies (anode – Ru/Pt

0.2/0.4 mg/cm2

; cathode – Pt 0.4 mg/cm2; total of

180 grams of Pt per stack) makes up 35% of the

stack cost.

Most of the fuel processor costs are in the

reformate generator (which includes the

reformer/shift reactor and associated heat

exchanger), the reformate conditioning system

(preferential oxidizer, or PROX, reactor), and steam

generator, as indicated in Table 5. In the fuel

processing system, thermal, water, and steam

management, controls, and packaging contribute

70% to the overall cost of this subsystem.

Consequently, in addition to advances in catalyst

technology needed to reduce bed size and improve

catalyst life, improved system design and

engineering will be required to reduce the cost of

peripheral systems in the fuel processor.

In the high production volumes assumed for the

cost modeling, materials and purchased components

make up approximately 80% of the total factory

cost.

The estimated power density for the baseline

system is approximately 80 W/kg. Table 6 provides

a breakdown by major subsystem. The total weight

includes 110 kg for components included in the

balance-of-plant.

Conclusions

Specification of high-efficiency operation

(i.e. 0.8 volts per unit cell) and the resulting modest

power density, 250 mW/cm2

, are major factors in the

high fuel cell stack cost. If the stack were optimized

for high power output instead, the stack cost would

be significantly reduced (perhaps by as much as

half). Operation at high power lowers the unit cell

voltage but increases the current density, resulting in

a net decrease in fuel cell materials. The active

volume is approximately inversely proportional to

the power density. Revisions to the design

guidelines are now being considered and will be

incorporated into the model as appropriate.

Calculations based on a drive cycle will lessen the

impact on estimated system efficiency of a lower

unit cell voltage at rated power.

Thermal and water management components

contribute approximately 20% to the baseline system

weight of 600 kg. Design of heat exchangers for

higher ambient temperatures (e.g., 120°F) and lower

fuel cell unit voltages will further increase this

percentage and the weight of the heat exchangers.

Consideration of higher fuel cell operating

temperatures (e.g., through membranes operating at

150°C) will reduce heat exchanger weight and

volume.

In our development of costs for many of the

purchased components, such as heat exchangers,

sensors, valves, controllers, the

compressor/expander, pumps, and motors, we found

that these components are in need of technology

development to satisfy performance requirements

and need to be made cost-effectively in high

volumes. These components presently contribute

approximately 20% to the total system cost.

Simplifications in design, alternative technologies,

and economies of scale in high-volume production

have the potential to lower these component costs.
Fuel Cell Power Systems FY 2000 Progress Report

20

Table 4. Breakdown of fuel cell stack costs (50-kWe net, 500,000 units per year).

Cost

Component % $ $/kW

Anode and Cathode Layers 50 3,625 75

Electrolyte 20 1,310 25

MEA

Gas Diffusion Layers 5 420 5

Bipolar Plates 15 1,035 20

Gaskets 5 380 10

Other 5 280 5

Total 100 7,050 140

Table 5. Breakdown of fuel processor costs (50-kWe net, 500,000 units per

year).

Cost

Component % $ $/kW

Fuel Supply 2 100 2

Reformate Generation 47 2,035 40

Reformate Conditioning 24 1,015 20

Water Supply 27 1,160 24

Total 100 4,310 86

Table 6. Increased power density of individual subsystems needed to meet PNGV

performance targets (50-kWe net)

Specific Power, Year 2000 (W/kg)

Subsystem Weight (kg)

Baseline System

Estimate PNGV Target

Fuel Cell 295 169 350

Fuel Processor 215 233 600

Total* 620 80 250

*Total includes 110 kg for balance-of-plant components.
Fuel Cell Power Systems FY 2000 Progress Report

21

D. Fuel Cell Systems Analysis

Romesh Kumar (primary contact), E. Danial Doss, Rajesh Ahluwalia, Howard Geyer, and

Michael Krumpelt

Argonne National Laboratory

9700 South Cass Avenue

Argonne, IL 60439-4837

(630) 252-4342, fax: (630) 252-4176; e-mail: kumar@cmt.anl.gov

DOE Program Manager: JoAnn Milliken

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

Objectives

• Identify key design parameters and operating efficiencies.

• Assess design, part-load, and dynamic performance.

• Support U.S. Department of Energy (DOE)/Partnership for a New Generation of Vehicles (PNGV)

developmental efforts.

OAAT R&D Plan: Task 8; Barrier J

Approach

• Develop, document, and make available an efficient, versatile system design and analysis code.

• Develop models of different fidelity (mechanistic detail).

• Apply models and modeling to issues of current interest as they evolve.

Accomplishments

• Defined a base-case system for the detailed manufacturing cost study being undertaken by Arthur D. Little, Inc.,

including system configuration, operating conditions, and state points.

• Completed a detailed analysis of a generic autothermal gasoline fuel processor, including effects of reforming

temperature, steam-to-carbon ratio, and operating pressure.

• Analyzed fuel cell vehicles on drive cycles to assess fuel cell performance parameters that are needed to meet

PNGV Goal 3, fuel economy up to 80 miles per gallon (mpg).

Future Directions

• Influence of vehicle weight and other parameters on onboard fuel storage requirements.

• Effects of revised performance targets for the compressor-expander module.

• Design/configuration issues for high ambient temperatures.

• Component weight and volume trade-offs vs. system parameters and efficiency.

• Additional trade-offs with respect to cost.
Fuel Cell Power Systems FY 2000 Progress Report

22

Introduction

While individual developers are addressing

improvements in fuel cells and stacks, fuel

processors, compressor/expander modules, and other

fuel cell system components, in this work we use

modeling and analysis to address issues of system

integration, thermal management, design point and

part-load operation, and component, system, and

vehicle-level efficiencies and fuel economies. We

provide modeling results and analytical support to

DOE program managers, fuel cell developers, the

relevant PNGV technical teams, and other

researchers in the field.

Approach

For this work, we use the GCtool software

package developed at Argonne National Laboratory1

to devise and analyze system configurations and

operation. We have adapted this software to the PC

platform with the Windows-95/98/NT operating

systems, and we have made GCtool available for

licensing by research and development

organizations, universities, etc. In response to

comments by fuel cell developers and program

reviewers, we are now using typical cell

performance data, recently obtained from Los

Alamos National Laboratory (see Figure 1). These

data replace the rather high-performance Energy

Partners “super cell” data used in our earlier

analyses.

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 200 400 600 800 1000 1200 1400

Current Density (mA/cm2)

Voltage (V)

0

100

200

300

400

500

600

Power Density (mW/cm2)

Figure 1. Cell polarization curve used in the fuel cell

system simulation. Pressurized (3 atm)

operation on gasoline reformate. (Courtesy of

Tom Zawodzinski, Los Alamos National

Laboratory.)

Results

During fiscal year (FY) 2000, we used systems

analysis to address three major tasks:

1. Base-case system definition for the detailed

manufacturing cost study by Arthur D. Little.

2. Detailed analysis of the authothermal fuel

processor operation and performance.

3. Vehicle-level simulations and analyses of design

and operating parameters needed to achieve

PNGV Goal 3, fuel economy up to 80 miles per

gallon of gasoline.

ANL/ADLittle Base-Case System Definition

for the Manufacturing Cost Study

Arthur D. Little is conducting a DOE-sponsored

study to assess the manufacturing costs of gasolinefueled automotive fuel cell systems (see report 2.C).

We have worked with them to define the operating

envelope (ambient temperature, design point system

power and cell voltage, etc.), system configuration

(e.g., placement of the water recovery condenser),

and other design and operating parameters. This

base-case system design is shown in Figure 2. In

continuing work, we will examine the effects of

varying some of the design parameters (e.g., designs

for higher ambient temperatures).

Gasoline Autothermal Fuel Processor

Analysis

We have analyzed in detail the operation and

performance of the fuel processor part of the fuel

cell system shown in Figure 2. These analyses were

helpful in quantifying the effects on efficiency of

varying the autothermal reforming conditions

(temperatures, water-to-carbon ratios), operating

pressure, and the use of thermal energy from the

anode exhaust burner in the fuel processor.

Figures 3 and 4 show the total system

efficiencies for an atmospheric pressure system and

a pressurized (3-atm) system. Subject to the

assumptions used in the analysis (e.g., 85%

electrochemical fuel utilization in the fuel cell stack,

fixed air and steam preheat temperatures), the

system efficiency increases with decreasing

reforming temperatures in both cases. In addition, at

the higher reforming temperatures, the fuel
Fuel Cell Power Systems FY 2000 Progress Report

23

Figure 2. Reference system design and configuration for the autothermal-reformed, gasoline-fueled, automotive polymer electrolyte fuel cell system.
Fuel Cell Power Systems FY 2000 Progress Report

24

32

34

36

38

40

42

01234

Water-to-Carbon Ratio (mole)

System Efficiency (%)

T_pox= 1300 K,with after-burn

T_pox= 1200 K,with after-burn

T_pox= 1100 K,with after-burn

T_pox= 1000 K,with after-burn

Figure 3. The overall system efficiency as a function of

the water-to-carbon ratio and reforming

temperature for an atmospheric pressure

system.

y

32

34

36

38

40

42

01234

Water-to-Carbon Ratio (mole)

System Efficiency (%)

T_pox= 1300 K, with after-burn

T_pox= 1300 K, no after-burn

T_pox= 1100 K, with after-burn

T_pox= 1100 K, no after-burn

Figure 4. Total system efficiency as a function of the

water-to-carbon ratio and reforming

temperature for a pressurized system.

processor efficiency decreases with increasing

amounts of water used in the fuel processor. For a

pressurized fuel cell system, Figure 4 shows that the

system efficiency actually increases if the thermal

energy at the anode exhaust burner is not used in the

fuel processor (but is recovered more effectively in

the expander). Thus, these results show that the

optimum fuel processor design and configuration

would be different for pressurized and

nonpressurized fuel cell systems.

Achieving PNGV Goal 3

Our earlier modeling results had shown that to

achieve the target efficiencies of 38.4% at rated

power and 48% at one-fourth of rated power,

average operating cell voltages of 0.772 V and

0.896 V would be needed at the respective power

levels. At these rather high cell voltages, the

corresponding current and power densities in today’s

fuel cells are low, requiring a large active area and a

concomitantly high-cost fuel cell stack. We

reanalyzed the gasoline-fueled systems, using the

more conservative fuel cell performance curve

shown in Figure 1. Vehicle-level analyses were then

conducted for three different vehicles, a lightweight

vehicle, a heavier but more aerodynamic vehicle,

and a lightweight and aerodynamic vehicle. For

these vehicles, the fuel economies on the Federal

Urban Driving Schedule (FUDS) and highway

cycles, as well as the combined fuel economies,

were determined. The key vehicle parameters used

in the analyses are given in Table 1. This table also

shows that the maximum and average power

requirements for the three vehicles on the two

driving schedules are approximately 22–35 kW and

3–8 kW, respectively.

We first analyzed an 80-kW (net) fuel cell

system, with 0.7 V/cell at the rated power (rather

than the 0.772 V/cell used in the earlier analyses).

Figure 5 shows the cell voltage and the

corresponding current density for part-load operation

between 0 and 80 kW, as would be needed on the

prescribed driving schedules. At the maximum

required power output of 35 kW or less, the current

densities are less than ~150 mA/cm2

. At the average

power requirement of <8 kW, the current densities

are less than ~35 mA/cm2. The combined fuel

economy for the three vehicles is shown in Figure 6.

The effect of using a smaller fuel cell system (40 kW

instead of 80 kW), as well as the effect of a lower

design-point cell voltage (0.65 V instead of 0.7 V) is

shown in Figure 7.

Table 1. Vehicle parameters used in the PNGV Goal 3

analyses and the vehicle power requirements

over the FUDS and Highway cycles.

Vehicle

Parameter Lightweight Aerodynamic

Lightweight &

Aerodynamic

Test weight, kg 1043 1379 1043

Frontal area, m2 2.18 2.18 2.18

Drag coefficient 0.25 0.163 0.163

Rolling resistance

coefficient

0.0064 0.0064 0.0064

Wheel radius, mm 326 326 326

Auxiliary power, kW 0.5 0.5 0.5

Max (avg) power FUDS,

kW

27.7 (3.97) 35.2 (4.54) 27.3 (3.77)

Max (avg) power

Highway, kW

22.9 (8.17) 28.7 (7.68) 22.4 (6.75)
Fuel Cell Power Systems FY 2000 Progress Report

25

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 20 40 60 80

Net Power, kW

V, J

A/cm2

V

Figure 5. Cell voltage and current density at part-load

for an 80-kW (net) fuel cell system.

0 20 40 60 80 100 120

Lt-Wt

Aero

Lt-Wt/

Aero

Miles per Gallon

Combined

Highway/FUDS

Highway

FUDS

Figure 6. Fuel economy of the three vehicles with an

80-kW system, 0.7 V/cell at the rated power.

0 20 40 60 80 100

Lt-Wt

Aero

Lt-Wt/

Aero

Miles per Gallon

80-kW, 0.65 V

40-kW, 0.7 V

80-kW, 0.7 V

Figure 7. Effect of fuel cell system size and the designpoint cell voltage on the combined

FUDS/Highway fuel economy for the three

vehicles.

Conclusions

• To achieve PNGV Goal 3, up to 80 mpg fuel

economy, a gasoline-fueled, 80-kW fuel cell

vehicle will need to be extremely lightweight

and reasonably to highly aerodynamic.

• The 40-kW (or smaller) fuel cell system can

meet FUDS and Highway cycle power

requirements for all of these vehicles (but it may

not be adequate to provide acceptable

acceleration performance).

• The fuel cell system is never operated at the

rated power on these drive cycles; average

power draw is ~10% of rated power, with short

bursts to ~35% of rated power.

• Operating current densities are low,

<35 mA/cm2

 on average, with a maximum of

~150 mA/cm2

 (for the 80-kW system) for short

periods.

• The effect of lowering the design point cell

voltage may be minor on fuel economy, but it

may reduce the fuel cell stack size significantly.

The sizes of the fuel processor and the heat

exchangers would increase, however, because of

the lower efficiency at the design point.

• Using a smaller fuel cell system would decrease

system weight, volume, and cost, with a

relatively small decrease in fuel economy (but

an appropriate battery would be required to

provide adequate acceleration and passing

performance).

References

1. H. K. Geyer and R.K. Ahluwalia, GCtool for

Fuel Cell Systems Design and Analysis: User

Documentation, Argonne National Laboratory

Report ANL-98/8, March 1998.

FY 2000 Publications/Presentations

• R. Kumar, E. Doss, R. Ahluwalia, H. Geyer, and

M. Krumpelt, “Fuel Cell Systems Air

Management Overview,” presented at the

Compressor/Expander Module Review Meeting,

held at USCAR, Southfield, Mich., Oct. 12,

1999.

• R. Kumar, E. Doss, R. Ahluwalia, H. Geyer, and

M. Krumpelt, “Design Considerations for

Developing Efficient Fuel Cell Systems,”

presented at the IEA PEFC Annex XI Meeting,

Argonne, Ill., Oct. 21-22, 1999.
Fuel Cell Power Systems FY 2000 Progress Report

26

• R. Kumar, “Fuel Processing Considerations:

Cold Start, Transients, Coking, and Related

Issues,” presented at the NRC/Fuel Cell Review

Meeting, held at USCAR, Southfield, Mich.,

Jan. 12, 2000.

• E. Doss, R. Ahluwalia, R. Kumar, and M.

Krumpelt, “Automotive Fuel Cell System

Design Points, Efficiency Targets, and Tradeoffs

to Achieve PNGV Goal 3,” presented at the Fuel

Cell Targets Workshop, held in conjunction with

the 2000 Future Car Congress and Exposition,

Arlington, Va., April 2-6, 2000.

• E. Doss, R. Ahluwalia, H. Geyer, R. Kumar, and

M. Krumpelt, “Transportation Fuel Cell Systems

Modeling and Analysis,” presented at the 2000

Annual National Laboratory R&D Meeting, Fuel

Cells for Transportation Program, held at Pacific

Northwest National Laboratory, Richland,

Wash., June 7-8, 2000.
Fuel Cell Power Systems FY 2000 Progress Report

27

III. FUEL PROCESSING SUBSYSTEM1

A. Advanced Fuel Processor Development for Next Millennium Fuel

ProcessorTM for Transportation Fuel Cell Power Systems

William L. Mitchell, P.E. (primary contact), Prashant Chintawar, Srinivasa Prabhu, and

James Cross

Nuvera Fuel Cells/Arthur D. Little, Inc., 35 Acorn Park, Cambridge, MA 02140

(617) 498-6149, fax: (617) 498-6655, e-mail: mitchell.william@adlittle.com

DOE Program Manager: Patrick Davis

(202) 586-8061, fax: (202) 586-9811, e-mail: patrick.davis@ee.doe.gov

ANL Technical Advisor: Walter Podolski

(630) 252-7558, fax: (630) 972-4430, e-mail: podolski@cmt.anl.gov

Contractor: Nuvera Fuel Cells/Arthur D. Little, Inc., Cambridge, Massachusetts

Prime Contract Nos. DE-RA02-97EE50443 (PRDA) and DE-FC02-99EE50580 (SFAA)

Subcontractors/Partners: Modine Manufacturing, Energy Partners, Illinois Department of Commerce and Community

Affairs, United Catalysts, Inc., Corning, Inc., and STC Catalysts, Inc.

Objectives

• Under our Department of Energy (DOE) PRDA program for advanced fuel processor development, Nuvera

Fuel Cells/Arthur D. Little, Inc. (Nuvera), is:

- Developing a 50-kWe fuel reformer capable of processing gasoline and alternative fuels, such as ethanol.

- Developing and testing an advanced 50-kWe preferential oxidation (PROX) device based on proprietary

catalyst technology, with a major focus on gas purity when reforming gasoline and ethanol.

- Supporting Plug Power in the development of a 50-kW fuel cell power system.

• Under our DOE SFAA project to develop a Next Millennium Fuel ProcessorTM for transportation fuel cell

power systems, we are utilizing our current in-depth understanding of fuel processing and fuel cell systems in a

three-part R&D program that will yield a fully optimized fuel processing subsystem:

- In Phase I, Nuvera will work with Energy Partners to integrate existing hardware into a 10-kWe multifuel

power system, to identify key system-level trade-offs in the design of a fuel processing subsystem, and to

allow validation of computer models developed both internally and by Argonne National Laboratory

(ANL).

- In Phase II, Nuvera will utilize existing integrated and modular fuel processors to perform endurance

testing to identify and address material and catalyst degradation mechanisms.

- In Phase III, Nuvera will conduct an in-depth core technology R&D program designed to identify highactivity, low-cost catalysts; develop and design compact adsorbents, catalysts, and heat exchangers to

enhance power density and specific power and reduce start-up time; develop fuel purification (sulfur

removal) and reformate clean-up technologies to address the issue of system durability; integrate the new

catalysts and supports into a fuel processor package specifically suited to the optimized catalyst suite; and

deliver a fully integrated fuel processing subsystem to the DOE that meets or exceeds 2004 Partnership for

a New Generation of Vehicles (PNGV) targets.

 

1

 The DOE technical targets for fuel-flexible fuel processors can be found in Table 2a, 2b, and 2c, Appendix B.
Fuel Cell Power Systems FY 2000 Progress Report

28

OAAT R&D Plan: Tasks 5 and 6; Barriers E, F, G, and H

Approach

• PRDA:

- Build and test a brassboard 10-kWe system based on existing reformer design, existing stack hardware, and

other available components as a proof of concept (3-atm pressure).

- Investigate multiple steady-state CO clean-up options at 10-kWe level.

- Integrate complete 10-kWe system and test it at Nuvera using a 10-kWe system test facility.

- Assist Plug Power in the development of a test facility for full-scale (50-kWe) system testing.

- Design and build an advanced 50-kWe fuel processor based on Phase I and Phase II testing.

- Continue catalyst refinement from Phase I.

- Test 50-kWe fuel processor/PROX combination at Nuvera/ADL labs, including transients.

- Provide integration assistance for testing 50-kWe brassboard (Phase III) system demonstration at Plug

Power.

- Aid Plug Power in the mechanical design and packaging of the 50-kWe Phase III system, focusing on

system functionality and efficiency of operation.

- Work with Plug Power to perform transient tests of the integrated Phase III system.

- Build and deliver a Phase IV 50-kWe fuel processor subsystem to Plug Power for final system integration.

The Phase IV system will meet PNGV weight and volume targets for the year 2000.

• SFAA:

- Perform automotive system analysis and identify strategies to meet PNGV targets.

- Evaluate the control strategies on a 10-kWe fully automated system.

- Set targets (weight, volume, performance, efficiency) for key technologies and components based on the

system analysis.

- Work closely with Nuvera partners to develop advanced catalyst, substrate, and heat-exchanger

technologies.

- Develop conceptual design of a fuel processor based on new technologies and draft control and fuel cell

integration strategies.

- Design, fabricate, and test the fuel processor on all fuels and investigate efficiency, emissions, steady-state

and transient performance, and reformate purity.

- Integrate the fuel processor and fuel cell and investigate the performance of the power system. Identify

system-level integration issues (Phase I).

- Continue technology development and refinement in Phase II, based on Phase I results.

- Test fuel processor, integrated power system, and obtain test data (Phase II). Phase II system will meet

PNGV targets for specific power and power density, transient response, and reformate purity.

Accomplishments

• PRDA:

- Designed, built, and integrated a fully automated 50-kWe Phase III fuel processor subsystem that exceeded

all Phase III targets.

- Demonstrated fuel processing efficiencies with California Phase II gasoline in excess of 85%.

- Demonstrated PROX exit efficiencies of 83% and exit CO concentrations lower than 10 ppm.

• SFAA:

- Designed 10-kWe fuel cell power system in conjunction with Energy Partners.

- Built a 15-kWe (gross) automated fuel processing subsystem for integration with the fuel cell.

- Identified “system level” strategies for weight and volume reduction of fuel cell power system.

- Developed transportation-specific substrate (monolith, foam) -based adsorbents, catalysts, and compact

heat exchangers for all reaction zones of multifuel processor.

- Investigated specialized heat exchanger in a test rig under simulated fuel processor conditions, with results

suggesting that novel heat exchangers are capable of obtaining ≥ 5 times improvement in heat-transfer

coefficient over conventional types.
Fuel Cell Power Systems FY 2000 Progress Report

29

- Developed a compact gasoline desulfurizer, designed for 5,000 miles at change-out.

- Performed catalyst studies in disintegrated fuel processor at 130-kWth firing rate. Results show that the new

catalysts have about an order of magnitude lower thermal mass and pressure drop, and need about an order

of magnitude lower contact time, than the conventional catalysts.

- Established that with advanced technologies, ≥ 750 W/L power density and ≤ 2 min start-up time should be

attainable for the fuel cell power system, and other PNGV targets can be met or exceeded.

Future Directions

• PRDA:

- Integrate Phase III unit with 60-kWe stack from Plug Power and evaluate system efficiency and thermal

and water balance issues.

- Develop Phase IV fuel processing system, based on performance of the Phase III integrated system.

• SFAA:

- Integrate 15-kWe fuel processing system with Energy Partners’ stack.

- Conduct detailed system trade-off and control strategy evaluation.

- Commence conceptual and detailed design of 50-kWe fuel cell power system.

- Improve core technology and system models to fully exploit the benefits of lightweight and low-thermalmass media.

Introduction

Nuvera Fuel Cells (NFC) is a leading supplier of

fuel cell power systems in the stationary and

transportation markets. Widespread implementation

of fuel cell systems requires significant

improvements in many aspects of the technology,

including power density, specific power, response,

efficiency, and cost. In addition, the ability to

operate on a number of hydrocarbon fuels that are

available through the existing infrastructure is a key

enabler for commercializing fuel cell systems. NFC

is working with the DOE to develop efficient, lowemission multifuel processors for transportation

applications. The fuels include gasoline, methanol,

ethanol, and natural gas.

In the PRDA program, NFC is developing

reformer subsystems (fuel processor, CO clean-up,

and exhaust clean-up) and integrating them with fuel

cells for system-level evaluation of issues like

efficiency, water balance, transient response,

thermal integration, and parasitic power. The results

of this program will identify and quantify the key

technology challenges that need to be addressed in

developing fuel processing systems for automotive

applications. The deliverable of the program is an

integrated power system that meets PNGV targets

for year 2000.

In the SFAA program, the challenges identified

in the PRDA program will be addressed through an

intensive technology development program.

Catalysis, novel heat-exchange media, and their

integration will be developed through internal efforts

and partnerships with leading companies in this

field. Two generations of fuel processors will be

developed and tested with fuel cells. The deliverable

of this program is an integrated fuel processing

system that exceeds PNGV targets for year 2004.

PRDA Phase III Results

The performance targets for the Nuvera

Phase III fuel processor are shown in Table 1. The

measured performance of the Phase III fuel

processing system is shown in Figures 1 and 2. The

overall efficiency of the fuel processor is defined as

the LHV of hydrogen output of the fuel processor

divided by the LHV of fuel input.

Table 1. PRDA Phase III fuel processor system targets.

Fuel Processor (kW) 175 40 18

Overall Fuel Processor

Efficiency, % 68 68 55

Exit Hydrogen Flow

Concentration, % 35 35 28

Exit Hydrogen Flow

Rate, kg/hr 3.65 0.81 0.3

Pressure Drop, psi 521

Emissions < Tier II < Tier II < Tier II

Parasitics, kW 0.5 0.2 0.2
Fuel Cell Power Systems FY 2000 Progress Report

30

Reformer-Exit Efficiency and Hydrogen Concentration vs Power

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180

Thermal Input Power (kW)

Hydrogen Efficiency (%)

Hydrogen Concentration (%)

Hydrogen efficiency - FPA

Theoretical Maximum Efficiency

Hydrogen % - FPA

Theoretical Maximum Hydrogen %

Reformer-Exit Hydrogen Concentration (%)

Reformer-Exit Hydrogen Efficiency (%)

(LHVH2 out / LHVfuel in)

Figure 1. PRDA Phase III reformer efficiency and

hydrogen concentration.

Figure 2. PRDA Phase III PROX performance.

The efficiency of the Nuvera fuel processing

system is about 85% at the higher powers and ~70%

at a turndown of 8:1. At these conditions, the dry gas

hydrogen concentration is in excess of 40%. Also

shown in Figure 1 are the maximum achievable

efficiencies and hydrogen concentrations at the

operating conditions of our system. The fuel

processing system exit (PROX exit) carbon

monoxide (CO) gas concentrations during steadystate and mild transients are shown in Figure 2. The

Nuvera PROX technology is able to maintain CO

concentrations below 20 ppm over these transients.

SFAA for Next Millennium Fuel ProcessorTM

Because automotive fuel processor catalysts are

subjected to rapid start-up and transient conditions

(e.g., ATR catalyst temperature rises from 25°C to

~800°C in less than 60 s), Nuvera has installed and

operated transient reactors (Figure 3) to evaluate

catalysts under those conditions. The results are

providing data under real-world conditions.

To improve the power density and specific

power of our system, Nuvera is developing

advanced substrate-based heat-transfer technology.

Figure 4 shows the test rig to evaluate new heatexchanger designs. We have identified compact and

moderate pressure drop heat-exchanger

configurations capable of providing 4-6 times

improvement in the heat-transfer coefficient over

that of the conventional shell and tube designs.

Currently, we are investigating durability, cost

reduction, and manufacturability issues of these

novel designs.

Figure 3. Transient catalytic reactor capable of

simulating automotive transients. It can

change the gas composition and flow rate

instantaneously and can raise the catalyst

temperature to 1100°C in < 30 s.

Figure 4. Heat exchanger test rig simulates the fuel

processor atmosphere.
Fuel Cell Power Systems FY 2000 Progress Report

31

Water-gas-shift catalysts (WGSCs) account for a

large share of the volume and weight of

autothermal-reforming-based automotive fuel

processors. Conventional WGSCs, based on Fe/Cr

and Cu/Zn oxides, are not suitable for the

intermittent operation of the automotive fuel cell

power system. By working closely with its partners,

Nuvera has developed a new generation of substratebased catalysts (Figure 5). Data obtained in the

modular pressurized reformer at 130 kWth suggest

that these new media need about six times lower

contact time than the conventional media. We are

conducting short-term and long-term durability

testing of these media.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

240 290 340 390 440 490 540 590 640

T (o

C)

CO Conversion

Equilibrium

Fe/Cr Powder

CAT A215

CAT A186

CAT A214

CAT A228

CAT A227

CAT A186 meth

CAT A214 meth

CAT A228 meth

Figure 5. Monolith-based water-gas-shift catalysts

exhibit higher activity than conventional

pelleted catalysts.

System modeling plays a significant role in

predicting the performance (conversion,

temperature, and concentration profile) of catalytic

reactors and heat-exchanger assemblies. This is

particularly true for PROX reactors, where high

temperatures can lead to runaway situations. On the

basis of single-component data, Nuvera has

developed and utilized computational fluid

dynamics (CFD) codes for improving reactor design

(Figure 6).

Figure 6. Computational fluid dynamics is used to

predict the behavior of compact heat

exchangers.
Fuel Cell Power Systems FY 2000 Progress Report

32

B. Multifuel Processor for Fuel Cell Electric-Vehicle Applications

Tom Flynn (primary contact)

McDermott Technology, Inc.

1562 Beeson Street

Alliance, OH 44601-2196

(330) 829-7622, fax: (330) 829-7283, e-mail:tom.j.flynn@mcdermott.com

Brian Engleman (subcontractor)

Catalytica Advanced Technologies

430 Ferguson Drive

Mountain View, CA 94043-5272

(650) 940-6391, fax: (650) 968-7129, e-mail: bde@mv.catalytica-inc.com

DOE Program Manager: Nancy Garland

(202) 586-5673, fax: (202) 586-9811, e-mail: nancy.garland@ee.doe.gov

ANL Technical Advisor: Walter Podolski

(630) 252-7558, fax: (630) 972-4430, e-mail: podolski@cmt.anl.gov

Contractor: McDermott Technology, Inc., Alliance, Ohio

Prime Contract No. DE-FC02-99EE50586, June 1999-September 2001

Objectives

Design, build, and demonstrate a fully integrated, 50-kWe catalytic fuel processor system. The fuel processor will

produce a hydrogen-rich gas for direct use in polymer electrolyte membrane (PEM) fuel cell systems for electricvehicle applications.

OAAT R&D Plan: Task 5; Barriers E, F, G, and H

Approach

• Develop preliminary design of 50-kWe fuel processor system, as well as performance goals for individual

components.

• Evaluate alternative approaches for the major catalytic components (e.g., desulfurizer, reformer, shift reactor,

and selective oxidation reactor).

• Conduct subsystem testing of major components, utilizing best catalyst approach.

• Develop final design of overall system and design specifications for individual components.

• Assemble 50-kWe fuel processor system.

• Perform demonstration testing, using gasoline and methanol as fuels.

• Ship fuel processor system to Argonne National Laboratory (ANL).

Accomplishments

• Developed process flow models for single-catalyst bed autothermal reformer (ATR) and plate reformer designs.

• Demonstrated liquid-phase gasoline desulfurizer that uses specifically tailored zeolitic adsorbents.

• Performed screening tests for candidate ATR catalysts and plate reforming catalysts.
Fuel Cell Power Systems FY 2000 Progress Report

33

• Evaluated three low-temperature shift catalysts.

• Assessed NexTech CARAT program medium-temperature shift catalyst.

• Established development agreements with Los Alamos National Laboratory and Battelle/Pacific Northwest

National Laboratory for selective oxidation reactor and microchannel heat exchangers.

Future Directions

• Proceed with detailed design and subsystem testing for plate-based 50-kWe fuel processor.

• Develop dynamic simulation model.

• Perform subsystem catalyst evaluation.

• Investigate options for fuel preconversion.

Deliverables

A 50-kWe fully integrated fuel processor.

Introduction

Development of a compact, efficient, and lowcost processor for converting carbon-based fuels to

hydrogen is an important aspect of the successful

implementation of fuel cells for transportation

applications. Current approaches based on

noncatalytic partial oxidation technology provide the

advantages of fast start-up and transient response,

but these approaches have not been fully

demonstrated on sulfur-bearing gasoline. A catalystbased reforming approach for fuel processing can

provide fast start-up and transient response, high

efficiency, and compactness. When coupled with a

liquid-fuel desulfurizer, the multifuel processor

under development by McDermott/Catalytica

promises to approach the Partnership for a New

Generation of Vehicles (PNGV) targets.

Approach

The fuel processor will consist of a liquid-fuel

desulfurizer, a catalytic reformer, high- and lowtemperature water-gas shift units, a selective

oxidizing unit, and ancillary components (including

pumps, compressor/expander, heat exchangers, and

controls). A conceptual drawing of the fuel

processor system is shown in Figure 1. The design

has been described previously [1].

The liquid-fuel desulfurizer will reduce the

sulfur in gasoline to less than 3 ppm. The reformer

unit, operating at an average temperature of 800°C,

will produce a hydrogen-rich gas from the fuel feed.

Two approaches will be evaluated during the

Figure 1. Process flow diagram.

program: (1) a packed bed that uses a single catalyst

and (2) a plate-based catalyst system. A shift reactor,

consisting of either a single catalyst bed or

individual high-temperature and low- temperature

catalyst beds, will reduce the CO concentration in

the reformate gas to approximately 2000 ppm. Final

reduction of CO in the reformate gas will be

achieved in a selective oxidation reactor.

McDermott Technology, Inc., will develop the

overall system design, including heat integration,

mechanical design, ancillary equipment, and

instrumentation/controls. Catalytica Advanced

Technologies will develop the catalytic components,

including improved catalysts. NexTech, as a

subcontractor on the project, will contribute its 
Fuel Cell Power Systems FY 2000 Progress Report

34

expertise and technology in the area of shift

catalysts. The program consists of five major tasks:

preliminary design, catalyst development, subsystem

testing, final design, and prototype assembly and

demonstration.

Results

During this reporting period, the first two tasks

were completed.

Preliminary Design

Steady-state ASPEN process simulation models

were generated for the catalyst-bed and platereformer concepts. The system using the catalystbed concept had a predicted efficiency of 87% at

25% load, assuming 70% hydrogen utilization in the

fuel cell and 50% fuel-cell efficiency. Actual

performance data for the fuel pump, humidifier,

compressor/expander, and fuel cell were

incorporated into the simulation model. The system

power density and specific power are 564 W/L and

316 W/kg, respectively. The compressor/expander,

humidification system, and start-up burner are

included in the fuel processor scope.

The plate concept showed a comparable system

efficiency. The plate approach yields a smaller-size

system with comparable weight.

For both systems, the heat-exchanger types and

sizes have been selected. A control system vendor

has also been selected.

Catalyst Development

Desulfurizer

We demonstrated removal of thiophenes and

methyl-substituted thiophenes from aromatic

solvents by using zeolitic adsorbents. The

thiophenes are most difficult to remove because of

steric hindrance around sulfur and competitive

adsorption by aromatics. A typical adsorption

profile, illustrating the adsorption of thiophene with

a low-aluminum ZSM5 zeolite, is shown in Figure 2.

Proprietary modifications of zeolites provided the

best performance. We obtained promising results

with California CARB Phase 2 gasoline (30 ppm

sulfur reduced to < 3 ppm sulfur).

Adsorption Profile For Low-Aluminum ZSM5 Zeolite

Feed: 1% S (as Thiophene) in Toluene at 60oC

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018

g Sulfur Fed / g Adsorbent

Sulfur in Effluent / Sulfur in Feed

Breakthrough

Point

Figure 2. Typical adsorption profile.

Reforming Catalyst

We completed a successful 100-hour test with

California CARB gasoline. The catalyst

demonstrated a capacity of approximately 5 kWe/kg.

Equilibrium conversions were maintained

throughout the run (Figure 3.)

We also demonstrated the feasibility of using

Catalytica’s XononTM combustion catalyst, in

combination with a reforming catalyst, in the plate

arrangement.

An evaluation of the advantages and

disadvantages of the two approaches was made. The

results are summarized in Table 1.

0

10

20

30

40

50

60

70

0123

Time, h

Composition, %

H2

CO

CO2

CH4

H2 eq.

CO eg

CO2 eq.

CH4 eq.

Feed, ml/min: N2-64;O2-16;Fuel-0.04,H2O-0.04.

 H2O/fuel=9.2; O2/fuel=2.9. P=11 psig

Tin=529o

C, Tcen=697oC, Tout=800oC.

Productivity: 1mol H2/kg min (1.7 kW/kg)

Figure 3. Approach to equilibrium for Catalytica

ATR-10 catalyst.
Fuel Cell Power Systems FY 2000 Progress Report

35

Table 1. Advantages and disadvantages of plate vs. bed

concepts.

Plate Concept Bed Concept

Advantages Advantages

Rapid start-up and

response

Rapid start-up and

response

No dilution – smaller

downstream components

Higher H2 partial

pressure for enhanced

fuel cell performance

Availability of existing

proprietary combustion

catalyst and washcoat

technology

Disadvantages Disadvantages

Preprocessor required Difficult thermal

balance within bed

Nitrogen dilution

Difficult thermal balance

across plate

Lower H2 partial

pressure results in

poorer fuel cell

performance

Neutral Neutral

Safety issues:

manifolding, leakage

Safety issues:

combustible mixtures

Catalyst formulation

work required

Catalyst development

required – no

available commercial

catalyst

Shift Catalysts

High-temperature shift (HTS) and lowtemperature shift (LTS) catalysts are traditionally

sensitive to oxygen, condensed moisture, and sulfur

poisoning. Commercial HTS catalysts tend to be

more rugged than LTS catalysts. For this reason, the

team focused on LTS catalyst development.

We completed benchmark tests of commercially

available catalysts. We assessed alternative LTS

catalysts, including high-activity supported Cu

catalysts, nanoscale Cu/Zn/Al mixed oxide catalysts,

and NexTech’s noble metal/ceria catalyst, which is

being developed under the CARAT program [2].

The best results were obtained with a proprietary

third-party catalyst. The relative reaction and

deactivation rate constants are summarized in

Table 2. (Catalyst C is a widely used commercial

LTS catalyst.)

The NexTech catalyst is a medium-temperature

shift (MTS) catalyst; as such, it is not intended to

operate in the same temperature range as lowTable 2. Catalyst properties.

Catalyst

Relative

Reaction

Rate

Constant

Relative

Deactivation

Rate Constant

Post-/PreActivity

Moisture

A 1.31 0.095 1.00

B 1.05 0.514 0.56

C 1.0 1.0 ----

temperature shift catalysts, so direct comparison is

not possible.

However, NexTech’s catalyst possesses some

important properties that warrant continued

consideration for the prototype design. The NexTech

catalyst remains active in the oxidized or

reduced state. It is less sensitive to condensed

moisture. Noble metal washcoating on a monolith

catalyst substrate is a proven technology. Finally,

because it operates at a higher temperature, it is less

sensitive to sulfur poisoning, the minimum

achievable CO concentration is limited by

equilibrium. As a result, the selective oxidation

reactor must be designed to handle a higher inlet CO

concentration. Therefore, its use must be assessed in

the context of the entire system design.

Conclusions

Significant progress has been made toward

meeting the PNGV targets. The size target is less

formidable than the weight target. On the basis of

first-year project results, the following major

decisions have been made:

• Proceed with subsystem testing of catalyst

formulations.

• Proceed with plate-based catalytic reforming

system design.

• Include MTS catalyst in determination of best

combination of HTS/MTS/LTS/selective

oxidation for CO clean-up.

References/Publications

1. T.J. Flynn, R.M. Privette, M.A. Perna, K.E.

Kneidel, D.L. King, and M. Cooper, “Compact

Fuel Processor for Fuel Cell-Powered Vehicles,”

International Congress and Exposition, Detroit,

Mich., March 1-4, 1999, SP-1425, pp. 47-53.

2. S.L. Swartz, “Nanoscale Water-Gas-Shift

Catalysts,” Snapshots of CARAT Projects,
Fuel Cell Power Systems FY 2000 Progress Report

36

Phase 2, published by Argonne National

Laboratory, Transportation Technology R&D

Center, March 2000, pp. 11-12.

C. Fuel-Flexible, UOBTM Fuel Processor System: Development and Status

Richard Woods (primary contact), John Cuzens, and Josh Mauzey

Hydrogen Burner Technology, Inc.

3925 Vernon Street

Long Beach, CA 90815

(562) 597-2442, fax: (562) 597-8780, e-mail: Rwoods@HydrogenBurner.com

DOE Program Manager: Patrick Davis

(202) 586-8061, fax: (202) 586-9811, e-mail: patrick.davis@ee.doe.gov

ANL Technical Advisor: William Swift

(630) 252-5964, fax: (630) 252-4176, e-mail: swift@cmt.anl.gov

Contractor: Hydrogen Burner Technology, Long Beach, California

Prime Contract No. DE-FC02-97EE50482, October 1997-December 1999

Objectives

• Research, develop, assemble, and test a 50-kWe net (12-kWe nominal), fuel-flexible fuel-processing (F3P)

subsystem.

• Conduct performance mapping of the subsystem on various fuels, including natural gas, gasoline, ethanol, and

methanol.

• Verify the humidified low-temperature shift (HLTS) concept and assess its applicability.

• Coordinate with fuel cell system developers in preparation for system-level integration activities.

OAAT R&D Plan: Task 5; Barriers E, F, G, and H

Approach

This program includes process and hardware design for a F3P subsystem, assessment of alternative materials and

catalysts, fabrication of integrated hardware assemblies, and evaluation of alternative carbon monoxide (CO)

polishing approaches.

• The hardware design approach selected for the prototype F3

P subsystem includes three assemblies – the F3P

assembly, fuel vaporizer assembly, and CO polishing assembly. A breadboard control package is also included

to allow automatic control of the subsystem.

• The F3

P assembly integrates the primary systems/functions required for a fuel processor – reformer reactor,

thermal management, shift reactors, and integrated steam generation.

• The fuel vaporizer assembly integrates the functions of fuel vaporization and anode off-gas combustion.

• The CO polishing concepts being evaluated include methanation and preferential oxidation (PROX) of CO.
Fuel Cell Power Systems FY 2000 Progress Report

37

The program also includes verification of the HLTS reactor concept, which encompasses the evaluation of

alternative hardware configurations and development of advanced low-temperature shift (LTS) catalysts with

improved activity at lower temperatures and higher humidity.

Accomplishments

• F3P subsystem hardware was successfully adapted from noncatalytic partial oxidation (POX) design to

autothermal reformer (ATR) design.

• A total of eight F3

P systems have been fabricated, and seven have been tested. Under parallel programs, four

prototypes have been delivered to an automotive manufacturer, a fuel cell integrator, and a national laboratory.

• A total of almost 800 combined hours of operation have been achieved on these units.

• “Push Button Start” automated control logic was completed for natural gas, propane, and gasoline operation.

• Packaged hardware design of a diesel fuel processing subsystem was completed. Successful initial operation

was achieved.

• Concept verification testing of HLTS hardware was completed.

• PROX hardware was integrated into the F3

P system.

• The technology foundation for fuel processing subsystems, which has been applied to both vehicular and

stationary applications, was established.

Future Directions

Submit final report to DOE.

Introduction

Fuel cells are considered to be a viable

alternative to the internal combustion engine for

automotive applications. The direct use of hydrogen

(H2) permits the easiest, smallest fuel cell system,

but “on-board storage” of H2 raises many concerns,

as does the absence of any H2 refueling

infrastructure. An alternative approach would be to

use existing liquid fuels, such as gasoline, or

evolving fuels, such as ethanol, methanol, or

synthetic liquids. Any of these fuels would require

an “on-board reformer” to convert the liquid fuel

into H2 gas on demand. Hydrogen Burner

Technology, Inc. (HBT), has entered into a

cooperative agreement with the U.S. Department of

Energy through the Office of Transportation

Technologies. This agreement is focused on

development and testing of a F3

P subsystem for

automotive applications.

Program Overview

The greater share of the work involves the

design, construction, and testing of a prototype F3

P

subsystem. A second effort is related to verification

of the HLTS concept.

Activities during FY00 have included the

following: conversion of F3

P hardware from the

POX design to the ATR design; completion of

controller software for natural gas, propane, and

gasoline operation; concept verification testing of

HLTS hardware; integration of PROX hardware into

the F3

P subsystem; and completion of a packaged

hardware design.

F3P Subsystem Design and Hardware

The basis of the F3P subsystem has changed

from a noncatalytic POX reactor to a catalytic ATR

reactor. The improvements this change offers are

threefold: (1) increased efficiency, (2) lower

operating temperatures, and (3) simplification of

process control.

