1999 A NNUAL

P ROGRESS

R EPORT

E NERGY

C ONVERSION

T EAM

U.S. Department of Energy

Energy Efficiency and

Renewable Energy

Office of Transportation

Technologies

Office of Advanced

Automotive Technologies

FUEL CELLS FOR TRANSPORTATION

T EAM

S ERIES

S

R EPORTS

ntrol

tive Fuels

Printed on recycled paper
This document highlights work sponsored by agencies of the U.S. Government. Neither the U.S.

Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied,or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privatelyowned rights. Reference herein to any specific commercial product, process, or service by trade name,trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. The views and opinions of authorsexpressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof.

d
U.S. Department of Energy

Office of Advanced Automotive Technologies

1000 Independence Avenue, S.W.

Washington, DC 20585-0121

FY 1999

Progress Report for Fuel Cells for Transportation

Energy Efficiency and Renewable Energy

Office of Transportation Technologies

Office of Advanced Automotive Technologies

Energy Conversion Team

Steven Chalk Energy Conversion Team Leader

October 1999
Fuel Cells for Transportation FY 1999 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. PEM Systems Modeling and Analysis ............................................................................. 19

III. FUEL PROCESSING SUBSYSTEM................................................................................... 23

A. Advanced Fuel-Flexible Fuel Processor Development SFAA for Next

Millennium Fuel ProcessorTM for Transportation Fuel Cell Power System......................... 23

B. Multifuel Processor for Fuel Cell Electric Vehicle Applications ........................................ 28

C. Fuel-Flexible, UOBTM Fuel Processor System Development and Status............................. 30

D. Integrated Fuel Processor Development........................................................................... 34

E. Microchannel Fuel Processor Components....................................................................... 37

F. On-Board Hydrogen Generation Technology................................................................... 42

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

in an Automotive PEM Fuel Cell Power Plant.................................................................. 48

H. Reformate Cleanup Technology ...................................................................................... 51

I. Evaluation of Partial Oxidation Fuel Cell Reformer Emissions.......................................... 57

J. Catalytic Partial Oxidation Reforming Materials and Processes......................................... 60

K. Alternative Water-Gas Shift Catalyst Development .......................................................... 63

IV. FUEL CELL STACK SUBSYSTEM................................................................................... 67

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

PEM Fuel Cell Stack System.......................................................................................... 67

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

Design for Operation on Reformate Used in Vehicle Power Systems................................. 71

C. Direct Methanol Fuel Cells ............................................................................................. 77

D. Efficient Fuel Cell Systems............................................................................................. 80

V. PEM STACK COMPONENT COST REDUCTION ........................................................... 85

A. High-Performance, Low-Cost Membrane Electrode Assemblies for

PEM Fuel Cells and Integrated Pilot Manufacturing Processes.......................................... 85

B. Low-Cost, High Temperature, Solid Polymer Electrolyte Membrane for Fuel Cells............ 89
Fuel Cells for Transportation FY 1999 Progress Report

iv

CONTENTS (Cont.)

Page

C. Nanopore Inorganic Membranes as Electrolytes in Fuel Cells............................................ 94

D. Development and Optimization of Porous Carbon Papers Suitable for

Gas Diffusion Electrodes................................................................................................ 97

E. Optimized Electrodes for PEM Operation on Reformate/Air ............................................. 100

F. New Alloy Electrocatalysts and Electrode Kinetics........................................................... 104

G. Cathode Catalysts........................................................................................................... 107

H. Development of a $10/kW Bipolar Separator Plate ........................................................... 110

I. Layered PEM Stack Development................................................................................... 113

J. Corrosion Test Cell for Metallic Bipolar Plate Materials................................................... 117

VI. AIR MANAGEMENT SUBSYSTEMS................................................................................ 121

A. Turbocompressor for PEM Fuel Cells.............................................................................. 121

B. Development of a Scroll Compressor/Expander Module for

Pressurization of 50-kW Automotive Fuel Cell Systems ................................................... 124

C. Fuel Cell Power System - Critical Components for Transportation

Development of Compact