The hardware approach taken in more recently

built packaged systems utilizes four separate

hardware assemblies to allow for evaluation testing

of alternative components. The four assemblies are

the fuel vaporizer/anode gas oxidizer assembly, the

F3

P assembly, the CO polishing assembly, and the

economizer. The overall process is shown in

Figure 1.
Fuel Cell Power Systems FY 2000 Progress Report

38

Figure 1. Fuel reformer subsystem.

The seven most critical chemical processes of

the F3

P subsystem are thermally and physically

integrated into the F3

P assembly hardware (see

Figure 2). The F3P assembly provides close thermal

interaction between the ATR reaction zone, which

operates at 760 to 870°C (1400 to 1600°F), and the

lower-temperature zones of the process air preheater

and high-temperature shift zones, which operate at

300 to 650°C (600 to 1200°F). This configuration

minimizes heat loss while maximizing reaction

temperature.

All of the processes identified in Figure 2 are

physically integrated into the hardware illustrated in

Figure 3. The prototype F3

P assembly, with

conventional, commercially available catalysts,

weighs about 104 kg (230 lb), approximately 25%

more than its target weight of 83 kg (183 lb). Most

of this excess mass is due to high-density

commercial catalyst and flange structures used for

easy disassembly and inspection. The volume of the

F3

P assembly is approximately 85 L (3 ft3).

Figure 2. Integrated F3P assembly.

Figure 3. Prototype F3P assembly configuration.

Increasing this size by the volume needed for the

vaporizer, CO polishing, and economizer assemblies

indicates that the prototype hardware is

approximately twice as great as its target volume.

A complete subsystem, including all four

required assemblies, is shown in Figure 4. The fuel

vaporizer/anode gas oxidizer provides a fully

vaporized fuel/steam mixture to the F3

P assembly.

This fuel/steam mixture mixes with preheated air

within the F3

P before entering the ATR reactor.

The reformate gas exits the F3

P assembly and

enters the PROX for CO polishing. Once fuel cell

operation begins, the remaining energy in the anode

off-gas is recovered in the fuel vaporizer/anode gas

oxidizer. Any remaining unburned hydrocarbons or

hydrogen will be oxidized in the economizer, where

any additional heat recovered contributes to steam

generation.

Results

To date, HBT has accumulated almost 800 hours

of operational experience on the F3

P subsystems

fabricated. This experience includes 268 start-stop

Figure 4. HBT-023 unit, right side.
Fuel Cell Power Systems FY 2000 Progress Report

39

cycles, and operation on five fuels: gasoline,

methanol, natural gas, propane, and diesel.

Table 1 provides a summary of operating

experience achieved to date. The summary

represents testing performed with both manual and

automatic controls.

This operating experience has partially mapped

the performance characteristics of the F3

P subsystem

on five fuels. A summary of achievements to date is

given in Table 2. Results shown are from tests in

which the ATR configuration of the F3

P was used

for all fuels except methanol, which has only been

tested with the noncatalytic POX configuration.

Figure 5 shows example test data taken over the

course of six tests. The F3

P subsystem used was

S/N 001. California reformulated gasoline was used

as the fuel.

Table 1. Operating experience on F3

P summary.

S/N 001 S/N 002 S/N 003 S/N 004

Customer HBT/DOE Auto

Mfg’er

LANL FC Devel

Fabrication 12/30/98 2/20/99 3/9/99 7/1/99

Delivered 1/1/99 3/5/99 5/28/99 9/13/99

Runs 90 14 43 45

Hours 175 20 102 150

Fuels NG,

Gasoline

NG,

Gasoline

NG,

Gasoline

Methanol

NG

S/N 005 S/N 006 S/N 007 S/N 008

Customer FC Devel FC Devel CeCert SMUD

Fabrication 9/20/99 1/20/00 3/31/00 TBD

Delivered 10/19/99 TBD 4/10/00 TBD

Runs 40 25 11 N/A

Hours 250 58 33 N/A

Fuels NG,

Propane

NG,

Diesel

NG,

Diesel

Diesel

Table 2. Performance of F3

P subsystem for five fuels.

Item Nat. Gas LPG Gasoline Diesel Methanol

Efficiency1 81% 75% 75-80% 73% 76%

Max H2, % dry 49.5% 44.0% 41-42% 42-42% 40%

Min. CO LTS Out 0.8% 0.2% 0.5-0.6% 1% 0.1-0.3%

Capacity kWe

2,3 35 3.5 35 15 38

1 Efficiency = (LHV H2 out)/(LHV Fuel into Reformer)

2 Estimated power based on fuel cell operational assumptions.

3 These are maximum capacities tested thus far. Max. subsystem

capacity is probably in the range of 40-50 kWe.

Figure 5. H2 concentration on gasoline.

Conclusions

To date, the F3P subsystem has successfully

demonstrated operation and fuel flexibility, and it

has approached its performance targets. These

efforts have provided the technology foundation for

advanced fuel processing subsystems being

fabricated at HBT; testing is due to begin in June

2000. This hardware represents the next leap

forward with respect to efficiency, size, and weight

performance targets.
Fuel Cell Power Systems FY 2000 Progress Report

40

D. Integrated Fuel Processor Development

S. Ahmed, S.H.D. Lee, E. Doss, C. Pereira, D. Colombo, and M. Krumpelt

Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439

(630) 252-4553; fax: (630) 972-4553, e-mail: ahmed@cmt.anl.gov

DOE Program Manager: JoAnn Milliken

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

Objectives

Determine the design and operating conditions for an integrated fuel processor that can meet the targets of the

Partnership for a New Generation of Vehicles (PNGV):

• With a microreactor process train (100 W).

• With an engineering-scale integrated reactor (5-10 kWe)

OAAT R&D Plan: Task 3; Barriers F and G

Approach

• Study fuel processing steps individually in microreactors to determine suitable catalysts, their kinetic

parameters, and desirable operating conditions.

• Verify component performance in the integrated reactor, validate the reactor model, and identify concepts that

could improve fuel processor performance.

Accomplishments

• Demonstrated fuel processor functions in the microreactor process train:

- Demonstrated conversion of hydrocarbon fuel to produce reformate containing 1% (dry basis) carbon

monoxide.

- Evaluated preferential oxidation catalysts for use in the integrated reactor.

• Developed algorithm to determine the optimal temperature profile for the shift reactor.

• Demonstrated operation of an integrated reactor with methanol at the 7-kWe level, with reformate containing

46% hydrogen.

• Demonstrated operation of an integrated reactor with hydrocarbon fuel at the 4-kWe level, 75% efficiency, with

reformate containing 40% hydrogen.

Future Directions

• Study fuel processing steps in the microreactor to evaluate catalysts and determine kinetics and favorable

operating conditions.

• Integrate a preferential oxidation unit into the engineering scale reactor.

• Transfer technology to industrial partners.
Fuel Cell Power Systems FY 2000 Progress Report

41

Introduction

The objective of this work is to determine the

fuel processor layout, design, and operating

parameters needed to meet PNGV targets

(efficiency, size, weight, cost, response, etc.) for the

automotive fuel cell system.

Approach

To achieve this objective, the fuel processor is

being studied at two levels. First, a microreactor

process train has been established, with a series of

reactors set up to represent the various unit

processes. Each microreactor is enclosed in an

electric furnace for accurate temperature control.

The feed stream to each unit can be a simulated

reformate gas metered in from a cylinder, or from

the previous unit process in the fuel processing train.

The feed and product streams can be sampled and

analyzed by using an on-line gas chromatography/

mass spectrometry (GC/MS) system or with infrared

analyzers.

Results

The effectiveness of two water-gas-shift (WGS)

reaction catalysts was evaluated in the process train.

The first microreactor was loaded with a commercial

high-temperature-shift (HTS) catalyst (Fe/Cr oxide)

and maintained at 300°C. This was followed by a

second microreactor, which was loaded with

Argonne National Laboratory’s (ANL’s) shift

catalyst to represent the low-temperature-shift (LTS)

reactor and was maintained at 215°C. A synthetic

reformate gas, with the composition shown in Figure

1, was passed through the reactors.

HTS: Fe/Cr Oxide, T = 300°C

LTS: ANLWGS, T = 215°C

H2 = 53.9

CO2 = 21.6

CH4 = 3.8

58.6

34.3

3.5

3.5

61.2

29.9

2.5

6.3

71.4

27.6

1.0

NA

0

20

40

60

80

100

Inlet HTS LTS HTS/LTS CO = 20.8

Composition

% (dry, N 2 -free)

Figure 1. The combination of a commercial HTS

catalyst and Argonne’s shift catalyst lowered

the CO level to 1%.

The product from the HTS unit reduced the CO

level from 21.6% to 3.5%. With the inlet gas fed

directly into the LTS, the CO level was reduced

from 21.6% to 2.5%, and some methanation activity

was also seen, as shown by the increase in the CH4

levels. With the two reactors operating in series, the

product gas emerging from the LTS unit contained

1% CO and undetected levels of CH4.

The rate of reaction for the conversion of carbon

monoxide in the shift reactor can be maximized by

maintaining temperatures high enough to favor fast

kinetics and yet cool enough that a large driving

force toward equilibrium CO concentrations can be

maintained. This is typically achieved by

maintaining a progressively declining temperature

profile within the shift reactor. An algorithm to

calculate this optimal temperature profile has been

developed; it calculates the smallest catalyst volume

necessary for the conversion of a given inlet gas

mixture to the desired outlet CO concentration,

given the specifications for the H2O/CO ratio and

the rate expression for the catalyst. Figure 2 shows

an optimal temperature profile and the resulting CO

profile for conversion of 85% of the inlet CO, using

Argonne’s shift catalyst and a H2O/CO ratio of 3. It

is noteworthy that ~50% of the catalyst volume is

needed to lower the CO level from 1.5% to the

desired 1%, due to the lower temperatures (slower

reaction rate) at the tail end of the reactor.

0

2

4

6

8

10

0 50 100

Bed Length, %

CO, % (dry)

250

300

350

400

450

500

Temperature, °C

Temperature

CO

Figure 2. Calculated optimal temperature and CO

concentration profile in a shift reactor using

ANL’s catalyst (COin = 7%, COout = 1%,

H2O/CO = 3).
Fuel Cell Power Systems FY 2000 Progress Report

42

Two preferential oxidation catalysts were

evaluated in the microreactor. The commercial

catalyst was able to reduce 1% CO (Figure 3) to

under 500 parts per million (ppm) at a gas hourly

space velocity (GHSV) of 5000/hr at 150°C, with

O2/CO = 2. At higher space velocities, methanation

activity was observed. A Mn-based catalyst

developed at ANL showed the ability to reduce the

CO, but at a much lower GHSV of 500/hr

(Figure 4). This type of material needs further

development before it can be considered as a

practical alternative.

0

2000

4000

6000

8000

10000

12000

6000 11000 16000

Time, seconds

CO in Reformate, ppm

Figure 3. CO preferentially oxidized with a commercial

catalyst (GHSV = 5000/hr, 150°C,

O2/CO = 2).

0

200

400

600

800

1000

1200

0 5000 10000

Time, seconds

CO in Reformate, ppm

Argonne Formulation

GHSV = 500/h

T = 150°C

Oxygen/CO = 1.1

Figure 4. CO preferentially oxidized with a Mn-based

catalyst (GHSV = 500/hr, 150°C,

O2/CO = 1.1).

Figure 5 shows a picture of the integrated

engineering-scale reactor. With a volume of 7 L, the

hardware includes the autothermal reformer, the

sulfur trap, and the shift reactor, together with

thermal integration.

The fuel processor was operated with methanol

(7 kWe) to yield a reformate that contained 46% (dry

basis) hydrogen but also 5% carbon monoxide.

With a synthetic hydrocarbon blend resembling

gasoline, the reactor was operated at 4 kWe. The

reformate contained 40% hydrogen and 2% CO, and

it operated at an efficiency of 75%. Figure 6 shows

the product gas compositions obtained during the

experiment.

Figure 5. Picture of the engineering-scale integrated fuel

processor.

0

10

20

30

40

50

60

70

80

90

0:00 1:00 2:00 3:00 4:00 5:00 6:00

Expt. Time, hh:mm

Product Gas, % (dry)

Hydrogen

Carbon Dioxide

Carbon Monoxide

Efficiency, %

Figure 6. Product gas compositions obtained from the

conversion of a synthetic gasoline blend.
Fuel Cell Power Systems FY 2000 Progress Report

43

Conclusions

Fuel processors are being studied with reactors

at the 100-W and 10-kW levels. The microreactor

has been used to study the kinetics and effectiveness

of WGS catalysts. An algorithm has been developed

for determining the optimal temperature profile in

the shift reactor, and this has been approximated

with two reactors in series. Commercial preferential

oxidation catalysts have also been evaluated in the

microreactor.

The engineering-scale integrated fuel processor

has been tested with methanol, iso-octane, and a

hydrocarbon blend resembling gasoline. The unit

was operated with hydrocarbon fuels at over 75%

efficiency, where the reformate contained >40%

hydrogen and ~2% carbon monoxide. This

engineering-scale integrated hardware currently

lacks the preferential oxidation unit and the spent

anode gas burner. A collaborative effort with Los

Alamos National Laboratory is under way to

incorporate the preferential oxidizer into the ANL

fuel processor.

Publications

1. S. Ahmed, B. Bergin, T. Krause, J.D. Carter,

J-M. Bae, L. Ruscic, D. Applegate, J. Kopasz,

D. Myers, J. Krebs, C. Pereira, S.H.D. Lee, and

M. Krumpelt, “Fuel Processor Development at

Argonne National Laboratory,” presented at the

Army Research Office Workshop, Detroit,

Mich., June 19-21, 2000.

2. S. Ahmed, J.P. Kopasz, B.J. Russell, and H.L.

Tomlinson, “Gas-to-Liquids Synthetic Fuels for

Use in Fuel Cells: Reformability, Energy

Density, and Infrastructure Compatibility,” to be

published in the Proceedings of the 3rd

International Fuel Cell Conference, Nagoya,

Japan, held Nov. 30–Dec. 3, 1999.

3. M. Krumpelt, S. Ahmed, R. Kumar, S. Chalk,

and J. Milliken, “Partial Oxidation Fuel

Reforming for Automotive Power Systems,” to

be published in the Proceedings of the 3rd

International Fuel Cell Conference, Nagoya,

Japan, held Nov. 30–Dec. 3, 1999.

4. S. Ahmed, R. Kumar, and M. Krumpelt, “Fuel

Processing for Fuel Cell Power Systems,” Fuel

Cells Bulletin, Elsevier Press, London, U.K.,

Sept. 1999.

5. S. Ahmed, J. Kopasz, B.J. Russell, and

H.L. Tomlinson (Syntroleum Corp.), “CobaltBased Fischer-Tropsch Paraffin Fuels for Fuel

Cell Power,” poster paper presented at the Sixth

Grove Fuel Cell Symposium, London, U.K.,

Sept. 13-16, 1999.

6. S. Ahmed, S.H.D. Lee, R. Kumar, J.D. Carter,

R. Wilkenhoener, and M. Krumpelt, “The

Argonne Catalytic Fuel Processor for

Automotive and Small Fuel Cell Power

Systems,” poster paper presented at the Sixth

Grove Fuel Cell Symposium, London, U.K.,

Sept. 13-16, 1999.

7. J. Kopasz, R. Wilkenhoener, S. Ahmed,

J.D. Carter, and M. Krumpelt, “Fuel Flexible

Partial Oxidation Reforming of Hydrocarbons

for Automotive Applications,” preprints of the

Symposium on Hydrogen Production, Storage,

and Utilization, 218th ACS National Meeting,

Vol. 44, No. 4, pp. 899-904, New Orleans, La.,

Aug. 22-26, 1999.

Patents Issued

1. S. Ahmed, R. Kumar, and M. Krumpelt,

“Methanol Partial Oxidation Reformer,” Patent

No. 5,942,346, issued on Aug. 24, 1999.

2. S. Ahmed, R. Kumar, and M. Krumpelt,

“Methanol Partial Oxidation Reformer,” Patent

No. 5,939,025, issued on Aug. 17, 1999.

3. M. Krumpelt, S. Ahmed, R. Kumar, and R.

Doshi, “Method for Making Hydrogen-Rich Gas

from Hydrocarbon Fuel,” Patent No. 5,929,286,

issued on July 27, 1999.

Awards/Recognitions

1. Best Poster Award at the Grove Symposium,

London, U.K., September 1999.

2. Annual National Laboratory R&D Award from

DOE/OTT/OAAT, Richland, Wash., June 2000.
Fuel Cell Power Systems FY 2000 Progress Report

44

E. Microchannel Fuel Processor Components

Greg A. Whyatt, Ward E. TeGrotenhuis, Robert S. Wegeng, Victoria S. Stencamp, James M. Davis,

John G.H. Geeting, and Larry R. Pederson (primary contact)

Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352

(509) 375-2731, fax: (509) 375-2167, e-mail: larry.pederson@pnl.gov

DOE Program Manager: JoAnn Milliken

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

Objectives

Develop compact reactors, separators, and heat exchangers for the onboard automotive production of hydrogen from

liquid hydrocarbons.

OAAT R&D Plan: Task 3; Barriers F, G, and H

Approach

Utilize unique heat and mass transport advantages available in engineered microstructures to develop and

demonstrate an integrated steam reforming subsystem. The integrated subsystem consists of multiple microchannel

reactors, combustors, multistream recuperative heat exchangers, fuel and water vaporizers, and vapor/liquid

separators.

Accomplishments

• High hydrogen selectivity and low methane slip were achieved for steam reforming of iso-octane in a

microchannel reactor at a rate sufficient to support a 0.5- to 1.0-kWe fuel cell.

• An integrated microchannel steam reformer subsystem consisting of a four-cell reactor, multistream

recuperative heat exchangers, and water/fuel vaporizers was designed and fabricated. Conservatively designed

to reform iso-octane to supply a 10-kWe fuel cell, the steam reforming subsystem incorporates an innovative

combustion gas reinjection approach that allows it to operate in an energy-efficient manner, a significant

improvement over previous designs.

• Integrated, multistream recuperative heat exchangers were developed to support operation of an energyefficient steam reformer. The exchangers recover heat from either the reformate or the combustion streams to

preheat reactants and combustion air and to vaporize fuel and water. Except for a low-temperature air preheater,

these heat exchangers provide all of the recuperator and vaporizer functions needed for the steam reforming

subsystem.

• A microchannel vapor-liquid separation concept was demonstrated in a single-microchannel device. Capillary

and surface forces were utilized to achieve qualitatively complete phase separation. Heat-exchange channels

were also incorporated in the single-channel phase separator, resulting in technology capable of performing

condensation and phase separation in a single compact device. The technology is projected to be substantially

smaller, with a lower pressure drop, than competing technologies.

Future Directions

• Demonstrate highly efficient operation of the steam reforming subsystem at 10 kWe and higher.

• Design and demonstrate steam generators and vapor/liquid separators to be incorporated into the integrated

steam reforming subsystem, or other systems, with target pressure drops of <0.1 psi.

• Evaluate long-term reactor, heat exchanger, and catalyst performance.
Fuel Cell Power Systems FY 2000 Progress Report

45

• Continue industrial interactions to evaluate microchannel reactors, recuperative heat exchangers, and fuel and

water vaporizers.

• Advance to the reforming of transportation fuels.

• Investigate means to lower manufacturing costs and improve manufacturability.

Heat Exchangers and Vaporizers

A recuperator demonstrated in late FY 1999

successfully confirmed the ability to accurately

predict microchannel recuperator performance. The

test unit, shown in Figure 1, had a volume of 37 cm3

.

Performance results for this recuperator operated

with balanced nitrogen flows are given in Figure 2.

At the design conditions, the unit is expected to

achieve 89% effectiveness, with a duty of 897 watts

and a heat-transfer intensity in the core of 56 W/cm3

.

Figure 1. Microchannel reformate recuperator test unit.

0

10

20

30

40

50

60

70

0 20 40 60 80 100 120 140

SLPM N2, (70F ref)

W/cm3 in HX Core __

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Effectiveness

W/cm3, 200-400C W/cm3

, 400-600C

eta, 200-400C eta 400-600C

Figure 2. Microchannel recuperator test unit

performance on balanced nitrogen flows.

On the basis of the successful demonstration of

the recuperator test unit, the microchannel heat

exchanger concept was extended to design and

fabricate multistream heat exchangers to support the

operation of an energy-efficient 10-kWe steam

reforming system. Two multistream exchangers

(shown in Figure 3) were designed so that, following

a successful demonstration, they can be integrated

into a single compact, multistream microchannel

heat exchanger that will, with the exception of a

low-temperature air preheater, contain all the

recuperators and vaporizers needed for the steam

reforming subsystem.

The microchannel design enables the water

vaporizer to efficiently extract heat from the

combustion exhaust, cooling it to just above 100°C

while still maintaining significant superheat in the

generated steam (see Figure 4).

Figure 3. Integrated multistream microchannel heat

exchangers prior to header attachment. Unit on

left contains a combustion gas recuperator and

water vaporizer. Unit on right contains a 90%-

effective reformate recuperator, a fuel

vaporizer, and a water preheater. These two

units are designed to support up to a maximum

of a 5-kWe steam reformer operating a 3:1

steam-to-carbon ratio.
Fuel Cell Power Systems FY 2000 Progress Report

46

100

150

200

250

300

350

400

0 0.005 0.01 0.015 0.02 0.025 0.03

mol/s Steam

Steam/Gas Exit Temp, C __

0

200

400

600

800

1000

1200

1400

Steam Duty, watts

gas steam out duty

Figure 4. Performance data on water vaporizer section

of integrated exchanger.

Steam Reformer Reactor Testing

The microchannel steam reforming reactor that

was designed, fabricated, and operated in FY 1999

was tested over a range of operating conditions. The

objective was to collect performance data for design

of the next-generation steam reformer at the 10-kWe

scale. The data demonstrated the reforming capacity

of the first-generation reactor design to validate

projections for power density, and it was used to

develop predictive models for microchannel

reforming for incorporation into models of the steam

reforming fuel processor.

The statistically designed experiment employed

a four-factor, full-factorial design using iso-octane

flow, water flow, combustor temperature, and

combustion air flow as variables. These variables

translate into the design parameters, reactant

residence time, steam-to-carbon ratio, reactor

operating temperature, and heat-transfer efficiency.

The steam-to-carbon ratio was varied between 3:1

and 12:1. Figure 5 shows a summary of selectivity

data over the range of conditions tested. Iso-octane

conversion ranged from about 50% to slightly over

90%. The equivalent power output ranged from 500

to 975 We (assuming 90% conversion and 100%

selectivity in the low-temperature-shift reactor, and

48% fuel cell stack efficiency), which translates to a

productivity sufficient to supply 16 to 32 kWe of

fuel cell capacity per liter of reactor core. Statistical

analysis of the data indicated that for iso-octane

conversion, the order of importance of the variables

is (1) fuel flow rate, (2) operating temperature,

(3) water flow rate, and (4) combustion air flow rate.

0

20

40

60

80

100

620 640 660 680 700 720 740

SR Reactor Outlet Temperature (C)

Selectivity (%)

Figure 5. Summary of selectivity data for the

statistically designed experiment operated

using the first-generation microchannel steam

reforming reactor. Data reflect a range of

operating conditions for reactant flows and

temperatures.

10-kWe Steam Reforming Subsystem

The 10-kWe steam reforming subsystem was

designed on the basis of data discussed in the

previous sections. The objectives of the 10-kWe

steam reforming system are to substantially scale up

the earlier steam reformer and, through an integrated

heat exchanger network and a redesign of the

reactor, produce a system that is energy-efficient.

This system has been designed and fabricated, and

will be tested in late FY 2000. It is designed to

operate at pressures up to 5 bar on the reaction side.

The 10-kWe system hardware is shown in Figure 6.

The 10-kWe reactor contains four independent

cells, each with 2.5-kWe capacity. The reactants and

products are processed through these four cells in

parallel, while the combustion gases providing the

heat to drive the reaction pass through the cells in

series. As the combustion gases pass from one cell

to the next, a small amount of additional fuel is

injected and burned to restore the temperature to the

desired level prior to entering the next cell. This

approach increases the product of (mass flow) ×

(heat capacity) of the combustion gases passing

through a single cell, which reduces the temperature

drop across the reactor and dramatically reduces the

incoming temperature required to sustain a given

reaction rate. It also reduces the overall amount of

combustion air used, thereby reducing the amount of

heat lost to the combustion exhaust. This approach

also allows test units to be manufactured and
Fuel Cell Power Systems FY 2000 Progress Report

47

Figure 6. Integrated 10-kWe steam reforming

subsystem. Reactor containing four cells is

located on the bottom, with one pair of

integrated exchangers provided for each cell of

the reactor. All reactor connections are made

on one face of the reactor for ease of

insulation and to reduce overall heat loss. The

many vertical tubes are for thermocouples and

pressure sensors for the experimental system,

and would not be part of a final commercial

system.

operated using 316L stainless steel. The optimal

operating temperature involves a trade-off between

reactor cost, productivity, efficiency, and operating

lifetime; this trade-off has not yet been resolved.

However, it is expected that the series use of

combustion gases will allow lower-cost alloys to be

used, compared to those required if 1,000°C

combustion temperatures were utilized.

Microchannel Condenser with Vapor/Liquid

Separation

Pacific Northwest National Laboratory (PNNL)

expanded efforts toward size and weight reduction

of balance-of-plant items by developing and

demonstrating a concept for combining partial

condensation with vapor/liquid phase separation

within a single compact microchannel device. This

approach would surpass conventional phase

separation technologies, such as centrifugal

separators, in capacity per unit hardware mass and

volume. The result is increased power density and

specific power for the overall fuel processor/fuel cell

system, regardless of the choice of reforming

technology.

This PNNL study demonstrated the concept of,

and collected performance data for, vapor/liquid

separation in a single-channel microchannel device.

Subsequently, heat-exchange channels were

incorporated to accomplish the combined functions

of partial condensation and phase separation. Future

work will include scale-up to multichannel devices.

Figure 7 shows flow capacity curves for two

configurations of the single-channel phase

separation device, indicating the maximum gas and

liquid flow rates that can be processed within the

device while achieving qualitatively complete phase

separation. Performance was compared to that of a

conventional centrifugal separator. A separation

achieved in 0.08 s residence time in the

microchannel device is projected to require 0.4 s in

the centrifugal separator. This corresponds to a

volume of 0.5 L for a full-scale device capable of

treating reformate stream from a steam reformer,

compared to a volume of > 2 L for a centrifugal

separator. Channel pressure drop was calculated to

be 0.08 in. of water, based on slit flow, while the

centrifugal separator is rated at 1.4 in. of water.

Microchannel Fuel Processing System

Implications

The current steam reforming subsystem is

projected to meet the Department of Energy’s

(DOE’s) targets for power density and fuel

processor efficiency, but improvements are needed

to meet specific power and cost targets.

0

2

4

6

8

10

12

0 500 1000 1500 2000

Gas flow (mL/min)

Maximum Water flow (mL/min)

Figure 7. Flow capacities for 100%-efficient phase

separation of a dispersed gas and liquid feed

stream for two configurations of the singlechannel microchannel phase separator.
Fuel Cell Power Systems FY 2000 Progress Report

48

Performance targets, current status, and short- and

long-term project goals are summarized in Table 1.

The overall system efficiency, including the

current fuel processor and PEM fuel cell, is

projected to be 39-41%. High system efficiency is

usually equated with high hydrogen utilization but

with relatively low stack current density. However,

because unused hydrogen from the fuel cell is

recycled to the fuel processor to provide heat for

reforming, system studies have shown the overall

efficiency to be relatively insensitive to hydrogen

utilization in the stack. Thus, it is expected that a

compact, microchannel steam reforming system

coupled with a fuel cell can ultimately provide both

high efficiency and high power density.

Table 1. Comparison of DOE-OAAT targets for an

automotive fuel processor.

Technical

Target

DOE 2004

Target

PNNL

Status

PNNL

FY 2001

Goals

PNNL

Long-Term

Goals

Power

Density

(We/L)

750 1500 3000 >6000a

Specific

Power

(We/kg)

750 280 600 >1500a

Cost ($/kW)

10 60b 30b <4a,b

Fuel

Processor

Efficiency

80% 83-85% 83-85% 83-85%

a Requires improvements to catalyst performance and/or

manufacturing costs.

b Based on cost of bonded unit only (no catalyst costs).

Publications and Presentations

• R.S. Wegeng, “Microchannel Fuel Processor

Hardware Development Status,” F-CELLS

2000, Palm Springs, Calif., May 22-26, 2000.

• R.S. Wegeng, “Reducing the Size of

Automotive Fuel Reformers,” Fuel Cells

Infrastructure Workshop, Chicago, Ill., Dec. 6-7,

1999.

• J.L. Zilka-Marco, A.Y. Tonkovich,

M.J. Lamont, S.P. Fitzgerald, D.P. VanderWiel,

Y. Wang, and R.S. Wegeng, “Compact

Microchannel Fuel Vaporizer for Automotive

Applications,” 4th International Conference on

Microreaction Technology,

AICHE/DECHEMA, Atlanta, Ga., March 2000.

• M.K. Drost, R.S. Wegeng, P.M. Martin,

K.P. Brooks, J.L. Martin, and C. Call,

“MicroHeater,” 4th International Conference on

Microreaction Technology,

AICHE/DECHEMA, Atlanta, Ga., March 2000.

• D.L. Brenchley, R.S. Wegeng, and M.K. Drost,

“Development of Micro-Chemical and Thermal

Systems,” 4th International Conference on

Microreaction Technology,

AICHE/DECHEMA, Atlanta, Ga., March 2000.

• S.P. Fitzgerald, R.S. Wegeng, A.Y. Tonkovich,

Y. Wang, H.D. Freeman, J.L. Marco,

G.L. Roberts, and D.P. VanderWeil, “A

Compact Steam Reforming Reactor for Use in

an Automotive Fuel Processor,” 4th

International Conference on Microreaction

Technology, AICHE/DECHEMA, Atlanta, Ga.,

March 2000.

• E.A. Daymo, D.P. VanderWiel, S.P. Fitzgerald,

Y. Wang, R.T. Rozmiarek, M.J. Lamont, and

A.Y. Tonkovich, “Microchannel Fuel

Processing for Man Portable Power,” 4th

International Conference on Microreaction

Technology, AICHE/DECHEMA, Atlanta, Ga.,

March 2000.

• T.M. Werner, S.C. Schmitt, E.A. Daymo, and

R.S. Wegeng, “Microchannel Gasoline

Vaporizer Unit Manufacturing Cost Study,”

PNNL-12226, June 1999.
Fuel Cell Power Systems FY 2000 Progress Report

49

F. Catalysts for Improved Fuel Processing

Rod Borup (primary contact), Michael Inbody, Byron Morton, JinKi Hong, and José Tafoya

ESA-EPE, MS J580

P.O. Box 1663

Los Alamos National Laboratory, Los Alamos, NM 87545

(505) 667-2823, fax: (505) 665-6173; e-mail: Borup@lanl.gov

DOE Program Manager: JoAnn Milliken

(202) 586-2480, e-mail: joann.milliken@ee.doe.gov

Objectives

• Understand fuel processor catalyst durability and causes for catalyst degradation.

- Examine fuel effects on fuel processor catalyst performance and durability. Of interest are effects on

catalyst activity associated with fuel composition, component, and impurities.

- Evaluate short-residence-time reaction events, leading to unique fuel processor designs and concepts.

- Evaluate catalysts to determine variation in rates and reaction mechanisms during use.

- Delineate catalyst degradation mechanisms.

OAAT R&D Plan: Task 3; Barrier E

Approach

• Understand and document catalyst performance over a range of relevant conditions.

- Measure adiabatic reforming performance under real operating conditions.

- Determine activity, kinetic rates, durability, and performance under isothermal conditions.

- Study the effects of varying fuel constituents and contaminants within candidate fuels.

- Examine combinations of catalyst and catalyst supports to understand catalyst component degradation.

• Utilize catalyst characterization and surface analytical techniques to help delineate catalyst degradation

mechanisms.

- Characterize catalyst’s elemental composition, particle size, and surface area before and after testing.

- Evaluate catalyst structural changes.

Accomplishments

• Tested and characterized catalysts with various fuel components.

- Nickel and rhodium catalysts (commercial and in-house).

- With individual fuel components.

- With fuel impurity (sulfur).

• Utilized catalyst characterization and surface analytical techniques to delineate catalyst degradation

mechanisms.

- Characterized catalysts and quantified surface area.

- Evaluated kinetic vs. equilibrium data for candidate catalysts for partial oxidation.

Future Directions

• Study fuel processor catalyst operation with petroleum-based fuels to evaluate effects of fuel constituents.

- Measure fuel processor catalyst activity and durability with individual fuel constituents and fuel blends, as

well as with fuel impurities.
Fuel Cell Power Systems FY 2000 Progress Report

50

- Monitor carbon formation in situ in adiabatic reactor with laser-scattering extinction apparatus. Map carbon

tendencies of individual catalysts, catalyst supports, and fuels constituents, and examine commercial

catalysts to observe carbon formation tendencies.

• Automate microscale test equipment, reactant mixtures, and sample injection system.

- Initiate long-term, unattended and automated catalyst testing for durability measurements.

- Evaluate fuel processing catalysts in both microscale and macroscale reactors to compare molecular-level

degradation mechanisms.

Introduction

This report covers technical progress during

fiscal year (FY) 2000 on fuel processing catalyst

characterization. These development efforts support

U.S. Department of Energy (DOE) activities in the

development of compact, transient-capable

reformers for on-board hydrogen generation starting

from candidate fuels. The long-term objectives

include increased durability and lifetime, in addition

to smaller volume, improved performance, and other

specifications required for meeting fuel processor

goals.

The technical barriers to compact fuel processor

size, transient capability, and compact, efficient

thermal management are all functions of catalyst

performance. Significantly, work at Los Alamos

National Laboratory (LANL) now involves testing

large-scale fuel processors for performance and

durability, as influenced by fuels and fuel

constituents, and complements that testing with

microscale catalyst evaluation, accomplished under

well-controlled conditions.

Approach

The fundamental tools for our research on fuel

processing catalysts are reactor test beds and catalyst

characterization techniques. Catalyst activity and

performance are measured in two different types of

reactor test beds, which serve complementary roles

in our laboratory. An adiabatic reactor exposes

catalysts to fuel processing conditions under actual

system conditions and relatively high power levels,

while an isothermal microscale reactor, in which

catalysts are used under extremely well defined and

controlled conditions, exposes the catalyst to

individual operating conditions. In addition, catalyst

characterization techniques are used to define the

catalyst structure and structural changes upon

exposure to fuel processor conditions in the reactor

test beds. These techniques, all available at LANL,

include elemental analysis techniques and

techniques to quantify surface area and particle size

changes, such as X-ray Photoelectron Spectroscopy

(XPS), BET/H2 or CO chemisorption, X-ray

Diffraction (XRD), and Scanning Electron

Microscopy and Energy Dispersive Spectroscopy

(SEM/EDS). Other techniques available at LANL

include Transmission Electron Microscopy (TEM),

X-ray Fluorescence Spectroscopy (XRF), and

temperature-programmed desorption (TPD), which

will be used as required to further delineate catalyst

degradation mechanisms.

The adiabatic reactor used to evaluate catalysts

and fuel components, including the tendency for

carbon formation, is shown in Figure 1. This reactor

features ease of catalyst replacement, the ability to

incorporate catalysts supported on commercially

used substrates (such as corderite monoliths or pellet

Figure 1. Adiabatic partial oxidation reactor.
Fuel Cell Power Systems FY 2000 Progress Report

51

and powder catalysts), in situ carbon formation

monitoring, and gas and temperature measurements

with radial and axial profiles. The reactor first

became operational in May 2000; the in situ carbon

formation monitoring will be added in the fourth

quarter of FY 2000. For in situ carbon formation

monitoring, an argon ion laser will be used with

extinction monitoring to observe the onset of carbon

formation. Scattering will also be utilized to observe

relative carbon particle-size distributions and the

initial onset of carbon formation, and spectral

detection will allow for fluorescence detection of

polycyclic aromatic hydrocarbons (PAHs).

The isothermal microscale catalyst reactor for

use in fuel and catalyst measurements under welldefined, controlled conditions is shown in Figure 2.

This reactor is constructed of a quartz tube and an

isothermal oven. Typical catalyst samples are 300–

500 milligrams. Vapor or liquid fuels combined with

oxidant (air) are mixed and preheated prior to

introduction into the catalyst, while the temperature

of the catalyst remains essentially constant because

of the isothermal furnace, small catalyst quantities,

and small reactant volumes.

Results

Results using two different metal catalyst

samples, rhodium and nickel, are described in this

report. The rhodium catalyst was a commercial

0.5-wt% catalyst supported on alumina; nickel

catalysts were prepared at Los Alamos with variable

nickel loadings from 0.5 wt% to 5 wt%. Initial tests

were conducted to measure catalyst performance

Figure 2. Microscale catalyst test station.

with partial oxidation and steam reforming

reactions. An example of these measurements is

shown in Figure 3 for the isothermal partial

oxidation of methane on a nickel catalyst. Methane

conversion reached nearly 100 % at 700°C, while

the selectivity for hydrogen production was highest

at 600°C. The isothermal partial oxidation of

methane on a rhodium catalyst is shown in Figure 4.

The rhodium catalyst shows slower oxidation

kinetics, and therefore less methane conversion, than

the nickel catalyst at similar temperatures, and it

does not reach 100% methane conversion, even at

750°C. However, the rhodium loading was an order

of magnitude less than the nickel, so the TON (turnover number) for each catalyst site was much higher

for the rhodium catalyst than the nickel catalyst;

thus, the rhodium has higher intrinsic activity than

the nickel. In Figures 3 and 4, XCH4 is the fraction of

methane converted, SH2 is the selectivity for

hydrogen production, and SCO is the selectivity for

CO production, as defined below.

SH2 = 0.5 H2, out /(CH4, in - CH4,out) (1)

SCO = CO, out /(CH4,in - CH4, out) (2)

Figure 5 shows XRD of nickel catalysts before

and after testing with iso-octane and methane. The

main nickel diffraction peak occurs at a 2 Theta of

44 degrees. The diffraction of the new nickel

catalyst is broad, indicating small dispersed nickel

particles, while after testing with methane, the peak

has grown sharper, and after testing with iso-octane,

500 550 600 650 700 750 800

Temperature(

oC)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

XCH4,SCOandSH2

XCH4

SCO

SH2

Figure 3. Isothermal POX of CH4 with temperature on

Ni/Al2O3 catalyst.
Fuel Cell Power Systems FY 2000 Progress Report

52

0

0.2

0.4

0.6

0.8

1

1.2

450 500 550 600 650 700 750 800

Temperature (o

C)

XCH4, SCO and SH2

XCH4

SCO

SH2

Figure 4. Isothermal POX of CH4 with Temperature on

Rh/Al2O3 catalyst.

Figure 5. XRD of nickel catalyst after testing.

the peak is still sharper. The sharpening peak

indicates nickel catalyst particle growth, either by

particle sintering or agglomeration, during the

testing with the hydrocarbons. BET surface area

analysis by CO chemisorption leads to similar

conclusions, and is summarized in Table 1 for

various rhodium and nickel catalyst samples.

Sample 1, the rhodium catalyst before testing, had

arhodium surface area of 0.718 m2

/g catalyst or

143.8 m2

/g rhodium. After testing with methane, the

rhodium surface area decreased to 50.8 m2

/g

rhodium (sample 2), while after testing with isooctane, the surface area was negligible (sample 3).

The negligible surface area of sample 3 probably

indicates a rhodium/alumina formation of a spinel,

and thus complete loss of pure rhodium particles –

but not loss of the rhodium itself. Nickel catalyst

samples show a similar trend toward decreasing

surface area. The initial surface area of the nickel is

much lower at 28 m2

/g nickel (sample 4); however,

this is typical for a catalyst with a much higher metal

loading. After testing, a decrease in nickel surface

area is observed – 23.6 m2

/g nickel (sample 5) after

testing with iso-octane and 4.7 m2

/g nickel after

testing with methane (sample 6).

A different fuel processor degradation

mechanism is carbon formation during the oxidation

and steam reforming of hydrocarbon fuels. Carbon

formation has been monitored by the carbon buildup

on the catalyst surface over time as a function of

different fuel components. Figure 6 shows the XPS

Table 1. Catalyst surface areas by CO chemisorption of rhodium and nickel catalysts.

Sample #

(Description)

CO Chemisorption

(ccSTP/g at 55 Torr)

Dispersion

(%)

Crystallite

Diameter

(nm)

Metal Surface

Area

(m2/g catalyst)

Metal Surface

Area

(m2/g metal)

1. (fresh 0.5%

Rh/Al2O3)

0.4278 39.31 3.4 0.718 143.6

2. (fresh 0.5%

Rh/Al2O3 with

CH4)

0.1502 13.8 9.6 0.254 50.8

3. (fresh 0.5%

Rh/Al2O3 with

iso-octane)

Negligible Very Low Very Large Negligible Negligible

4. (fresh 5%

Ni/Al2O3)

0.97 5.08 24.1 1.4 28

5. (5% Ni/Al2O3

with iso-octane)

0.819 4.29 28.5 1.18 23.6

6. (5% Ni/Al2O3

with CH4)

0.164 0.86 143 0.235 4.7

0

100

200

300

400

500

0 10 20 30 40 50

2 Theta

Intensity

CH4

iso-C8

Fresh
Fuel Cell Power Systems FY 2000 Progress Report

53

Figure 6. XPS of catalysts, (a) initial carbon signal and

after partial oxidation with (b) iso-octane, (c)

1-pentene, (d) methylcyclohexane, and (e) pxylene.

C1s signal for nickel catalyst samples tested with

iso-octane, pentene, methylcyclohexane, and xylene.

This shows relative carbon formation to be much

higher with the aromatic and unsaturated compounds

than with the aliphatic hydrocarbons. All nickel

samples after testing showed at least a small amount

of carbon present.

Conclusions

Catalyst characterization techniques and

different catalyst test beds are employed to

understand catalyst durability and degradation

mechanisms, leading to the development of fuel

processing catalysts with longer durability. Testing

of catalysts to observe their degradation under welldefined conditions and actual fuel processing

conditions leads to a better understanding of such

degradation. The catalysts are examined to

determine their relative activity and degradation

during fuel processing reactions under different

conditions, including different fuel components and

fuel impurities.

Both noble metal (rhodium) and base metal

(nickel) catalysts have been shown to decrease in

surface area during fuel processing reactions. The

decrease in surface area is catalyst- and fueldependent. The rhodium catalyst, after testing with

iso-octane, showed a complete loss of pure rhodium

particles.

Carbon formation has also been observed to be a

degradation mechanism. The tendency toward

carbon formation has been observed to be a function

of the fuel component; the general trend is as

follows: xylene > methylcyclohexane > pentene >

iso-octane.

G. R&D on a Novel Breadboard Device Suitable for Carbon Monoxide

Remediation in an Automotive PEM Fuel Cell Power Plant

Nguyen Minh (primary contact) and Stan Simpson (co-principal investigator)

Honeywell Engines and Systems

2525 W. 190th Street, MS-36-1-93140

Torrance, CA 90504-6099

Nguyen Minh: (310) 512-3515, fax: (310) 512-3432, e-mail: nguyen.minh@honeywell.com

Stan Simpson: (310) 512-4604, fax: (310) 512-4128, e-mail: Stan.Simpson@ honeywell.com

Di-Jia Liu (co-principal investigator)

Honeywell Des Plaines Technology Center

50 E. Algonquin Road

Des Plaines, IL 60017-5016

DOE Program Manager: Patrick Davis

(202) 586-8061, fax: (202) 586-9811, e-mail: patrick.davis@ee.doe.gov
Fuel Cell Power Systems FY 2000 Progress Report

54

ANL Technical Advisor: William Swift

(630) 252-5964, fax: (630) 252-4473, e-mail: swift@cmt.anl.gov

Contractor: Honeywell Engines and Systems, Torrance, California

Prime Contract No. DE-FC02-99EE50578, October 1999-December 2001

Objectives

Develop, implement, and demonstrate a new carbon monoxide removal system for use in polymer electrolyte

membrane fuel cell (PEMFC) systems that provides high carbon monoxide (CO) removal efficiency, low parasitic

hydrogen consumption, and tolerance to CO input variation in an easily controlled manner. The system will be

designed for removal of CO from a continuous reformate flow sized for a 10-kW PEMFC stack with a CO input

level of 5000 to 8000 parts per million (ppm).

OAAT R&D Plan: Task 7; Barrier E

Approach

• In a 27-month program, Honeywell will research and develop a novel technology to selectively remove CO

from reformate fuel for use in PEMFCs. Two approaches to CO removal will be explored and developed: the

adsorption/catalytic oxidation of CO (ACO) and the adsorption/electrocatalytic oxidation of CO (ECO).

Following an initial 12-month R&D phase, the two approaches will be evaluated critically for downselection on

the basis of efficiency, system compatibility, and cost criteria. A breadboard CO-remediation system sized for a

10-kW PEMFC stack will then be constructed and tested on both synthetic reformate and reformate obtained

from an operating fuel processor.

• The program consists of four major tasks:

- Research and development on two potentially viable approaches to remove CO from reformate.

- Downselection of the most promising technique, on the basis of performance and cost.

- Design and fabrication of a brassboard CO-removal device based upon the selected technology of choice.

- Testing of the CO-removal system.

Accomplishments

• Proof-of-principle experiments for both technologies have been demonstrated.

• CO-removal efficiency for both ACO and ECO has been increased significantly through optimization of

catalyst, support, and active adsorption surface.

• Significant progress has been made in preliminary ACO/ECO engineering design.

Future Directions

• Catalyst aging studies (currently in progress).

• Evaluation of parasitic hydrogen consumption and tolerance to CO transients.

• System engineering to reduce pressure drop and volume.

Introduction

The PEMFC continues to benefit from intense

development efforts for its potential application in

automobiles. PEMFCs offer a number of inherent

advantages, including high efficiency, low noise,

low chemical emissions, and low operating

temperature. Hydrogen is the most energetic fuel for

the PEMFC, but the lack of an existing

infrastructure for the routine handling and

distribution of hydrogen severely limits its utility.

Alternatively, such hydrocarbon fuels as gasoline or
Fuel Cell Power Systems FY 2000 Progress Report

55

methanol can be reformed to a hydrogen-containing

fuel mixture, known as reformate, via a fuel

processor. Unfortunately, a typical reformate

consists of a mixture of gaseous products that

includes CO at concentration levels near 1%; the

detrimental effect of CO at even the ppm

concentration levels on the performance of a

PEMFC operating with platinum catalysts is well

documented. One approach to the CO problem is to

incorporate a pretreatment device or process in the

fuel line (between the fuel processor and the fuel

cell) to significantly decrease the CO concentration

in the reformate. This process can be either by

physical removal (as in the case of membrane

separation) or by chemical reaction (as in the case of

methanation or the use of preferential oxidation,

PROX). These techniques suffer from various

disadvantages, including high cost and complexity,

high parasitic hydrogen consumption, and a lack of

tolerance for large CO transients (without

complicated and expensive control processes).

Approach

The goal of this program is to develop and

demonstrate a novel, easily controlled CO-removal

system that provides high CO removal efficiency

plus an increased tolerance for CO input variation.

This system will be incorporated in a working

PEMFC system, between the fuel processor and the

PEMFC stack, as shown in Figure 1. The system

will be based upon the use of a selective CO

removal device that can be regenerated periodically

when saturated with CO. Potential advantages of this

approach include a high tolerance toward variations

in CO input during the change of load dynamics,

low parasitic hydrogen consumption,

relative simplicity of operation, and an ability to

control and operate during the “cold-start”

condition.

Two innovative approaches to selective CO

removal and regeneration are being investigated in

this project. Both approaches make use of multiple,

CO-selective adsorption surfaces that can be

regenerated quickly, simply, and efficiently with

minimal consumption of hydrogen fuel in the

reformate stream. The methods, referred to as the

adsorption/catalytic oxidation (ACO) technique and

the electrocatalytic oxidation (ECO) technique,

differ in the manner by which the active adsorption

surfaces are regenerated. In ACO, CO is adsorbed

over a bifunctional material bed and subsequently

oxidized chemically to CO2. In ECO, the adsorbed

CO is removed through electrocatalytic oxidation.

Results

Proof-of-Principle Experiments

Initial proof-of-principle experiments for both

ACO and ECO have been successfully demonstrated

in laboratory-scale testing. These experiments

clearly indicated the potential of both techniques for

continuous, efficient removal and treatment of CO in

fuel reformate streams. In the case of ACO,

continuous CO removal can be achieved through the

use of multiple adsorption beds that are alternately

cycled between adsorption and regeneration modes.

In ECO, the adsorption/regeneration cycle is

generated electrically, and continuous CO removal

is achieved by changing the frequency of cell

operation. Importantly, this approach can be

controlled electronically without the need for

moving parts.

Figure 1. The CO removal system in a reformer-fueled PEMFC power system.
Fuel Cell Power Systems FY 2000 Progress Report

56

ACO/ECO Material Development

A sorption bed material suitable for ACO

application must meet the following basic criteria: it

must be capable of selectively adsorbing CO in the

presence of high levels of hydrogen, steam, carbon

dioxide, etc.; it must be capable of oxidizing the

adsorbed CO to CO2 to regenerate the capacity in a

rapid and repeatable manner; and it should possess

an extended lifetime for long-term use in the

PEMFC application. One of the primary objectives

in the initial phase of this R&D effort is to identify

low-cost ACO materials that possess these

attributes.

Two parallel routes to the development of a

robust ACO sorption material that meets the

previously described criteria have been explored.

The first route focuses on the active component used

in ACO. Thus far, a wide range of metals and

preparation methods have been evaluated at the

laboratory scale. Specific chemical precursors and

preparation methods have been selected to

emphasize the effective metal utilization and to

minimize cost.

The second route focuses on the support

material upon which the active adsorption medium

is dispersed. Criteria used for support material

selection include high surface area, good pore size

distribution to ensure effective mass transfer, and

stability during the repeated swings in temperature

and humidity that accompany the alternate

adsorption and catalytic oxidation steps. A variety of

support materials and geometries have been

evaluated. The catalyst and support development

activities are ongoing.

Figure 2 illustrates an experimental

demonstration of the tolerance of a developmental

ACO metal-substrate combination to a rapid change

in reformate CO concentration. In the initial portion

of the experiment, a synthetic reformate mixture

bypasses the ACO device. A 30-second injection of

CO (representing a CO transient) is introduced into

the reformate stream, resulting in a 40% increase in

the CO concentration in the gas mixture, as shown

by the detector trace. To demonstrate the tolerance

of the ACO material to CO transients, the gas

mixture is directed into the ACO unit prior to a

second equivalent injection of CO. An immediate

depletion of CO to a near-zero level is observed

initially. During the second, identical 30-second

injection of CO, virtually no CO leakage is

Figure 2. Demonstration of tolerance to CO transient

variation in an ACO reactor.

observed. This experiment illustrates clearly the

ability of the ACO technique to tolerate CO spikes.

A similar material development effort was

performed for the ECO approach, with slightly

different development criteria. While the need for

high CO adsorption capability and selectivity

remains, the ECO material must also demonstrate

high catalytic activity toward CO electro-oxidation

during the regeneration phase. A wide range of ECO

materials have been evaluated on the basis of these

criteria. Several have demonstrated the necessary

selectivity and regenerability; optimization studies

of these materials are under way.

Preliminary Engineering Design and

Improvement

Several engineering design studies are under

way for both ACO and ECO. As an example, ACO

design activities are in progress to optimize CO

removal efficiency and minimize the system

pressure drop. Additional studies on alternative

operating modes will begin soon to further improve

efficiency and reduce system volume and cost. For

ECO, efforts are under way to optimize both

electrode and system performance. As a result of

these efforts, CO removal capacity has been

improved by a factor of four over that observed at

the beginning of the program.

Figure 3 offers an example of CO removal by

using a periodically regenerated ECO unit. During

the experiment, the CO concentration in a synthetic

reformate formulation was monitored by a broadband infrared spectrometer located at the exit of the

ECO device. As shown in Figure 3, over 90% of the
Fuel Cell Power Systems FY 2000 Progress Report

57

Figure 3. Demonstration of removal of CO by a

regenerated ECO unit.

CO in the reformate stream was removed during the

continuous period of ECO operation.

Conclusions

Two new technologies for the removal of CO

from processed hydrocarbon reformate for the

PEMFC application have been introduced. The

feasibility of both approaches, adsorption/catalytic

oxidation and adsorption/electrocatalytic oxidation,

was demonstrated through proof-of-concept

experiments. Significant progress has been made in

improving CO removal efficiency, capacity, and

selectivity for both technologies. Preliminary

engineering studies have demonstrated the benefit of

both approaches and have identified directions for

further improvement.

Publications/Presentations/Patents

• D-J Liu, J. Williams, M. Kaiser, D. Winstead,

J. Kudart, S.F. Simpson, and T.J. Rehg, “Two

New Approaches for CO Removal from

Reformate Fuel for the PEM Fuel Cell

Application,” Society of Automotive Engineers,

Paper No. 2000-01-0379, Detroit, Mich., 2000.

• D-J Liu, D. Winstead, M. Kaiser, and T.J. Rehg,

“Removing CO from Reformate for Fuel Cell

Application using a Regenerable CO

Adsorption/Catalytic Oxidation Bed Device,”

U.S. Patent Pending.

• T.J. Rehg, D-J Liu, M. Kaiser, and J. Williams,

“An Electro-Catalytic Oxidation (ECO) Device

to Remove CO from Reformate for Fuel Cell

Application,” U.S. Patent Pending.

H. CO Clean-Up Development

Michael Inbody (primary contact), Rod Borup, James Hedstrom, Byron Morton, JinKi Hong, and

José Tafoya

ESA-EPE, MS J576

Los Alamos National Laboratory, Los Alamos, NM 87545

(505) 665-7853, fax: (505) 665-9507, e-mail: inbody@lanl.gov

DOE Program Manager: JoAnn Milliken

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

Objectives

Research and develop carbon monoxide clean-up technology for integration into fuel processor systems to enable

them to meet the fuel purity requirements for a fuel cell stack by:

• Removing trace contaminants to purity levels required by the fuel cell stack.

• Maintaining system efficiency by minimizing hydrogen consumption.

• Operating effectively through automotive transients – changes in power level, start-up, and shutdown.

• Meeting overall fuel processor targets for energy efficiency, power density, specific power, and cost.
Fuel Cell Power Systems FY 2000 Progress Report

58

OAAT R&D Plan: Task 3; Barrier E

Approach

• Combine laboratory investigation with industrial collaboration to develop working processes and hardware for

fuel processor systems.

• Investigate and develop CO clean-up technology.

- Investigate catalysts and catalyst performance to improve baseline performance.

- Use carefully instrumented and controlled experiments at the component level to measure performance.

- Develop proof-of-concept hardware on a laboratory scale.

- Develop design tools and models for application to specific design problems.

• Work with fuel processor developers to integrate CO clean-up technology into fuel processor systems.

- Collaborate on specific designs for automotive hardware and system integration.

- Fabricate hardware and test performance of integrated CO clean-up technology.

Accomplishments

• Developed a laboratory PROX system for testing PROX concepts and catalysts, based on a multistage reactor

approach.

• Conducted catalyst evaluation in a single-stage PROX configuration.

- Measured temperature and gas composition profiles of catalyst volumes in the baseline PROX

configuration.

- Conducted initial series of tests on catalyzed ceramic foams.

• Conducted transient PROX experiments in the four-stage configuration; measured dynamic response to inlet

CO concentration variation.

• Measured kinetic data on precious metal catalysts in a microscale isothermal catalyst test reactor.

Future Directions

• Work on technology transfer through industrial collaborations; integrate PROX technology into developer fuel

processor designs.

• Continue testing of catalysts and of multistage PROX hardware.

- Measure reformate composition effects, hydrogen consumption, and CO conversion.

- Conduct transient tests, including power transients and start-up transients.

- Test catalysts and catalyst supports for compact automotive designs.

• Continue development of PROX design methodology to delineate successful understanding of PROX

mechanisms.

• Address further challenges to automotive implementation; develop technology to reduce start-up times and

enable cold starts.

Introduction

This report describes research conducted

during fiscal year (FY) 2000 on the development of

carbon monoxide clean-up technologies as a subset

of reformate clean-up technology for integration into

automotive fuel processor systems. Reformate cleanup typically is the last unit operation in the fuel

processor process stream in most fuel processor-fuel

cell system architectures. Its function is to remove

the trace contaminants from the fuel processor outlet

stream to meet the fuel purity requirements of the

fuel cell stack. The research objective then is to

develop reformate clean-up technology that not only

removes the trace contaminants, but does so with

minimal hydrogen consumption to maintain system

efficiency. Automotive applications require that the

technology enable the fuel processor to meet the fuel
Fuel Cell Power Systems FY 2000 Progress Report

59

purity requirements of the fuel cell stack through

automotive transients and lead to commercially

viable fuel processor systems that meet automotive

requirements for cost, volume, weight, and

durability.

The primary focus of reformate clean-up has

been removal of CO to levels less than 10 ppm

under steady-state conditions and less than 100 ppm

in transients. The program at Los Alamos National

Laboratory (LANL) has researched preferential

oxidation (PROX) as a method to remove CO to

these levels. Work in prior years (FY 1996-FY

1999) focused on developing laboratory and

demonstration PROX reactor hardware for gasoline

fuel processing systems.

Work this year (FY 2000) focused on expanding

fundamental knowledge of CO removal processes

and then codifying that knowledge for technology

transfer. Also, work was done to address automotive

requirements for the reformate clean-up system by

investigating catalysts and catalyst supports that

reduce system size and are rugged, and by

investigating transient control requirements to

reduce the number of sensors and actuators in the

systems.

Approach

Our approach combines laboratory

investigations to research and develop the

fundamentals of reformate clean-up technology with

industrial collaborations to apply that technology.

We first develop laboratory PROX reactor hardware

for carefully instrumented and controlled

experiments at the component level to measure

performance. These experiments allow us to

investigate catalysts and quantify catalyst

performance in working hardware under simulated

reformate conditions. We also conduct transient

experiments on multistage hardware to identify the

transient response and control requirements.

Measured profiles of temperature and gas

composition through the catalyst volume and the

measured temperature and pressure response of the

reactor components in transients provide the basis

for developing detailed models of PROX reactor

performance. The understanding developed in the

proof-of-concept hardware is applied to design

PROX hardware for integration into specific fuel

processor systems, in collaboration with fuel

processor developers.

Results

The reformate clean-up method is based on

preferential oxidation of CO in an adiabatic reactor.

A multistage reactor has been implemented to obtain

a low CO output while minimizing hydrogen

consumption. A schematic of the reactor (Figure 1)

shows a four-stage configuration for reducing 2%

CO at the inlet to less than 10 ppm CO at the outlet.

The reactor operates as a series of short-residencetime reactor stages, each having thermal

management, air injection and mixing, and catalyst

volume. The catalysts in each stage are selected to

work together to improve the transient performance

and minimize the control requirements. Temperature

and air injection are controlled so that CO is

removed primarily by oxidation, with some

additional removal by methanation and water-gasshift reactions. Temperature control is critical to

preventing the reverse water-gas-shift reaction and

runaway methanation reactions.

The laboratory reactor shown in Figure 2

implements this reactor schematic. The performance

of the reactor in removing CO from 2% CO to less

than 10 ppm CO has been verified in operation on

natural gas reformate (reported in FY 1999) and on

simulated gasoline reformate (during testing

conducted in the last quarter of FY 1999 through

FY 2000). The modular laboratory design is flexible

for testing catalysts, reactor configurations, and

control schemes. The design of the reactor and use

of lightweight internal components enhance

transient performance. The design has been verified

to give uniform air distribution and mixing into the

catalyst volume and to provide the desired control of

the inlet temperature to the stages.

air supply/metering

fuel stream out 

(to fuel cell)

(< 10 ppm CO)

thermal 

management

fuel stream in

(up to 2% CO)





Particulate filter

Catalysts selected to work 

together to improve transient 

performance, minimize control 

requirements







































































Gas distribution/mixing 

elements

air supply/metering

fuel stream out 

(to fuel cell)

(< 10 ppm CO)

thermal 

management

fuel stream in

(up to 2% CO)





Particulate filter

Catalysts selected to work 

together to improve transient 

performance, minimize control 

requirements







































































Gas distribution/mixing 

elements

Figure 1. Schematic of the four-stage PROX reactor.
Fuel Cell Power Systems FY 2000 Progress Report

60

Figure 2. Four-stage configuration of the laboratory

PROX reactor.

A single-stage PROX reactor setup was used for

measuring temperature and gas composition profiles

of catalyst volumes and for testing catalysts on

automotive supports. The measured profiles provide

data for detailed modeling of the reactor stages. The

initial focus of our catalyst testing was on

characterizing the performance of the PROX inlet

stages because they use a new catalyst that we had

not characterized before. We also think that a greater

understanding of these stages will lead to a further

reduction in the parasitic hydrogen loss.

Figures 3 and 4 show some examples of

measured profiles of CO concentration and CO

conversion, respectively, as a function of depth

within the catalyst volume. Four inlet CO

concentrations are shown, at a constant overall flow

0

5000

10000

15000

20000

25000

0 2 4 6 8 10 12

20000 ppm

16000 ppm

12000 ppm

8000 ppm

CO Concentration (ppm)

Distance (cm)

30 KW Thermal

10 slpm Air

Inlet CO Concentration

Figure 3. CO concentration profile of the PROX reactor

inlet stage.

0

0.1

0.2

0.3

0.4

0.5

0.6

0 2 4 6 8 10 12

20000 ppm

16000 ppm

12000 ppm

8000 ppm

CO Conversion

Distance (cm)

30 kW Thermal

10 slpm Air

Inlet CO Concentration

Figure 4. CO conversion as a function of depth in the

PROX reactor inlet stage.

rate and air injection rate. Flow rates and air

injection rates were varied to map the catalyst

volume over its expected range of operation. These

data were compiled to develop curves such as the

one shown in Figure 5, which shows the CO

conversion as a function of oxygen stoichiometry at

a single flow rate for four different inlet CO

concentrations. The solid line on the graph shows

the ideal curve for no parasitic hydrogen

consumption. Points lying further to the right from
Fuel Cell Power Systems FY 2000 Progress Report

61

0

0.1

0.2

0.3

0.4

0.5

0.6

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

20000 ppm

16000 ppm

12000 ppm

8000 ppm

CO Conversion

Oxygen Stoichiometry

30 KW Thermal

Inlet CO Concentration

187

196 Inlet Temp, o

C

177 177

187

168

169

162

168

Figure 5. CO conversion as a function of oxygen

stoichiometry for the PROX inlet stage.

the curve have increased hydrogen consumption.

Thus, the curves show the relationship between

increasing CO conversion and increasing hydrogen

consumption, and they indicate our rationale for

using staging to minimize hydrogen consumption.

The data also provide the input to our models for

optimizing the PROX staging and operating

conditions.

Figures 6 and 7 show an example of the use of

the model to optimize the PROX for an operating

condition. The Stage 1 oxygen stoichiometry is

varied for a constant inlet CO concentration and

total flow rate. Figure 6 shows the CO concentration

at the stage outlets as a function of the Stage 1

oxygen stoichiometry. The Stage 2 and 3 oxygen

stoichiometries are held constant, and the fourth

stage is set to achieve 10 ppm CO at its outlet in this

model. Figure 7 shows the hydrogen produced (as a

percent of the hydrogen inlet flow) as a function of

stoichiometry. The H2 total curve shows a peak at an

oxygen stoichiometry of about 0.25, suggesting an

optimal operating point for Stage 1.

Other catalyst testing this year included testing

of catalyzed ceramic foams in the single-stage

PROX reactor setup. We are investigating catalyzed

ceramic foams as a possible rugged catalyst support

for automotive use that may also reduce the size by

increasing turbulent mixing and combining gas

mixing and distribution elements with the catalyst

supports. Initial tests showed no improvement over

monoliths; we are iterating to optimize pore size and

0

5000

10000

15000

20000

25000

0 0.1 0.2 0.3 0.4 0.5 0.6

Inlet

Stage 1 Outlet

Stage 2 Outlet

Stage 3 Outlet

Stage 4 Outlet

CO Concentration (ppm)

Stage 1 Oxygen Stoichiometry

Figure 6. Model predictions of the outlet CO

concentrations from each stage as a function

of the Stage 1 oxygen stoichiometry.

-3

-2

-1

0

1

2

3

4

0 0.1 0.2 0.3 0.4 0.5 0.6

H2 Total

H2 Stages 1-2

H

H2 Stages 3-4

2 Produced (%)

Stage 1 Oxygen Stoichiometry

Inlet CO Concentration = 20,000 ppm

Figure 7. Net hydrogen produced as a percent of total

hydrogen flow as a function of the Stage 1

oxygen stoichiometry.

catalyst. We are also investigating higher-density

cpsi (>600 cpsi) monoliths and a catalyzed particle

filter for use as PROX catalyst substrates.

The four-stage PROX reactor setup is being

used for investigating the transient response of the

reactor components. Initial tests have been

conducted to identify the PROX response to a sinewave-modulated CO input at an overall steady flow.
Fuel Cell Power Systems FY 2000 Progress Report

62

These tests measure the sensitivity of the PROX to

changes in inlet CO concentration. These data are

critical to the development of control strategies and

to determining the requirements for a CO sensor.

Both power transient testing and start-up transient

testing will be conducted in the fourth quarter of

FY 2000. These tests will be used to quantify the

limiting factors on the transient response of the

PROX to changes in the total flow rate,

corresponding to changes in power demand, and on

the start-up time.

Industrial collaborations have been initiated to

apply and develop the CO clean-up technology for

specific fuel processor designs. An industrial

collaboration has been started with McDermott

Technology to integrate a PROX system with their

multifuel fuel processor. A second collaboration has

started with Argonne National Laboratory to

integrate a PROX with their integrated fuel

processor.

Conclusions

A working laboratory reactor has been

developed to investigate the fundamentals of CO

clean-up technology. The multistage reactor has

demonstrated CO removal from a 2% CO inlet to

less than 10 ppm CO at the outlet. Detailed

measurements of the catalyst and reactor

performance of the inlet stages were used to

determine optimal operating points. Transient

experiments on the multistage configuration are

being used to measure the limits of the dynamic

response and the requirements for controls.

Industrial collaborations were begun to apply the

technology to specific fuel processors and to transfer

the technology. Remaining work this fiscal year

includes continuation of catalyst testing to lead to

more compact designs, testing of transient response

to changes in power level and start-up, and work on

industrial collaborations.

I. Evaluation of Partial Oxidation Fuel Cell Reformer Emissions

Stefan Unnasch (primary contact)

Arthur D. Little, Inc.

Acurex Environmental

10061 Bubb Road

Cupertino, CA 95014

(408) 517-1550, fax: (408) 517-1553, e-mail: unnasch.stefan@adlittle.com

DOE Program Manager: Nancy Garland

(202) 586-5673, fax: (202) 586-9811, e-mail: nancy.garland@ee.doe.gov

ANL Technical Advisor: Walter Podolski

(630) 252-7558, fax: (630) 972-4430, e-mail: podolski@cmt.anl.gov

Contractor: Arthur D. Little, Inc., Cupertino, California

Prime Contract No. DE-FC02-99EE50585, September 1999-June 2001

Subcontractors: Nuvera Corporation, Hydrogen Burner Technology

Objectives

• Measure the emissions from partial oxidation/autothermal fuel processors for polymer electrolyte membrane

fuel cell (PEMFC) systems under both cold-start and normal operating conditions.

• Assess the feasibility of meeting emissions standards for automobiles and light-duty trucks through the use of a

fuel cell vehicle with a multifuel reformer.
Fuel Cell Power Systems FY 2000 Progress Report

63

OAAT R&D Plan: Task 5; Barriers F and G

Approach

• Define a representative test cycle consisting of both cold-start and normal operating conditions.

• Use the established test cycle to quantify emissions from a partial oxidation (POX) reformer before and after

anode-gas-burner treatment.

• Perform the test procedure using four different feed fuels in the reformer (gasoline, methanol, ethanol, and

natural gas), as well as different catalyst formulations for the anode gas burner.

• Perform the test procedure on both Nuvera (formerly Epyx) and Hydrogen Burner Technology (HBT) fuel

processors to quantify the emissions impact of fuel reformer design.

• Use reasonable approximations and estimates to convert emissions data from a gram-per-unit fuel basis to a

predicted gram-per-mile basis.

Accomplishments

• Assessed sensitivity of gas chromatograph.

• Identified sampling procedures.

Future Directions

Develop control strategies to minimize emissions.

Introduction

The operation of fuel reformers is generally

divided into two operating modes: start-up and

normal partial oxidation. During start-up, the fuel

processor burns fuel at near-stoichiometric

conditions until critical system temperatures and

pressures stabilize to target values. Once the target

conditions are reached, the reformer operates in the

normal mode, in which the fuel processor burns fuel

at very rich conditions. Since the two modes

encompass considerably different operating

conditions, it follows that the emissions associated

with each of these modes also differ considerably.

The combustor is typically cold under start-up

conditions, so the emissions produced during this

brief period (target times are under 30 seconds) can

be substantially higher than those produced during

the remaining, much longer portion of the driving

cycle. The pollutant emissions produced in this

operating mode include NOx, CO, formaldehyde,

and organic compounds. These organic compounds,

which include hydrocarbons, alcohols, and

aldehydes, are referred to in California and are

regulated as nonmethane organic gases (NMOG).

Under normal operating conditions, in which the

combustor is sufficiently warm and operated under

fuel-rich conditions, virtually no NOx is formed

(although the formation of ammonia is possible).

Most hydrocarbons are converted to carbon dioxide

(or methane, if the reaction is incomplete); however,

trace levels of hydrocarbons can pass through the

fuel processor and fuel cell. The shift reactors and

the preferential oxidation (PROX) reactor reduce

CO in the product gas, resulting in a feed

concentration to the fuel cell that can be less than

20 ppm. The fuel cell may also convert CO to CO2,

thereby further reducing exhaust CO levels. Thus, of

the criteria pollutants (NOx, CO, and hydrocarbons

[NMOG]), NOx and CO levels are generally well

below the most aggressive standards. NMOG

concentrations, however, can exceed emission goals

unless these compounds are efficiently eliminated in

the catalytic burner.

Figure 1 shows estimated NMOG emissions

from partial oxidation (POX) systems fueled by

compressed natural gas (CNG) and gasoline [1]. The

figure clearly indicates the trend described above

with respect to the relative contribution of start-up

emissions and the emissions levels over the total

driving cycle. Furthermore, the figure also indicates

the importance of catalyst performance in reducing

NMOG emissions. For example, if the catalyst
Fuel Cell Power Systems FY 2000 Progress Report

64

  









  











0

0.005

0.01

0.015

0.02

CNG

POX

Low

CNG

POX

High

Gasoline

POX

Low

Gasoline

POX

High

Emissions (g/mi) .

 Running Exhaust

 Start-up

CA SULEV

Figure 1. Estimated NMOG exhaust emissions for

POX/PEMFC systems with varying anode gas

combustor efficiencies.

efficiency is reduced from 85% (low emissions) to

20% (high emissions), a gasoline-fueled POX

reformer/PEMFC can no longer meet the California

super ultra-low emissions vehicle (SULEV) standard

for NMOG emissions.

Approach

In this study, POX fuel reformers will be

operated under conditions simulating both cold-start

and normal operation. Emissions will be measured

before and after treatment by an anode gas burner in

order to quantify the effectiveness of the burner

catalyst in controlling start-up emissions. The

emissions sampling system will comprise

continuous emissions monitors (CEMs) for O2, CO2,

CO, NOx, and total hydrocarbons (THC). Also,

integrated gas samples will be collected in Tedlar

bags for hydrocarbon speciation analysis via gas

chromatography (GC). This analysis will yield the

concentrations of the hydrocarbon species required

for the California NMOG calculation. In addition,

the particulate concentration in the anode burner

exhaust will be measured through either isokinetic

sampling or the placement of a filter in the exhaust

stream.

Concentrations of the aforementioned species

will be obtained by using an emissions sampling

system similar to the one shown schematically in

Figure 2. Because emissions from a POX system

vary significantly between start-up and normal

operation (see Figure 1), a wide range of analyzer

capabilities will be required. Specifically, NOx, CO,

and hydrocarbon levels will each be between 10 and

1000 ppm during start-up and will fall below

10 ppm during normal operation.

This study will explore the sensitivity of

reformer emissions to several variations in the

Air







Exhaust

Burner

FFFP Product Gas

Start-Up Exhaust

Simulated

 Cathode Gas

N2

 NMOG Cat 2

∆P T

CH3OH

HCOH

HC by GC

CEM

NOx CO

CO2

NMHC

On-Line GC

N2

THC

CO

CO2

T

Fuel Flexible

 Fuel Processor

Fuel Tank

















xAir

 Mass Flow

Figure 2. Emission testing setup.

system. In particular, the impact of fuel reformer

design will be assessed by testing systems from two

different manufacturers: Nuvera and HBT. The

sensitivity of reformer emissions will also be

quantified by repeating identical test procedures for

four different fuels: gasoline, methanol, ethanol, and

natural gas. Similarly, the sensitivity of emissions to

anode burner catalyst formulations will also be

quantified. An example test matrix based on the

aforementioned variations (assuming the use of two

catalyst formulations) is shown in Table 1.

To make quantitative conclusions regarding the

impact of fuel composition on reformer emissions,

the measured volumetric exhaust concentrations of

each pollutant will be converted to a gram-per-unit

fuel basis. To make further conclusions regarding

the feasibility of meeting California SULEV

emissions standards, appropriate assumptions and

estimates with respect to the powertrain of a fuel cell

vehicle will be used to convert the measured

emissions levels to a predicted gram-per-mile basis.

These results will be presented in a final report that

evaluates the reformer/anode-gas-burner

configurations.
Fuel Cell Power Systems FY 2000 Progress Report

65

Table 1. Example test matrix for testing multifuel

reformer emissions.

Test ID Nuvera HBT

Test # 1 Gasoline Gasoline

Test # 2 Gasoline/Control

Strategy B

Gasoline/Control

Strategy B

Test # 3 Natural Gas Natural Gas

Test # 4 Natural Gas/Control

Strategy B

Natural Gas/Control

Strategy B

Test # 5 Methanol Methanol

Test # 6 Methanol/Control

Strategy B

Methanol/Control

Strategy B

Test # 7 Ethanol Ethanol

Test # 8 Ethanol/Control

Strategy B

Ethanol/Control

Strategy B

Conclusions

The purpose of the proposed project is to assess

the emissions from partial oxidation fuel cell

reformer systems and to evaluate the performance of

catalytic burners in controlling startup emissions.

This objective will be achieved by testing the

emissions from the HBT and Nuvera fuel-flexible

fuel processors.

Reference

1. Unnasch, S., “Evaluation of Fuel Cell Reformer

Emissions,” Final Report for Contract 95-313,

prepared for California Air Resources Board,

Sacramento, Calif., Aug. 1999.

J. Catalytic Autothermal Reforming

Michael Krumpelt (primary contact), Rolf Wilkenhoener, David J. Carter, Joong-Myeon Bae,

John P. Kopasz, Theodore Krause, and Shabbir Ahmed

Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439

(630) 252-4553; fax: (630) 972-4553, e-mail: krumpelt@cmt.anl.gov

DOE Program Manager: JoAnn Milliken

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

Objectives

• Improve catalytic activity and reduce cost of autothermal reforming (ATR) catalyst.

• Determine long-term (>1000-h) stability of the catalyst.

• Investigate the effect of catalyst structure (e.g. pellet, monolith, microchannel) on catalyst activity.

• Develop a better understanding of the reaction mechanism.

OAAT R&D Plan: Task 3; Barrier E

Approach

• Measure hydrocarbon conversion and H2 selectivity vs. temperature and space velocity for new catalyst

formulations.

• Conduct life tests to evaluate catalyst stability during >1000-h period.

• Fabricate different catalyst structures, and investigate the relationship between structure and activity.

• Subcontract catalyst characterization studies to academia.
Fuel Cell Power Systems FY 2000 Progress Report

66

Accomplishments

• Several non-noble metal formulations with excellent activity were identified.

• The importance of oxide ion conductivity in the catalyst substrate was clearly established.

• Catalyst stability during 1,000 h was demonstrated.

• With the catalyst in a microchannel configuration, an H2 selectivity of >50% (dry, N2-free basis) was observed

at a space velocity of 125,000 h-1.

• Strong metal-support interactions were observed by using x-ray photoelectron spectroscopy (XPS) and

extended x-ray absorption fine structure (EXAFS) methods.

• Patent for catalyst formulation was licensed to United Catalysts (now known by SudChemie, Inc.)

Future Directions

• Catalyst cost vs. activity issues will be addressed.

• Work will continue on determining optimal metal(s) and support composition that maximizes catalytic activity,

provides long-term stability, and provides tolerance to catalyst poisons.

• Surface area will be increased.

• Surface stability and mechanical properties need more attention.

• Relationship between structure (supported vs. free-standing configurations) and catalytic activity will be

evaluated.

• Understanding of the chemical and physical properties of the catalyst and how these properties influence

catalytic activity will be increased.

Introduction

In prior years, Argonne National Laboratory has

articulated the merits of autothermal reforming for

automotive fuel cell systems in terms of reactor

volume and weight, as well as for fast transient

response and start-up. We have reported good

success with a catalyst derived from solid oxide fuel

cell technology, where the metal is a transition metal

element and the substrate is an oxide ion conductor,

such as zirconia, ceria, or lanthanum gallate. We

have also shown that a good operating temperature

is 700o

C, which requires catalytic enhancement of

the reaction rates.

Approach

During the past year, we have synthesized new

catalyst formulations in which either the metal or the

substrate composition was varied. We have

evaluated the catalytic activity of these new catalyst

formulations by measuring the hydrocarbon

conversion and H2 selectivity as a function of

temperature and space velocity in a microreactor

system. We have conducted life tests (>1000 h) to

evaluate the stability of these catalysts toward

deactivation. We have fabricated new structured

forms of the catalyst, such as a monolith or a spiral

microchannel configuration, to improve catalyst

durability and to minimize diffusional resistances.

Using characterization techniques, such as

inductively coupled plasma (ICP), energy-dispersive

x-ray spectroscopy (EDX), XPS/Auger, EXAFS,

x-ray absorption near-edge spectroscopy (XANES),

and transmission electron microscopy (TEM), a

better understanding of the chemical and physical

properties of the ATR catalyst and how these

properties influence the catalytic activity has begun

to develop.

Results

A major focus of the work during this period

was to identify potential non-noble transition metals

to replace precious metals, such as Pt, in order to

reduce the cost of the catalyst. The catalytic activity

of various metals supported on a doped ceria

substrate was evaluated by measuring the

hydrocarbon (2,2,4-trimethylpentane) conversion

and H2 selectivity as a function of temperature and

space velocity. The percent conversion of
Fuel Cell Power Systems FY 2000 Progress Report

67

hydrocarbon in the feed and H2 selectivity as a

function of temperature for the various metals tested

are shown in Figures 1 and 2, respectively. These

data were obtained by using an O2/C ratio of 0.46

and a H2O/C ratio of 1.14 at a space velocity

~3000 h-1 in a temperature-controlled microreactor.

Although all of these catalysts were prepared in an

identical manner, substantial differences exist in the

BET surface areas that may account for the

differences observed in H2 selectivity. In general, the

BET surface area of the non-noble transition metal

catalysts is 50-80% lower than that of Pt catalyst.

Some of the non-noble metals (e.g., nickel,

copper, iron, cobalt) are as active as the more

expensive platinum or palladium at temperatures as

low as 700o

C. Considering that the partial oxidation

80

85

90

95

100

450 500 550 600 650 700 750 800 850

Temperature at Catalyst Bottom, °C

iC8 Conversion, %

Ru Pt Pd

Ni

Fe

Cu

Co

Ag

Figure 1. Hydrocarbon conversion for autothermal

reforming of iso-octane (2,2,4-

trimethylpentane) as a function of temperature

for various transition metals supported on a

doped ceria substrate.

0

20

40

60

80

100

450 500 550 600 650 700 750 800 850

Temperature at Catalyst Bottom, °C

H2 Selectivity (H2 / H2 max), %

Ru

Pt

Pd

Ni

Fe

Cu

Co

Ag

Figure 2. H2 selectivity for autothermal reforming of

iso-octane (2,2,4-trimethylpentane) as a

function of temperature for various transition

metals supported on a doped ceria substrate.

of methane using a Pt/alumina catalyst requires a

reaction temperature of 1000o

C to achieve high

conversion [1], it appears that an oxide-ionconducting substrate may play a significant role in

the reaction sequence. To better understand the role

of this substrate, three different oxide-ionconducting substrates (ceria, zirconia, and

lanthanum gallate) were tested. As shown in

Figure 3, the H2 yield ranged from 34% to 60% (dry,

N2-free basis) for these different oxide-ionconducting substrates. In comparison, the H2 yield

was less than 30% using a Pt/alumina catalyst under

similar reaction conditions. Work is continuing to

find the optimal metal/oxide formulation in terms of

activity, stability, and cost.

Long-term (>1000-h) life cycle studies were

conducted to evaluate the stability of the ATR

catalyst toward deactivation. As shown in Figure 4,

the H2 concentration in the product gas was

relatively constant at ~35% (dry basis) over a 47-day

life test. For this test, a benchmark fuel was used,

and the catalyst was Pt supported on a doped ceria

substrate. In view of the fact that this catalyst was

far from being optimized, particularly with respect

to maximizing the surface area, it proved remarkably

stable. (See the report by Kopasz et al. for the

stability of the catalyst in the presence of sulfur [2].)

From an engineering perspective, a structured

form of the ATR catalyst, such as a monolith or a

microchannel configuration, is preferred over a

pellet form to minimize such potential problems as

back-pressure buildup. Furthermore, if the reaction

is severely mass-transfer-limited, a structured form

of the ATR catalyst that minimizes diffusional

Pt on various substrates at 800oC

0.8 - 0.9 wt% Pt, GHSV 2602/h, O2C = 0.5, H2O/C = 1.14

0

10

20

30

40

50

60

70

Product Composition, % (dry, N2-free)

H2 Total HC's

8-YSZ ZrO2

CeO2 Ce.8Sm.15Gd.05O2

La.8Ga.8Cr.2O3

La.8Sr.2Ga.8Cr.2O3

La.8Sr.2Ga.8Mg.2O3

Figure 3. H2 selectivity for autothermal reforming of

iso-octane (2,2,4-trimethylpentane) for Pt

supported on various oxide ion substrates.
Fuel Cell Power Systems FY 2000 Progress Report

68

0

5

10

15

20

25

30

35

40

0 5 10 15 20 25 30 35 40 45 50

Time (days)

Gas Composition (% dry)

CO

H2

CO+COx

CO2

Figure 4. H2 selectivity for autothermal reforming of

iso-octane (2,2,4-trimethylpentane) for Pt

supported on a doped ceria substrate over a

47-day test.

resistances will have a higher activity per unit

volume than a pellet form. The higher activity of the

structured form of the catalyst will allow for higher

processing rates (space velocities), which means that

a reactor designed for use with a structured form of

the catalyst will be smaller and require less catalyst

than a reactor designed for use with pellets. For

these reasons, we have developed a microchannel

form of the catalyst, as shown in Figure 5. With the

ATR catalyst in a spiral microchannel configuration,

a reformate having a H2 concentration of >50% (dry,

N2-free basis) is produced at space velocities as high

as 125,000 h-1 (Figure 6).

Figure 5. Spiral microchannel configuration of ATR

catalyst.

0

10

20

30

40

50

60

70

0 20000 40000 60000 80000 100000 120000 140000

GHSV (h-1)

Product vol% (N 2 ,H O free) 2

% H2 after WGS

% H2

 % HCs

Maximum H2 possible: 68.7%

Figure 6. H2 selectivity for autothermal reforming of

iso-octane (2,2,4-trimethylpentane) as a

function of space velocity for a spiral

microchannel configuration.

To optimize the catalytic activity, an

understanding of how the chemical and structural

properties (e.g. metal particle size and size

distribution, oxidation state of the metal, surface

composition, and interaction between the metal and

the oxide) of the catalyst influence the reaction rate

is required. Catalyst characterization studies, using

such techniques as ICP, EDX, XPS/Auger, EXAFS,

and XANES to measure and investigate these

properties, have been initiated. Argonne National

Laboratory (ANL) is working with the University of

Alabama to investigate the nature of the interaction

between the metal and the oxide by using ICP, EDX,

and XPS/Auger, and the metal particle size and size

distribution by using TEM. Results from this work

will be disclosed in detail at a later date. In an

EXAFS study conducted at ANL by Christopher

Marshall, small Pt clusters (Pt4) are present on Pt

supported on an undoped ceria substrate, whereas

there is no evidence of Pt clusters (no Pt-Pt bonding)

on Pt supported on a doped (Sm or Gd) ceria

substrate (see Table 1). This suggests that the metalTable 1. Particle size determination and Pt nearest

neighbor for Pt supported on doped and

undoped ceria, as determined by EXAFS.

Composition

Particle

sizes

Reduction

Stability Comments

TARK-44 Pt/CeO2 >10Å High Pt4

No Pt-O

TARK-13 Pt/CSAO

(prep 1)

<5 Å High No Pt-Pt

Pt-O-(Ce)

TARK-19 Pt/CSAO

(prep 1)

<5 Å Med. No Pt-Pt

Pt-O-(Ce)

TARK-34 Pt/CGO <5 Å Low No Pt-Pt

Pt-O-(Ce)
Fuel Cell Power Systems FY 2000 Progress Report

69

support interaction is stronger between Pt on doped

ceria than Pt on undoped ceria [3]. Experimental

work is continuing to explore how the metal-support

interaction influences the reaction mechanism as

well as the reaction rate.

Conclusions

We have demonstrated that high hydrocarbon

conversions and H2 selectivity, comparable with

those observed with Pt, can be achieved with certain

less costly, non-noble metals supported on oxide ion

conductors. Long-term reactor tests demonstrated

that the Pt catalyst is stable, with little evidence for

deactivation. The Pt catalyst does not appear to be

poisoned by sulfur at concentrations in the fuel

comparable to fiscal year (FY) 2004 sulfur targets

[2].

We have developed structured forms of the

catalyst, including a monolith and a spiral

microchannel configuration, and demonstrated that a

reformate containing >50% H2 (dry, N2-free basis)

can be produced at a space velocity of 125,000 h-1

using the microchannel configuration. We have

observed that the addition of a dopant, such as Sm or

Gd, to ceria results in a strong metal-support

interaction that minimizes the formation of Pt

clusters and strongly influences the reaction rate.

Future work will focus on developing a

nonprecious-metal catalyst to reduce the cost. New

formulations of these nonprecious-metal catalysts

and oxide ion conductors will be investigated to

maximize catalytic activity, provide long-term

stability, and minimize the effects of sulfur

poisoning. Characterization and reaction mechanism

studies will continue to determine which chemical

and physical properties of the catalyst should be

optimized. Work will continue on optimizing the

catalytic activity and improving the mechanical

properties of new structured forms of the catalyst.

References

1. P.M. Torniainen, X. Chu, and L.D. Schmidt,

J. Catal. 146:1-10 (1994).

2. J.P. Kopasz, D. Applegate, L. Ruscic,

S. Ahmed, and M. Krumpelt, “Effects of

Fuels/Contaminants on Reforming Catalyst

Performance and Durability,” presented at the

Annual National Laboratory R&D Meeting of

the DOE Fuel Cells for Transportation Program,

Richland, Wash., June 7-8, 2000 [to be

published in Advanced Petroleum-Based and

Alternative Fuels – 2000, Annual Progress

Report, Energy Conversion Team,

U.S. Department of Energy, Office of Advanced

Automotive Technologies, Washington, D.C.,

2000].

3. S. Bernal, J.J. Calvino, M.A. Cauqui,

J.M. Gatica, C. Larses, J.A. Perez Omil, and

J.M. Pintado, Catal. Today 50:175-206 (1999).

Publications

1. S. Ahmed, B. Bergin, T. Krause, J.D. Carter,

J-M. Bae, L. Ruscic, D. Applegate, J. Kopasz,

D. Myers, J. Krebs, C. Pereira, S.H.D. Lee, and

M. Krumpelt, “Fuel Processor Development at

Argonne National Laboratory,” presented at the

Army Research Office Workshop, Detroit,

Mich., June 19-21, 2000.

2. M. Krumpelt, S. Ahmed, R. Kumar, S. Chalk,

and J. Milliken, “Partial oxidation fuel

reforming for automotive power systems,” to be

published in Proceedings of the 3rd International

Fuel Cell Conference, Nagoya, Japan,

Nov. 30-Dec. 3, 1999.

3. S. Ahmed, J. Kopasz, B.J. Russell, and

H.L. Tomlinson (Syntroleum Corporation),

“Cobalt-based Fischer-Tropsch Paraffin Fuels

for Fuel Cell Power,” poster paper presented at

the Sixth Grove Fuel Cell Symposium, London,

U.K., Sept. 13-16, 1999.

4. S. Ahmed, S.H.D. Lee, R. Kumar, J.D. Carter,

R. Wilkenhoener, and M. Krumpelt, “The

Argonne Catalytic Fuel Processor for

Automotive and Small Fuel Cell Power

Systems,” poster paper presented at the Sixth

Grove Fuel Cell Symposium, London, U.K.,

Sept. 13-16, 1999.

5. J. Kopasz, R. Wilkenhoener, S. Ahmed,

J.D. Carter, and M. Krumpelt, “Fuel flexible

partial oxidation reforming of hydrocarbons for

automotive applications,” preprints of the

Symposium on Hydrogen Production, Storage,

and Utilization, 218th ACS National Meeting,

44(4):899-904, New Orleans, La., Aug. 22-26,

1999.
Fuel Cell Power Systems FY 2000 Progress Report

70

Patents Issued

1. M. Krumpelt, S. Ahmed, R. Kumar, and R.

Doshi, “Method for making hydrogen-rich gas

from hydrocarbon fuel,” Patent No. 5,929,286,

issued on July 27, 1999.

2. M. Krumpelt, S. Ahmed, R. Kumar, and R.

Doshi, “Partial Oxidation Catalyst,” patent

application pending.

Awards/Recognitions

1. Best Poster Award at the Grove Symposium,

London, U.K., Sept. 1999.

2. Annual National Laboratory R&D Award from

DOE/OTT/OAAT, Richland, Wash., June 2000.

K. Alternative Water-Gas Shift Catalyst Development

Deborah J. Myers, John F. Krebs, Theodore R. Krause, and Michael Krumpelt

Argonne National Laboratory, Argonne, IL 60439-4837

(630) 252-4261, fax: (630) 252-4176, e-mail: myers@cmt.anl.gov

DOE Program Manager: JoAnn Milliken

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

Objectives

• Develop alternative water-gas shift (WGS) catalysts to:

- Eliminate the need to sequester catalyst during system shutdown.

- Eliminate the need to activate catalyst in situ.

- Increase tolerance to temperature excursions.

- Reduce size and weight of the shift reactor(s).

- Extend lifetime of the catalyst.

OAAT R&D Plan: Task 3; Barriers E and G

Approach

• Develop metal-support combinations to promote bifunctional mechanism of catalyst action:

- One component to adsorb CO (e.g., metal with intermediate CO adsorption strength).

- Second component to adsorb and dissociate H2O (e.g., mixed-valence oxides with redox properties under

reformate conditions).

• Develop bimetallic or polymetallic oxide mixtures to perform the regenerative WGS mechanism:

- Each metal oxide catalyzes one-half of the WGS reaction.

- Metals need to be in intimate contact for efficient electron transfer.

Accomplishments

• Demonstrated <1% CO at 230-300°C from diesel and 1.1% CO from simulated reformate (Nov. 1999

milestone).

• ANL Pt/mixed oxide shift catalyst reduces WGS catalyst volume to 68% of Fe/Cr - Cu/ZnO combination and

does not lose activity with exposure to air (not pyrophoric).
Fuel Cell Power Systems FY 2000 Progress Report

71

• Platinum loading reduced by a factor of three while maintaining catalyst’s WGS activity.

• A nonprecious-metal/mixed oxide catalyst was identified that reduces cost of catalyst to <1% that of Pt/mixed

oxide.

• Binary oxides show promise as inexpensive, air- and thermally-stable WGS catalysts.

Future Directions

• Increase low-temperature activity of nonprecious-metal catalysts.

• Explore other metal/oxide and oxide/oxide combinations.

• Determine durability and stability of metal/mixed oxide catalysts under reformate conditions, including

tolerance to sulfur.

• Set up catalyst fabrication equipment to supply industry with evaluation-scale quantities.

Introduction

The water-gas shift (WGS) reaction,

CO + H2O → CO2 + H2

is used to convert the bulk of CO in raw reformate to

CO2 and additional H2. In the chemical process

industry (e.g., in the manufacture of ammonia), the

shift reaction is conducted at two distinct

temperatures. The high-temperature shift (HTS) is

carried out at 350–450°C, using an Fe-Cr catalyst.

The low-temperature shift (LTS) is carried out at

160–250°C with the aid of a Cu-Zn catalyst.

The commercial HTS and LTS catalysts require

activation by careful pre-reduction in situ and, once

activated, lose their activity very rapidly if they are

exposed to air. Moreover, the HTS catalyst is

inactive at temperatures below 300°C, while the

LTS catalyst degrades if heated to temperatures

above 250°C. For the automotive application, with

its highly intermittent duty cycle, it is important to

develop alternative WGS catalysts that (1) eliminate

the need to sequester the catalyst during system

shutdown; (2) eliminate the need to activate the

catalyst in situ; (3) increase tolerance to temperature

excursions; and (4) reduce the size and weight of the

shift reactors.

Approach

No single metal, with the exception of copper,

has high activity for both the water dissociation and

carbon monoxide oxidation steps of the WGS

reaction. Therefore, we are investigating

bifunctional catalysts, where one component of the

catalyst adsorbs or oxidizes CO and the other

component dissociates the water. Our present

research is focused on metal-support and

bimetallic/polymetallic oxide combinations to

promote this bifunctional mechanism.

For the metal-support bifunctional catalysts, the

metallic component is chosen to adsorb CO at

intermediate adsorption strengths (Pt, Ru, Pd, PtRu,

PtCu, Co, Ag, Fe, Cu, Mo). The support, chosen to

adsorb and dissociate water, is typically a mixedvalence oxide with redox properties (such as

lanthanide oxides, manganese oxide, vanadium

oxide) under the highly reducing conditions of the

reformate.

For the bimetallic/polymetallic oxide catalysts,

one metal oxide is raised to a higher oxidation state

while reducing water to form hydrogen; another

metal oxide donates electrons to this first oxide and

oxidizes carbon monoxide to complete the cycle. A

structural requirement for this mechanism is that the

two metal centers be in intimate contact for efficient

electron transfer. The metal oxides are chosen on the

basis of the two halves of the reaction being

thermodynamically favored (in particular, materials

with solid-state structures). An example of this type

of catalyst is vanadium-cobalt oxide.

Results

Early in this project, a platinum/mixed oxide

catalyst was identified as a potential WGS catalyst

with several desirable properties. As opposed to

copper/zinc oxide, this catalyst does not have to be

reduced in situ, it does not lose activity upon

exposure to air at 21°C to 550°C, and it is active

over a 180-400°C temperature range. Over the first

two years of the project, the WGS activity of the

platinum/mixed oxide catalyst was quadrupled,

while the platinum loading was reduced from 1 wt%

to 0.42 wt%. The catalyst was also supported on an
Fuel Cell Power Systems FY 2000 Progress Report

72

alumina extrudate. This past year, we developed a

new synthesis method for the alumina-supported

catalyst to further reduce the platinum loading. As

shown in Figure 1, the new method allowed a

reduction in platinum loading from 0.42 wt% to

0.14 wt%, with no loss of WGS activity.

Argonne’s platinum/mixed oxide/alumina

catalyst can reduce shift reactor volumes

significantly. Figure 2 shows a comparison of the

calculated shift reactor volumes for the commercial

HTS and LTS catalysts and for the Argonne catalyst

used at 300°C and 400°C. The calculated reactor

volumes were based on the measured intrinsic

reaction rates and activation energies for the

Argonne catalyst, and on the published kinetic data

for the commercial catalysts. The HTS and LTS

stages were assumed to operate adiabatically. The

calculated amount of catalyst is that needed to

reduce the exit CO concentration to 1% (dry basis)

from an inlet reformate gas consisting of 10% CO,

10% CO2, 34% H2, 33% N2, and 13% H2O (wet

basis). As shown in Figure 2A, for the commercial

HTS and LTS catalysts operated at 400°C and

200°C, respectively, a total catalyst volume of

19.2 L is needed for a 50-kWe fuel cell system. In

comparison, with the Argonne catalyst operated at

400°C and 300°C, respectively, the total required

catalyst volume is 13.5 L, a 30% reduction. Also

shown in Figure 2 are the improvements in the

activity of the platinum/mixed oxide catalyst

throughout the duration of this project, as reflected

in the estimated reactor size, and the reduction in the

1/Reactant Flow Rate (min/mol)

0

1000

2000

3000

0 40 80 120 160

ln(([CO]in-[CO] eq )/[CO]out-[CO] eq ))/liter catalyst

0.42 wt% Pt, old method

0.2 wt% Pt, old method

0.14 wt% Pt, new method

Slope ∝ WGSrate constant

Figure 1. New synthesis method reduced the platinum

loading of the catalyst while maintaining high

activity.

0

5

10

15

20

25

30

Commercial June,

'98

June,

'99

Nov.,

’99

ANL Pt/Mixed Oxide Catalysts

Volume of Shift Catalyst

for 50 kWe (liters)

LTS

HTS

A

0

5

10

15

20

25

30

Commercial June,

'98

June,

'99

Nov.,

’99

ANL Pt/Mixed Oxide Catalysts

Volume of Shift Catalyst

for 50 kWe (liters)

LTS

HTS

A

Figure 2. The Argonne catalyst can reduce shift reactor

volumes significantly. Projected size (A) and

cost (B) of the Argonne shift reactors are

being reduced.

amount of platinum needed. The platinum loading

has been reduced from 1 wt% to 0.14 wt%, for an

overall platinum weight of 32 grams for a 50-kWe

system.

Although the noble metals have desirable air

stability and temperature stability, their high cost

may limit their acceptability for transportation

applications. This past year, we developed a

nonprecious-metal/mixed oxide alternative to the

platinum/mixed oxide catalyst. As shown in

Figure 3, the nonprecious-metal/mixed oxide

catalyst has WGS activity comparable to that of

platinum/mixed oxide and does not lose activity at

temperatures up to 400°C. The nonpreciousmetal/mixed oxide catalyst is not initially as active

as commercial copper/zinc oxide (United Catalyst

Incorporated’s C18-7), but the Argonne catalyst

does not lose its activity after exposure to air at

230°C (Figure 4).
Fuel Cell Power Systems FY 2000 Progress Report

73

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

1.4 1.6 1.8 2.0 2.2 2.4

1000/Reactor Temp. (1/K)

ln (rate constant) (min-1 )

n-p. metal/mixed oxide Inc. temp.

n-p. metal/mixed oxide after 400°C

0.14 wt% Pt/mixed oxide/alumina

400°C 180°C

Figure 3. Nonprecious-metal/mixed oxide catalyst

shows activity comparable with that of

platinum/mixed oxide/alumina.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

Initial After 230°C

Air Exposure

Initial After 230°C

Air Exposure

ANL Non-Precious Metal UC Cu/ZnO C18-7

/Mixed Oxide

WGS Reaction Rate

(moles COx10 5 /min/ g catalyst)

Figure 4. Nonprecious-metal/mixed oxide catalyst

retains activity after exposure to air at 230°C.

Another promising nonprecious-metal WGS

catalyst, developed using the bimetallic/

polymetallic oxide approach, is vanadium-cobalt

oxide. This material has been prepared by two

different routes: glycine-nitrate combustion and

solid state synthesis. As shown in Figures 5 and 6,

vanadium-cobalt oxides prepared by the glycinenitrate process have activities (normalized to catalyst

surface area) that are comparable with those of

copper/zinc oxide; the activities (normalized to

catalyst surface area) are higher than those of

copper/zinc oxide when prepared by the solid-state

synthesis route. In addition, these materials can be

operated at temperatures up to 400°C and can be

oxidized and re-reduced without loss of activity.

They have low surface areas, and thus low overall

conversions of carbon monoxide. We are currently

attempting to prepare these materials in highsurface-area forms.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 50,000 100,000 150,000 200,000

Wet GHSV (1/h)

%CO conversion/m2 (wet eq. basis)

#2 1:2 V:Co (250°C)

#2 1:2 V:Co (250°C; air)

#2 1:2 V:Co (400°C)

UCI LTS (250°C)

#1 1:2 V:Co (250°C)

#1 1:2 V:Co (400°C)

Cu/ZnO

V-Co Oxide #1

V-Co Oxide #2

Figure 5. Vanadium-cobalt oxides prepared by

combustion technique have activities (per m2

)

comparable with that of Cu/ZnO.

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

0 50,000 100,000 150,000 200,000 250,000

Wet GHSV (1/h)

%CO conversion/m2 (wet eq. basis)

Co2V2O7 (250°C)

Co2V2O7 (400°C)

CoV2O6 (400°C)

CoV2O6 (250°C)

UCI LTS (250°C)

Cu/ZnO

Co-V Oxide

Figure 6. Vanadium-cobalt oxides prepared by solidstate technique have higher WGS activity

(per m2

) than Cu/ZnO.

Conclusions

In the past year, we have demonstrated the

operation of a single-stage adiabatic reactor using

ANL’s platinum/mixed oxide/alumina catalyst. The

reactor was shown to reduce the carbon monoxide

level in simulated reformate from 10.5% (dry) to

1.1% (wet) and to <1% in actual diesel reformate.

During the past year, the platinum loading on this

catalyst has been reduced from 0.42 wt% to

0.14 wt% while maintaining the WGS activity.

Estimates based on isothermal kinetic data show that

the platinum/mixed oxide catalyst has the potential

to reduce WGS catalyst volume to 70% that of the

commercial Fe/Cr-Cu/ZnO combination. In addition,

the Argonne catalyst does not lose activity after

exposure to air.

A nonprecious-metal/mixed oxide catalyst was

identified that has activity comparable with that of
Fuel Cell Power Systems FY 2000 Progress Report

74

the platinum/mixed oxide/alumina catalyst in the

180-400°C temperature range. This material does

not lose activity upon exposure to air and rereduction at 230°C. Another alternative to the

platinum catalyst, a binary oxide of cobalt and

vanadium, shows promise as an inexpensive, airand thermally-stable WGS catalyst.
Fuel Cell Power Systems FY 2000 Progress Report

75

IV. FUEL CELL STACK SUBSYSTEM1

A. R&D on a 50-kW, High-Efficiency, High-Power-Density, CO-Tolerant PEM

Fuel Cell Stack System

Tim Rehg (primary contract) and Nguyen Minh

Honeywell Engines & Systems

2525 W. 190th Street, MS-36-1-93193

Torrance, CA 90504-6099

Rehg, (310) 512-2281, fax: (310) 512-3432, e-mail: Tim.Rehg@Honeywell.com

Minh, (310) 512-3515, fax: (310) 512-3432, e-mail: Nguyen.Minh@Honeywell.com

DOE Program Manager: Patrick Davis

(202) 586-8061, fax: (202) 586-9811, e-mail: patrick.davis@ee.doe.gov

ANL Technical Advisor: William Swift

(630) 252-5964, fax: (630) 272-4473, e-mail: swift@cmt.anl.gov

Contractor: Honeywell Engines & Systems, Torrance, California

Prime Contract No. DE-FC02-97EE50470, October 1997-September 2000

Objectives

Research, develop, assemble, and test a 50-kW net polymer electrolyte membrane (PEM) fuel cell stack system

composed of a PEM fuel cell stack and the supporting gas, thermal, and water management subsystems. The PEM

fuel cell stack system will be capable of integration with at least one of the fuel processors currently under

development by Hydrogen Burner Technology (HBT) and Arthur D. Little, Inc.

OAAT R&D Plan: Task 11; Barriers A, B, C, D, and E

Approach

This phased program includes the fabrication and testing of three 10-kW subscale PEM fuel cell stacks, leading up

to the final 50-kW system. Stack technology development and system analysis are conducted iteratively to identify

pertinent technology advances to be incorporated into successive subscale stack builds. The final system analysis

will define the 50-kW stack and system configuration.

• Phase I:

- PEM stack R&D to demonstrate multifuel capability and carbon monoxide (CO) tolerance.

- PEM stack R&D to advance technologies toward U.S. Department of Energy (DOE) targets.

• Phase II:

- Subscale integration, electronic control system development, transient characteristics and

durability testing.

• Phase III:

- Testing of the 50-kW PEM fuel cell stack system.

- Hardware delivery of 50-kW PEM fuel cell stack system.

 

1 The DOE technical targets for fuel cell stack systems running on hydrogen-rich fuel from a fuel-flexible fuel processor

can be found in Table 3, Appendix B.
Fuel Cell Power Systems FY 2000 Progress Report

76

Accomplishments

• A >200-ppm CO tolerance was demonstrated in single-fuel-cell tests.

• The second 10-kW-class stack containing conducting composite bipolar plates has been built and tested. This

112-cell stack showed significant improvements in cell-to-cell uniformity and attained a specific power of

0.87 kW/kg and a power density of 1.6 kW/L.

• An 82-cell stack was subjected to a 250-hour life test, running on CO-containing reformate.

• A subscale (15-cell) stack was subjected to several freeze-thaw cycles to −40o

C without damage, as judged by

subsequent performance testing.

• The 50-kW brassboard system design was completed. Component performances have been specified, and

balance of plant component procurement is scheduled to be completed in 3Q 2000.

• Most of the balance of 50-kW brassboard plant hardware assembly (minus fuel cell stacks) will be completed in

3Q 2000.

• Controls and interfaces for real-time operation of the 50-kW brassboard are being designed, and the Hardware/

Software Interface definition is nearly complete.

• The stack engineering design has been completed for the third 10-kW subscale PEM fuel cell stack. Component

procurement is in process.

Future Directions

• Build and test the third 10-kW-class PEM stack (scheduled for November 2000).

• Deliver 50-kW net PEM fuel cell stack system brassboard to Argonne National Laboratory (ANL) at the

conclusion of the project (March 2001).

• Continue collaboration with ANL and fuel processor contractors on system integration issues.

• Continue to drive development toward DOE 2000 technical targets for high-volume production costs ($100/kW

for 5,000,000 units/year).

Introduction

Fuel cell power plants will become viable

substitutes for the internal combustion engine (ICE)

in automotive applications only when their benefits

of increased fuel efficiency and reduced emissions

are accompanied by performance and cost

comparable to those of the ICE. Meeting these

requirements is a significant technical challenge that

calls for an integrated systems approach. This effort

encompasses the technical and developmental

activities required to incorporate innovations

necessary to develop a 50-kW fuel cell stack system

to meet the requirements set forth by the DOE.

During this reporting period, Honeywell is in Phase

II of the program.

Approach and Results

The PEM fuel cell stack system consists of the

fuel cell stack and supporting gas, thermal, and

water management systems, as shown in Figure 1.

Overall system performance depends on the careful

integration of these subsystems.

Figure 1. Performance of second 10-kW stack.
Fuel Cell Power Systems FY 2000 Progress Report

77

The brassboard system design for the 50-kW

fuel cell stack has been completed. Six hexagonally

shaped stacks are pictured in Figure 2. Component

performances have been specified, and procurement

of major components is nearly completed. The

brassboard has been designed for 50-kW electric

power output, operating at high efficiency on

gasoline reformate. It incorporates full integration

and management of on-board thermal, water, and air

subsystems, and it makes use of off-the-shelf

components to minimize cost and assembly time.

Controls are being designed on the assumption of

full dynamic control capability, but provisions are

being made for a variety of actuation schemes.

Supervisory controls and built-in tests have been

partially completed. The Hardware/Software

Interface definition, which is nearly complete, will

be finalized once the remaining actuated control

valves have been selected.

In the area of membrane electrode assembly

(MEA) technology development, Honeywell has

demonstrated that our cells can tolerate >200 ppm

CO contamination without appreciable performance

loss. Honeywell plans to use these MEAs, along

with molded conducting composite bipolar plates, in

the upcoming third 10-kW stack and the final 50-kW

brassboard system build. The designs have been

completed for these builds and the procurement is in

process.

Figure 2. 50-kW brassboard system design.

The second 10-kW-class stack containing

conducting composite bipolar plates has been built

and tested. A comparison of the first and second

stack designs is given in Figure 3, and a photo of the

second stack is shown in Figure 4. This 112-cell

stack showed significant improvements in cell-tocell uniformity over the first stack (compare

Figures 5 and 6). Improvements for the second stack

included a new flow field with lower stoichiometry

capability, conducting composite bipolar plates, 13%

increase in active cell area, and substantial

improvements in stack weight, volume, and

manufacturability. The performance data for the

second stack are presented in Table 1, and 250-hour

life testing data (run on gasoline reformate/air) are

indicated in Figure 7.

Figure 3. 10-kW stack designs. Comparison of stack I

(left) and stack II (right) designs.

Figure 4. Photo of second 10-kW-class stack.
Fuel Cell Power Systems FY 2000 Progress Report

78

Figure 5. Stack I cell uniformity.

Figure 6. Stack II cell uniformity.

Table 1. Performance of second 10-kW stack.

Item Second Stack

Number of Cells 112

Stack Weight (lb) 38

Absolute Peak Power (kW) 15

Specific Power at Peak (kW/kg) 0.87

Power Density at Peak (kW/L) 1.6

H2 Stoichiometry at Nominal 1.25x

Figure 7. Stack II life test data.

Conclusions

In this reporting period, Honeywell has made the

transition to Phase II of the program. The focus is

now on the design and construction of the 50-kW

brassboard final deliverable, incorporating our third

stack design and molded composite bipolar plates.

The current projected brassboard system nominal

efficiency is 45% and the projected power densities

are ~0.2 kW/kg and ~0.15 kW/L, versus the

PNGV/DOE targets of 55%, 0.35 kW/kg, and

0.35 kW/L. It should be noted that the above

numbers include contributions from off-the-shelf

components for the brassboard, i.e., oversized heat

exchangers and valves.

FY 2000 Publications/Presentations

• R. Loda, “Development of PEM Fuel Cells at

Honeywell,” presented at Long Beach 2000,

Annual Battery Conference on Applications and

Advances, California State University, Long

Beach, Calif., Jan. 11, 2000.

• J. Ferrall, T. Rehg, and P. Sokolov, “Design and

Development of an Air-Reformate PEM Fuel

Cell Stack System for Light-Duty Vehicles,”

Paper No. 00FCC-6 presented at 2000 Future

Car Congress, Arlington, Va., April 2000.

• J. Ferrall, “Automotive PEM Fuel Cell

Development at AlliedSignal,” presented at the

Joint Fuel Cell Technology Review Conference,

Chicago, Ill., Aug. 3-5, 1999.
Fuel Cell Power Systems FY 2000 Progress Report

79

B. Development of Advanced, Low-Cost PEM Fuel Cell Stack and System

Design for Operation on Reformate Used in Vehicle Power Systems

Michel Fuchs (primary contact) and Frano Barbir

Energy Partners, L.C.

1501 Northpoint Parkway, #102

West Palm Beach, FL 33407

(561) 688-0500, fax: (561) 688-9610, e-mail: mfuchs@energypartners.org

DOE Program Manager: Donna Ho

(202) 586-8000, fax: (202) 586-9811, e-mail: donna.ho@ee.doe.gov

DOE Program Support: Larry Blair

(202) 586-0626, fax: (202) 586-9811, e-mail: larry.blair@ee.doe.gov

ANL Technical Advisor: William Swift

(630) 252-5964, fax: (630) 972-4473, e-mail: swift@cmt.anl.gov

Contractor: Energy Partners, L.C., West Palm Beach, Florida

Prime Contract No. DE-FC02-97EE50476, September 30, 1997-June 30, 2001

Objectives

• Develop low-cost bipolar collector plates through improvements in materials and processes.

• Evaluate and optimize membrane-electrode assembly (MEA) configurations with enhanced carbon monoxide

(CO) tolerance and low platinum loading:

- Stable, usable performance with steady-state CO levels of 10 ppm and transient levels of 100 ppm.

- Platinum loading less than 0.5 mg/cm2

 per MEA.

• Design and demonstrate a reformate-capable fuel cell stack with a 50-kWnet power output.

• Design, integrate, and demonstrate a reformate-capable 50-kWnet automotive fuel cell power system.

OAAT R&D Plan: Task 11; Barriers A, B, C, and D

Approach

• Phase I: Demonstration and delivery of a polymer electrolyte membrane (PEM) 10-cell stack with reformate

capability and 10 additional bipolar plates manufactured by the compression molding process.

• Phase II: Demonstration and delivery of a high-efficiency, reformate-tolerant 50-kWnet fuel cell stack and power

system utilizing injection-molded bipolar plates (with compression molded plates as an alternative), excluding

power conditioning and fuel processor, to Argonne National Laboratory (ANL) for independent testing and

verification.

Accomplishments

• Bipolar plates:

- Completed compression molding development for high performance.

- New injection molding of advanced molded composite bipolar plates results in high performance,

low cost (<$10/kW), and 100% recyclability, with less than 20 seconds cycle time per part per

machine on 232-cm2

 plates.

- Tested injection-molded plates in a Model NG2000 stack.
Fuel Cell Power Systems FY 2000 Progress Report

80

• Demonstration of hydrogen and reformate fuel cell performance:

- Scale-up of 50-kWnet automotive reformate design Model NG3000 comparable to previous

20-kWgross Model NG2000.

- Built and tested 10-cell Model NG3000 on H2/air.

- Achieved target performance with 10-cell Model NG3000 on reformate/air.

- Completed nearly 2000 hours of endurance testing.

- Performed freeze-tolerance testing with coolant temperature down to −10°C.

- Performed cold start-up testing from −40°C, with stack in an environmental chamber.

- “Field” tested an 8-kWgross Model NG2000 (hydrogen fuel cell stack) in a Deere & Co. Gator

industrial vehicle.

• Packaged 50-kWnet system components into an automotive test stand.

• System optimization and analysis:

- Performed trade-off studies to increase efficiency to perform at temperature extremes.

- Reduced componentry with thermally integrated system approach.

- Water balance achievable.

- Tested Arthur D. Little compressor-expander under simulated system conditions.

- Enhanced 50-kWnet system model using actual component performance data.

Future Directions

• Continue evaluations of new MEA materials for reformate performance.

• Optimize bipolar material compounding process and increase conductivity.

• Injection-mold net-shaped bipolar plates with all features (500 cm2

).

• Injection-mold large-scale blank bipolar plates (1000 cm2

).

• Deliver reformate-tolerant 10-cell stack.

• Finish fabrication, assembly, controls, and testing of the 50-kWnet system and prepare it for delivery.

Introduction

Energy Partners’ program objective is to

develop a state-of-the-art, reformate-tolerant PEM

fuel cell stack and integrate it into a reformatecapable operating system that meets automotive

design requirements. The development effort,

focused on a systems approach, is broken down into

three discrete areas: bipolar collector plates, PEM

fuel cell stack, and integrated system.

Results

Composite Bipolar Collector Plate

Development

An optimal bipolar collector plate should be

low-cost, impermeable, highly conductive,

chemically inert, lightweight, and easily

manufactured. The available choices for PEM fuel

cells are metals, graphite, and graphite-composite

materials. Energy Partners has used compressionmolded graphite composite plates in all of its fuel

cell stacks since 1992. With the advances made in

fillers, binders, and processes, these plates have

properties comparable to those of pure graphite.

However, compression molding is not suitable for

automotive-style mass production because of its

long processing time and high energy consumption.

Energy Partners is developing materials and

processes suitable for high-speed injection molding

(patents pending). Graphite materials are initially

compounded with thermoplastic polymers and

formed into pellets in a continuous process. We have

demonstrated a production rate of over 60 kg/h, with

much higher rates possible on larger machines.

Composite bipolar plates are currently injectionmolded with cycle times under 20 seconds. With

proper tool design, cycle time can be reduced to

about 10 seconds. This is more than 8 times faster

than injection-molded processes for conductive

thermoset materials. By comparison, Energy

Partners’ thermoplastic technology offers greatly
Fuel Cell Power Systems FY 2000 Progress Report

81

reduced cycle time and processing cost, improved

hydrolytic stability and corrosion resistance, and

potential for recycling. Table 1 compares properties

of Energy Partners’ compression- and injectionmolding technologies to specified DOE

requirements.

Recently, 500-cm2

 injection-molded blank plates

were machined to include fluid flow fields and

evaluated in a fuel cell stack. For comparison, cells

containing Energy Partners’ compression-molded

plates (performance similar to that of cells using

POCO graphite plates) were assembled in the stack

adjacent to the injection-molded plates. The

polarization curves for a 4-cell stack are shown in

Figure 1. The difference in performance corresponds

to higher conductivity for compression-molded

plates. Work in progress indicates that optimization

of the formulation and compounding process will

provide injection-molded plates with improved

conductivity. Figure 2 shows some of the current

collector plates molded at Energy Partners.

PEM Fuel Cell Stack

For the past year, work has been focused on

testing short fuel cell stacks of both the NG2000

(~300 cm2

) and NG3000 (~600 cm2) designs. The

Table 1. Bipolar plate status and properties.

Plate Property

Compression

(complete)

Injection

(in progress) DOE Specs.

Bulk conductivity >320 S/cm >110 S/cm > 100 S/cm

4-point probe method

<30 mΩ-cm2 <50 mΩ-cm2 Surface resistance

<20 mΩ-cm2

 (POCO)

None

Corrosion rate < 16 μA/cm2 < 16 μA/cm2 < 16

μA/cm2

H2 permeability <<2 x 10 –6

cm3/cm2-s

<< 2 x 10 –6

cm3/cm2-s

< 2 x 10 –6

cm3/cm2-s

Crush strength ~14,000 psi ~14,000 psi None

Flexibility

(modulus)

1.35 x 106 psi >1 x 106 psi None

Flexural strength 6,000-6,500

psi

6,500-9,000

psi

None

Material cost ~$7.5/kW ~$7.5/kW None

Manufactured

cost estimate

$146/kW <$10/kW $10/kW

Production cycle

time

< 40 min < 20 s None

Recyclability None 100% None

Durability @ 60oC >5,000 h >5,000 h None

Dimensions:

 Total plate

 Active area

 Thickness

 Weight

In Production

1,045 cm2

600 cm2

<3.0 mm

~ 450 g

Development

500 cm2

300 cm2 

<3.0 mm

< 200 g

None

Material density 2.0-2.2 g/cm3 ~2.0 g/cm3 None

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 250 500 750 1000 1250 1500 1750 2000

Current density (mA/cm2

)

Cell potential (V)

cell1

cell2

cell3

cell4

Compression-molded

plates

Injection-molded

Active area(cm2) :292

H2/Air stoich.:1.5/2.5

Temp. (deg. C):60

Pressure (kPa):308

Figure 1. Injection- vs. compression-molded plates.

Figure 2. Compression- and injection-molded bipolar

plates.

program baseline is the advanced hydrogen PEM

fuel cell stack NG2000 rated at 20 kWgross, which

also has a reformate-tolerant equivalent

(NG2000R). The new NG3000 was designed

specifically for reformate, with automotive design

criteria as specified by the program (50 kWnet).

Testing has shown comparable performance of both

the NG2000 and NG3000 designs (Figure 3). A

10-cell version of the NG3000 (Figure 4) was also

assembled and tested to obtain information related to

scaling up the design. The 10-cell version exhibited

very good cell-to-cell consistency (i.e., there was

very low variation in voltage between the individual

cells, even at high current densities). Figure 5 shows

cell-to-cell voltage variation at different current

densities.

The configuration of both the NG2000 and

NG3000 is flexible, ranging from 2 to 250 cells.
Fuel Cell Power Systems FY 2000 Progress Report

82

0.4

0.5

0.6

0.7

0.8

0.9

1

cell potential (V)

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Current density (A/cm2)

NG2000 H2 NG3000 H2 NG2000 ref NG3000 ref

NG2000

NG3000

Figure 3. Comparison of NG2000 and NG3000

stacks on hydrogen and on reformate.

Figure 4. NG3000 10-cell stack.

0.600

0.650

0.700

0.750

0.800

0.850

0.900

0.950

1.000

1 2 3 4 5 6 7 8 9 10

Cell position

Cell potential (V)

210 mA/cm2 600 mA/cm2 930 mA/cm2

Stack Size: 10-cell Temp. (deg. C):60

Active area(cm2

) :594 Pressure (kPa):308

H2/Air stoich.:1.5/2.5

Figure 5. NG3000 10-cell stack, cell voltage variation

on H2/air.

They operate at between 0.2 and 3 atm pressure with

reformate (40% H2, 40%N2, 20%CO2) and are

CO-tolerant to 100 ppm (steady state). Testing has

shown durability of nearly 2000 hours on a

NG2000 4-cell stack running on hydrogen.

Figure 6 shows that after nearly 2000 hours,

performance still remains relatively constant.

To prove automotive design concepts on actual

hardware, freeze-tolerance testing was performed

with the stack coolant temperature as low as −10°C.

Figure 7 shows performance of the stack when held

for one hour at negative 10°C and 15 minutes at all

other temperatures. In addition, Los Alamos

National Laboratory has been able to successfully

start up an NG2000 12-cell stack from –40°C,

with the use of an environmental chamber.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 250 500 750 1000 1250 1500 1750 2000

Operating hours

Stack potential (V)

Stack size: 4-cell

Active area(cm2

):292

H2/Air stoich.:1.5/2.5

Temp. (deg. C):60

Pressure (kPa):308

Current dens. (mA/cm2

):600

Figure 6. Durability of a 4-cell stack @0.60 A/cm2

 at

100% humidification on H2/air.

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0 200 400 600 800 1000 1200

Current Density (mA/cm2

)

Comments:

Date:03-26-99

Cell #:5 x 10-074

Test Stand #:5

Comp./ele.(in.):

H2/Air stoic:1.2/2.0

Temp.(deg. C):see legend

Pressure (PSIG):30

Membrane:

Active area(cm2

):

Res.(ohm-cm2

):.

Current Density(mA/cm2

):

60 C 50 C 40 C 30 C 20 C 10 C 5 C 0 C -10 C

Figure 7. Freeze-tolerance performance on H2/air at

1.2/2.0 stoich.
Fuel Cell Power Systems FY 2000 Progress Report

83

Since the introduction of the Model NG2000,

two in-vehicle evaluations of the stack have taken

place. The first was in Virginia Tech’s hybrid

vehicle, which took second place in the 1999

FutureCar Challenge. The second was in a Deere &

Co. Gator industrial vehicle, which used an

8-kWgross version of the stack (Figure 8). Both

vehicles provided extensive information on our fuel

cell in an actual vehicle application.

Integrated System Analysis

The system simulations that were previously

performed were enhanced by incorporating actual

system component performance data. All of the

major system components [i.e., radiator fan motor,

compressor/expander system (Figure 9), and coolant

pump] were tested individually under the integrated

system operating envelope. This enabled the

integrated system model to provide more realistic

performance information (Table 2).

Operating conditions were optimized to permit

the smallest heat-exchanger equipment size while

maintaining water balance. The resulting system is

shown in Figures 10 and 11. A control strategy was

developed to maintain neutral water balance over the

entire system operating range (kW) and under

different ambient conditions (patent pending).

Simplified humidification techniques were

investigated, which led to the design and

certification of an air humidifier able to meet the

necessary requirements.

Rapid start-up from an extreme ambient

temperature of −40o

C is possible with Energy

Figure 8. NG2000, 8 kW, installed in Deere & Co.

Gator industrial vehicle.

Figure 9. Picture of Arthur D. Little compressor/

expander machine.

Table 2. Energy Partners’ status vs. DOE goals.

Characteristic EP Status (7/00) DOE Goals

System efficiency

 @50 kWnet (wo/FP)

 @12.5 kWnet (wo/FP)

42-44%

50-51%

≥44%

≥55%

Net power density (W/L) 163 W/L 350 W/L

Net specific power (W/kg) 116 W/kg 350 W/kg

Cost/kW <100 (est.) 100/kW

Durability >1880 h 2000 h

Emissions <<Tier 2 <<Tier 2

Transient performance

(10% to 90%)

~0 s 3 s

Precious metal

(anode + cathode)

0.6 mg/cm2,

1.17 g/kW

0.5 mg/cm2,

0.9 g/kW

Cold start-up to full power

−40°C

 20°C

<5 min

97% in ~0 s

5 min

1 min

CO tolerance (<20 mV loss at

0.7 V) (steady state)

~0 mV

with 2% air bleed

>10 ppm

CO tolerance (<20 mV loss at

0.7 V) (3-s transient)

~0 mV

with 2% air bleed

>100 ppm

Partners’ system design. Experimental results from

freeze-tolerance tests (explained earlier) were used

in the simulations. The quick start-up feature is the

result of optimal utilization of feed gas thermal

energy and fuel cell stack thermal dissipation (patent

pending). Currently, the integrated system’s impact

on the start-up process, from –40°C, is being

investigated at Los Alamos National Laboratory

(LANL).

Conclusion

Energy Partners is developing an automotive

fuel cell power system to meet DOE performance

goals. Significant progress has been made in
Fuel Cell Power Systems FY 2000 Progress Report

84

Figure 10.Resulting 50-kWnet automotive system.

Figure 11. Picture of 50-kWnet automotive system.

development of mass-producible bipolar plates, in

stack and system design, and in development of a

control strategy that will result in neutral water

balance over the entire system operating range and

under different ambient conditions.

Presentations/Publications:

• M. Fuchs, F. Barbir, and M. Nadal, “Fuel Cell

Powered Utility Vehicle with Metal Hydride

Fuel Storage,” submitted to the GlobeEx 2000

Conference, Las Vegas, Nev., July 2000.

• F. Barbir, “Recent Progress and Remaining

Technical Issues in PEM Fuel Cell

Development,” submitted to the World

Hydrogen Energy Conference, WHEC XIII,

Beijing, China, June 2000.

• F. Barbir, “Air, Water and Heat Management in

Automotive Fuel Cell Systems,” presented at the

Intertech Conference on Commercializing Fuel

Cell Vehicles 2000, Berlin, Germany,

April 2000.

• M. Fuchs, F. Barbir, A. Husar, J. Neutzler,

D. Nelson, and M. Ogburn, “Performance of

Automotive Fuel Cell Stack,” presented at the

2000 Future Car Congress, Arlington, Va.,

April 2000.

• F. Barbir, “Bi-polar Plates, Flow Fields and

Stack Design Criteria,” presented at the

American Physical Society Meeting,

Minneapolis, Minn., March 2000.

• F. Barbir, M. Fuchs, A. Husar, and J. Neutzler,

“Design and Operational Characteristics of

Automotive PEM Fuel Cell Stacks,” Fuel Cell

Power for Transportation, SAE SP-1505, Proc.

SAE International Congress & Exhibition,

Detroit, Mich., March 2000, pp. 63-69, SAE,

Warrendale, Pa., 2000.

• V. Gurau, F. Barbir, and H. Liu, “An Analytical

Solution of a Half-cell Model for PEM Fuel

Cells,” Journal of Electrochemical Society,

Vol. 147(7), 2000.

• F. Barbir, M. Nadal, and J. Neutzler,

“Development of PEM Fuel Cell Power Systems

for Transportation Applications,” presented at

the IQPC Conference, Fuel Cell Technology

Asia 99, Tokyo, Japan, Dec. 1999.

• F. Barbir, B. Balasubramanian, and J. Neutzler,

“Trade-off Design Study of Operating Pressure

and Temperature in PEM Fuel Cell Systems,”

Proc. ASME Advanced Energy Systems

Division – 1999 ASME International

Mechanical Engineering Congress & Exposition,

AES Vol. 39, pp. 305-315, ASME, 1999.

• F. Barbir, B. Balasubramanian, and J. Neutzler,

“Optimal Operating Temperature and Pressure

in PEM Fuel Cell Systems in Automotive

Applications,” Proc. 218th ACS National

Meeting, Vol. 44, No. 4, pp. 977-981, American

Chemical Society, 1999.

• F. Barbir, J. Braun, and J.Neutzler, “Properties

of Molded Graphite Bi-Polar Plates for PEM

Fuel Cells,” International Journal on New

Materials for Electrochemical Systems, No. 2,

pp. 197-200, 1999.
Fuel Cell Power Systems FY 2000 Progress Report

85

C. Cold-Start Dynamics of a PEM Fuel Cell Stack

Kirk Weisbrod (primary contact), Jim Hedstrom, José Tafoya, Rod Borup, and Mike Inbody

Los Alamos National Laboratory

MS J576, Los Alamos, NM 87545

(505) 665-7847, fax: (505) 667-0600, e-mail: weisbrod@lanl.gov

DOE Program Manager: JoAnn Milliken

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

Objective

Develop cold-start strategies for stacks through the use of models, verified by experiments.

OAAT R&D Plan: Task 11; Barriers B and C

Approach

• Develop a global model of heat requirements and water transients associated with start-up from subfreezing

temperatures.

• Experimentally verify two cases:

- Autothermal start-up, applicable with stored hydrogen.

- Start-up with coolant heated by fuel processor waste heat.

Accomplishments

• Developed two transient models for stack/system start-up.

• Completed test apparatus in an environmental chamber that operates down to −40°C.

• Performed initial cold start-up tests with 12-cell stack from Energy Partners.

Future Directions

Complete autothermal and coolant-heated cold-start tests, using electrochemical impedance diagnostic tools to

characterize stack and individual cell performance.

Introduction

Rapid fuel cell system start-up to full power is

an automotive requirement. Quantification of

limiting parameters on cold-start stack response

starting from –40°C is the primary objective of this

study. Start-up of the stack on reformate at low

temperature is hindered by high sensitivity of the

anode catalyst to CO poisoning, low ionomer

conductivity, potential blocking of the catalyst layer

through ice accumulation in the backing layer, and

ice plugging of feed channels. Through

measurements and generic model predictions, fuel

cell subsystem and component requirements will be

defined.

Approach

Two models were developed. An autothermal

model represented start-up on stored hydrogen gas.

An overall heat and mass balance was defined

around the stack. Assumptions for the autothermal

model include the following:

• No interaction with a coolant system takes place.

• Measured polarization curves are available down

to –10°C. Below –10°C, the curves are

estimated.

• Dry air is available from a compressor at 78°C

(isentropic compression from –40°C).
Fuel Cell Power Systems FY 2000 Progress Report

86

• Vent gases leave the stack at 100% relative

humidity.

• Bipolar plates are thermally isolated from the

end plates.

The second model included an external heat

source that simulated waste heat from a fuel

processor. Equations were solved by the Applied

Engineering Equation Solver (EES) software from

F-Chart Software.

All stack hardware, including the stack cooling

loop, was installed in an environmental chamber that

operated down to – 40°C. A 12-cell stack

specifically designed by Energy Partners for coldstart tests was used. A schematic of the flow loop,

given in Figure 1, includes a reservoir containing a

60% ethylene glycol/water mixture and a heating

element. Coolant is pumped through the fuel cell

stack cooling channels and returns to the reservoir

until the stack reaches operating temperature.

Subsequently, coolant may be circulated through the

heat exchanger, which removes waste heat to the

environmental chamber. Figure 2 shows the

equipment layout.

Results and Discussion

Autothermal modeling results predicted both the

temperature rise and the accumulation of water in

the backing layer. It was assumed in the simulation

that 0.5 A/cm2

 was produced until the stack reached

0°C. After that point, a constant current of 1 A/cm2

was produced by the stack. Figure 3 indicates that

approximately 6.5 minutes would be required to

reach an operating temperature of 60°C.

Figure 1. Schematic of the cold-start system with

external heat source.

Figure 2. Environmental chamber and apparatus for

cold-start measurements.

Figure 3. Autothermal cold-start predictions of cell

temperature and water saturation.

The fraction of the pore volume, within an

11-mil-thick backing layer, that would be occupied

by ice was also calculated. To reach 0°C,

approximately 40% of the void volume of the

cathode backing layer would be occupied. The

impact of ice upon gas diffusion into the active

catalyst layer, though it is uncertain at this time, will

be evaluated in future experiments.

Figure 4 illustrates the impact of constant

voltage control instead of constant current. Under a

constant average cell voltage of 0.3 V, the stack

reached operating temperature 1.5 minutes earlier.

Greater chemical energy was converted to heat at

current densities up to 2 A/cm2

.

Multiple start-up tests were conducted with the

Energy Partners stack and cooling loop, starting

from –40°C. Start-up with simulated waste heat

from the fuel processor involved use of 2 kW heat

input up to 0°C, followed by full power draw at

1 A/cm2

 with feed gas humidification. Figure 5 
Fuel Cell Power Systems FY 2000 Progress Report

87

Figure 4. Autothermal cold-start model results for

current vs. voltage control.

Figure 5. Temperature history during cold start of the

Energy Partners’ stack.

traces heating transients. The outlet gas temperatures

rose when gas flow began at 0°C. Stack end plates

lagged in temperature.

System transients were modeled as described

above. A match between system performance and

model results is given in Figure 6. On the basis of

the validated model, predictions were made of heatup rate. Figure 7 indicates that with no external heat

input, 20 minutes is required to bring the stack to

operating temperature (60°C). With 5 kW of input,

5 minutes is required. To attain the FY2004 goal of

0.5 minute for stack heat-up, approximately 50 kW

of heat would be required for this specific system.

Thus, coolant system thermal mass will have to be

minimized.

Figure 6. Validation of fuel cell/system model.

Figure 7. Model predictions for fuel cell/coolant system.

Conclusions

The following operation and design guidelines

are recommended to minimize start-up times. For

autothermal start-up:

• Reduce the thermal load of end plates on the

stack by thermal isolation or by lowering their

heat capacity or thermal conductivity.

• If feasible, operate the stack at a constant low

stack voltage to maximize stack heat production.

• Use dry feed gases up to 0°C to eliminate

plugging of feed lines and internal stack

components with ice.

Additional issues connected with start-up when

an external heat source is available include the

following:

• The thermal mass of the coolant flow loop

should be minimized.

• A large external heat source is required to obtain

start-up times approaching 0.5 minutes.
Fuel Cell Power Systems FY 2000 Progress Report

88

D. Efficient Fuel Cell Systems

Mahlon S. Wilson (primary contact), Steffen Moeller-Holst, and Christine Zawodzinski

Los Alamos National Laboratory

Materials Science and Technology Division, MST-11, MS D429

Los Alamos, NM 87545

(505) 667-6832, fax: (505) 665-4292, e-mail: mahlon@lanl.gov

DOE Program Manager: JoAnn Milliken

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

Objective

Develop a simple, low-parasitic-power, low-cost fuel cell system with high net power densities and efficiencies.

OAAT R&D Plan: Task 13; Barriers B and C

Approach

• Utilize direct liquid water hydration of the membrane/electrode assemblies (MEAs).

• Operate the cathodes at near-ambient pressures to attain minimal parasitic power losses.

• Operate the stack in an “adiabatic” configuration.

Accomplishments

• Demonstrated a surplus water balance with <2% parasitic power at nominal power (and high-altitude

conditions).

• Demonstrated system efficiencies on neat hydrogen that exceed 55% (low heat value, LHV, of hydrogen) at

nominal power.

• Attained net stack volumetric power densities of 350 W/L (based on the graphite bipolar plate area) or 450 W/L

(based on active area) at nominal power.

• Simplified system to require a single water pump to handle both water makeup and recirculation.

Future Directions

• Further simplify system (e.g., by eliminating the hydrogen recirculation pump).

• Simplify stack design and decrease unit cell thickness by introducing new design approaches.

• Improve stack performance and reliability.

Introduction

Of all the potential fuel cell markets,

transportation is probably the most demanding and

competitive. The challenge for fuel cells becomes

more severe if the overall systems are highly

complex and intrinsically expensive. Therefore, the

basic thrust of this effort is to develop a fuel cell

system that is as simple as possible but still provides

competitive net power densities and efficiencies.

The primary benefits of simplicity are low costs and

reliability, both critical factors in the competitive

transportation market. As systems become simpler,

the parasitic power requirements of the peripherals

are inherently lower. It is possible to attain overall

high efficiencies and power densities by minimizing

parasitic power losses instead of maximizing stack

performance (i.e., pressurized systems).
Fuel Cell Power Systems FY 2000 Progress Report

89

Approach

The key to simplifying our fuel cell system is to

directly humidify the fuel cell membrane/electrode

assemblies (MEAs) with liquid water, as previously

developed in this program. The humidification is

accomplished by the introduction of an anode

wicking backing, which conveys liquid water in the

anode flow-field plenum through the nominally

hydrophobic gas diffusion layer directly to the

membrane throughout the active area.

A second critical element is the operation of the

air-side of the fuel cell stack at very near ambient

pressure; even relatively modest pressures can result

in surprisingly high power requirements. For this

reason, inlet air pressures of less than six inches of

water are targeted. With the use of the membrane

hydration scheme described above, the higher

pressure drops associated with humidification

modules, internal manifolding, and two-phase flows

in the cathode channels are eliminated, which allows

the use of low air pressures in our system.

The result of operating a well-humidified fuel

cell stack with a dry, ambient-temperature cathode

air inlet is that the airstream becomes heated and

water-vapor-saturated as it passes through the cells.

This configuration then provides in situ evaporative

cooling of the stack, which eliminates the need for a

separate cooling system or cooling plates within the

stack. Since evaporation is a very effective heattransfer mechanism, the waste heat is transferred to

the air as generated and where generated. The air

inlet is at room temperature and the effluent is at

60–70°C, so a large temperature gradient develops

across the stack. This differs from most fuel cell

stack designs, which typically strive to attain

isothermal conditions. In our case, the stack is

designed to encourage a monotonically increasing

temperature as the air passes through it, to

discourage any condensation from occurring within

the flow-field channels. This general scheme of

nonisothermal operation with in situ evaporative

cooling results in an “adiabatic” stack.

Since the system relies on evaporative cooling

instead of conventional stack cooling plates and

radiator, the ability to maintain a net positive water

balance under standard and more severe ambient

conditions is among the issues addressed this year.

Results

Over the past year, the adiabatic stack system

has been further simplified. A current schematic of

our roughly 1.5-kW system is depicted in Figure 1.

Water recirculation through the stack (for the direct

liquid hydration) and makeup from the ambientpressure main water reservoir are now accomplished

by using a single water pump in conjunction with a

pressure switch and float valve. With this scheme, a

second pump, liquid level controller, and motor

controller are eliminated or replaced by lower-cost,

nonpowered components.

One of the primary issues with utilizing

evaporative cooling in the adiabatic stack system

was the ability to operate with a net positive water

balance. A plastic flat-plate condenser with a

roughly 1/6-ft3

 exchange volume and a 12-W

cooling fan was used for water recovery from the

cathode effluent. In the water balance tests, the

thermally isolated end plates were heated to

minimize passive cooling that would skew the water

recovery results. In a typical run at 24°C ambient

temperature, the 26-cell, 300-cm2

-active-area stack

was operated at a voltage of 17.5 V (0.673 V/cell, or

a voltage efficiency of 57% based on LHV of

hydrogen) and a current of 83 A, for 1.45 kW gross

power. The blower provided roughly three times

stoichiometric air flow at a 5.5-in. H2O inlet

pressure. The total power draw for the various

components (blower, hydrogen and water pumps,

and condenser fan) was 26.1 W, or 1.8% of the stack

power. Net power is then 1.43 kW at a 56% overall

efficiency. Surplus water was recovered at a rate of

2.5 g/min.

Figure 1. Schematic of the adiabatic stack fuel cell

system.
Fuel Cell Power Systems FY 2000 Progress Report

90

While surplus water was easily recovered under

the high desert conditions (0.76 ambient pressure,

24°C, low humidity) in the experiment described

above, a parametric study using a system heat and

mass balance model was used to anticipate water

recovery under other scenarios (e.g., Florida).

Whereas the effect of humidity is relatively

insignificant, much more critical factors are the

ambient temperature and pressure, because the

condenser inlet temperatures increase strongly with

both. In addition, the heat-transfer coefficients are

proportional to ambient pressure. The net result is

that, for equivalent condensers and cooling air mass

flow rates, operating at a 25°C ambient temperature

in Los Alamos (0.76-atm ambient pressure) is akin

to operating at a 40°C ambient temperature at sea

level. For this and other reasons, it may be that

evaporative cooling plus water recovery is actually a

superior alternative to the conventional radiator plus

coolant approaches.

The less than 2% parasitic power level is of

critical importance to allow the modest performance

of the adiabatic stack to compete favorably with

pressurized fuel cell stacks in terms of net power

density and efficiency. The parasitic power

significance is illustrated in Figure 2. Here, a

Figure 2. Effect of parasitic power requirements on net

efficiencies.

polarization curve depicting the rather modest

performance of the adiabatic stack is depicted.

However, for a higher parasitic power

(e.g., pressurized) system to match the net efficiency

of the adiabatic stack, it must operate at a higher cell

voltage. For example, if a system has a 15%

parasitic power level (probably optimistic for a

30-psig stack), then it must operate at about

0.81 V/cell to attain the same net efficiency. The

unit cells will actually need to be thinner to achieve

the same net power density, because the pressurized

stack must also accommodate cooling plates etc.

Conclusions

A complete and simple version of an adiabatic

stack system has been developed and demonstrated.

Water self-sufficiency has been shown to be readily

achievable. System modeling indicates that the

experimental results attained at high altitude are

equivalent to those for sea-level conditions

(i.e., 40°C ambient temperature). Parasitic power

levels of less than 2% have been demonstrated.

Because of such low losses, net power efficiencies

and power densities of the adiabatic stack are

comparable with those for pressurized stacks. All

else being equal, it would appear that the adiabatic

system’s intrinsic simplicity and low cost would

give it a competitive edge over pressurized systems

for transportation applications.

Patents Issued/Pending

1. M. S. Wilson, “Fuel Cell Membrane

Humidification,” U.S. Patent No. 5,952,111.

2. M. S. Wilson, “Ambient Pressure Fuel Cell

System,” U.S. Patent Pending.
Fuel Cell Power Systems FY 2000 Progress Report

91

E. Direct Methanol Fuel Cells

Xiaoming Ren, Piotr Zelenay, Huyen Dinh, John Davey, and Shimshon Gottesfeld (primary contact)

Los Alamos National Laboratory, Los Alamos, NM 87545

(505) 667-6853, fax: (505) 665-4292, e-mail: gottesfeld@lanl.gov

DOE Program Manager: JoAnn Milliken

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

Objectives

Develop materials, components, and operation conditions for direct methanol fuel cells (DMFCs) so as to prove the

potential of DMFCs for transportation applications in terms of power density, energy-conversion efficiency, and

cost. Specifically,

• Continue to optimize anode and cathode catalyst layers to enhance cell performance;

• Prove that low fuel utilization can be resolved through a combination of ionomeric membranes of good protonic

conductivity and optimized stack structure and operation conditions; and

• Prove the stability of all cell components – primarily anode catalyst – in longer-term operation subject to these

combined requirements.

OAAT R&D Plan: Task 14; Barriers B, F, H, and I

Approach

• Operate DMFCs and stacks near 100°C with a variety of membrane/electrode assemblies (MEAs), using

optimized catalyst layers to demonstrate performance and stability.

• Optimize other cell components, including backing layers and bipolar plate/flow fields, to maximize

demonstrated performance in DMFC small stacks operating near 100°C.

Accomplishments

• Small DMFC Stack Development: 30-cell, 45-cm2 active area, methanol/air stack fabricated, employing Los

Alamos National Laboratory (LANL) hardware; 80 W generated by stack in initial testing near ambient

conditions ( 200 W expected near 90o

C).

• Lowered Pt Loading: Low-Pt DMFCs (50 cm2

) demonstrated: 5 g Pt/kW, with peak power of 0.15 W cm-2;

2 g Pt/kW with peak power of 0.12 W cm-2.

Future Directions

• Further lowering of precious catalyst loading.

• Possible scale-up of stack to the 1.0-kW level (budget permitting).

Introduction

The objective of the direct methanol fuel cell

effort at LANL, sponsored by the U.S. Department

of Energy’s Office of Advanced Automotive

Technologies (DOE/OAAT), has been to develop

materials, components, and operation conditions for

such cells and small stacks, to prove their potential

for transportation applications in terms of power

density, energy conversion efficiency, and cost.

Introduction of a DMFC as a primary power source

for transportation could provide the combined

attractive properties of a liquid fuel of good potential

availability, high system simplicity (liquid fuel + air

in, DC power out), good potential for packaging as

required to achieve 350-mile range in a passenger
Fuel Cell Power Systems FY 2000 Progress Report

92

vehicle, and good potential for achieving zeroemission-vehicle (ZEV) characteristics.

Results

Our DMFC work in fiscal year (FY) 2000

included advances in DMFC stack component

development, stack assembly, and stack testing. In

addition, we made significant headway in

demonstrating DMFCs with catalyst loadings that

were lower by a factor of 10 compared with the

loading used in military applications of the

technology, at a cost in peak power of only about

30%. The demonstration of operation on such lowerPt loadings has provided hope for bringing preciousmetal catalyst levels in DMFCs to within a factor of

two of the precious metal level per kilowatt used

today in fuel cell systems, based on on-board

reforming. Figure 1 shows a comparison at 100°C

and 110°C of DMFC (single-cell) performance on

>10 mg Pt/cm2

 and on <1 mg Pt/cm2. It is clear that

the lowering in peak power, observed as a result of

lowering the Pt loading by an order of magnitude, is

rather modest. The trade-off between DMFC Pt

loading per kilowatt and cell peak power is

summarized in Table 1. For comparison, fuel cell

power systems based on reforming-on-board use at

present attain near 2 g Pt/kW, while generating stack

peak power near 0.5 W cm-2.

We extended our DMFC work to the level of a

30-cell stack of 50-cm2 cells, shown in Figure 2.

Novel stack hardware has been developed in-house.

We have demonstrated initial power output of 80 W

under close-to-ambient conditions, and by the end of

this calendar year we expect to be able to

demonstrate 200 W from the same stack under the

higher temperature and pressure applicable for

transportation applications. We showed that very

effective packaging could be achieved with our stack

structure, which has a pitch per cell of 2 mm, or

5 cells/cm. This corresponds to a power density of

1 W/cm3

, or 1 kW/L of active volume of the stack

when operated at a higher temperature, around 90o

C,

and at 30-psig air. We see the success in building the

small stack as a substantial basis for scale-up to the

1-kW level.

Another important demonstration this year was

the applicability of “factory-grade” methanol to

DMFC operation, without any further purification.

Analytic-grade methanol and methanol from the

factory gate yielded the same cell performance and

performance stability. Significantly, no special “fuel

cell grade” methanol will apparently be required for

DMFCs.

An important development this year has been the

interest expressed by Motorola in working with

LANL on DMFC technology for a variety of

V for 1058 vs AP for 1058 

V For 1042 vs AP for 1042 

Cell Current Density (A cm-2)

0.0 0.2 0.4 0.6 0.8

Cell Voltage (V)

0.0

0.2

0.4

0.6

0.8

110°C

0.8 mgPt cm-2

(total)

16.6 mgPt cm-2

(total)

Cell Current Density (A cm-2)

0.0 0.2 0.4 0.6 0.8

Cell Voltage (V)

0.0

0.2

0.4

0.6

0.8

100°C

0.8 mgPt cm-2

(total)

16.6 mgPt cm-2

(total)

Figure 1. DMFC polarization curves for ultra-high and low Pt loadings at 100 and 100°C (45-cm2

 cell).
Fuel Cell Power Systems FY 2000 Progress Report

93

Table 1. Trade-off between peak power density and

catalyst requirement per kilowatt with lower

overall Pt loading.

Total Pt Loading

(mg cm-2) g/kW (peak)

Peak Power

(W cm-2)

16.6 66.0 0.250

1.9 10.0 0.190

1.1 6.1 0.185

0.8 4.9 0.170

0.4 2.7 0.140

0.2 1.4 0.130

Milestone of 5 g Pt/kW achieved with 45-cm2 cell

at peak power of 0.17 W cm-2 (at 2 g Pt/kW, peak

power is still ~0.14 W cm-2).

Figure 2. LANL 30-cell 45-cm2

 DMFC stack.

applications. The first application chosen, leading to

a cooperative research and development agreement

(CRADA) with Motorola, has been a power system

for cellular phones, based on a hybrid DMFC/battery

system (see Figure 3).

Conclusions

As a result of the DOE/OAAT-sponsored efforts

at LANL targeting potential transportation

applications of DMFCs, the technical status reached

is significant. In terms of power density and energyconversion efficiency, the DMFC (based on short

stack results) is today comparable with an on-board

methanol reforming system. There is a remaining

(although smaller than perceived) gap in preciousmetal catalyst requirements, with the DMFC

requiring 5 g Pt kW-1 vs. about 2 g Pt kW-1 required

today for an on-board reforming system. We plan

(budget permitting) to extend our DMFC work in

FY 2001 to fabrication and testing of stacks in the

range of 1 kW, operating near 100°C.

Figure 3. DMFC application: portable power for cellular phones.
Fuel Cell Power Systems FY 2000 Progress Report

94
Fuel Cell Power Systems FY 2000 Progress Report

95

V. PEM STACK COMPONENT COST REDUCTION1

A. High-Performance, Matching PEM Fuel Cell Components and Integrated

Pilot Manufacturing Processes

Mark K. Debe and Judith B. Hartmann (primary contact)

3M Company

3M Center, Building 201-1C-30

St. Paul, MN 55144-1000

(651) 736-1772, fax: (651) 575-1187, e-mail: jbhartmann@mmm.com

DOE Program Manager: JoAnn Milliken

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

ANL Technical Advisor: James Miller

(630) 252-4537, fax: (630) 972-4537, e-mail: millerj@cmt.anl.gov

Contractor: 3M Company, St. Paul, Minnesota

Subcontractor: Energy Partners, Inc., West Palm Beach, FL

Prime Contract Nos. DE-FC02-97EE50473, September 1997-March 31, 2000

DE-FC02-99EE50582, September 1999-December 2001

Objectives

• Conclusion of Contract #1, Phase 2: Demonstrate scale-up potential for fabricating CO-tolerant anode catalysts

and targeted performances of prototype manufactured membrane electrode assemblies (MEAs) in a

subcontractor-provided fuel cell stack.

• Contract #2: Develop a set of high-performance, matched polymer electrolyte membrane (PEM) fuel cell

components and pilot manufacturing processes to facilitate high-volume, high-yield stack production, and

demonstrate the matched component performance in a subcontractor-provided 10-kW fuel cell stack.

OAAT R&D Plan: Task 13; Barriers A and B

Approach

• Contract #1, Phase 2:

- Transfer anode catalyst fabrication from laboratory- to pilot-scale facility.

- Conduct single-cell tests at subcontractor facility to define flow field design; prepare MEAs for evaluation

in their short stack design at subcontractor facilities.

• Contract #2, Phase 1:

- Develop anode catalyst compositions and structures with higher reformate tolerance, based on a proprietary

catalyst support system.

- Investigate catalyst compositions and structures to produce higher-activity cathodes, based on a proprietary

catalyst support system.

- Carry out pilot manufacturing scale-up of the process for fabrication of catalyst-coated membrane (CCM)

assemblies.

 

1 The DOE draft technical targets for fuel cell system and fuel cell stack components, sensors, and catalysts can be

found in Tables 3, 4a, and 4b, Appendix B.
Fuel Cell Power Systems FY 2000 Progress Report

96

- Develop carbon electrode backing (EB) media, optimized for performance with the catalyst system.

- Optimize the fuel cell flow field, with the stack manufacturing subcontractor, for water management and

air bleed utilization with the catalyst system.

• Contract #2, Phase 2:

- Evaluate matched component system’s performance in subcontractor stack tests.

- Fabricate and deliver a 10-kW stack.

Accomplishments

• Successfully scaled up anode catalyst, completed large-area short stack testing at Energy Partners, and prepared

final report on Contract #1.

• Defined and implemented development of methods for fast screening of new anode and cathode catalyst

compositions and structures, which have direct correlation with fuel cell performance.

• Implemented and refined multiple in-situ techniques for characterizing MEA properties relevant to fuel cell

performance.

• Systematically evaluated multiple PEMs and gas diffusion layer media in MEAs to select the optimal set for

catalyst screening experiments.

• Developed a quantitative understanding of optimal water management and operating conditions for the

nanostructured MEAs.

• Identified critical factors in MEA components and fuel cell break-in conditioning, leading to significant

improvements in performance.

• Identified and implemented improvements in pilot-scale CCM fabrication, which resulted in improved fuel cell

performance.

• Achieved improved definition of process windows for catalyst and CCM fabrication; identified key process

parameters for statistically designed scale-up and quality improvement studies in the next stage of the effort.

• Completed the greater portion of the work needed to establish test stations, in-line process equipment, and

monitoring equipment to support the laboratory- and pilot-scale studies.

• Completed fuel cell evaluations and characterization studies of ~50 different electrode backings, which fall

under four different media categories. Identified key EB characteristics related to fuel cell performance and

developed increased understanding of differences among the types of media that influence how to optimize

their use.

• Evaluated the effects of EB coating properties on fuel cell performance for the different types of EB media.

• Implemented three-dimensional flow field model for simulation of down-channel and cross-channel

distributions of oxygen, temperature, current density, and water saturation levels.

Future Directions

• Continue development and evaluation of anode and cathode catalysts, emphasizing scaleable process methods

that yield higher specific surface area activities for oxygen reduction.

• Continue EB materials and process development to optimize water management with a high-volume

manufacturing process.

• Continue development of the CCM pilot-scale process to improve on-line process control methods, yields,

quality, and performance.

• Continue flow field optimization modeling and verification.
Fuel Cell Power Systems FY 2000 Progress Report

97

Introduction

The membrane electrode assembly is the core

component set of a PEM fuel cell stack. An MEA

consists of five basic components: anode and

cathode catalysts, ion exchange polymer membrane,

and anode and cathode gas diffusion layers. The

functions of these basic components are intimately

related, and the interfaces between them are critical

for optimal performance. For large-scale volume

fabrication at the costs and quality targets required

by transportation applications, very high yields and

in-line process control of integrated processes based

on cost-effective materials are required. This

contract is directed toward demonstrating highperformance, matching PEM fuel cell components

manufacturable by integrated pilot processes,

utilizing a proprietary nanostructured thin-film

catalyst support system.

In fiscal year (FY) 2000, the initial contract

(DOE-1) to demonstrate the feasibility for such an

approach was concluded, and a follow-on, expanded

contract was initiated (DOE-2). In this report, we

summarize the progress in Phase 2 of the initial

contract and in the current contract to date. Phase 2

of DOE-1 focused on evaluating full-size MEAs,

based on a nanostructured support system and

fabricated by feasibility process methods, in a short

stack at the subcontractor facilities. The objective of

DOE-2 is to build on the feasibility of the first

contract, further optimizing the component

performances, their integration, and development of

high-volume pilot manufacturing processes for

continuous fabrication of the catalyzed membranes

and gas diffusion layers used to form five-layer

MEAs. In the second phase of DOE-2, the

performance of the matched component system will

be demonstrated in a 10-kW fuel cell stack.

Approach

The objectives and approaches of DOE-1 are

described in the FY 1999 edition of this report. In

completing Phase 2 of DOE-1, the proprietary

nanostructured anode catalysts developed in Phase 1

were scaled up and used to fabricate 150- and

300-cm2

 MEAs for single-cell and, finally, short

stack testing. Evaluation of single-cell MEAs with

different catalysts, membranes, and gas diffusion

layers was performed using different subcontractor

flow field designs to determine a likely best

component set for the short stack. New short stack

bipolar plates were fabricated for the short stack

tests and combined with the best MEA component

set fabricated by the feasibility pilot process.

The objectives of DOE-2 both extend and add to

those of DOE-1, and the approach reflects this as

well. In Phase 1 of DOE-2, new cathode catalyst

compositions and structures based on nanostructured

support films are being developed for higher

performance and efficiency on low-pressure air, and

development is continuing on improved anode

catalysts for operation on reformate with better air

bleed utilization. For both areas of catalyst

development, the unique nanostructured support and

catalyst coating methods are similar and offer many

potential combinations of materials and process

conditions to obtain higher-performing, more costeffective electrodes. Because of the large number of

potential new multicomponent catalyst structures

that can be fabricated by this approach, a fast

screening methodology is being developed to permit

the electrochemical evaluation of the new catalysts

as quickly as possible, to support selection of those

that merit more thorough evaluation. In addition,

multiple in-situ techniques for characterizing MEA

properties relevant to fuel cell performance have

been defined and implemented on the fuel cell test

stations.

Scale-up of the processes for producing the

catalyst support structures and CCMs is being done

in a pilot-plant facility. Initial work has focused on

experiments to better define the process windows

and to identify key process parameters.

Improvements to the processes and equipment are

being made as the need is identified through

experiments. On-line monitoring and inspection

methods are being defined and implemented, and

fuel cell test stations are being installed to support

pilot-scale, statistically designed process

experiments and quality improvement studies, which

will begin when the test station installation is

completed.

Electrode backings in four categories of media

are being evaluated by fuel cell performance tests

and by a variety of characterization studies.

Preliminary assessment of relative process

feasibility and cost is also part of the selection

process. Experiments are being conducted to

identify key characteristics and to develop an

understanding of the differences among the types of

media. Future work will include more detailed
Fuel Cell Power Systems FY 2000 Progress Report

98

evaluation of the most promising types of substrates,

one of which will be selected for scale-up.

Finally, the proprietary nanostructured-catalystbased MEAs have different water management

requirements than MEAs fabricated with

conventional carbon-particle-supported catalysts,

requiring optimized gas diffusion layers and flow

field designs for best performance. An empirical

approach was used in DOE-1 for investigation of

two types of existing flow fields. In the current

contract, modeling via computational fluid dynamics

(CFD) is being utilized by the subcontractor to

simulate the operating environment within the cell

for different flow field design parameters and gas

diffusion layer properties.

Results

A six-cell stack was fabricated at Energy

Partners, using their bipolar plate technology, and

3M CCMs were fabricated by continuous process

methods with anode and cathode catalysts developed

under DOE-1. Figure 1 shows a set of three stack

polarization curves taken under pure hydrogen, 40%

H2 with 60% N2, and 40% H2 with 40% N2 and 20%

CO2. No H2 dilution effects or loss in performance

from the CO2 are seen. Performance did not match

the single-cell tests, but it was discovered after the

tests were completed that the anode flow rates were

inadequate because of a test station leak. The stack

will be retested for benchmarking under DOE-2.

Figure 1. Short stack polarization curves from DOE-1,

Phase 2, final tests of 300-cm2

 MEAs

fabricated by the pilot continuous process

methods.

Significant progress has been made, since the

beginning of DOE-2, in determining materials,

process, and fabrication factors that give improved

performance, but are still based on the anode and

cathode catalysts developed in DOE-1. These factors

involve water management, the type of PEM and gas

diffusion layer, and the conditions for assembling

them. Figure 2 illustrates a series of four

polarization curves representing the best

performance at the date indicated, with constant Pt

cathode loadings of ~0.22-0.28 mg/cm2

. All

measurements were taken at ambient pressure in a

potentiodynamic scanning mode.

The nanostructured catalyst process is very

facile, and many new catalyst alloys and composites

can be made rapidly for evaluation. A rapid

screening technique had to be implemented with a

close correlation to fuel cell performance to facilitate

the catalyst evaluations, which guide the process

development. A 16-segment cell (16 working

electrodes) and 16-channel potentiostat now under

development will allow AC-impedance

characterization of the CCMs made with the new

catalyst types, specifically to allow simultaneously

measuring and distinguishing the catalyst reaction

polarization impedances from membrane, contacts,

and interfacial impedances. Figure 3 illustrates AC

impedance plots obtained at open circuit voltage

Figure 2. Illustration of the continuing improvement in

ambient pressure performance obtained since

the start of DOE-2 with the same

nanostructured catalysts, by advances in other

MEA components, fabrication methods, and

testing protocols.
Fuel Cell Power Systems FY 2000 Progress Report

99

Figure 3. AC impedance plots obtained at open-circuit

voltage under reformate with a prototype

segmented cell from five different catalyst

compositions. The low-frequency intercept is

seen to be a strong function of catalyst

composition. The final 16-segment cell and

potentiostat will be used to rapidly screen new

anode and cathode catalysts.

under reformate, with a prototype segmented cell,

from five different catalyst compositions. The lowfrequency intercept is seen to be a strong function of

catalyst composition.

Improvements to the pilot-plant CCM

fabrication process and equipment resulted in

material having improved fuel cell performance.

Ambient-pressure polarization curves taken in

potentiodynamic/constant flow (PDS) and

galvanostatic/constant stoichiometry (GSS) scanning

modes for this material are shown in Figure 4. The

discrepancy at low current densities between the

PDS and GSS curves reflects the need for optimized

electrode backings and flow fields. Experiments

conducted on the catalyst fabrication process

resulted in better definition of the process windows

and identification of major variables for future,

statistically designed experiments. Installation of

pilot-plant test equipment to support statistically

designed scale-up and process quality improvement

studies is nearing completion.

Fuel cell evaluations and characterization

studies were completed for ~50 different EBs, which

fall under four different media categories. Also,

Figure 4. Ambient-pressure polarization curves

comparing two scanning protocols for CCMs

fabricated by pilot process methods. PDS =

potentiodynamic scan, constant flow,

10 sec/point; GSS = galvanostatic scan,

constant stoichiometry, 10 min/point.

several experiments were completed to evaluate the

effects of coating properties on fuel cell performance

and identify differences among the different types of

media. Key EB characteristics that relate to fuel cell

performance were identified, and an increased

understanding of differences among the types of

media that influence how to optimize their use was

developed. Methods for achieving improved

performance are being identified and implemented

as needed to complete the evaluation and selection

process.

The final deliverable of DOE-2 (and the focus of

Phase 2) is assembly of a 10-kW stack by the

subcontractor. The bipolar-plate flow field design is

an important factor affecting MEA performance,

particularly with respect to water management and

air bleed utilization across the area of an individual

cell. A final task of DOE-2 is thus directed at

utilizing experience from the DOE-1 short stack

testing and the subcontractor’s computer modeling

and simulation programs to design a flow field that

optimizes the performance of the MEAs with the

nanostructured-catalyst system in an operating stack.

CFD simulations (single phase with heat

transfer) of five different flow field designs have

been examined for qualitative implications, and the

feature(s) examined that have the most influence on

uniformity of current density, temperature, oxygen,

and water vapor distributions across and along the
Fuel Cell Power Systems FY 2000 Progress Report

100

flow field channels. Measurements of critical gas

transport properties of the gas diffusion layer are put

into the model. Designing for the optimized

feature(s) and most effective water removal through

the gas diffusion layer will provide guidelines for

the initial design of the flow fields.

Conclusions

Significant progress is being made in all aspects

of our efforts to develop high-performance, matched

PEM fuel cell components and pilot manufacturing

processes.

B. Design and Installation of a Pilot Plant for High-Volume Electrode

Production

James Arps (primary contact)

Southwest Research Institute (SwRI)

P.O. Drawer 28510

San Antonio, TX 78228-0510

(210) 522-6588, fax: (210) 522-6220, e-mail: jarps@swri.org

DOE Program Manager: JoAnn Milliken

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

ANL Technical Advisor: James Miller

(630) 252-4537, fax: (630) 972-4537, e-mail: millerj@cmt.anl.gov

Contractor: Southwest Research Institute, San Antonio, Texas

Contract No. DE-FC02-00EE50625, Period of Performance December 1, 2000-May 1, 2002

Subcontractors: General Motors, Warren, MI; W.L. Gore and Associates, Elkton, MD

Objectives

• Demonstrate proofs-of-concept for the large-scale preparation of high-performance electrodes for membrane

electrode assemblies (MEAs) and review electrode and MEA architecture against Partnership for a New

Generation of Vehicles (PNGV) cost targets.

• Design, build, and install equipment for a high-volume pilot plant capable of catalyzing 100,000 square meters

of electrode material per shift per year.

• Complete process development and qualification of the pilot plant.

• Benchmark MEAs fabricated at SwRI against commercially available products.

• Incorporate MEAs into a 50-kW fuel cell stack built by General Motors (GM) and deliver to Argonne National

Laboratory (ANL) for testing and evaluation.

OAAT R&D Plan: Task 13; Barrier B

Approach

• Optimize catalyst loading composition, uniformity, and throughput on a pre-pilot scale.

• Prepare MEAs, using ultra-low-load (<0.10 mg/cm2

 Pt) electrodes, and test them under representative operating

conditions.
Fuel Cell Power Systems FY 2000 Progress Report

101

• Finalize system specifications, including detailed requirements for material handling dimensions, throughput,

process controls, interfaces, and diagnostics.

• Solicit bids for equipment and construct pilot plant.

• Assess the impact of large-scale catalyzation methods on MEA performance.

• Determine process yields, metal recovery approaches, and methods to optimize them.

• Fabricate sufficient ultra-low-load MEAs from catalyzed electrode material for incorporation into 50-kW stack.

Accomplishments

• Completed MEA test fixtures, fabrication equipment, and facility space for pilot system.

• Took delivery of more than 3,000 linear feet of intermediate electrode substrate material from W.L. Gore and

Associates.

• Prepared laboratory quantities (~100 ft2

/batch) of catalyzed electrode material, utilizing various alloy

compositions and loadings of from 0.005 to 0.1 mg/cm2

.

• Reviewed MEA preparation methods at Los Alamos National Laboratory (LANL) and produced baseline

MEAs at SwRI.

• Fabricated and tested experimental MEAs having a total catalyst loading on the order of 0.10 mg Pt/cm2

.

• Developed robust quality control approaches to characterize catalyzed electrode material.

• Drafted comprehensive requirements list for system, based on pre-pilot trials and discussions with several

equipment suppliers.

• Prepared an analysis detailing key manufacturing and ownership costs of the catalyzation process and their

contributions to overall MEA costs.

Future Work

• Continue efforts to reduce electrode precious-metal content while maintaining or increasing power density.

• Finalize system design and begin construction.

• Prepare several full-scale MEAs (>500-cm2

 active area) for short stack testing at GM.

Introduction

Commercial acceptance of fuel cell technology

for use in the automotive area requires a fuel cell

system that meets the PNGV cost target of $50/kW.

One of the most critical components affecting

overall system performance and economics is the

membrane electrode assembly. It is anticipated that

the MEA must be available for $10/kW or less in

order to meet the overall PNGV cost targets.

The primary objective of this project is the

design and installation of a pilot manufacturing

process for a crucial (cost-prohibitive) element in

the high-volume production of fuel cell MEAs that

will address the need for fuel cells in transportation

applications. This pilot line will be scaled to

catalyze up to 300,000 m2

 of electrode material on a

three-shift basis (enough to allow the fabrication of

MEAs for more than 50,000 fuel-cell-powered

automobiles).

Approach

To support this effort, SwRI will acquire

electrode substrate materials, membranes, and

reference MEAs (that do not utilize SwRI

technology) from W.L. Gore and Associates; these

will be used by SwRI for MEA assembly and

benchmarking. The products delivered by the end of

the project are projected to demonstrate sufficient

production levels to achieve MEA production costs

below $10/kW. The centerpiece of this effort will be

a vacuum coating unit with the capability to produce

millions of square feet of high-performance, ultralow-load electrodes per year. SwRI initially

demonstrated the feasibility of this nanoscale,

precious-metal technology as part of a DOEsponsored program on advanced fuel cells for

transportation applications. The electrodes produced

by the high-volume process will be assembled with

available polymer electrolyte membranes (PEMs),
Fuel Cell Power Systems FY 2000 Progress Report

102

using established assembly technologies, into

complete MEAs. Once the pilot quantities of

material are produced, General Motors (Global

Alternative Propulsion Center), a major participant

in the PNGV program, has agreed to design and

construct a 50-kW stack utilizing SwRI-supplied

MEAs. Upon completion, this system will be

delivered to ANL for evaluation.

Results

SwRI has developed novel technologies that

provide high-performance electrodes (anode and

cathode) that are intimately bonded to the membrane

to produce high-performance MEAs. Efforts at

SwRI have been aimed at creating electrode layers

employing ultra-low levels of precious metals by

utilizing vacuum deposition techniques. As shown in

Figure 1, superior power density has been

demonstrated for MEAs with electrode layers

prepared by vacuum deposition, compared to the

performance of MEAs with the same or higher

levels of precious metals that were prepared by

conventional and other electrode-coating techniques.

This superiority can also be expressed in terms

of catalyst mass activity (mA/mg Pt) and specific

power (mW/mg Pt). For example, specific power

values approaching 5 kW per gram of platinum have

been achieved with the new technology. Ultra-low

loadings as low as 0.001 mg/cm2

 have been

demonstrated in the laboratory, with catalyst

uniformity within 5% achieved across 15-cm widths

of material. To our knowledge, such levels cannot

currently be achieved with conventional processes.

Work continues to further optimize catalyst

composition and reduce precious metal

Figure 1. Comparison of SwRI-catalyzed MEAs with

baseline sample.

content, with a target of less than 0.10 mg/cm2

thought to be achievable.

Pre-pilot trials, conducted at SwRI and off-site

at a contract facility, have indicated that high feed

material rates of 20 m/min and catalyst deposition

rates in excess of 0.05 mg/cm2

 · s are possible. To

date, W.L. Gore and Associates have provided more

than 3,000 linear feet of intermediate electrode

substrate material for use in these ongoing trials. A

representative roll of this material (~500 ft2

) is

shown in Figure 2. Additional large-volume orders

will further aid in accelerating MEA material

manufacturing capabilities.

Conclusions

The clear potential of SwRI’s vacuum

deposition methods to manufacture high volumes of

electrode material at extremely low cost and with a

high degree of uniformity promises to help break the

barrier to commercialization of polymer electrolyte

fuel cells on a broad scale. Vacuum deposition

methods for rolled products, commonly referred to

as “web coating,” have been applied for more than

15 years in the manufacture of thin-film capacitors,

magnetic media, and packaging for food products.

Figure 2. Continuously manufactured intermediate

electrode material.
Fuel Cell Power Systems FY 2000 Progress Report

103

Typical costs for manufacture of metallized plastic

are in the range of pennies per square meter of

material. Typical production volumes for single

industrial web coaters are in the range of 30 million

square meters per year. Thus, the work at SwRI

points to the tremendous potential cost reductions

that are possible with the improved power density,

lower loadings of precious metals utilized in the

electrode layers of the MEAs, and high volumes of

material that can be processed. If this approach is

successful, the total projected platinum loading for

an automotive stack utilizing this technology could

be comparable to the amount found in a modern-day

catalytic converter. Efforts in the coming year will

focus on final design and installation of the pilot

facility, performance assessment of MEAs

fabricated with electrodes utilizing this technology,

and integration of materials into test stacks for

evaluation at GM.

C. Low-Cost, High-Temperature, Solid-Polymer Electrolyte Membrane for

Fuel Cells

Robert F. Kovar, Paul Osenar, and Leslie Rubin

Foster-Miller, Inc

195 Bear Hill Avenue

Waltham, MA 02154

(781) 684-4000, fax: (781) 290-0693, e-mail: bkovar@foster-miller.com

DOE Program Manager: Donna Lee Ho

(202) 586-8000, fax: (202) 586-9811, e-mail: donna.ho@ee.doe.gov

ANL Technical Advisor: James Miller

(630) 252-4537, fax: (630) 972-4537, e-mail: millerj@cmt.anl.gov

Contractor: Foster-Miller, Inc., Waltham, Massachusetts

Prime Contract No. DE-FC02-97EE50478, Period of Performance: September 30, 1997-September 29, 2000

Subcontractor: Giner, Inc., Waltham, MA 02154

Objectives

Demonstration of a new class of low-cost, high-temperature solid-polymer electrolyte composite membranes for use

in automotive (Partnership for a New Generation of Vehicles) and stationary power applications.

OAAT R&D Plan: Task 13; Barrier B

Approach

The following tasks are required to develop and qualify the composite membrane (and membrane electrode

assemblies):

• Identify and develop a qualifying ion-conducting polymer (ICP); the ICPs employed must show less than 10%

ionomer degradation in accelerated fuel cell life testing.

• Identify and develop qualifying microporous polymeric substrates; the substrates employed must be

dimensionally stable, thin, and pinhole-free structures.
Fuel CellPower Systems FY 2000 Progress Report

104

• Develop fabrication methods for high-temperature composite membranes (using the selected ICP and

substrate). The ICP and substrate must be combined to form an interpenetrating network.

• Develop appropriate electrode structure and corresponding attachment methods for fabrication of membrane

electrode assemblies (MEAs).

• Demonstrate MEA via single-cell testing.

Accomplishments

• Identified, synthesized, and evaluated several aromatic ICPs:

- Selected most promising system, based on commercially available starting polymers, and completed

synthesis and scale-up studies.

- Identified several ICP systems for advanced development, with the focus on improved stability and

lifetime.

• Identified, synthesized, and evaluated selected substrate polymers:

- Selected poly-p-phenylene benzobisoxazole (PBO) as the most promising polymeric substrate material.

- Demonstrated fabrication methodology for high-porosity, unoriented substrates for PBO on a batch scale.

- Identified fabrication methodology for oriented substrates (for increased strength) with improved porosity.

Feasibility of extruding 6-wt.% PBO was demonstrated at laboratory scale.

• Developed an imbibition/pressing fabrication method for processing the ICP/substrate combination into

composite membranes with good proton conductivity and barrier properties.

• MEAs are being developed by industry and Los Alamos National Laboratory (LANL) with the investigation of

electrode structures and corresponding electrode attachment methods.

• Continued single-cell testing of MEAs:

- Demonstrated performance curves similar to those of state-of-the-art perfluorinated membranes.

- Began looking at high-temperature performance and long-term stability of composite MEAs operating in a

fuel cell.

Future Directions

• Continue development of low-cost, high-temperature aromatic-based ICPs that show long-term fuel cell

stability.

• Continue development of improved substrates with microstructure suitable for interpenetrating network

formation:

- Design and build a continuous casting operation to improve substrate quality.

- Continue development of oriented (higher-strength) substrates.

• Continue development of electrode application method(s) and evaluation of their structure in conjunction with

LANL.

• Continue single-cell fuel cell testing, including analysis of fuel cell performance curves to optimize operating

conditions.

Introduction

The objective of this work is to develop a lowcost, high-temperature solid-polymer electrolyte

membrane (HTSPEM) for use in fuel cells. This

advanced membrane is designed to address the

present shortcomings of today’s Nafion-based solidpolymer electrolyte fuel cells (SPEFCs). The

HTSPEM will lower fuel cell cost, improve power

density, reduce sensitivity to carbon monoxide, and

facilitate thermal water management in the hydrogen

fuel stream. The goal of the membrane technology is

to provide a clean, efficient, lightweight, and highdensity power source that will be useful over a wide

range of applications, from next-generation vehicles

to stationary power.
Fuel Cell Power Systems FY 2000 Progress Report

105

Ion-Conducting Polymer Development

The ion-conducting polymer component of the

HTSPEM must satisfy a number of criteria

simultaneously, the most important of which are as

follows:

• Easily synthesized from available, low-cost

starting materials

• Highly water-insoluble and film-forming

• Highly ion-conducting (ionic conductivity

> 0.1 S/cm)

• Chemically stable to acids/free radicals

• Possessing a thermal/hydrolytic stability

temperature > 150 oC

• Surviving in reformate/air fuel cells for 5,000

hours (automotive applications).

During this project, we have evaluated a large

number of sulfonated aromatic polymers produced

in our laboratories and elsewhere. Initial evaluation

of the polymers’ chemical stability (free radical

stability, in particular) was conducted with an

accelerated peroxide screening test. Although

controversial, this test provides some comparative

stability data for potential ICPs. By monitoring the

mechanical changes and the degradation in ion

conductance of a sample in the peroxide test, we can

evaluate an ICP’s utility without having to develop a

composite PEM and corresponding MEA. If the

sample passes the peroxide test, it is likely to

perform well in long-term, high-current-density

single-cell tests. Currently, not much can be said of

ultimate ICP performance if the peroxide test

performance is less than optimal.

Our testing indicates that select aromatic

polymers show promise as fully qualified ICPs for

use in fuel cell applications, with continued

development. This is one of the objectives for an

ongoing Department of Energy (DOE) program for

stationary fuel cells (a project in which long-term

stability and high-temperature operation are primary

goals). For the automotive fuel cell project, we have

developed sulfonated poly(phenyl sulfone)-based

ICPs, utilizing Amoco’s Radel R as a starting point

(see Figure 1). To date, we have completed the

synthesis and scale-up of this ICP, as well as its

incorporation into SPEMs (see discussion of testing,

below).

Microporous Substrate Development

The microporous substrate portion of the

HTSPEM must provide not only mechanical support

for the ICP, but also a porous network, in-plane

dimensional stability, and outstanding barrier

properties. The greater part of this effort has

centered on the development of poly(phenylene

benzobisoxazole) microporous substrates. At FosterMiller, we have previously produced biaxially

oriented films of PBO via a proprietary extrusion

process. In the fully dense state, these films possess:

• Exceptionally high strength and dimensional

stability,

• Superior barrier (gaseous) properties,

• Excellent crease/crack resistance and tear

strength, and

• Superior thermal and hydrolytic temperature

stability (300oC).

We have developed a casting process that yields

microporous PBO substrates with very high

porosity. We have demonstrated that ICPs can be

incorporated into these substrates to provide SPEMs

with outstanding dimensional stability and proton

conductivity equal to or better than that of standard

Nafion films. Samples of these membranes have

been evaluated at Giner, Inc., and at LANL.

In an effort to develop substrates of higher

ultimate strength, allowing for thinner composite

membranes and improvements in long-term stability,

we continue to investigate the extrusion process.

Initial substrates produced via extrusion did not have

a pore volume high enough to allow incorporation of

sufficient ICP. Although proton conduction could be

measured, it was not sufficient for fuel cell

requirements. Several experiments have been

performed to date to establish the feasibility of

extruding the PBO substrate with higher total

porosity. Ultimately, the extrusion process should

provide continuous substrates with both orientation

and sufficient porosity.

Composite Solid-Polymer Electrolyte

Membranes

Composite membranes have been made from

cast substrates and sulfonated poly(phenyl sulfone)

ICP via a solution imbibition process. Control of the
Fuel Cell Power Systems FY 2000 Progress Report

106

Figure 1. Foster-Miller’s composite SPEM consists of a microporous substrate infused with an ion-conducting

polymer. The substrate provides mechanical support, mitigating the properties required of the ion-conducting

portion and controlling the dimensional change of the membrane during hydration. Each of the components

employed in our current version is shown.

substrate porosity and the solution concentration of

the ICP allows us to control the final composition.

Ideally, the minimum ICP content would be used to

achieve sufficient proton conduction, thereby further

limiting fuel crossover and water management

issues. Membranes are characterized for ionexchange capacity, ion conductance, gas

permeability (nitrogen), and dimensional stability.

Some variation occurs in the membrane properties

produced via the batch processing approach

employed to date; in general, however, our

membranes compare favorably with those available

commercially. Significant improvements are seen

specifically in the gas transmission and dimensional

stability (virtually unchanged on hydration).

Membrane Electrode Assembly and SingleCell Testing

Initial evaluations of the composite SPEMs were

performed in an iterative fashion with Giner, Inc., to

allow the refinement of the composite fabrication

techniques and the components. This work proves

the feasibility of the composite concept (see

Figure 2). Giner was able to surpass the performance

of Nafion 112 with several of the Foster-Miller

membranes, using their proprietary electrode and

catalyst attachment methods.

Recently, we have been working with LANL in

an effort to better understand the performance of our

membranes and the techniques needed to attach
Fuel Cell Power Systems FY 2000 Progress Report

107

Figure 2. Comparative single-cell performance of

Foster-Miller’s composite polymer electrolyte

membrane (Tcell = 80oC, 100oC).

catalyst and electrodes. LANL researchers have been

able to make MEAs via modifications of standard

techniques and test them in single-cell fixtures.

Several issues have come to light during their work:

• The composite PEMs developed show very

good conductivity when electrodes are properly

bonded to the surface.

• Aromatic ionomers behave very differently than

commonly used perfluorinated ionomers.

Optimization of catalyst and electrode

attachment methods will require further efforts

with these ionomers.

• The composite membranes of PBO and

sulfonated poly(phenyl sulfone) initially

fabricated (via cast substrates) may require postprocessing to improve their long-term stability.

This project has demonstrated that FMI’s

composite polymer electrolyte membrane (PEM) is a

potentially viable solution for high-temperature

SPEFCs. Although further materials development is

needed for commercial success, we believe this

concept will lead to dramatic advances over current

PEM technology – advances that are necessary to

make fuel cells a viable power source in the future.

Publications and References

1. R. Formato, R. Kovar, P. Osenar, N. Landrau,

and L. Rubin, “Composite Solid Polymer

Electrolyte Membranes,” PCT Application

WO 00/22684.

2. J.E. McGrath, J. Mecham, W. Harrison,

S. Mecham, R. Kovar, and R. Formato,

“Sulfonated Poly(arylene ether)s as Potential

Proton-Exchange Membranes,” Abstracts of

Papers of the American Chemical Society 1999,

Vol. 217, Part 2, p. 342.

3. R. Formato, P. Osenar, R. Kovar, N. Landrau,

and L. Rubin, “Novel Ion Conducting Materials

Suitable for Use in Electrochemical

Applications and Methods Related Thereto,”

PCT Application WO 00/24796.
Fuel Cell Power Systems FY 2000 Progress Report

108

D. Development and Optimization of Porous Carbon Papers Suitable for Gas

Diffusion Electrodes

Gerald J. Fleming, Principal Investigator

Spectracorp Ltd.

599 Canal St.

Lawrence, MA 01840

(978) 682-1232, fax: (978) 682-3253, e-mail: spectragif@aol.com

DOE Program Manager: Donna Lee Ho

(202) 586-2480, fax: (202) 586-9811, e-mail: donna.ho@ee.doe.gov

DOE Program Support: Larry Blair

(202) 586-0626, fax: (202) 586-9811, e-mail: larry.blair@ee.doe.gov

ANL Technical Advisor: James Miller

(630) 252-4537, fax: (630) 252-4176, e-mail: millerj@cmt.anl.gov

Contractor: Spectracorp Ltd., Lawrence, Massachusetts

Prime Contract No. DE-FC02-97EE50474, September 1997-July 2000

Subcontractors: PSI, Andover, MA; Energy Partners, West Palm Beach, FL; and HPower, Clifton, NJ

Objectives

• Reduce cost of polymer electrolyte membrane (PEM) fuel cell stack by optimizing (through cost reduction

and/or improved performance) carbonaceous gas diffusion electrode (GDE).

• Perform manufacturing feasibility analysis on optimized GDE, exploring both optimized batch processing and

continuous processing to reduce costs.

• Manufacture small run of optimized GDEs on production equipment and distribute to Department of Energy

(DOE) partners for commercial evaluation.

OAAT R&D Plan: Task 13; Barrier B

Approach

• Design and manufacture a matrix of carbonaceous GDEs, utilizing varying compositions and manufacturing

techniques (more than 30 variants, including thickness, density, fiber type and length, pore size and distribution,

electrical conductivity).

• Test GDE variants in fuel cells to establish performance with respect to industry standard materials.

• Using fuel cell test results, perform manufacturing cost/benefit analysis to determine optimal GDE material.

• On the basis of cost/benefit analysis, manufacture a small production run of optimized GDEs.

Accomplishments

• GDE matrix was designed and all variants of the GDE were manufactured and tested for physical and electrical

properties, as well as pore size, pore size distributions, and gas flow. These properties were then correlated

(e.g., air flow vs. density, resin content, thickness, and pore size).
Fuel Cell Power Systems FY 2000 Progress Report

109

• Numerous fuel cell testing parameters (stoichiometries, temperatures, humidification levels, pressures,

membranes, electrode treatments) were investigated to obtain a high-performance baseline cell using current

state-of-the-art papers.

• Initial cell screening demonstrated very strong performance by several low-cost variants; nonperforming

variants were eliminated.

• Combinations of the most promising material variants were produced to explore the limits of potential cost

reduction while maintaining excellent cell performance.

• The most promising materials from initial cell screening were retested in short stacks and longer-term single

cells to establish reproducibility.

• The lowest-cost, best-performing GDE variant was manufactured on production equipment and is available for

evaluation by DOE partners.

• Optimized batch and continuous manufacturing processes are being examined, and proof-of-concept samples

have already been produced for several manufacturing steps.

Future Directions

• Distribute optimized GDE to DOE partners for commercial stack evaluation.

• Complete large-volume manufacturing analysis.

• Explore possibility of manufacturing GDE material by means of optimized manufacturing equipment and

processes.

Introduction

This program seeks to optimize the physical

structure of porous carbon papers for use as gas

diffusion electrodes in membrane electrode

assemblies (MEAs) for fuel cells. This optimization

is directed toward maximizing cell and stack

performance with regard to such characteristics as

mass transport (H2O removal) and appropriate

electrical conductivity, while reducing costs

(e.g., with current state-of-the-art materials).

Our work in the current fiscal year (FY2000) has

focused on completing fuel cell screening tests of the

GDE matrix, retesting the most promising GDE

variants to demonstrate reproducibility, analyzing

large-volume GDE manufacturing processes, and

manufacturing the optimized GDE for distribution to

DOE partners for commercial stack testing.

Approach

The initial fuel cell screenings conducted in

FY1999 produced promising results with low-cost

materials that were well suited to high-volume

and/or continuous production. In FY2000, we sought

to establish more robust test conditions that would

provide reproducible results on industry standard

materials so that subsequent tests on GDE matrix

materials would be viable. Once the baseline was

established and reproducible results were produced,

we would analyze the data, incorporate them into a

production analysis for the leading GDE variants,

and manufacture a batch of the lowest-cost, bestperforming GDE variant on existing production

equipment. The possibility of continuously

manufacturing the optimized GDE would then be

explored.

Results

In FY2000, we worked with several fuel cell

manufacturers to ensure stable performance on

industry standard baseline materials. During the

course of this work, we determined that we would

have to sacrifice some raw fuel cell performance in

order to obtain reproducible results across the broad

range of GDE variants. As a result, the polarization

curves presented this year display a 5-10% voltage

reduction at a given current with respect to some of

the curves presented in FY1999. Raw performance

was sacrificed solely to achieve the program’s

purpose of evaluating variations in the GDE under

similar cell conditions; the results do not reflect the

GDE’s potential in an optimized cell. After several

cell test modifications, we reproduced the results

with low-cost materials and with some of the more

promising GDE variants. The curves demonstrate
Fuel Cell Power Systems FY 2000 Progress Report

110

comparable performance for lower-cost and industry

standard GDE materials.

Figure 1 shows cell voltages at discrete

amperages for several materials that were tested in a

13-cell short stack. The low-cost Spectracorp variant

is equal to or better than the industry standard

material at the high voltages that many companies

are utilizing for high efficiencies, and it comes close

to matching the industry standard material at lower

voltages. Figure 2 shows the performance of the

low-cost Spectracorp material versus that of industry

standard materials across the full polarization curve.

A polarization curve obtained with the low-cost

material from a previous screening using an

optimized cell is also shown to demonstrate the

potential performance of the low-cost material.

These figures demonstrate that the low-cost

Spectracorp material can match the performance of

current state-of-the-art GDE materials.

Figure 1. Representative gas diffusion electrode

performance at discrete amperages.

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.4 0.8 1.2 1.6

C urrentDensity (A/cm 2

)

Cell Voltage

Spectracorp Low -C ost

Spectracorp Std.

Industry Std.

Spectracorp Low -C ost(optim ized

cell)

Figure 2. Comparative polarization curves for low-cost

gas diffusion electrode.

On the basis of these results, we were able to

begin a manufacturing feasibility analysis, including

some preliminary processing trials, on a largevolume, continuous manufacturing process for lowcost GDE. We also completed a manufacturing run

on the low-cost GDE material, utilizing a batch

process on production equipment.

Conclusions

We have demonstrated that it is possible to

manufacture a high-performance, carbon-paperbased GDE material at a much lower cost than that

of existing materials. Our initial projections indicate

that commercial pricing for the new material should

be less than $10/m2

, compared with $20/m2 or

higher for existing materials. In addition, the GDE

developed in this program is well suited to

continuous production leading to a roll product,

which is essential for large-volume production of

multilayer MEAs. Following initial evaluation of the

batch-manufactured GDE resulting from this

program, we will continue to work with DOE fuel

cell stack partners in order to accelerate the

transition to continuous commercial-scale

production.
Fuel Cell Power Systems FY 2000 Progress Report

111

E. Electrodes for PEM Operation on Reformate/Air

Thomas A. Zawodzinski (primary contact), Francisco Uribe, Jayson Bauman, Tommy Rockward,

Paul Mombourquette, Markus Vogt, Thomas Springer, Judith Valerio, David Verson, and

Shimshon Gottesfeld

Los Alamos National Laboratory

Electronic and Electrochemical Materials and Device Research Group

Los Alamos, New Mexico 87545

(505) 667-0925; fax: (505) 665-4292; e-mail: zawod@lanl.gov

DOE Program Manager: JoAnn Milliken

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

Objectives

To achieve maximum performance in polymer electrolyte fuel cells (PEFCs) under conditions appropriate for

reformate/air operation and with methods that allow cost and efficiency targets to be met for transportation.

OAAT R&D Plan: Task 13; Barrier A

Approach

We seek to develop an understanding of electrocatalysis and transport issues related to cathode performance and to

use this understanding to guide the development, testing, and demonstration of improved electrodes. To approach

requirements for anode performance, we test single cells under conditions of steady-state and transient exposure to

various levels of CO, focusing especially on conditions appropriate for off-design conditions of the fuel processor

(such as during system start-up). This latter work exploits the ever-increasing levels of CO tolerance achieved.

Through applied R&D, we seek to achieve the following cell characteristics simultaneously:

• Highest possible performance at 0.8 V.

• Minimal air injection for CO cleanup.

• Minimal catalyst loading.

• Minimal losses due to dilution at high fuel utilization.

Accomplishments

• Cathode Performance: The cell performance at 0.8 V was studied. Improvements, relative to performance

obtained at steady state in cells using Pt, were obtained with different alloy catalysts and using low-duty-cycle

pulsing of the cell voltage to lower voltages.

- Demonstrated stable operation of cell yielding 0.4 A/cm2

 @ 0.8 V (on H2).

- Dependence of performance on catalyst loading indicates utilization problem.

- Implementing studies of radically different electrode structures.

- Completed studies of a series of alloy catalysts, including stability assessment.

• CO Tolerance: Achieved reduction in both precious-metal loading (to 0.1 mg/cm2

) and in air bleed (none for

100 ppm) since last review (different cells).

- New, reconfigured membrane electrode assembly (MEA) allows us to tolerate 100 ppm in reformate with

only 0.1 mg/cm2

 of catalyst (with air bleed).

- New catalysts with reconfigured anode allow full tolerance to 500 ppm in reformate with <5% air bleed,

using 0.3 mg/cm2

 anode catalyst (tested for 100 hours), and improved transient behavior for system start-up

conditions; 50 ppm in reformate, sometimes higher, was tolerated without air bleeding.

- Completed combined poisoning/dilution model.
Fuel Cell Power Systems FY 2000 Progress Report

112

• System Start-up: Tests exploiting improved catalysts to assess effects of severe poisoning.

Future Directions

• Cathode Work: Overall goal of increasing achievable current density at 0.8 V.

- Improve cathode catalysts.

- Vary catalyst layer and backing compositions to improve hydration.

- Experiment with elevated-temperature operation/alternative hydration methods.

- Investigate catalyst layer with controlled nanostructures.

• Anode Work: Overall goal of minimizing effects of dilution and CO.

- Improve anode catalysts, reconfigure anodes and effectiveness of air injection for ever higher CO

tolerance.

- Improve catalyst layer composition to further minimize dilution effects, increase fuel utilization.

- Improve start-up.

• New Activity on High-Temperature Membranes.

• Practical Studies of Critical Impact

- MEA durability issues: accelerated life test protocols, “brute force” testing, materials evolution modeling.

- Break-in effects.

- New MEA fabrication approaches.

• Diagnostics

- Complete segmented cell development; make design/specs available to companies; implement additional

probes for local temperature etc.

- Devote increased attention to diagnosing long-term performance limitations.

• Industrial Interactions

- Extensive, direct interaction with industrial partners to implement best strategies in stacks.

- Continue MEA development with outside parties.

- Implement Web site to allow rapid updating of DOE partners on current work, receive “instant feedback.”

Introduction

The requirements for overall PEFC performance

include operation under conditions of maximum fuel

utilization efficiency, as well as the best possible

performance using gasoline-derived reformate.

These requirements are tightly coupled; the former

entails higher cell voltages, and thus some focus on

the PEFC cathode, while higher cell voltages may

also provide some “relief” in the context of the

stringency of the CO tolerance requirements. As the

targets for CO tolerance have been met or exceeded,

the focus of this project has shifted to increased

emphasis on achieving improved cathode

performance at high cell voltages.

Cathode Performance

To meet efficiency requirements for operation

with reformed gasoline, the cathode performance

must be improved at high cell voltages. Our

investigation of this problem has included several

studies.

We began with a study of the relative oxygen

reduction reaction (ORR) activity of various alloy

catalysts in the cell (see Figure 1). So far, PtNi and

0.7

0.75

0.8

0.85

0.9

0.95

0 0.2 0.4 0.6 0.8 1

Pt-Ni

Pt-Cr

Pt

Cell Voltage, V

Current Density, A cm-2

Figure 1. Polarization curves for a series of different

cathode catalysts.
Fuel Cell Power Systems FY 2000 Progress Report

113

PtCr cathode catalysts have been the most active.

We were able to achieve our target of 0.4 A/cm2

 @

0.8 V on hydrogen. These experiments were carried

out in 5-cm2

 cells. Scaling up such results is often

difficult. We employed the highly active PtCr alloy

catalyst in 50-cm2

 cells; Figure 2 shows a typical

polarization curve obtained with such a cell.

Operation at high cell voltages necessarily

implies operating with little water production at the

cathode. We had previously shown that dry

conditions lead to poorer ORR kinetics. Figure 3

shows the decline in steady-state current with time

after changing the cell voltage from 0.6 to 0.8 V. We

tried to overcome this problem by “pulsing” the cell

to lower voltages, thus generating more water. The

results of such an operation mode, with a 1% duty

cycle at the lower cell voltage, are also shown in

Figure 3. Clearly, the application of such a pulse

provided improved steady-state performance. The

nature of the improvement is under investigation.

Our ability to achieve 100 hours of stable cell

operation with neat H2 at 0.8 V, 0.4 A/cm2 at 80o

C

meets the target for our fiscal year (FY) 2000 (June)

milestone. By September of FY 2000, we seek to

extend that targeted operation to a cell employing

reformate feed to the anode.

Further work was carried out to assess, on a

more fundamental level, the utilization of the

cathode catalyst. The key finding of this work was

that, given our catalyst layer preparation method,

there appears to be a limit to how much catalyst is

actually accessed; our current estimate is that this

amount is less than 40%.

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.2 0.4 0.6 0.8 1

Cell Current, A cm-2

Cell Voltage, V

Figure 2. Polarization curve for a 50-cm2

 cell, using a

PtCr alloy catalyst on the cathode.

0

100

200

300

400

500

0 20 40 60 80 100

Current, mA cm-2

Time, hours

Figure 3. Bottom curve: response of the cell with time

after changing the cell voltage from 0.6 to

0.8 V; top curve: effect of pulsing the cell

voltage between 0.8 V (99% of the time) and a

lower voltage (1%).

CO Tolerance

In Figure 4, we show results from a 500-hour

life test of a 50-cm2

 cell, demonstrating tolerance to

100 ppm CO in simulated reformate (meeting our

February 2000 milestone). We also met our

July 2000 goal of 100 hours of stable performance at

500 ppm CO in reformate with an advanced PtRu

catalyst.

We continued to progress toward the

simultaneous goals of enhanced CO tolerance with

minimal air injection and catalyst loading. We

showed that certain new catalysts allowed us to

approach a high level of tolerance to 500 ppm CO

(see Figure 5). In short-term tests, we can

simultaneously lower the catalyst loading to

0.1 mg/cm2

 and achieve complete tolerance to

100 ppm CO with <4% air bleed.

In another set of tests, we have continued our

work on the effects of transient excursions in CO

levels, which are typical of nonsteady-state reformer

operation. Perhaps the most technologically

significant result is our finding that injection of air

can dramatically improve the recovery from large

excursions in CO level. Recovery under such

conditions was sluggish without air injection.

We capitalized on the high level of CO tolerance

to begin simulating start-up conditions. As shown in

Figure 6, even small amounts of air injection can

yield tolerance to high levels of CO. Without air
Fuel Cell Power Systems FY 2000 Progress Report

114

100 ppm CO in Reformate + 4% Air

A: 0.5mg Pt/cm2, Reconfigured Anode

C: 0.3 mg Pt/cm2

, Single-Sided E-TEK V2.22

0

10

20

30

40

50

0 200 400 600

Time, hours

Cell Current, A

H2 @ 1.5 stoich

N1135, 50cm2

Cell Temp: 80 oC

Pressure:30/30 PSIG

500 hrs.

Figure 4. Life test of cell with reconfigured anode,

exposed continuously to 100 ppm CO in

simulated reformate. (Air bleeding [4%] was

used in this cell to achieve complete CO

tolerance during the life of the test.)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Current Density, A/cm2

Cell Voltage, V

Neat H2 : 1.5 stoich

Ref. No CO (400 sccm H2, fixed)

Ref. + 500 ppm CO + 4% air (400 sccm H2, fixed)

 N1135 , 30/30 psig , T cell/H2/air: 80/105/80 oC

 A: 0.21 mg Pt + 0.19 mg Pt/cm2

 , C: 0.21 mg Pt/cm2

Figure 5. Polarization curves showing combined effects

on new catalyst and reconfigured anode,

providing near-complete tolerance to 500 ppm

CO in reformate.

24

26

28

30

32

34

36

38

0 500 1000 1500 2000 2500 3000 3500 4000

Time (s)

Current (A)

CS E 4% Air

CS E 2% Air

CS E 0% Air

500 ppm

5 ppm

A: 0.36 mg Pt/cm 2 , 60% PtRu, Single-Sided E-TEK

C: 0.23 mg Pt/cm2 , 44% Pt3 Cr, Double-Sided E-TEK

H2 @ 1.3 stoich for 1 A/cm2

N1135, 50 cm 2

Cell Temp: 80 o C

Pressure: 30/30 PSIG

Figure 6. Response of cell to a simulated start-up; the CO level in reformate was

systematically decreased from 500 ppm to 50 ppm (75 ppm per minute),

then to 5 ppm (15 ppm per minute).

bleeding, it is difficult to achieve full recovery of the

cell, even with as little as 5 ppm CO left in the feed

stream.

Summary

During FY 2000, we made significant progress

toward our R&D goal of improved performance at

high cell voltages while operating on reformate/air

feeds. We demonstrated that we could achieve stable

performance of 0.4 A/cm2

 at 0.8 V with neat

hydrogen as a fuel. Although we need to lower the

required catalyst loading and operate on reformate,

this does represent a substantial first step on the road

to simultaneously achieving acceptable performance

and high-voltage efficiency. We have also advanced

our understanding of limiting factors in cathode

performance.

We took advantage of newly available, highly

CO-tolerant catalysts to demonstrate a substantial

increase in the level of CO that we could accept in

reformate. We also capitalized on that high level of

tolerance and started to investigate how we could

make the system performance more robust in the

face of increased CO levels during start-up or
Fuel Cell Power Systems FY 2000 Progress Report

115

transient phases of operation. Also, we further

advanced fundamental understanding of the anode

performance by completing and submitting for

publication a paper describing combined

experimental and modeling studies of the anode.

Finally, we are adopting a more proactive

approach to interacting with industry and

universities to transfer technology from this program

as efficiently as possible.

F. New Electrocatalysts for Fuel Cells

P.N. Ross, N.M. Markovic, T.J. Schmidt, and V. Stamenkovic

Materials Sciences Division, Lawrence Berkeley National Laboratory

University of California, Berkeley, CA 94720

(510) 486-6226, fax: (510) 486-5530, e-mail: pnross@lbl.gov

DOE Program Manager: JoAnn Milliken

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

Objectives

Understand the kinetics and mechanism of electrode reactions in low-temperature fuel cells. Develop new

electrocatalysts, using materials-by-design approach.

OAAT R&D Plan: Task 13; Barrier A

Approach

• Study the kinetics of fuel cell electrode reactions on well-characterized model electrodes and high-surface-area

fuel cell electrocatalysts, using modern electroanalytical methods.

• Study the mechanisms of the reactions, using state-of-the art in-situ spectroscopes.

• Use ultra-high vacuum (UHV) methods of surface preparation and surface analyses to form tailored surfaces.

Synthesize nanoclusters to have the tailored surface.

• Characterize the microstructure of the nanoclusters by high-resolution electron microscopy.

• Transfer technology to catalyst developers/vendors.

Accomplishments

• Development of Pd-based (Pd-Au) CO-tolerant anode electrocatalysts that are three times more active for

electrooxidation of CO/H2 mixtures than is Pt-Ru.

• Elucidation of the reaction mechanism for the “cleansing” of CO adsorbed on Pt and platinum-based alloy

surfaces by air bleeding.

• Establishment of the oxygen reduction activity/stability on Pt3Ni and Pt3Co bulk alloys and high-surface-area

catalysts.

Future Directions

Anode side:

• Determine the optimal surface composition of Pd-Au catalysts for CO tolerance.
Fuel Cell Power Systems FY 2000 Progress Report

116

• Determine CO tolerance of tailored electrodes consisting of thin films, 1-10 monolayers (ML) in thickness, of

Pd on the close-packed single-crystal surfaces of Ta, Re, and W.

Cathode side:

• Optimize PtNi and PtCo catalysts for the oxygen reduction reaction (ORR).

• Pursue Pt-skin structures as novel air cathode electrocatalysts and determine the stability of alloying elements.

• Develop new class of Pt-free catalysts for the ORR.

LBNL’s activities during the past fiscal year are

described here in terms of two main task areas.

CO-Tolerant Anode Electrocatalysts Based

on Bulk Pd Alloys

Using a materials-by-design approach, we found

that it is possible to replace one of the best COtolerant Pt-based catalysts (Pt-Ru) with new, Pdbased bimetallic catalysts (Pd-Au). We chose to test

Pd catalysts because Pd has catalytic properties very

similar to those of Pt with respect to the hydrogen

oxidation reaction (HOR), but it is more oxophilic

than Pt. The latter property may facilitate the

oxidative removal of CO at lower potentials than on

Pt. Although the HOR kinetics of Pt and Pd are

similar, the extraordinary ability of a pure Pd

electrode to absorb large amounts of hydrogen into

the bulk necessitates restricting the negative limit of

Pd to ≈ 0.3 V with respect to the reversible hydrogen

electrode (RHE) (see upper panel of Figure 1).

Consequently, the bulk Pd electrode cannot be used

as anode material for the HOR at potentials relevant

for fuel cell applications.

Recently, we have explored the possibility of

creating Pd electrocatalysts with the ability to

suppress the absorption of hydrogen into the Pd

lattice, while keeping Pd activity for the HOR and

CO electro-oxidation at relatively low potentials. In

the hope that combining Pd with different metals

would yield superior activity and stability relative to

the pure Pd metal, we studied the electro-oxidation

of potential fuels for fuel cells on different Pd

bimetallic alloys and thin metal films of Pd

deposited on early-period transition metals. Of the

various systems examined, we found bimetallic PdAu alloys of particular interest because these

systems exhibited both high resistance toward the

absorption of hydrogen and significant catalytic

enhancement for the electro-oxidation of hydrogen

in the presence of CO. The upper panel of Figure 1

shows that hydrogen absorption is suppressed on the

E [V/RHE]

0.0 0.2 0.4 0.6 0.8 1.0

i [mA/cm2

]

-1

0

1

2

-0.10

-0.05

0.00

0.05

0.10

Pd45Au55

Pd80Au20/Vulcan

250ppm CO/H2

Pt50Ru50/Vulcan

Pd

333 K

0.5 M H2SO4

298 K

no Habsorption

Habsorption starts here

particle size [nm]

0 2 4 6 8 10 12 14 16

[%] 0

2

4

6

0.1 6.3 ± 2.8 nm

PdAu

Figure 1. Upper panel: Base CV for Pd45Au55 and pure

Pd bulk electrodes. Lower panel: Base CV for

Pd80Au20/Vulcan electrode and polarization

curves for oxidation of 250-ppm CO/H2 on

Pd80Au50/Vulcan and Pt50Ru50/Vulcan at 333

K. Inset: Particle size distribution of the

Pd80Au20/Vulcan catalyst via HRTEM.

Pd-Au alloy with surface composition of 55 at% Au,

presumably because the electronic properties of Pd

are modified by Au.

The electrocatalytic properties of a Vulcansupported Pd-Au electrocatalyst with bulk

stoichiometry of Pd80:Au20 were investigated by

means of the thin-film rotating disk electrode (RDE)

method. In the base cyclic voltammetry (dotted

curve), two potential regions can be distinguished:

The potential region of hydrogen adsorption

(0.1<E<0.35) is followed by the double-layer region,

up to 0.75 V. The similarity of the voltammetry for

the bulk electrode and a high-surface-area catalyst is

striking and important, because the cyclic

voltammetry (CV) of the bulk alloys (see above) has

established an “alloy fingerprint” for the Pd-Au
Fuel Cell Power Systems FY 2000 Progress Report

117

system. The polarization of the anode with a

250-ppm CO/H2 mixture (open circles) at 60°C is

used to measure the CO tolerance of Pd-Au alloy at

a particle size of ca. 6 nm (see inset). The findings

are compared with previous results for Pt-Ru alloy

(closed circles). Interestingly, high current densities

can be reached at low potentials on the Pd-Au alloy

(e.g., 73 and 206 mA/mg metal at 0.05 and 0.2 V,

respectively). Compared with Pt-Ru, the Pd-Au

alloy exhibits three times higher catalytic activity, a

very promising result for the practical application.

The mechanism of action of the Pd-Au electrode

during electrooxidation of the H2/CO mixture may

be ascribed to electronic effects, where inactive Au

atoms alter the electronic properties of the

catalytically active Pd atoms. To summarize, the PdAu system is a new class of CO-tolerant catalysts,

where the adsorption energy of CO on Pd-Au is

reduced with respect to pure Pd. Oxidative removal

of CO from Pd sites is thus enhanced, allowing

hydrogen oxidation to take place on freed Pd sites.

Testing of Prototype Pt Alloy Air Cathode

Electrocatalysts

For phosphoric acid fuel cells (PAFCs), Pt-alloy

cathode catalysts (e.g., PtNi and PtCo) were found

to improve the gas diffusion electrode’s

performance. Recent work on polymer electrolyte

membrane fuel cell (PEMFC) cathode catalysts has

indicated similar effects, but the magnitude of this

effect is still unclear. It is not yet known whether

these materials are stable under PEMFC conditions

or whether the leaching of alloy components may

lead to ionomer contamination. For the

unambiguous determination of the intrinsic catalytic

activity of Pt3Ni and Pt3Co, we use the rotating ringdisk method (RRDE) with model bulk alloys and the

thin-film RRDE method for the carbon-supported

fuel cell catalysts. Using these techniques, the

intrinsic catalytic activity of electrocatalysts can be

assessed in the absence of mass transport resistance,

which occurs in membrane electrode assemblies

(MEAs). Figure 2 summarizes our preliminary

results for the ORR on UHV prepared and

characterized bulk Pt3Ni and Pt3Co alloy catalysts.

Pure Pt is also shown as a reference. The figure also

shows that the activity increases at 333 K in the

order Pt3Ni>Pt3Co>Pt, the catalytic activity of Pt3Ni

alloy being ca. 25 mV improved with respect to the

ORR on pure Pt. We found that Pt alloys were stable

i

k [mA/cm2

]

0.1 1 10 100

E [V/RHE]

0.6

0.7

0.8

0.9

E [V/RHE]

0.0 0.2 0.4 0.6 0.8 1.0

xH2O2 [%]

0

2

4

6

8

Pt3Ni

Ptpc

Pt3Co

0.5 M H2SO4

1600 rpm, 333 K

Figure 2. Upper panel: Tafel plots for the ORR on

polycrystalline Pt, Pt3Ni, and Pt3Co bulk

electrodes, respectively. Lower panel:

Fraction of peroxide produced during the ORR

on these electrodes.

under our experimental conditions. Figure 2 also

shows that similar small amounts of peroxide are

detected on the ring electrode on all three surfaces.

This may imply that the reaction mechanism on

Pt3Ni and Pt3Co alloy surfaces is the same as one

proposed for pure Pt. The kinetics of the ORR on

high-surface-area Pt3Ni and Pt3Co catalysts prepared

by ETEK is very similar to that observed on the bulk

electrodes. Although the difference in activity

between pure Pt and Pt3Ni-supported catalysts is

rather small (ca. 20 mV), confirmation of the high

activity of Pt3Ni catalysts may offer the possibility

of decreasing the amount of Pt in air cathode fuel

cell catalysts.

In research directed toward improved air

electrodes for fuel cells, we had sought to utilize

what we termed a “skin effect” to produce a more

active state of Pt for the ORR. The skin effect arises

from strong Pt surface segregation in Pt3Ni and
Fuel Cell Power Systems FY 2000 Progress Report

118

Pt3Co alloys (i.e., a monolayer “skin” of Pt, the

second layer being nearly pure Co and Ni).

Preliminary studies of the oxygen reduction activity

and stability of the skin structure on Pt3Co and Pt3Ni

bulk alloys indicate that the Pt “skin” is not stable at

relatively high potentials (E > 0.6 V vs RHE).

Consequently, the skin structure of Pt3Co and Pt3Ni

cannot be used as a cathode material for the ORR at

potentials relevant for fuel cell applications. Studies

of other possible “skin effect” bimetallic systems are

in progress.

Publications

1. N.M. Markovic, B.N. Grgur, C.A. Lucas, and

P.N. Ross, “Surface Chemistry of CO on

Pt(100)-Bimetallic Surfaces: Displacement

Effects,” Langmuir, 16:1998 (2000).

2. N.M. Markovic, C.A. Lucas, B.N. Grgur, and

P.N. Ross, “Surface Electrochemistry of CO and

H2/CO Mixture at Pt(100) Interface: Electrode

Kinetics and Interfacial Structures,” J. Phys.

Chem.,103:9616 (1999).

3. N.M. Markovic, T.J. Schmidt, B.N. Grgur, H.A.

Gasteiger, R.J. Behm, and P.N. Ross, “The

Effect of Temperature on Surface Process at the

Pt(111)-Liquid Interface: Hydrogen Adsorption,

Oxide Formation, and CO Oxidation,” J. Phys.

Chem., 103:8568 (1999).

4. C.A. Lucas, B.N. Grgur, N.M. Markovic, and

P.N. Ross, “Structural Effects during CO

Adsorption on Pt-Bimetallic Surfaces: The

Pt(100) Electrode,” Surf. Sci., 448:77 (2000).

5. C.A. Lucas, N.M. Markovic, and P.N. Ross,

“Structural Effects during CO Adsorption on PtBimetallic Surfaces: The Pt(111) Electrode,”

Surf. Sci., 448:65 (2000).

6. S. Baldelli, N. Markovic, P. Ross, Y-R Shen,

and G. Somorjai, “Sum Frequency Generation

of CO on (111) and Polycrystalline Platinum

Electrode Surfaces: Evidence for SFG Invisible

Surface CO,” J. Phys. Chem., 103:8920 (1999).

7. V. Climent, N.M. Markovic, and P.N. Ross,

“Kinetics of Oxygen Reduction on an Epitaxial

Film of Palladium on Pt(111),” J. Chem Phys.

104:3116 (2000).

8. N.M. Markovic and P.N. Ross, “Electrocatalysis

by Design: From the Tailored Surface to a

Commercial Catalyst,” review article,

Electrochim. Acta, in press.

9. N.M. Markovic and P.N. Ross, “New

Electrocatalysts for Fuel Cells: From Model

Surfaces to Commercial Catalysts,” review

article, Cattech, in press.

Book Chapter

1. N.M. Markovic and P.N. Ross.,

“Electrocatalysis at Well-Defined Surfaces,” in

Interfacial Electrochemistry, Theory,

Experiment, and Applications. A. Wieckowski,

Ed., Marcel Dekker, Inc., New York, Chapter 46

(1999), p. 821.

Other Publications

1. “Fuel Cell Reactions on Well-Characterized

Catalysts,” 3rd International Symposium on

New Materials for Electrochemical Systems,

Montreal, Canada, July 1999. Extended abstract,

pp. 64-67.

2. “Electrocatalysis by Design: From Atomic Level

Structures to High Surface Area Catalysts,” 3rd

International Symposium on Electrocatalysis,

Portoroz, Slovenia, September 1999. Extended

Abstract, pp. 49-51.

3. “Electrocatalysis on Well-Characterized

Bimetallic Catalysts,” Workshop on Direct

Methanol Fuel Cells, Portoroz, Slovenia,

September 1999. Extended Abstract, pp. 63-65.
Fuel Cell Power Systems FY 2000 Progress Report

119

G. Development of a $10/kW Bipolar Separator Plate

Leonard G. Marianowski (primary contact)

Institute of Gas Technology (IGT)

1700 South Mount Prospect Road

Des Plaines, IL 60018

(847) 768-0559, fax: (847) 768-0916, e-mail: marianow@igt.org

DOE Program Manager: Donna Lee Ho

(202) 586-8000, fax: (202) 586-9811, e-mail: donna.ho@ee.doe.gov

DOE Program Support: Larry Blair

(202) 586-0626, fax: (202) 586-9811, e-mail: larry.blair@ee.doe.gov

ANL Technical Advisor: Walter Podolski

(630) 252-7558, fax: (630) 972-4430, e-mail: podolski@cmt.anl.gov

DOE Contractor: Institute of Gas Technology, Des Plaines, Illinois

Prime Contract No. DE-FC02-97EE50477, November 1998-June 2001

Subcontractors: PEM Plates, LLC, Elk Grove Village, IL 60007; Stimsonite Corporation, Niles, IL 60714; Superior

Graphite Corporation, Chicago, IL 60638; and Honeywell, Inc., Torrance, CA 90504

Objectives

• Develop a low-cost molded graphite bipolar separator plate for polymer electrolyte membrane (PEM) fuel cells.

• Evaluate the IGT-molded graphite bipolar separator plate’s performance and endurance in fuel cell stacks.

• Build a pilot production molding line with capacity of five plates per hour at PEM Plates, LLC, to evaluate

mass production of molded plates.

OAAT R&D Plan: Task 13; Barrier B

Approach

• Select, blend, and optimize inexpensive raw materials for necessary electrical, chemical, and physical properties

of bipolar separator plates for a $10/kW manufactured target cost.

• Design, build, and operate the five-plate-per-hour (5-plate/hr) pilot production molding line at PEM Plates,

LLC.

• Produce molded bipolar plates from the pilot line for the IGT and Honeywell fuel cell stack tests.

• Assemble fuel cell stacks at IGT to establish the functional performance and endurance of molded plates in

stack environments.

• Honeywell, Inc., will assemble and test molded plates from PEM Plates in a fuel cell stack and compare

performance against a machined graphite stack.

Accomplishments

• Electrical, chemical, and physical property targets were met or exceeded with an optimized blend of

components, in laboratory tests and single-cell tests.

• Fuel cell performance was within 5% of that of state-of-the-art, machined graphite fuel cells in side-by-side

tests.
Fuel Cell Power Systems FY 2000 Progress Report

120

• A 5-plate/hr pilot molding production line facility (with equipment) was built and produced plates for testing at

IGT and Honeywell, plus samples for several fuel cell stack developers.

• IGT tested performance of molded bipolar plates produced by PEM Plates in multiple fuel cell stacks of 4, 7,

20, and 52 cells, in both continuous and intermittent operation modes.

• The first 20-cell IGT fuel cell stack using plates produced by PEM Plates operated over 2,300 hours, with

excellent plate performance. Extended life testing of the molded plates was accomplished by reuse in

subsequent fuel cell stacks; some plates exceeded 5,000 hours of operation.

• Operational functionality of the molded plates was determined in multi-cell fuel cell stacks for heat

management, sealing, stacking stability, and water management.

• Several fuel cell developers confirmed the excellent properties of PEM Plates’ samples.

• $10/kW cost target is within reach with a separator plate materials cost of $4/kW; however, manufacturing

costs at $6/kW are dependent upon details and complexity of the bipolar plate design.

Future Directions

• Design and build the higher-capacity, pre-commercial molding line, incorporating process improvements.

• Continue discussions with commercial fuel cell stack developers to supply molded separator plates.

Introduction

The U.S. Department of Energy (DOE)

sponsored a program with the Institute of Gas

Technology to develop a molded composite graphite

bipolar plate that would be inexpensive and perform

as well as state-of-the-art, machined graphitized

bipolar plates. IGT and its subcontractors, Superior

Graphite Corporation and Stimsonite Corporation,

identified moldable blends of graphites, resins, and

additives and produced a molded composite graphite

bipolar separator plate that is equivalent in function

and performance to state-of-the-art, machined

graphite plates.

Applications for patents for the blended

components and the process have been submitted.

PEM Plates, LLC, was formed to commercialize the

production of the molded graphite bipolar separator

plates. Material and production costs for commercial

quantities of the plates are estimated to be on the

order of $10/kW; however, manufacturing cost

depends on the complexity of the design of the

bipolar plate and fuel cell stack.

A variety of different designs of anode and

cathode gas flow channels, with water cooling

channels, have been molded (i.e., molded directly to

net shapes, with no post-molding finishing or

machining steps). No reasonable geometric or shape

limitations have been encountered, so most cell

design configurations are possible. Also, because the

molded plates exhibit some degree of inherent

flexibility combined with sufficient strength, thinner

plates are possible (compared with the plates

machined from graphitized carbon).

Results

Molded Bipolar Plate Tests

The molded graphite plates have been tested

over the past two years at IGT and also evaluated by

other fuel cell stack developers. Numerous out-ofcell tests have measured electrical, chemical, and

physical properties. Extensive single-cell tests of the

plates have shown consistent performance in excess

of 5,000 hours. The molded plates have been

successfully scaled up from lab-size 60-cm2

 active

area to the full-size DOE vehicular specification of

300-cm2

 active area. Figure 1 compares the

hydrogen-air performance at atmospheric pressure of

a single cell with molded graphite flow field plates

to that of a cell with an identically machined flow

field in POCO graphite plates. The performance

with the molded plates is within 5% of that with the

POCO plates at a typical current density of

400 mA/cm2

. However, at higher currents, the

performance is better because the hydrophilic nature

of the IGT composition aids the removal of product

water.
Fuel Cell Power Systems FY 2000 Progress Report

121

911

803 767 740 718 680

639

567

391

193

911

371

460

510

610

654

757 727 700

567

795

0

200

400

600

800

1000

1200

0 100 200 300 400 500 600 700 800 900

Current Density (mA/cm2)

Performance (mV) 

Constant Flow

Fuel H2 = 1.2 Stoic. (366 cc/min)

Oxidant air = 2.0 Stoic. (1447 cc/min)

@800 mA/cm2

Tcell = 60°C

Anode Vapor = 29°C 

Cathode Vapor = 60°C

Pcell=1/1 atm.

Operating Time = 244 hours

Machined POCO Graphite

IGT Molded Composite 

Pl t

Figure 1. Comparison of molded graphite cell to

machined graphite cell.

Tests of the molded plates in a wellinstrumented, 300-m2

, 20-cell water-cooled stack

were conducted for over 2,300 continuous hours (see

Figure 2). This demonstrated the endurance of the

plates with active thermal management in the

300-cm2

-size stacks with the use of water cooling.

Stack testing was conducted mostly in a continuous

operation mode of 24 hr/day and 7 days/week, but

some tests were also conducted in daily cycles of

8 hours on and 16 hours off, allowing the stack

plates to cool and then be reheated each day. In both

test modes, the molded plates maintained their

integrity, and the fuel cell stack performance was

equivalent to that of stacks made with machined

graphite plates. Post-test chemical analysis and

physical measurements indicated a stable plate

composition, with no change in measured properties.

Results of tests of the molded plates operating in

fuel cells at various pressures from one to three

atmospheres showed that gas sealing and water

cooling were accomplished. Figure 3 shows a

variety of multi-cell stacks tested, from 7 to 52 cells.

Measurements of Specific Plate Properties

The DOE-specified requirements for

conductivity, corrosion, and permeability have been

met or exceeded, as indicated in Table 1. In addition,

other property assessments of the molded plates that

are important in the operation and structure of a fuel

cell stack were made by IGT. These included

measurements and investigations of crush strength,

strength within stacks and during handling, and

elastic and permanent creep; water uptake; chemical

leachability; cyclic immersion in boiling water

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

0 250 500 750 1000 1250 1500 1750 2000 2250

TIME, hrs

STACK VOLTAGE

20-Cell Stack 

Molded Bipolar Plates

300 cm2

 Active Area

Temperature: 60o

C

Pressure: Ambient

Fuel: H2 @ 1.6 Stoics

Oxidant: Air @ 4.0 Stoics

Current Density: 400 mA/cm2 

Figure 2. Life test of IGT 20-cell molded bipolar plate

fuel cell stack.

Figure 3. Fuel cell stacks of 7, 20, and 52 cells.

Table 1. Molded plate properties: DOE target values

plus IGT measurements.

Plate Property Measured Value

DOE Specified Properties

Conductivity

DOE Target:

> 100 S/cm

300+ S/cm, about 80% of

POCOTM graphite value

Corrosion

DOE Target: < 16μA/cm2 < 5 μA/cm2

H2 Permeability

DOE Target:

< 2 x10-6 cm3/cm2-sec

<< 2 x10-6 cm3

/cm2-sec

(dry, nonporous plates)

Additional Properties Measured by IGT

H2 Bubble Pressure > 15 psig

(wet, porous plates)

Crush Strength > 3000 psi

Flexibility 3 – 6% deflection at

midspan

Total Creep ~1% elastic deformation at

200 psi and 100 °C

Flexural Strength 6420 psi (820 std. dev.)

Combustibility Zero (in propane flame)
Fuel Cell Power Systems FY 2000 Progress Report

122

followed by freezing; noncombustibility;

recyclability of components; and potential reuse of

components in new plates or other products.

The values of conductivity were measured using

the American Society for Testing and Materials

(ASTM) C-661 method, and the values were

typically exceeded by a factor of three to eight,

depending on plate density. Conductivity and

surface resistance measurements were always

compared with measurements of POCO graphite

plates, used as a standard.

The corrosion rate target of less than 16 μA/cm2

was also satisfied. This was done in hydrogen, air,

and oxygen atmospheres in a dilute sulfuric acid

solution with 2 ppm fluoride, using the ASTM G5

method at 90°C and pH ~ 4. The IGT molded

composite blend had total corrosion rates below

5 μA/cm2

. Hydrogen permeability was measured as

a function of plate density, related to molding

pressure. Plates can be molded either more or less

dense than POCO graphite, thereby controlling the

porosity. The hydrogen permeability rate measured

for the dense, nonporous plates, at 90°C and 207 kPa

(30 psig), was always well below the DOE-specified

value of 2 × 10-6

 cm

3

/cm2-s.

Additional measurements were made of the plate

crush strength, flexural strength, mid-span

flexibility, and creep characteristics. The molded

plates are expected to survive an anticipated holding

force exerting 200-psi pressure in the fuel cell stack,

including stacking dimensional nonuniformities

induced by gasketing or assembly methods, plus a

myriad of handling and packaging actions from the

production line to stack assembly. The measured

strength values shown in Table 1 yield a good safety

margin. The strength and slight flexibility of the

molded composite plates give the stacks the

advantage of greater durability. The plates have

retained their electrical and physical properties after

being subjected to immersion in boiling water

followed by freeze-thaw cycles. Maximum loss of

weight in any of the tests has been on the order of

0.5%.

Molded Plate Production and Cost Estimates

IGT and Stimsonite formed a joint venture

company called PEM Plates, LLC, with the purpose

of producing molded composite bipolar separator

plates for fuel cell stack developers. The various

steps in the process were explored, and

modifications were developed for mass production

of the plates. With the knowledge gained from

molding the composite plates in the 5-plate/hr pilot

line, plus corporate experience with rapid molding

machines and inexpensive molds, machine

production rates of hundreds of plates per hour are

possible. In carload quantities, raw material costs

will be $4/kW or less. Production costs are expected

to be about $6/kW; however, this cost depends upon

the production quantity and the complexity of the

plate designs.

Capital and operating costs were analyzed for

the custom machines to produce hundreds of plates

per hour. To attain production costs below $6/kW,

annual production quantities of 100 MW of fuel

cells are needed. This is equivalent to about

2,000 cars per year with 50-kW fuel cell engines. As

the demand for plates increases, the number of

production machines can be increased.

Conclusions

After identifying a unique blend of component

materials for a molded graphite bipolar separator

plate for PEM fuel cells, development of a rapid

molding process began with a pilot production line.

Thousands of plates have been molded and

thousands of hours of fuel cell stack tests have been

conducted, yielding performance practically

equivalent to state-of-the-art, machined graphite

plates. In commercial production quantities, the

manufactured cost of PEM Plates’ molded separator

plates is estimated to be about $10/kW.

More needs to be done to reach commercial

production:

• The new molding process needs to be validated

at the pre-commercial manufacturing level.

• Successful molding trials using stack developer

designs must be demonstrated.

• Additional stack endurance and verification

testing is needed.

• Additional orders from developers are needed in

order to increase production volumes to the

levels needed to achieve cost reductions.
Fuel Cell Power Systems FY 2000 Progress Report

123

H. Layered PEM Stack Development

Michael Pien (Project Director)

ElectroChem, Inc.

400 W. Cummings Park

Woburn, MA 01801

(781) 938-5300, fax: (781) 935-6966, e-mail: fuelcell@fuelcell.com

DOE Program Manager: Donna Lee Ho

(202) 586-8000, fax: (202) 586-9811, e-mail: donna.ho@ee.doe.gov

DOE Program Support: Larry Blair (LANL)

(202) 586-0626, fax: (202) 586-9811, e-mail: larry.blair@ee.doe.gov

ANL Technical Advisor: James Miller

(630) 252-4537, fax: (630) 972-4537, e-mail: millerj@cmt.anl.gov

Contractor: ElectroChem, Inc., Woburn, Massachusetts

Prime Contract No. DE-FC02-97EE50475, October 1, 1997-December 31, 2000

Objective

• ElectroChem will validate the suitability of its low-cost, layered separator plate design for light vehicle

applications. This novel design will be tested in two stack design versions for reliability and performance under

the harsh conditions associated with light vehicle use, and it will also be life-tested.

OAAT R&D Plan: Task 13; Barrier B

Approach

• A 5-kW polymer electrolyte membrane (PEM) fuel cell stack will be designed, assembled, and tested. The

design will include water cooling and will be based on a 232-cm2

 (6 in. × 6 in.) active area cell.

• The 5-kW fuel cell will be initially tested under high-energy-density hydrogen/oxygen (H2/O2) conditions.

• The 5-kW fuel cell will be integrated into a prototype hydrogen/air system that provides the necessary support

for efficient hydrogen/air operation. Dynamic testing will be performed in an attempt to simulate stressful light

vehicle operating conditions.

• Simultaneously, a smaller-cell (50-cm2

), 200-W stack will be constructed and life-tested under harsh H2/O2

conditions for a minimum of 3,000 hours to validate the survivability of the materials used in the layered plate

design.

• The resulting performance data from both stacks will be analyzed. In particular, a detailed external and internal

inspection of the 200-W stack for potential signs of degradation and corrosion will be carried out.

Accomplishments

• Both stacks have been designed and are under construction.

• The support system for the 5-kW test system has been initially designed, and component selection is in

progress.

• Plans for the stepwise integration of the 5-kW stack are proceeding.
Fuel Cell Power Systems FY 2000 Progress Report

124

Future Directions

• Conduct dynamic testing of 5-kW stack to simulate light-duty vehicle operation.

• Conduct life-testing of 200-W stack for 3,000 hours.

• Analyze performance data from 5-kW and 200-W stacks.

Introduction

The principal hardware element in a PEM fuel

cell is the bipolar separator plate, which in

conventional designs is a major cost item in a fuel

cell system. The bipolar separator plate must

perform a number of important tasks

simultaneously, while remaining lightweight and

low-cost. It must provide excellent electrical

conductivity, keep the gaseous reactants separated,

be leak-free, support intricate gas flow patterns to

uniformly distribute reactants and water vapor and

remove waste products from the membrane

electrode assembly (MEA), permit stack cooling,

and be fabricated to relatively high tolerances in

volume production. Finding a single material for use

in inexpensively producing monolithic separator

plates remains a challenge. Long experience has

shown that graphite has the chemical stability to

survive the fuel cell environment, but producing

nonporous graphite is a long and expensive

industrial process.

Approach

Our approach has been to fabricate separator

plates from several materials, thereby relaxing the

performance requirements for any one material. Our

basic design approach is shown in Figure 1, where a

single monolithic plate design (a) is compared with

the layered design (b). The principal components of

the new design are porous graphite, polycarbonate

plastic, and stainless steel.

Previous work had shown that this design

provides high performance at low cost while

enabling a leak-free stack design that yielded no

signs of corrosion or degradation under the harsh

test conditions examined. This program is explicitly

aimed at extending the testing range to include

longer life testing under harsh conditions, as well as

a larger-scale (5-kW) stack design. The overall goal

is to extend the range of confidence in this plate

design for commercial light vehicle mass production

applications.

Nonporous

(expensive)

Graphite

Gasket MEA

MEA

Thin Stainless

Sheet

Molded

Polycarbonate

Molded Porous

(inexpensive)

Graphite

Conductive

Bonding & Sealing

Layer

(a)

Conventional Plate Design

(b)

Layered Plate Design

Figure 1. Schematic comparison of a conventional fuel

cell separator plate with ElectroChem’s

layered structure. The typical monolithic plate

is usually composed of expensive nonporous

graphite or graphite composite. ElectroChem’s

design uses three primary materials selected

for low cost, high performance, and ready

availability.

Technical Challenges

A particular feature of the layered separator

plate design is its facility for the flexible application

of manufacturing technology. The fabrication

process for these layered bipolar plates lends itself to

low-cost mass production by means of techniques,

equipment, and processes used across several

industries. Each step, though it comprises several

pieces that require individual fabrication and

handling, is quite low-cost and rapidly executed. A

cost analysis has been carried out specifically for

volume production associated with the auto industry.

Some of the results of this analysis are shown in

Figures 2 and 3. Of primary interest to the vehicle

manufacturer is that the fuel cell separator and

cooling plates (one cooling plate for every two

active cells) meet the simultaneous requirements of

low weight and low cost. The layered separator plate

design readily meets both of these requirements,
Fuel Cell Power Systems FY 2000 Progress Report

125

0

200

400

600

800

1000

1200

0.2 0.4 0.6 0.8 1 1.2

Current density, A/cm2

Number of plates

0

200

400

600

800

1000

1200

Specific power, W/kg

number of plates

specific power

Figure 2. Specific power analysis of layered separator

plus cooling plates for a 50-kW stack

operating at 0.8 V/cell.

0

200

400

600

800

1000

1200

0.2 0.4 0.6 0.8 1 1.2

Current density, A/cm2

Number of plates

0

5

10

15

20

25

30

35

40

Cost, $/kW

number of plates

cost

Figure 3. Cost analysis results of layered separator

plates plus cooling plates for a 50-kW stack

operating at 0.8 V/cell.

using commercially available materials, on the basis

of reasonable assumptions about cost savings

obtained from volume production techniques.

Our next stage in the validation of this novel

plate design comprises extensive testing in

(a) subscale stacks, which can examine potential

materials degradation scenarios (200 W); and in

(b) a 5-kW stack, which operates at a scale and

power density comparable with light vehicle

applications. Toward this end, two stacks are being

developed, and an extensive testing process is

planned. A schematic drawing of the 5-kW test

system is shown in Figure 4.

Cooling Air Fan Condenser

Heat Exchanger

Air Humidifier

Hydrogen

Humidifier

Air Blower Air Intake

Coolant

Return

Coolant

Input

Figure 4. Schematic drawing of the laboratory-scale

5-kW fuel cell system for dynamic testing of

the full-scale separator plate design.

Future Challenges

Our design has been developed with an eye

toward the progressive commercialization of fuel

cells. The approach taken permits us to adapt these

materials to a wide range of designs that may vary

between fuel cell manufacturers. This successful

separator plate design is quite generic and can be

adapted to a wide range of flow field patterns. These

materials are already produced in bulk, are well

engineered, and offer economies of scale that can be

attained rapidly with minimal investment.

Meanwhile, this material combination can also

be obtained in small volumes at modest cost and

inexpensively machined to provide parts that already

cost less than their nonporous graphite equivalents.

This leads us to anticipate the introduction of these

less expensive parts into fuel cells while

manufacturing volumes are still small, providing

substantial cost savings at every level of production

volume.
Fuel Cell Power Systems FY 2000 Progress Report

126
Fuel Cell Power Systems FY 2000 Progress Report

127

VI. AIR MANAGEMENT SUBSYSTEMS1

A. Turbocompressor for PEM Fuel Cells

Mark K. Gee

Honeywell Engines & Systems

2525 W. 190th Street, MS-36-2-93084

Torrance, CA 90504

(310) 512-3606, fax: (310) 512-4998, e-mail: mark.gee@honeywell.com

DOE Program Manager: Patrick Davis

(202) 586-8061, fax: (202) 586-9811, e-mail: patrick.davis@ee.doe.gov

ANL Technical Advisor: Robert Sutton

(630) 252-4321, fax: (630) 252-4176, e-mail: sutton@cmt.anl.gov

Contractor: Honeywell Engines & Systems, Torrance, California

Prime Contract No. DE-FC02-97EE50479, October 1997-July 2000

DE-FC02-99EE50579, October 1999-June 2001

Objectives

An optimal turbocompressor configuration will be developed, working with fuel cell system manufacturers and

carrying on the work currently being performed. A vehicle-ready motor controller will be developed. The

turbocompressor/motor controller will be made available for integration in a fuel cell system.

OAAT R&D Plan: Task 13; Barrier D

Approach

Honeywell’s approach makes use of

• Automotive and aerospace turbomachinery technology for low cost and low weight/volume ratio.

• Variable nozzle turbine (VNT) inlet geometry for improved performance across the flow range.

• A mixed-flow-type compressor for improved low-flow performance.

• Contamination/oil-free and zero-maintenance-compliant foil air bearings.

• A high-efficiency, low-cost two-pole toothless motor.

• Low-cost, sensorless variable-speed motor controller topology design.

Accomplishments

• Numerous start/stop cycles with no appreciable wear.

• Stable operation at full turbine temperature (150o

C).

• Performance of compressor and turbine mapping close to that predicted.

• Completion of power consumption evaluation.

 

1 The DOE technical targets for fuel cell system compressor/expanders can be found in Table 5, Appendix B. These

targets will be reviewed and possibly revised at a workshop being held early in FY 2001.
Fuel Cell Power Systems FY 2000 Progress Report

128

• Completion of modification and testing of the turbocompressor with increased turbine inlet temperature (315oC)

capability for the Honeywell fuel cell brassboard system.

• Assembly and testing of an aerospace-quality variable-speed brassboard motor controller used to drive the

turbocompressor with increased turbine inlet temperature.

• Completion of trade study of the turbocompressor and other compressor/expander designs, with the

turbocompressor approach recommended.

• Analysis and design of the turbocompressor with a mixed flow compressor and VNT under way.

• Analysis and design of the vehicle-ready motor controller under way.

Future Directions

• Complete testing of the turbocompressor with increased turbine inlet temperature in the Honeywell fuel cell

brassboard system.

• Complete analysis, design, and fabrication of the latest turbocompressor design with the mixed-flow

compressor and VNT.

• Complete analysis, design, and fabrication of the vehicle-ready motor controller.

• Complete testing of the turbocompressor and vehicle-ready motor controller.

Introduction

The objective of this work is to develop an air

pressurization system to pressurize a fuel cell system

for a light-duty vehicle. The turbocompressor is a

motor-driven compressor/expander that pressurizes

the fuel cell system and recovers energy from the

high-pressure exhaust streams. Under contract to the

Department of Energy (DOE), Honeywell has

designed and developed the motor-driven

compressor/expander and evaluated data on its

performance, weight, and projected cost. Compared

to positive displacement technology, the

turbocompressor approach offers the potential for

high efficiency and low cost in a compact and

lightweight package.

Approach

The turbocompressor, shown in Figures 1 and 2,

consists of a compressor impeller, an expander/

turbine wheel, and a motor magnet rotor

incorporated onto a common shaft that is operated at

speeds of up to 110 thousand revolutions per minute

(krpm) on compliant foil air bearings. A motor

controller drives the motor, which is capable of

driving the turbocompressor to the maximum design

speed. The air bearings are lubrication-free, in

addition to being lightweight, compact, and selfsustaining (i.e., no pressurized air is required for

their operation). The turbocompressor works by

drawing in ambient air through the motor/bearing

Figure 1. Honeywell fuel cell turbocompressor.

 COMPRESSOR

 IMPELLER

 MOTOR ROTOR

 POSITION

 SENSOR

 TIE ROD

 COMPRESSOR

 DIFFUSER/SCROLL

BEARING MOTOR ROTOR BEARING

TURBINE/

EXPANDER

TURBINE

TORUS

TURBINE

NOZZLE

MOTOR

STATOR

BEARING

 MOTOR

 HOUSING

 INLET DUCT

 BEARING

 HOLDER

TIE ROD

Figure 2. Fuel cell turbocompressor details.
Fuel Cell Power Systems FY 2000 Progress Report

129

cavities, where it is pressurized by the compressor,

delivered to the fuel cell stack, and then expanded

through the turbine to enhance the overall

turbocompressor/fuel cell system efficiency.

Results

The turbocompressor has operated for more than

300 hours under varying conditions, with and

without motor operation. To date, the motor has

reached a maximum speed of 110 krpm.

The current Phase II Turbocompressor occupies

10 liters of volume (including the motor) and weighs

8.1 kg mass. It is the only machine that incorporates

the motor within both its volume and mass. Even so

the machine is still larger than the DOE goals of

4 liters (without motor) and mass of 3 kg (without

motor). The power consumption testing of the

turbocompressor has also been completed (see

Figure 3). To support testing of the Honeywell fuel

cell brassboard system, the turbocompressor was

modified to handle increased turbine inlet

temperatures. In addition, a modified, aerospacequality controller, intended to replace the

commercial unit used previously, has been

assembled and tested. Integrated testing prior to

delivery to the Honeywell fuel cell brassboard

system is scheduled for completion by mid-2000.

As outlined in the Variable Geometry for PEM

Fuel Cells program (awarded in March 1999), a

trade study to compare the turbocompressor with

other compressor/expander devices was completed.

The turbocompressor was favored mainly because of

its small size, low weight, and increased reliability,

as well as for the lack of contamination issues with

the air bearings. After reviewing the trade study

results with DOE, it was decided to incorporate a

mixed flow compressor and a variable nozzle turbine

(VNT). The changes will improve the low-flow

performance while maintaining efficiency across the

flow range. The vehicle-ready motor controller will

be of reduced size, incorporate sensorless

technology, and have a topology that is configured

to reduce production cost. The analysis and design

of the turbocompressor with a mixed-flow

compressor and VNT and the vehicle-ready motor

controller are currently under way.

Conclusions

The turbocompressor concept, using selfsustaining compliant foil air bearings, has

demonstrated low power consumption and moderate

pressure ratio at low flow rates in a compact,

lightweight package. Power consumption can be

further lowered if higher expander/turbine

0

2

4

6

8

10

12

0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 100.00

% FLOW (100% = 76 GRAMS/SEC DRY AIR)

SHAFT POWER (kW)

0

0.5

1

1.5

2

2.5

3

3.5

COMPRESSOR PRESUURE RATIO

BASELINE TURBOCOMPRESSOR POWER WITH 150

DEG C TURBINE INLET TEMPERATURE

BASELINE TURBOCOMPRESSOR PRESSURE RATIO WITH 150

DEG C TURBINE INLET TEMPERATURE

TURBOCOMPRESSOR PRESSURE RATIO W/MIXED

FLOW COMPRESSOR AND VNT TURBINE W/150 DEG

C TURBINE INLET TEMPERATURE

TURBOCOMPRESSOR POWER W/MIXED FLOW

COMPRESSOR AND VNT TURBINE W/150 DEG C

TURBINE INLET TEMPERATURE

Figure 3. Turbocompressor shaft power/compressor outlet pressure ratio vs. % flow.
Fuel Cell Power Systems FY 2000 Progress Report

130

temperatures can be provided by the fuel cell

system. A turbocompressor capable of increased

expander/turbine temperatures will be demonstrated

in a Honeywell fuel cell brassboard system by late

2000. The latest turbocompressor/variable-speed

motor controller will incorporate a mixed-flow

compressor and variable inlet nozzle turbine to

improve the pressure ratio at low flows. The

variable-speed motor controller’s size, weight, and

reliability are being addressed with the new

sensorless design. The latest design is scheduled to

be tested in early 2001.

B. Development of a Scroll Compressor/Expander Module for

Pressurization of 50-kW Automotive Fuel Cell Systems

Detlef Westphalen, Ronald Forni, William Murphy, and John Dieckmann

Arthur D. Little, Inc.

20 Acorn Park

Cambridge, MA 02140

(617) 498-5821, fax: (617) 498-7213, e-mail: Westphalen.D@ADLittle.com

John McCullough

Scroll Corporation

Carlisle, MA 01741-1553

(978) 287-4407

DOE Program Manager: Patrick Davis

(202) 586-8061, fax: (202) 586-9811, e-mail: patrick.davis@ee.doe.gov

ANL Technical Advisor: Robert Sutton

(630) 252-4321, fax: (630) 252-4176, e-mail: sutton@cmt.anl.gov

Contractor: Arthur D. Little, Cambridge, Massachusetts

Prime Contract No. DE-FC02-97EE50487, September 30, 1997-December 31, 2000

Objectives

Design, develop, and demonstrate a scroll compressor-expander suitable for pressurization and energy recovery for a

50-kW automotive fuel cell system.

OAAT R&D Plan: Task 13; Barrier D

Approach

• The second-generation design concept was developed through hardware testing of our first-generation

compressor/expander module (CEM).

• The second-generation design has increased displacement and higher speed than the first-generation CEM in

order to meet the flow requirements for 50-kW fuel cells.

• A second-generation prototype has been fabricated and tested.

• The CEM is being integrated with a fuel cell system as a final step in the development.
Fuel Cell Power Systems FY 2000 Progress Report

131

Accomplishments

• Designed and demonstrated first-generation CEM and double-ended compressor based on first-generation

design.

• Demonstrated key design components of second-generation CEM:

- Improved, extended-life oil seals.

- Improved orbiting drive design with better orbiting scroll alignment, less power loss, and no drive belts.

• Designed, fabricated, and successfully tested second-generation CEM at up to 80% of design flow.

Future Directions

• Demonstrate compressor-expander in a fuel cell system.

• Pursue size/weight reduction for hybrid compressor technology while maintaining superior performance

characteristics.

Introduction

Nearly all designs for automotive fuel cell

systems are based on operation at a pressure up to

3 atm at full load. The viability of these fuel cell

systems requires a highly efficient compressor and

an efficient expander in order to keep parasitic

power demand manageable.

Phase I of the scroll compressor-expander

module (CEM) development culminated in the

successful demonstration of an efficient scroll CEM

capable of pressurization and energy recovery for a

28-kW fuel cell. This first-generation prototype was

tested at flow rates up to 42 g/s and compressor

discharge pressures up to 32 psig.

The goals of the Phase II work were:

• Increase flow rate,

• Improve oil and cooling systems,

• Eliminate belt drive,

• Demonstrate reliability, and

• Integrate CEM with a fuel cell.

The second-generation prototype compressor is

shown in Figure 1. The compressor and expander are

mounted on either side of the centrally located

orbiting drive. Expander power is transferred to the

compressor mechanically through the drive. The

orbiting drive is oil-lubricated; oil is prevented from

being introduced into the compressor air flow by

two sets of oil seals with vented intermediate space.

Figure 1. Second-generation scroll CEM.

Approach

The Phase II work included construction of a

“back-to-back” (BTB) compressor based on the firstgeneration design: the expander side was replaced

with a second compressor. The BTB unit was used

for evaluation of individual CEM component

efficiencies and durability testing. It has been

operated without incident at flow rates up to 46 g/s

and pressures up to 30 psig for a total of 272 hours.

In addition, the first prototype CEM was

modified to demonstrate (1) integration of the oil
Fuel Cell Power Systems FY 2000 Progress Report

132

pump into the orbiting drive and (2) a new orbiting

oil-seal system that involves no surface-to-surface

contact at the seal point. Both of these modifications

have been successfully demonstrated to improve

CEM reliability.

Extended reliability testing has been done to

verify durability of the first-generation orbiting drive

design. About 500 test hours have been accumulated

with the BTB compressor and the modified firstgeneration CEM, without incident, at machine

speeds up to 3,450 rpm.

Results

The second-generation CEM has been designed,

fabricated, and tested. Design changes (compared

with the first generation) are:

• Larger displacement and higher speed in order to

achieve 76-g/s flow, suitable for a 50-kW fuel

cell.

• Improved thrust bearing to improve scroll

alignment.

• Better integration of the oil pump and cooling

fans.

• Central-drive design, rather than belt drive, to

improve reliability, reduce parasitic losses, and

reduce size.

• Additional orbiting drive design changes that

will improve reliability and reduce drive losses.

• Magnesium alloy scrolls to reduce weight and

reduce bearing loads.

Testing of the second-generation machine was

done at up to 80% of design flow. This initial testing

has verified the performance projections shown in

Figures 2 and 3. Further testing may occur after

completion of the fuel cell system testing described

below.

Demonstration of the CEM integrated into a fuel

cell system is currently in process. This work is

being done with Energy Partners. The CEM is

shown in the test rig in Figure 4.

Initial testing of the CEM integrated with the

permanent-magnet direct-drive motor has been done

in conjunction with Energy Partners’ humidifier

testing. Further work is awaiting final assembly of

the fuel cell system. The work will allow testing of

system control issues and will show the viability of

the scroll compressor for automotive fuel cell

applications.

Figure 2. Second-generation scroll CEM operating

envelope.

Figure 3. Second-generation scroll CEM projected shaft

power.

Figure 4. CEM integrated with PM motor in Energy

Partners’ facilities.

The projected performance envelope of the

second-generation scroll CEM is shown in Figure 2.

The scroll technology allows for a wide flow range

while maintaining system pressure level.
Fuel Cell Power Systems FY 2000 Progress Report

133

The efficiency benefit of scroll technology for

fuel cell pressurization is shown in Figure 3. The

figure shows shaft power projections for Department

of Energy (DOE) guideline pressures and for the

projected maximum pressure curve of Figure 2. The

points labeled “Corrected Data” are based on CEM

testing at operating conditions nearly identical to the

DOE guidelines. The scroll CEM uses a very modest

amount of the net fuel cell stack power over the

entire flow range. However, the second generation

scroll CEM is 27 liters in volume (not including the

motor) and has a mass of 36 kg (not including the

motor). These parameters are far in excess of the

original DOE guidelines of 4 liters volume and 3 kg

mass, both without the motor.

C. Variable Delivery Compressor/Expander Development

Ski M. Milburn, Principal Investigator

VAIREX Corporation

3044 Valmont Road

Boulder, CO 80301

(303) 444-4556, fax: (303) 444-6150, e-mail: VAIREX@VAIREX.com

DOE Program Manager: Patrick Davis

(202) 586-8061, fax: (202) 586-9811, e-mail: patrick.davis@ee.doe.gov

ANL Technical Advisor: Robert Sutton

(630) 252-4321, fax: (630) 252-4176, e-mail: sutton@cmt.anl.gov

Contractor: VAIREX Corporation, Boulder, Colorado

Prime Contract No. DE-FCO2-98EE50481, December 19, 1997-June 19, 2000

Objectives

The primary objective for fiscal year (FY) 2000 was to complete development of a second-generation integrated air

compressor/expander/motor suitable for installation in 50-kW fuel cell demonstration systems. In particular, we

sought to:

• Expand, through research and development, the performance envelope of the VAIREX dry piston technology for

use as a fuel cell power system air compressor and expander.

• Focus on performance improvements in the areas of operating speed, compressor power consumption, and

expander power recovery, as well as on the volume and weight of both devices.

• Define the development pathway to the manufacture of an integrated compressor/expander/motor (iCEM) that

will satisfy cost, weight, and volume, as well as performance, requirements for a fuel-cell-powered production

vehicle.

OAAT R&D Plan: Task 13; Barrier D

Approach

The current R&D phase moved beyond demonstration of basic capabilities to Department of Energy (DOE)

guidelines and projected industry requirements. Specific steps during FY 2000 included:

• Implementation of an improved, simplified mechanism building on the Generation 1 results.
Fuel Cell Power Systems FY 2000 Progress Report

134

• Design and construction of a Generation 2 integrated, variable-delivery compressor and expander.

• Independent testing of the Generation 2 compressor, expander, and integrated compressor/expander to establish

performance envelopes.

• Submission of the final report and the operating manual for the deliverable hardware.

Accomplishments

• Fully demonstrated that the Generation 2 VAIREX integrated compressor/expander system meets or exceeds

DOE performance guidelines and can be scaled to meet air management system requirements for fuel cell

power systems with net power ratings from 2 to 100 kWe (patents applied for).

• Developed a mechanical design in which major elements of the compressor and expander are identical, with the

exception of inlet and outlet valving.

• Developed a unique variable valving system for the expander that allows independent control of inlet timing

and duration, as well as pressure regulation independent of air flow or exhaust conditions (patents applied for).

• Integrated a high-efficiency, brushless direct-current (DC) motor and controller suitable for powering by fuel

cell stack output voltages.

• Developed and are implementing the development path to the manufactured product; projected cost and

durability meet industry requirements.

• Submitted draft of final report and operating manual for this contract phase.

Future Directions

• Continue testing of expander configurations in fuel cell power system environments.

• Continue integration of the air system into the overall fuel cell power system.

• Deliver customer evaluation units in calendar year (CY) 2000.

• Demonstrate a compressor operating envelope that supports net fuel cell power systems in excess of 50 kWe.

• Continue to reduce power consumption across the operating window.

• Continue to reduce dynamic mass, inertia(s), and overall component weights and costs.

• Continue to implement pathway to manufacture, achieving technical targets within cost constraints acceptable

to automotive industry.

Introduction

Automotive fuel cell power systems require

pressurized air as a source of oxygen in the fuel cell

stack itself, as well as in the fuel reformation

process. It has been determined that pressurized air,

at a ratio of about 3.2 times the ambient air pressure

(3.2 bar), is appropriate for optimal power system

performance.

Conventional air systems do not meet the

requirements for clean, variable air delivery,

independent of pressure, and having power

consumption within the available power budget of a

fuel cell power system.

VAIREX has used its dry cylinder compressor

technology to develop, under DOE auspices, an

integrated air system capable of meeting the air

requirements for the DOE 50-kW power system

guidelines and beyond. An expander, capable of

recovering significant energy from the power system

exhaust streams and regulating system pressure, is

an integrated part of the VAIREX system. This

integrated air system operates within the parasitic

power budget required by the system guidelines.

Approach

Comparison of contact (piston) compressor

technology with noncontact (e.g., twin screw or

turbine) compressor technology indicated that the

piston approach had significant merit in the areas of

variable flow control independent of pressure, and of

lower power consumption across the operating

range, especially at the dominant (20–30%)
Fuel Cell Power Systems FY 2000 Progress Report

135

operating levels. Also, energy recovery from the

power system exhaust gases and system pressure

regulation are simplified and are more flexible in the

piston approach.

In the first phase of the program, the VAIREX

technology was demonstrated to be capable of

meeting DOE system performance requirements for

an automotive fuel cell power system. In the second

phase, covered by the referenced contract, the

program objectives included improvements in

performance; reduction in size, weight, and cost; and

definition of a clear path to manufacture.

Results

Mechanical complexity of the air system has

been significantly reduced in the current

configuration. It should be noted that the compressor

and expander in Generation 2 are mechanically

identical in every respect except for inlet and outlet

valving. Compressor valving is passive, while the

expander valving is a unique design permitting

dynamic variation of inlet timing and duration, with

independent system pressure control. Figure 1 shows

the basic mechanical module. Figure 2 is the

deliverable configuration of this contract, while

Figure 3 shows the customer evaluation version of

the iCEM. This latter version is scheduled to be

delivered for customer evaluation during CY 2000.

Figure 1. Common compressor/expander module.

Figure 2. Integrated compressor/expander/motor as

delivered.

Figure 3. iCEM, customer evaluation unit.

Modeling, testing, and design efforts on the

current configuration have reduced the volume and

mass of the compressor and expander hardware by a

third with respect to the Generation 1 system.

However, the current Generation 2 Vairex

compressor occupies a volume greater than 65 liters

(not including the motor) and has a mass of more

than 27 kg (not including the motor). The new iCEM

is expected to have a volume of about 48 liters and a

mass below 27 kg, neither of which include the

integrated motor. Although this is far above the

DOE guidelines of 4 liters volume and 3 kg mass,

respectively, the new machine is capable of

achieving any desired pressure profile with flow and

is capable of pumping more than 125 g/sec. Ongoing

development is expected to further reduce the

volume and mass of the iCEM by an additional third

or more.
Fuel Cell Power Systems FY 2000 Progress Report

136

Conclusions

The compressor/expander system has

demonstrated that pressure ratios well in excess of

3.5 can be generated in one compressor stage, with

turn-down ratios (ratio of maximum to minimum air

flow) greater than 10:1. The expander section has

demonstrated its ability to recover substantial

amounts of energy across the system operating

range, thus reducing parasitic power consumption.

The expander valving system can regulate system

pressure independent of air flow rates or exhaust gas

conditions. The Generation 2 integrated

compressor/expander has significantly reduced

power consumption across the operating range.

The net shaft power required to drive the CEM

unit as a function of percent compressor flow is

presented in Figure 4. Note that Vairex uses an

expander inlet temperature of 250°C to present the

parasitic loss while most of the other CEM

contractors present their data at 150°C. The higher

expander inlet temperature allows more power to be

extracted from the expander and, thus, reduces the

net shaft power to drive the entire unit.

Operating tests indicate the VAIREX air system

technology is capable of meeting the emerging

automotive industry requirements for air flow in the

range of 125 grams per second (g/s) at pressure

ratios of 4 bar, as compared to the earlier

specifications of 76 g/s and 3.2 bar.

Figure 4. Projected power consumption.

Customer evaluation units in various

configurations are being prepared for delivery in

CY 2000. These units are designed to assist system

integrators in advancing the design and testing of

prototype power systems.

References and Publications

J. Cronin and S. Milburn, Report to DOE Blue

Ribbon Panel, October 1999.

S. Milburn and W. Butler, Draft Final Report,

Program Research and Development Announcement

2A.
Fuel Cell Power Systems FY 2000 Progress Report

137

D. Turbocompressor for Vehicular Fuel Cell Service

G. Fonda-Bonardi

Meruit, Inc., 1450 23rd St., Santa Monica, CA 90404-2902

(310) 453-3259, fax: (310) 828-5830, e-mail: fbarch@concentric.net

DOE Program Manager: Patrick Davis

(202) 586-8061, fax: (202) 586-9811, e-mail: patrick.davis@ee.doe.gov

ANL Technical Advisor: Robert Sutton

(630) 252-4321, fax: (630) 252-4176, e-mail: sutton@cmt.anl.gov

Contractor: Meruit, Inc.

Prime Contract No. DE-FC02-97EE-50480, October 1997-December 2000

Subcontractor: FD Contours, Costa Mesa, California

Objectives

• Validate the design and performance of the gas bearings for the turbocompressor.

• Validate the design and performance of the expander and compressor for fuel cell service.

OAAT R&D Plan: Task 13; Barrier D

Approach

• Design, build, and test a specialized, instrumented test rig for measuring the performance of a new, highperformance gas bearing.

• After completion of the bearing tests, use the test rig to measure the performance of the Department of Energy

(DOE)/Argonne National Laboratory near-frictionless carbon (NFC) coating.

• Design, build, and test the prototype of a turbocompressor supplying 76 g/s of air and optimized for service with

a 50-kW (net) fuel cell.

Accomplishments

• The gas bearings perform essentially as predicted and are suitable for use in the turbocompressor.

• The test rig is available for further use by DOE for testing the NFC coating.

• The desirable characteristics of a turbocompressor have been quantified, and specialized software for the

detailed design has been written.

• Engineering drawings for the fabrication of the prototype turbocompressor have been released.

Future Directions

Build and test the turbocompressor prototype.
Fuel Cell Power Systems FY 2000 Progress Report

138

Introduction

The design of the turbocompressor is

constrained by severe requirements, not all of them

purely technical. The compressor supplies air to the

fuel cell, and the turbine is driven by the exhaust

from the cell, which depends on the type of fuel cell

and its mode of operation, as well as on the system

components (e.g., reformers, water separators, etc.).

Operation of the fuel cell at a higher pressure has the

advantages that the efficiency is higher

(Hirschenhofer et al. 1994) and the cell volume and

weight are smaller, but it has the disadvantage of

requiring an air compressor, which requires power to

run it.

On the other hand, the exhaust from a highpressure fuel cell contains recoverable energy, which

can be extracted by a turbine and used to offset the

parasitic power absorbed by the compressor, but

with the added complications (and cost) of a turbine.

The amount of energy available depends on many

factors, such as

• The pressure and temperature of the exhaust gas

from the fuel cell,

• The composition of the exhaust gas,

• The mass flow rate of the exhaust gas, and

• The conditions for which the turbine has been

optimized.

Results

Compressor Design

Meruit, Inc., designed a family of compressor

wheels (designated by the letters A to Z) with

varying characteristics (specific speed, dimensional

ratios, etc.) that represent different compromises in

providing performance compatible with the DOE

specifications. Figures 1 and 2 show the expected

performance of two typical wheels, 7016G and

7016T. Both show the pressure vs. mass flow lines

required by DOE specifications. Operation of the

compressor to the left of the limiting line (“surge

line”) is impossible because of stall instabilities.

Consequently, there is a region in the performance

space, between the surge line and the DOE

specification, that cannot be reached. This area can

be minimized by design, but at some cost elsewhere

in the performance plane.

This trade-off is illustrated in a comparison

between wheel “G” and wheel “T”: the surge line

can be moved to the left at the cost of increasing the

power consumption at the point of maximum

pressure and mass flow. Adding power to the shaft

of the turbocompressor by means of an auxiliary

motor does not help; it can increase revolutions per

minute (RPM) but cannot move the surge line to the

left. There seem to be two approaches to solving this

problem:

1. Choosing an operating line for the fuel cell that

follows the DOE specification from maximum mass

flow down to the point where it intersects the surge

line, and then following the surge line (or just to the

right of it) down to idle.

2. Removing the auxiliary motor from the shaft of

the turbocompressor and using it instead to power a

separate compressor in series with the

turbocompressor. The disadvantage of this approach

is the addition of another component to the system.

Expander Design

The basic expander configuration comprises

variable inlet vanes (nozzle segments) for the

convenient control of back pressure and mass flow

for matching the performance of the compressor.

Figure 3 schematically shows the geometry of the

inlet vanes and their relationship to the blades of the

turbine wheel. The gas is injected tangentially

through a set of openings, which are adjustable from

zero to a maximum by rotating the nozzle segments

about their pivots. This rotation is driven by pins

engaged in slots (not shown) in a ring surrounding

the structure. The gas enters the space at the outer

diameter (OD) of the turbine wheel with a velocity

that depends on the inlet temperature and the

pressure drop across the segments. Meruit, Inc., has

designed a family of expander wheels optimized for

each of the various types of fuel cell exhaust.

Turbocompressor Performance

The performance of the turbine can be shown in

terms of the same variables and units used in the

case of the compressor; the graphs can be juxtaposed

for immediate visual comparison (Figures 4 and 5).
Fuel Cell Power Systems FY 2000 Progress Report

139

Figure 1. Compressor 7016G Figure 2. Compressor 7016T
Fuel Cell Power Systems FY 2000 Progress Report

140

Figure 3. Variable inlet geometry.

The turbine performance graph, showing lines of

constant nozzle aperture, is limited to the left by the

surge line of the compressor that supplies the air,

even though the expander itself has no such

limitations: the expander must process what comes

from the fuel cell (i.e., the air supplied by the

compressor, plus hydrogen and minus water, if such

is the case). The compressor graph now shows the

line corresponding to 100% open nozzles: no more

flow can be demanded than can be processed

through the expander. Hence, the operating area for

the turbocompressor is constrained by the surge line

on one side and the 100% open nozzle line on the

other. Within this area, a given point (pressure, mass

flow) will correspond to certain well-defined values

of RPM and nozzle opening. Conversely, each value

of RPM and nozzle opening corresponds to a

definite operating point; these are independent

variables that can be used in a feedback loop to

control the operation of the fuel cell.

Conclusion

Task 1 of the contract (validation of the gas

bearings) is completed. The first part of Task 2

(design of a turbocompressor for vehicular fuel

cells) is completed, and the expected performance

has been quantified and reported. The second part of

Task 2 (construction and testing of the

turbocompressor) is under way.

Bibliography

J.H. Hirschenhofer et al., Fuel Cells: A Handbook

(Revision 3), U.S. Department of Energy,

Morgantown Energy Technology Center,

DOE/METC-94-1006, 1994.
Fuel Cell Power Systems FY 2000 Progress Report

141

Figure 4. Expander 7016F and Compressor 7016T Performance at 370°C
Fuel Cell Power Systems FY 2000 Progress Report

142

Figure 5. Expander 7016F and Compressor 7016T Performance at 250°C
Fuel Cell Power Systems FY 2000 Progress Report

143

E. Innovative, High-Efficiency Integrated Compressor/Expander Based on

TIVM Geometry

Sterling Bailey, Ph.D., PE (primary contact) and Steve Chomyszak

Mechanology, LLC, 8 North Main Street, Suite 403, Attleboro, MA 02703

(508) 223-1920, fax: (508) 226-3697, e-mail: sterling@mechanology.com, steve@mechanology.com

DOE Program Manager: Patrick Davis

(202) 586-8061, fax: (202) 586-9811, e-mail: patrick.davis@ee.doe.gov

ANL Technical Advisor: George Fenske

(630) 252-5190, fax: (630) 252-4798, e-mail: gfenske@anl.gov

Contractor: Mechanology, LLC, Attleboro, Massachusetts

Prime Contract Nos. 991602401 and OF-00505, June 1999-December 2000

Objectives

• Design an integrated compressor/expander based on the Toroidal Intersecting Vane Machine (TIVM) geometry,

following the Department of Energy (DOE) 50-kWe automotive fuel cell guidelines.

• Predict the performance of the TIVM compressor/expander over the operating range specified in the DOE

guidelines.

• Identify the technology developments necessary for this component.

• Fabricate and test a first-generation prototype TIVM compressor/expander.

OAAT R&D Plan: Task 13; Barrier D

Approach

• Modify the geometric design parameters of the TIVM concept to provide a design consistent with the DOE

guidelines for a 50-kWe automotive fuel cell system.

• Develop an engineering simulation model of the design to predict key performance parameters for specified

operating conditions and to examine sensitivities to design assumptions.

• Analyze the performance of the design across the DOE-specified operating range.

• Determine the performance impact of variations in friction and leakage characteristics.

• Identify the major uncertainties in achieving the predicted performance and the technology developments

necessary to meet the DOE guidelines.

• Design, build, and test a first-generation prototype compressor/expander to confirm the basic operating

characteristics of the design and to guide further design refinement.

• Plan and initiate development for the key technology requirements.

Accomplishments

• A TIVM compressor/expander was designed to meet the DOE guidelines.

• A performance prediction model was developed and mathematically validated.

• The design’s performance was analyzed across the operating range.
Fuel Cell Power Systems FY 2000 Progress Report

144

• The predicted parasitic power load is less than that in the DOE guidelines for specified flows and pressures,

based on reasonable assumptions for friction and leakage.

• Manufacturing options have been identified that could provide costs near the DOE targets for high-volume

production.

• Design features and material properties have been identified to minimize noise.

• Technology needs have been identified and development roadmaps developed.

• Key technology tasks have been initiated in cooperation with national laboratories and commercial vendors.

• A testing facility has been constructed at Mechanology that allows measurement of the TIVM

compressor/expander operating characteristics, variation of operating conditions, simulation of fuel stack and

other system parameters, and mapping of compressor/expander performance.

• A first-generation TIVM compressor/expander prototype has been designed and is being fabricated. This will be

tested in the fourth quarter of 2000.

Future Directions

• The first-generation compressor/expander prototype will be tested over the full range of operating variables, and

measured performance will be compared to predictions.

• On the basis of analysis of the experimental data, design features will be refined to optimize performance.

• In parallel with the design evolution, development tasks for materials, manufacturing, cost, and noise

minimization will be performed.

Introduction

The Toroidal Intersecting Vane Machine

(TIVM) is an innovative mechanical concept,

invented and patented by Mechanology, that can be

configured as an integrated, positive displacement

compressor/expander. Figure 1 illustrates the generic

TIVM prototype fabricated by Mechanology to

Figure 1. Generic TIVM prototype fabricated by

Mechanology.

demonstrate the basic operating viability of the

concept. In fiscal year (FY) 1999, DOE investigated

the TIVM concept for potential application to

automotive fuel cell systems and determined that the

inherent efficiency, compactness, and

thermodynamic attributes of this concept might be of

significant benefit. Mechanology was asked to

develop a design specifically for the 50-kWe

automotive system and to evaluate its potential

performance. On the basis of the encouraging results

obtained, a prototype compressor/expander is being

fabricated and will be tested in the fourth quarter of

2000.

Approach

In the TIVM geometry, the four functions of

intake, compression, expansion, and exhaust occur

simultaneously around an intersection that is

dynamically created by the intersecting vanes and

their housings. With appropriate porting, this

produces an integrated, positive displacement

compressor/expander. From this basic concept, a

design was developed in accordance with the DOE

“Supplemental Air-System Guidelines.” The TIVM

geometry allows considerable flexibility, and the

compression and expansion cycles can be

individually optimized to the system thermodynamic
Fuel Cell Power Systems FY 2000 Progress Report

145

requirements. A wide range of designs was found to

be capable of meeting the flow and pressure

requirements for the compressor and for the

expander. A representative design was selected that

provides a good balance between operating speed,

size, and efficiency. A dynamic engineering

simulation model of this design was developed to

analyze the performance at specified operating

conditions. This model was validated as much as

possible with the generic prototype. Where possible,

data from the generic prototype were used for the

compressor/expander analysis. Incorporating

operating conditions from the DOE guidelines, the

pressure, flow, and driver power required were

predicted from 10% flow to 120% flow. The

sensitivity of performance to design assumptions

was examined through a series of parametric

analyses, which were used to determine material and

technology requirements. This design also provides

the basis for the full-scale compressor/expander

prototype that is being fabricated and will be tested

in the fourth quarter of 2000. Future development of

the concept will involve iterative prototypes and

concurrent technology and manufacturing tasks to

satisfy performance, cost, and noise requirements.

At this stage of development the projected volume of

the TIVM unit is 5.5 liters without the motor and the

projected mass is 12 kg, also without the motor. If

the development continues as projected this will

potentially be the smallest CEM unit, and nearly the

lightest in mass, developed under the DOE contracts.

Results

Analysis of the baseline compressor/expander

design indicates that it can develop the required

compressor outlet pressure of 3.2 atm and flow of

76 g/s at a speed of 4500 rpm. This pressure could

be provided at the lower flow operating points;

however, it was decreased according to the DOE

guidelines. The parasitic electric power required to

drive the compressor/expander was calculated,

assuming that the motor/controller would have a

combined efficiency of 85% (see Figure 2). The

predicted power requirements are based on

conservative assumptions for friction and leakage;

the development tasks are aimed at achieving

considerably better values.

Conclusions

The design study has shown that the TIVM

compressor/expander can meet the DOE flow and

pressure requirements with many specific design

points that involve different balances between speed,

material requirements, size, and efficiency. The

predicted parasitic driver power is quite low

compared to the DOE guidelines, even when using

conservative assumptions. The technology and

manufacturing development needed to achieve or

exceed the predicted performance appear to be

practical within reasonable time and funding

constraints. It is anticipated that the prototype

compressor/expander tests in the fourth quarter of

2000 will demonstrate performance that benefits the

overall system performance significantly.

Figure 2. Predicted driver power vs. flow for the TIVM

compressor/expander.
Fuel Cell Power Systems FY 2000 Progress Report

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Fuel Cell Power Systems FY 2000 Progress Report

147

VII. HYDROGEN STORAGE1,2

A. High-Pressure Conformable Hydrogen Storage for Fuel Cell Vehicles

Andy Haaland

Thiokol Propulsion

P.O. Box 707, M/S 230

Brigham City, UT 84302-0707

(435) 863-6373, fax: (435) 863-8782, e-mail: haalaac@thiokol.com

DOE Program Managers: Sigmund Gronich and JoAnn Milliken

(202) 586-1623, fax: (202) 586-5127, e-mail: sigmund.gronich@ee.doe.gov

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

LLNL Technical Advisor: Andrew Weisberg

(925) 422-7293, fax: (925) 424-3731, e-mail: weisberg1@llnl.gov

ANL Technical Advisor: Walter Podolski

(630) 252-7558, fax: (630) 972-4430, e-mail: podolski@cmt.anl.gov

Contractor: Thiokol Propulsion, Brigham City, Utah

Prime Contract No. DE-FC02-97EE-50484, May 1997-May 2000

Subcontractors: Aero Tec Laboratories, Inc., Ramsey, NJ; Rotational Molding of Utah, Brigham City, UT; and

Powertech Testing Labs, Surrey, B.C., Canada

Objectives

• Demonstrate ability to fabricate lightweight, noncylindrical pressure vessels capable of storing hydrogen gas at

5,000 psig. These vessels have been termed “conformable tanks” because they provide the option of configuring

the tank geometry to conform to a given fuel storage envelope on a vehicle.

• Demonstrate ability of conformable tanks to meet an industry design standard for gaseous fuel storage. In the

absence of an industry-accepted specification for hydrogen gas storage, the NGV2-1998 ANSI standard

[modified for 5,000 pounds per square inch, gauge (psig)] was chosen as the design standard for this effort.

OAAT R&D Plan: Task 1; Barrier I

Approach

• Develop technology necessary to produce a plastic-lined, composite-overwrap Type IV tank, using subscale

tanks and simple cylindrical geometries.

• Incorporate technology advancements into a subscale, two-cell Type IV conformable tank that will be tested for

structural integrity.

• Demonstrate the structural integrity of conformable tank technology on a full-scale tank designed to fit within a

storage envelope of 12.8 in. × 21.2 in. × 27.9 in., with a capacity of 3.4 lb of hydrogen. This tank envelope is

consistent with space constraints on Ford’s P2000 fuel cell vehicle.

 

1

The Hydrogen Storage System Development Projects are cofunded by the DOE Office of Transporation Technologies

and the Office of Power Technologies Hydrogen Program.

2

The new draft DOE technical targets for on-board hydrogen storage can be found in Table 6, Appendix B.
Fuel Cell Power Systems FY 2000 Progress Report

148

• Subject full-scale tanks to tests defined in the NGV2-1998 standard (modified for 5,000 psig) that best identify

and address critical safety and durability issues for the tank design.

Accomplishments

• Subscale tank development allowed key technologies to be identified for conformable tank manufacture.

• Subscale conformable tank testing demonstrated structural integrity of the tank and validated the design

approach.

• Full-scale tank testing demonstrated the tank’s ability to operate at 5,000 psig, with a burst safety factor greater

than 2.25.

• Full-scale testing of tanks to the drop, penetration, accelerated stress rupture, environmental, and temperature

cycling criteria outlined did not reveal any design issues with the current conformable tank design. All tests

were successfully passed according to the criteria outlined in the standard (modified for 5,000 psig).

Future Directions

This contract has been completed. An additional proposal has been submitted for a follow-on effort. Future tasks

will be completed either on the follow-on contract or using Thiokol discretionary funding. Additional future efforts

are defined below:

• Complete the remaining tests on the full-scale tank, outlined in the NGV2-1998 standard.

• Extend the conformable tank design to operate at 10,000 psig.

• Incorporate component and manufacturing cost improvements into the existing tank design.

Introduction

On-board high-pressure storage of hydrogen for

fuel-cell-powered vehicles presents a number of

technical and economic challenges. Because the

energy density of hydrogen is significantly less than

that of conventional fuels, larger tanks are required

for equivalent range. Furthermore, the geometry of

traditional high-pressure cylinders generally does

not conform to the available space on the vehicle,

thereby raising tank packaging issues. Tank cost and

weight also significantly influence the amount of

fuel that can be carried.

Thiokol is addressing these issues through the

development of high-pressure conformable tanks for

on-board hydrogen storage. The lightest-weight

approach uses high-strength, filament-wound carbon

fiber composite for structural efficiency, with plastic

liners to act as permeation barriers. Thiokol’s

conformable storage concept uses multiple cells,

with the number and shape of the cells tailored to

maximize internal volume within a rectangular

envelope while maintaining membrane loading for

structural efficiency. Each cell is filament-wound

with a combination of hoop and helical layers,

followed by a hoop overwrap over the assemblage of

cells. Depending on the shape of the envelope, up to

50% more storage is possible with a conformable

tank than with cylinders.

Approach

The full-scale tank under development is a twocell configuration that fits in an envelope 12.8 in. ×

21.2 in. × 27.9 in., with a capacity of 3.4 lb of

hydrogen. The conformable tank provides 23% more

capacity than two cylinders in the same volume

envelope. An optional third cell would increase the

tank width to 29.6 in. and the capacity to 4.8 lb of

hydrogen. Tank envelopes are consistent with space

constraints on Ford’s P2000 fuel cell vehicle.

The tank is designed for a service pressure of

5,000 psi, with a burst safety factor of 2.25,

consistent with existing standards for high-pressure

vehicle fuel tanks. Activities completed in fiscal

year (FY) 1999 included full-scale tank design,

structural capability demonstration, and liner

material evaluation and selection.

Successful completion of FY 1999 activities

demonstrated the primary functional requirement for

a full-scale, high-pressure conformable hydrogen

tank: the capability for safely withstanding the
Fuel Cell Power Systems FY 2000 Progress Report

149

service pressure of 5,000 psi. However, additional

requirements must be satisfied to demonstrate safe

and reliable operation of the tank within the motor

vehicle environment. Over a lifetime of service, the

tank will experience cyclic loading due to repeated

fills, extremes of temperature, exposure to corrosive

fluids, potential damage both during handling and

vehicle operation, and possible creep and stress

rupture due to sustained high-pressure loading.

The ANSI/AGA NGV2-1998 standard provides

a comprehensive set of design and qualification test

requirements for compressed natural gas (CNG)

vehicle fuel tanks to ensure safe operation over their

lifetime. In the absence of a comprehensive standard

for hydrogen vehicle fuel tanks, and because of their

similarity to CNG tanks, Thiokol will use NGV2-

1998 qualification requirements (modified for tank

operation at 5,000 psig) as the basis for safety and

durability testing and evaluation under the present

program.

The primary approach employed in FY 2000

efforts is to subject a total of six tanks produced

using the technology developed in FY 1999 to

qualification testing based on NGV2-1998 (modified

for 5,000 psig tank operation) to identify and

address critical safety and durability issues.

Results

A total of six two-cell conformable tanks were

fabricated and delivered to Powertech Laboratories

in Surrey, British Columbia, Canada, for testing.

The tests conducted, defined in the NGV2-1998

standard, included temperature cycling, accelerated

stress rupture, drop, environmental, penetration, and

permeation data. Test criteria for the complete

NGV2-1998 standard and results obtained on the six

tanks are summarized in Table 1.

Conclusions

Thiokol has successfully designed and

demonstrated a two-cell conformable tank capable

of storing hydrogen at 5,000 psig (5.5 wt.% H2) that

will meet the design criteria of the NGV2-1998

standard. Additional testing will be required to

certify the design to the NGV2-1998 standard.

Additional challenges for this effort include

increasing the tank operating pressure to 10,000 psig

and incorporation of lower-cost manufacturing

components and techniques. Increasing the pressure

to 10,000 psig increases the amount of hydrogen

stored by about 70%, but because of the increased

amount of carbon fiber required, the weight

percentage of hydrogen remains about the same.

Table 1. Conformable hydrogen tank test criteria and results.

Test Criteria for Successful Testa Result

Burst Safety factor of 2.25 * 5,000 psig = 11,250 psig Pass

Ambient cycle 15,000 cycles without failure: 45,000 cycles without rupture to 1.25 safety

factor * 5,000 psig = 6,250 psig

Pass

Environmental cycling Subject to fluid exposure, pendulum impact, gravel impact,

high/low/ambient temperature cycling, burst above 9,000 psig

Pass

Flaw tolerance Machined flaws followed by cycling (15,000 cycles to 6,250 psig) Not testedb

Drop A total of six drops from a height of 6 ft, followed by ambient cycling of

15,000 cycles to 6,250 psig

Pass

Penetration Bullet penetration of tank pressurized to 5,000 psig with hydrogen. Tank

must not fragment.

Pass

Permeation Specified leak rate for hydrogen 1.2 scc/LAh

Bonfire Must safely vent Not tested

Hydrogen gas cycling 1,000 cycles with hydrogen to 5,000 psig, followed by leak test and

destructive inspection

Not tested

Accelerated stress

rupture

Tank pressurized to 6,250 psig and held at pressure for 1,000 hours at

149oF. At conclusion, tank must burst above 8,438 psig.

Pass

a Requirements for a tank with 5,000-psig service pressure and 20-year service life.

b

Tank expected to pass this test, based on positive results for a CNG tank of similar design operating at 3,600 psig.
Fuel Cell Power Systems FY 2000 Progress Report

150

B. Advanced Chemical Hydride Hydrogen-Generation/Storage System for

PEM Fuel Cell Vehicles

Andrew W. McClaine (primary contact), Ronald W. Breault, Christopher Larsen, Ravi Konduri,

Jonathan Rolfe, and Fred Becker

Thermo Technologies (a Thermo Electron Company)

P.O. Box 9046

45 First Avenue

Waltham, MA 02454-9046

(781) 622-1032, fax: (781) 622-1025, e-mail: amcclaine@tecogen.com

DOE Program Managers: Sigmund Gronich and JoAnn Milliken

(202) 586-1623, fax: (202) 586-5127, e-mail: sigmund.gronich@ee.doe.gov

(202) 586-2480, fax: (202) 586-9811, e-mail: joann.milliken@ee.doe.gov

LLNL Technical Advisor: Andrew Weisberg

(925) 422-7293, fax: (925) 424-3731, e-mail: weisberg1@llnl.gov

ANL Technical Advisor: Walter Podolski

(630) 252-7558, fax: (630) 972-4430, e-mail: podolski@cmt.anl.gov

Contractor: U.S. Department of Energy (DOE)

Prime Contract No. DE-FC02-97EE50483, September 30, 1997-June 30, 2000

Cofunding provided by the California South Coast Air Quality Management District,

Contract No. 98111

Objectives

Develop hydrogen storage and delivery system for the transportation sector, based on the use of chemical-hydride

slurry technology, and deliver a 50-kWe-equivalent hydrogen supply.

OAAT R&D Plan: Task 1; Barrier I

Approach

• Complete the design and fabrication of the prototype hydrogen generation system.

• Evaluate the prototype performance.

• Integrate H2 supply system into operating conditions of simulated fuel cell power source.

• Test and evaluate performance of the final system.

Accomplishments

• Produced pumpable lithium hydride slurry that is safe to handle and stable for several months.

• Demonstrated that the hydride slurry can be reacted to generate hydrogen on demand.

• Demonstrated that lithium-hydride-slurry hydrogen generator can meet the demands of a light vehicle following

the California highway and city protocols.

• Operated hydrogen generator pumps and motors with the hydrogen produced.
Fuel Cell Power Systems FY 2000 Progress Report

151

Future Directions

This program will be completed this year. Future work should address the integration of the lithium-hydride-slurry

hydrogen generator with a PEM fuel cell. Additional development will also be required to address some issues not

sufficiently developed during the performance of this contract.

Introduction

The objectives of this year’s work were to

complete the design and fabrication of a prototype

hydrogen generator; to test this generator for its

ability to meet the program objectives of providing

hydrogen at a rate of 3 kg/hr; to identify the

components requiring improvement; and to modify

the system to better meet the DOE technical targets

for on-board hydride storage of 7,000 WAh/kg and

930 WAh/L.

Approach

During this past year, we have completed the

design and fabrication of a prototype mobile

hydrogen generator system. We have evaluated the

performance of this system, and we have modified

the system to improve the performance of several of

its components. We are currently working on the

final performance evaluation of the mobile hydrogen

generator.

Discussion

The chemical-hydride hydrogen-storage system

developed during this program has achieved all its

goals. An advanced system design based on the

developed system and recycling water from the fuel

cell would have a gravimetric energy density of

3,364 WAh/kg and a volumetric energy density of

1,954 WAh/L. The system has been demonstrated to

follow the hydrogen demand rapidly and to produce

in excess of the 3-kg/hr hydrogen flow rate target.

The generator is performing well. When the

slurry is turned on, the hydrogen pressure ramps

rapidly up to its operating level of 50 psig, and

hydrogen flows from the device. Hydrogen

production also stops rapidly when the hydride

slurry is stopped. (This is important because it

shows that the hydrogen production from the slurry

is completed in the generator portion of the system.)

Hydrocarbon and carbon monoxide (CO) levels in

the hydrogen have been measured by mass

spectroscopy/gas chromatography (MSGC) at less

than 1-ppm levels. The thermal management system,

using excess water supply to carry away the heat of

reaction, has proven to be effective. Generator

temperatures have been maintained at about 150°C.

Hydrogen flow rates of 2 kg/hr have been achieved

for the full test duration, and hydrogen flow rates of

3 kg/hr have been achieved for shorter periods.

Another important accomplishment is the

recognition that the hydride slurry resists burning.

This is an important safety feature of the chemicalhydride slurry approach.

Slurry Production

Over the past couple of years, we have

developed the ability to produce lithium hydride

slurries in a nearly continuous operation. Figure 1

shows a three-gallon batch of lithium hydride slurry

being poured into a storage vessel. This is 60%

lithium hydride in mineral oil, with a dispersant to

maintain the slurry properties. The viscosity of the

Figure 1. Lithium hydride slurry.
Fuel Cell Power Systems FY 2000 Progress Report

152

slurry is about 2000 cp. This slurry is stable for

several weeks or more.

Safety Feature

An important feature of the slurry is its ability to

protect the lithium hydride from inadvertent

exposure to water or water vapor. If allowed to do

so, powdered lithium hydride will absorb water

vapor from the air. The reaction of the water vapor

and the hydride produces hydrogen and heat. If the

day is sufficiently humid, the heat can build up until

it ignites the hydrogen. Mixed with mineral oil, the

hydride cannot absorb moisture rapidly enough to be

a hazard. In addition, because mineral oil has such a

high vapor pressure, it actually prevents the ignition

of the lithium hydride by open flames. Figure 2 is a

sequence of photographs of a test performed with a

propane torch. A spoonful of lithium hydride slurry

was placed in our fume hood. The flame from the

torch, brought near, did not light the slurry. Gasoline

would have been ignited. When the flame was held

on the slurry for a sufficient time, some of the

mineral oil evaporated and burned, but the flame

went out when the torch was removed.

Hydrogen Generator Design

The hydrogen generator is made up of storage

vessels for the lithium hydride slurry and a small

amount of water, pumps for both the slurry and the

water, a mixing reactor, a heat exchanger, and a

hydroxide storage tank (see Figure 3). Figure 4

shows the prototype hydrogen generator after one of

its final test sequences. The reactor is a tube with an

auger/mixer running through it. Hydride slurry and

water are pumped into the reactor at one end. The

auger/mixer moves this mixture through the reactor

and mixes it at the same time. Excess water is

evaporated, absorbing and carrying the heat of

reaction out of the reactor with the hydrogen.

Hydrogen and water vapor are separated from the

hydroxide product in the head of the hydroxide tank.

The water vapor is condensed in the heat exchanger

and returned to the water circuit, while the hydrogen

is delivered to the fuel cell.

Figure 2. Flame test with LiH slurry.

Figure 3. Diagram of the hydrogen generation system.
Fuel Cell Power Systems FY 2000 Progress Report

153

Figure 4. Picture of the prototype hydrogen generator.

Hydrogen Generator Performance

Figure 5 shows the hydrogen and hydride slurry

flow rates during a typical test of the system. The

maximum flow rate was a little over 2 kg/hr of

hydrogen. It is important to note the rapid rise in

hydrogen flow rate with increases of the slurry and

the rapid drop in the hydrogen flow rate with

decreases of the slurry. Because the hydrogen flow

stopped when the hydride slurry flow stopped, we

were assured that the mixing and reaction in the

reactor were complete.

Quality of the Hydrogen

In order to be acceptable in a fuel cell, the

hydrogen produced from the lithium-hydride-slurry

reactor must have very low CO concentrations (less

than 10 ppm).

During one test, measurements were made of the

hydrogen leaving the system at points before and

after a carbon filter. Table 1 displays the results of

these measurements. In both cases, the CO

Figure 5. Data showing the slurry and hydrogen flow

rates.

Table 1. Measured contaminants in hydrogen.

Mode Contaminant ppm

Before Carbon Trap CO2 = 2.4

O2 = 25

N2 = 95

CO = 1.5

Oil = 0.1

HC = 1.2

After Carbon Trap CO2 = 0.7

O2 = 10

N2 = 40

CO = 0.1

Oil = 0.1

HC = 0.8

measurements showed that levels were well below

the tolerable levels of a PEM fuel cell. Also

measured were concentrations of oxygen, nitrogen,

carbon dioxide, mineral oil, and hydrocarbons. The

ratio of oxygen to nitrogen was the same as that in

air and was different in each measurement,

indicating that air contamination may have occurred

during the measurement process. Measurements of

mineral oil, hydrocarbons, and carbon dioxide were

all low. One possible source of the carbon dioxide is

from the water used in the system. Untreated tap

water was used in all our experiments.

As expected, the CO and hydrocarbon levels

were lower after passage through a carbon filter. The

results of this test indicate that a carbon filter is

probably not necessary for this system.

Economic Analysis

An economic analysis was performed for the

regeneration process described above to determine

the cost of hydrogen to be expected. Table 2 displays

the assumptions used in the economic analysis. The

analysis began with a preliminary design of the

various components required in the process.

We found this process to be sensitive to the cost

of carbon. However, carbon sources appear to be

available at costs that will make this process

economical. Figure 6 gives the results of our

analyses for two plant sizes. The first plant would

serve about 250,000 cars per day, whereas the larger

plant would serve about 2,000,000 cars per day.

Figure 7 displays the cost of hydrogen from the

lithium-hydride-slurry system and from other

systems. Given the cost of stored hydrogen from

other production methods, the chemical-hydride
Fuel Cell Power Systems FY 2000 Progress Report

154

Table 2. Assumptions used in economic evaluation.

Capital $58.8 million

Carbon Variable

Labor

Operators 25 at $35,000/yr

Super. & Cleric. 15% of operators

Mainten. & Repairs 5% of capital

Overhead 50% of tot. lab. + mtnc.

Local Tax 2% of capital

Insurance 1% of capital

G&A 25% of overhead

Fed. and State Tax 38% of net profit

Figure 6. Results of economic analysis.

Figure 7. Cost of stored hydrogen as a chemical hydride

and by conventional methods.

slurry approach appears very competitive, even

against tax-free gasoline.

This analysis began with a preliminary

regeneration plant design, which was generated by

using ASPEN Plus, version 10.1. Costs determined

from this analysis (using methods from Ulrich)

ranged from $6.04 to $11.30/106 Btu, depending on

the cost of the carbon. (A hydrogen cost of

$10/106 Btu is approximately equivalent to a

gasoline cost of $1.14/gal.) This analysis assumes a

15% after-tax rate of return, a carbon cost of $0.025-

$0.075/lb ($50-$150/ton), and a high-volume

production plant serving 2,000,000 cars per day. The

analysis is quite sensitive to the cost of carbon. At

$0.04/lb, the carbon is assumed to be obtained from

coal at a cost four to eight times the cost of the coal.

This cost compares favorably with that of

producing hydrogen from conventional means and

storing it as a liquid or compressed gas (Padró and

Putsche). Total stored hydrogen costs of hydrogen

from steam methane reformation (SMR) range from

$11.90 to $44.39/106 Btu. SMR is about the cheapest

source of hydrogen, with costs ranging between

$5.97 and $7.46/106 Btu. Long-term storage

(>30 days) costs range between $7.35 and

$36.93/106 Btu for compressed hydrogen and

between $5.26 and $17.12/106 Btu for liquid storage,

depending on the size.

Conclusions

In summary, the lithium hydride slurry approach

for storing hydrogen provides a viable alternative to

storage as liquid hydrogen or highly compressed

hydrogen. Storage densities are higher than those for

metal hydrides. The gravimetric energy density of

60% lithium hydride slurry is 5,110 WAh/kg, or

15.3% hydrogen. The volumetric energy density is

3,937 WAh/L, or 118 kg H2/m3. This is more than

twice the volumetric energy density of liquid

hydrogen, and it is at ambient pressure and

temperature. The slurry is easily pumped and can be

reacted with water via mixing to produce hydrogen

on demand.

The mobile generator developed for the vehicle

program has been shown to produce hydrogen on

demand, with complete reaction occurring in the

reactor volume. Hydrogen production has been

measured up to 3 kg/hr. Based on the prototype

generator design, an advanced design is anticipated
Fuel Cell Power Systems FY 2000 Progress Report

155

to provide a gravimetric energy density of

3,361 WAh/kg and a volumetric energy density of

1,954 WAh/L, assuming that the water from the fuel

cell is condensed and used to produce hydrogen in

the hydride reactor.

The cost of hydrogen resulting from the carbothermal regeneration of lithium hydroxide to lithium

hydride is estimated to range from $6.04 for carbon

costing $50/ton to $11.30 for carbon costing

$150/ton. This is competitive with hydrogen

produced by natural gas and stored as a liquid.

The chemical-hydride slurry approach provides

other desirable features. The slurry protects the

hydride from accidental contact with moisture in the

atmosphere (or otherwise). Hydrogen production by

reaction of the slurry with water can be performed at

elevated pressures, allowing additional power to be

generated from the exhaust hydrogen/steam from the

reactor and/or allowing the exhaust hydrogen/steam

to be used to pressurize air for a more compact fuel

cell. Production of hydrogen at elevated pressures

also allows the components of the hydrogen

generator to be reduced in size.

Acknowledgments

This work is supported by the U.S. Department

of Energy (DOE), the California South Coast Air

Quality Management District (AQMD Contract No.

98111), and Thermo Power Corporation. The

opinions, findings, conclusions, and

recommendations are those of the author(s) and do

not necessarily represent the views of DOE or

AQMD. DOE, AQMD, their officers, employees,

contractors, and subcontractors make no warranties,

expressed or implied, and assume no legal liability

for the information in this report. DOE and AQMD

have not approved or disapproved this report, nor

have they passed upon the accuracy or adequacy of

the information contained herein.

The authors would like to thank DOE, AQMD,

and Thermo Power Corporation for the opportunity

to demonstrate the chemical-hydride-slurry approach

for storing hydrogen. We would also like to thank

Ford Motor Company, Air Products, and Morton

International for participating in our technical review

panel.

References

1. C.E.G. Padró and V. Putsche, Survey of the

Economics of Hydrogen Technologies, National

Renewable Energy Laboratory, NREL/TP-570-

27079, Sept. 1999.

2. G.D. Ulrich, A Guide to Chemical Engineering

Process Design and Economics, John Wiley &

Sons, 1984.

FY 2000 Publications and Presentations

• R.W. Breault, C. Larson, and J. Rolfe,

“Hydrogen for a PEM Fuel Cell Vehicle Using a

Chemical-Hydride Slurry,” American Chemical

Society Meeting, New Orleans, La., Aug. 24-26,

1999.

• A.W. McClaine, R.W. Breault, J. Rolfe,

C. Larsen, R. Konduri, G. Miskolczy, and

F. Becker, “Hydrogen Storage Using Slurries of

Chemical Hydrides,” In Advances in Hydrogen

Energy, to be published by Kluwer

Academic/Plenum Publishers, 2000.
Fuel Cell Power Systems FY 2000 Progress Report

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Fuel Cell Power Systems FY 2000 Progress Report

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APPENDIX A: ACRONYMS, INITIALISMS, AND

ABBREVIATIONS

ACO adsorption/catalytic oxidation

AGO anode gas oxidizer

ANL Argonne National Laboratory

AQMD California South Coast Air Quality Management District

ASTM American Society For Testing and Materials

ATR autothermal reformer

BET Brunauer-Emmett-Teller

BTB back-to-back

CARAT Cooperative Automotive Research for Advanced Technology

CARB California Air Resources Board

CCM catalyst-coated membrane

CEM continuous emission monitor or compressor expander module

CFD computational fluid dynamics

CMEU compressor/motor/expander unit

CNG compressed natural gas

CO carbon monoxide

Cpsi channels per square inch

CRADA cooperative research and development agreement

CV cyclic voltammetry

DC direct current

DMFC direct methanol fuel cell

DOE U.S. Department of Energy

EB electrode backing

ECO electrochemical oxidation

EDX Energy-Dispersive Spectroscopy

EES Engineering Equation Solver

EXAFS Extended x-ray absorption fine structure

F

3

P Fuel-flexible, fuel-processing or fuel-flexible, fuel-processor

FMI Foster-Miller, Inc.

FPS fuel processing system

FUDS Federal Urban Driving Schedule

FY Fiscal Year

GC gas chromatography or gas chromatographic

GC/MS gas chromatography/mass spectrometry

GDE gas diffusion electrode

GHSV gas hourly space velocity

GM General Motors

H2 Hydrogen

HAZOP Hazardous Operations

HBT Hydrogen Burner Technology

HLTS humidified low-temperature shift

HOR hydrogen oxidation reaction

HRSG Heat-recovery steam generator

HRTEM High-Resolution Transmission Electron Microscopy

HTS high-temperature shift

HTSPEM high-temperature solid polymer electrolyte membrane
Fuel Cell Power Systems FY 2000 Progress Report

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ICE Internal Combustion Engine

ICEM integrated compressor/expander/motor

ICP Inductively coupled plasma or ion-conducting polymer

IFC International Fuel Cells

IGT Institute of Gas Technology

krpm 103 revolutions per minute

LANL Los Alamos National Laboratory

LBNL Lawrence Berkeley National Laboratory

LHV lower heating value

LTS low-temperature shift

MEA membrane electrode assembly or membrane/electrode assembly

MSGC mass spectroscopy/gas chromatography

MTS medium-temperature shift

NFC near-frictionless coating

NMOG nonmethane organic gases

NRC National Research Council

OAAT Office of Advanced Automotive Technologies

OD outer diameter

OEM original equipment manufacturer

ORR oxygen reduction reaction

OTT Office of Transportation Technologies

PAC process and control

PAFC phosphoric acid fuel cell

PAH polycyclic aromatic hydrocarbon

PBO poly-p-phenylene benzobisoxazole

PEFC polymer electrolyte fuel cell

PEM polymer electrolyte membrane

PEMFC polymer electrolyte membrane fuel cell

PNGV Partnership for a New Generation of Vehicles

PNNL Pacific Northwest National Laboratory

POCO synthetic graphite product from Poco Graphite, Inc. Decatur, Texas

POX Partial-oxidation reformer or partial oxidation reactor

PROX preferential oxidizer

RDE rotating disk electrode

RFG reformulated gasoline

RHE reversible hydrogen electrode

RPM revolutions per minute

RRDE rotating ring disk electrode

scc/LAh standard cubic centimeters per liter per hour

SEM Scanning Electron Microscopy

SMR Steam Methane Reformation

SPEFC solid polymer electrolyte fuel cell

Stoics stoichiometry (in some figure labels)

SULEV super ultralow emissions vehicle

SwRI Southwest Research Institute

TEM Transmission Electron Microscopy

THC total hydrocarbon(s)

TIVM Toroidal Intersecting Vane Machine

TPD Temperature-Programmed Desorption

UHV ultrahigh vacuum

UOB Under-Oxidized Burner
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VNT Variable Nozzle Turbine

WGS water gas shift

XANES X-ray Absorption Near-Edge Spectroscopy

XPS X-ray Photoelectron Spectroscopy

XRD X-ray Diffraction

XRF X-ray Fluorescence Spectroscopy

ZEV zero-emission vehicle
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Fuel Cell Power Systems FY 2000 Progress Report

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APPENDIX B: DOE TECHNICAL TARGETS FOR

FUEL CELL SYSTEMS, SUBSYSTEMS,

AND COMPONENTS

Table 1. DOE technical targets for integrated fuel cell power systems operating on gasoline reformate (including

fuel processor, stack, and auxiliaries; excluding gasoline tank and DC-DC converter).

Calendar Year

Characteristic a Units 1997 2000 2004

Energy efficiency b @ 25% of peak power % 35 40 48

Power density W/L 200 250 300

Specific power W/kg 200 250 300

Cost c $/kW 300 150 50

Start-up to full power min 2 1 0.5

Transient response (time from 10 to 90% power) sec 30 20 10

Emissions d <Tier 2 <Tier 2 <Tier 2

Durability e hour 1000 2000 5000

a Targets pertain to gasoline fuel; all targets will be refined through Systems Analysis and Vehicle Engineering

analyses (consistent with those of the PNGV).

b Ratio: [dc output energy] ⁄ [lower heating value of the input fuel (gasoline)] c Includes projected cost advantage of high volume production and includes cost for assembling/integrating the

fuel cell system and fuel processor.

d Emission levels will comply with emission regulations projected to be in place when the technology is available

for market introduction. e Less than 5% power degradation in the time between catalyst replacement.
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Table 2a. DOE technical targets for fuel-flexible fuel processors a

(includes controls, shift reactors, CO clean-up, heat exchangers; excludes fuel storage).

Calendar Year

Characteristics Units 1997 2000 2004

Energy efficiency b % 70 75 80

Power density W/L 400 600 750

Specific power W/kg 400 600 750

Cost c $/kW 50 30 10

Start-up to full power min 2 1 0.5

Transient response (time from 10 to 90% power) sec 30 20 10

Emissions d <Tier 2 <Tier 2 <Tier 2

Durability e hour 1000 2000 5000

CO content steady state f ppm 100 10 10

CO content transient f ppm 5000 500 100

H2S content in product stream

NH3 content in product stream ppm

0

<10

0

10

0

<10

a Targets pertain to gasoline fuel and are consistent with those of the PNGV.

b Fuel processor efficiency = (total fuel cell system efficiency)100% ⁄ (fuel cell stack system efficiency),

 where total fuel cell system efficiency accounts for thermal integration.

c High-volume production: 500,000 units per year.

d Emission levels will comply with emission regulations projected to be in place when the technology is available

for market introduction. e Time between catalyst replacement. f Dependent on stack development (CO tolerance) progress.
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Table 2b. Target PROX specifications.

Characteristic Value

Output CO concentration < 20 ppm, based on an input reformate composition of 2% CO,

 30-75% H2, balance CO2 and N2

Transients < 20 ppm CO after 1 minute start-up

< 20 ppm CO within 2 sec after + 90% electrical load transient

Hydrogen consumption < 20% of CO removed

Device volume ≤ 2.0 × catalyst volume

Device cost < $300 (sized for 50-kW fuel cell system)

Device pressure drop 21 kPa (3.1 psi)

Particulates Device must be tolerant of soot and debris
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Table 2c. Draft technical targets for fuel processor catalysts (gasoline w/30-ppmw sulfur [S])

ATR: Autothermal Reformer / WGS: Water-Gas Shift / PrOx: Preferential Oxidizer.

ATR S Removal WGS PrOx

GHSV a,b (hr-1) 200,000 50,000 30,000 150,000

Conversion c (%) > 99 > 97 > 90 > 99.8

H2 Selectivity d

(or consumption)

(%)

> 80 < 0.1 > 99 < 0.2

Volume e (L/kWe) < 0.013 < 0.06 < 0.1 < 0.02

Weight e (kg/kWe) < 0.015 < 0.06 < 0.1 < 0.03

Durability (hr) 5000 5000 5000 5000

Cost ($/kWe) < 5 < 1 < 1 < 1

a Gas Hourly Space Velocity:

 [volumetric flow rate of the product gases (25°C, 1atm)] ⁄ [bulk volume of the catalyst]

b STP equivalents for wet inlet gas; target values are guidelines for single reactor R&D; system/subsystem targets

take precedence. c [reactant in (moles) − reactant out (moles)]100% ⁄ [reactant in (moles)]

d At the ATR: [H2 in product (moles)]100% ⁄ [H2 "extractable" from ATR feed (moles)]

 At the shift reactor: [CO converted to H2 (moles)]100% ⁄ [total CO converted (moles)] e The volume and weight targets include only the catalysts, not the hardware needed to house the catalysts, nor the

heat exchangers.
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Table 3. DOE technical targetsa

 for 50-kW peak power (continuous)b fuel cell stack systems running on hydrogenrich fuel from fuel-flexible fuel processor (includes fuel cell ancillaries: heat, water, air management

systems; excludes fuel processing/delivery system).

Calendar Year

Characteristic Unit 1997 2000 2004

Stack system power density b W/L 300 350 500

Stack system specific power W/kg 300 350 500

Stack system efficiency c @ 25% of peak power % 50 55 60

Stack system efficiency c @ peak power % 40 44 48

Precious metal loading g/peak kW 2.0 0.9 0.2

Cost d $/kW 200 100 35

Durability (< 5% power degradation) hour >1000 >2000 >5000

Transient performance

(time from 10 to 90% power)

sec 10 3 1

Cold startup to maximum power at −40°C

Cold startup to maximum power at 20°C min

15

2

5

1

2

0.5

Emissions e <Tier 2 <Tier 2 <Tier 2

CO tolerance (steady state) ppm 10 100 1000

CO tolerance (transient) ppm 100 500 5000

a Technical targets are consistent with those of the PNGV.

b Power refers to net power (i.e. stack power minus auxiliary power requirements).

c Ratio: (output dc energy) ⁄ (lower heating value of hydrogen-rich fuel stream)

d High-volume production: 500,000 units per year.

e Emission levels will comply with emission regulations projected to be in place when the technology is

available for market introduction.
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Table 4a. Draft DOE technical targets for fuel cell stack components a

.

Component Requirement

Membranes Cost: $5/kW

Stability: < ∆2 mV @ RH 20-100% , < 10% swelling

H2 cross-over: < 1mA/cm2

Area specific 0.1 ohm-cm2

Gas crossover: < 1%

Electrodes Cost: $5/kW

CO tolerance: 500 ppm steady state, 1000 ppm transient @ 0.2 g Pt/peak kW

Durability: 5000 hours

Utilization: 85% H2, 60% O2

Membrane-electrode

assembly

Cost: $10/kW

Voltage @ current density: 0.8V @ 0.45 A/cm2

Power Density: 360 W/cm2 @ 0.8V

Bipolar plates Cost: $10/kW (<1kg/kW)

H2 permeation rate: < 2x10-6 cm3

/sec-cm2 @ 80oC, 3atm (<0.1mA/cm2)

Corrosion limit: 16 μA/cm2

Resistivity: 0.02 ohm-cm

a For operation on gasoline reformate: 40% H2 b Targets listed are for conventional membrane technologies (operating temperatures of 60-90°C).

High temperature membranes for operation above 100°C might have different characteristics.
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Table 4b. Draft DOE technical targets for fuel cell sensors a

.

Sensor Requirements

Carbon Monoxide a) 1 - 100 ppm reformate pre-stack sensor

− Operating temperature: < 150o

C

− Response time: 0.1 - 1 sec

− Gas environment: high humidity reformer/partial oxidation gas: H2 30-75%, CO2,

CO, N2, H2O @ 1-3 atm total pressure

− Accuracy: 1 - 10 % full scale

b) 100 - 1000 ppm CO sensors

− Operating temperature: 250o

C

− Response time: 0.1 - 1 sec

− Gas environment: high humidity reformer/partial oxidation gas: H2 30-75%, CO2,

CO, N2, H2O @ 1-3 atm total pressure

− Accuracy: 1 - 10 % full scale

c) 0.1 - 2% CO sensor

− Operating temperature: 250o

C - 800oC

− Response time: 0.1 - 1 sec

− Gas environment: high humidity reformer/partial oxidation gas: H2 30-75%, CO2,

CO, N2, H2O @ 1-3 atm total pressure

− Accuracy: 1 - 10 % full scale

Hydrogen in fuel

processor product gas

− Measurement range: 1 - 100%

− Operating temperature: 70 - 150o

C

− Response time: 0.1 - 1 sec for 90% response of step function

− Gas environment: 1-3 atm total pressure, 10-30 mol% water, total H2 30-75%, CO2, N2

− Accuracy: 1 - 10 % full scale

Hydrogen in ambient air

(safety sensor)

− Measurement range: 0.1 - 10%

− Operating temperature: −30 - 80o

C

− Response time: <1 sec

− Accuracy: 5%

− Gas environment: ambient air, RH 10 - 98%

− Lifetime: 5 years

− Selectivity from interference gases, such as hydrocarbons, is needed.

Sulfur compounds

(H2S, SO2, organic

sulfur)

− Measurement range: 0.05 - 0.5 ppm

− Operating temperature: < 400o

C

− Response time: < 1 min @ 0.05 ppm

− Gas environment: H2, CO, CO2, hydrocarbons, H2O

Flow rate of product gas

from fuel processor

− Flow rates: 30 - 300 standard L/min

− Operating temperature: 80o

C

− Gas environment: high humidity reformer/partial oxidation gas: H2 30-75%, CO2, N2,

H2O, CO @ 1-3 atm total pressure

Ammonia − Measurement range: 1 - 10 ppm

− Operating temperature: 70 - 150o

C

− Selectivity: < 1 ppm from matrix gases

− Lifetime: 5 - 10 years

− Response time: sec

− Gas environment: high humidity reformer/partial oxidation gas: H2 30-75%, CO2, N2,

H2O, CO @ 1-3 atm total pressure
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Table 4b. Cont.

Sensor Requirements

Temperature − Measurement range: −40 - 150o

C

− Response time: < 0.5 sec with 1.5% accuracy @ −40 - 100o

C; < 1 sec with 2 %

accuracy @ 100 - 150o

C

− Gas environment: high humidity reformer/partial oxidation gas: H2 30-75%, CO2, N2,

H2O, CO @ 1-3 atm total pressure

− Insensitivity to flow velocity is needed.

Relative humidity for

cathode and anode gas

streams

− Operating temperature: 30 - 110o

C

− Measurement range: 20 - 100 %

− Accuracy: 1%

− Gas environment: high humidity reformer/partial oxidation gas: H2 30-75%, CO2, N2,

H2O, CO @ 1-3 atm

Oxygen concentration in

fuel processor and at

cathode exit

(a) Oxygen sensors for fuel processor reactor control

− Measurement range: 0 - 20% O2

− Operating temperature: 200 - 800o

C

− Response time: < 0.5 sec

− Accuracy: 2% full scale

− Gas environment: high humidity reformer/partial oxidation gas: H2 30-75%, CO2, N2,

H2O, CO @ 1-3 atm

b) Oxygen sensors at the cathode exit

-- Measurement range: 0 - 50% O2

− Operating temperature: 30 - 110o

C

− Response time: < 0.5 sec

− Accuracy: 1% full scale

− Gas environment: H2, CO2, N2, H2O @ 1-3 atm total pressure

Differential pressure in

fuel cell stack

− Measurement range: 0-1 or 0-10 or 1-3 psig

(depending on design of fuel cell system)

− Temperature range: 30 - 100o

C (−40oC survivability)

− Response time: < 1 sec

− Accuracy: 1%

− Size: ≤ 1in.2

− Orientation cannot be a problem.

− Must be able to withstand and measure liquid and gas phases.

a Sensors must conform to size, weight, and cost constraints required for automotive applications.
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Table 5. Current DOE targets for compressors/expandersa

.

Characteristic (units) Requirement

Input power b,c at max flow (kW) 4.3

Efficiency at 100% flow d compressor: 75% @ 3.2 PR

expander c

: 90%

Efficiency at 20% flow e compressor: 65% @ 1.6 PR

expander c

: 80%

Volume f (liters) 4

Weight f (kg) 3

Cost f @100K/yr $200

Turndown ratio 10

Noise < 80 dB

a

 A workshop being held early in FY 2001 will review and update the compressor/expander performance

targets.

b Input power to the controller to power a compressor/expander system producing 76 g/sec (dry)

maximum flow. This flow rate roughly corresponds to maximum power for a 50 kW fuel cell system. c

 Input power and expander efficiency calculated assuming tail gas composition specified by DOE

d

 100% flow: 82 g/sec (150oC, 2.8 atm inlet, unless otherwise specified)

e

 25% flow: 19 g/sec (150oC, 2.8 atm inlet, unless otherwise specified)

f DOE guidelines for volume, weight, and cost do not include the motor/controller or heat rejection

 (if required).
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Table 6. New Draft DOE Targets for On-board Hydrogen Storage Technologies a,b.

Units Physical Storage c Chemical Storage d

Storage weight percent e %6 6

Storage efficiency f % 95 90

Energy density (gas) Wthh/liter 1050 g 1500 g

Specific energy h Wthh/kg 2000 2000

Costi $/kW-h 5 5

Cycle life Cycles 500 500

Operating pressure (gas) psig 7500 g N/A

Refueling time min < 5 < 5

Permeation rate scc/hr-liter 2.0 N/A

a To meet PNGV 380-mile range target; based on LHV of hydrogen.

b Work carried out in collaboration with DOE Hydrogen Program. c Includes compressed gas and cryogenic liquid tanks.

d Includes materials such as carbon nanostructures, fullerenes, metal hydrides,

organometallics, or catalyzed hydrides. e Weight percent H2 is assumed to be: [weight of H2]100% ⁄ [weight of (H2 + tank)] f Includes power associated with capturing and releasing hydrogen. g Conceptual designs showed 180 liters (3 tanks) could be packaged without

compromising trunk or passenger compartments; assuming 5 kg for +300 mile range in

a PNGV-type vehicle yields 0.028 kg/L. Derated by 10% for tank system yields

0.031kg/L. This corresponds to tank pressure of 7500 psig, and 1050 Wthh/L. Chemical

storage target is more aggressive because tanks are marginal in meeting vehicle

requirements. h Specific energy is assumed to be: [LHV of H2 contained] ⁄ [weight of (H2 + tank)] i Based on high volume production of 500,000 units.
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Printed on recycled paper
O FFICE OF T RANSPORTATION T ECHNOLOGIES

S ERIES OF

2000 A NNUAL P ROGRESS R EPORTS

• Vehicle Propulsion and Ancillary Subsystems

• Automotive Lightweight Materials

• Automotive Propulsion Materials

• Fuels for Advanced CIDI Engines and Fuel Cells

• SIDI Engine R&D

• Combustion and Emission Control for 

Advanced CIDI Engines

• Transportation Fuel Cell Power Systems 

• Vehicle Power Electronics and Electric Machines

• Advanced Technology Development 

(High-Power Battery)

• Exploratory Technology Research 

(High-Power Battery)

• Vehicle High-Power Energy Storage

• Electric Vehicle Batteries R&D

and Office of Advanced Automotive Technologies

FY2000 Program Highlights

www.ott.doe.gov/oaat

Clean Energy

– for the –

21st Century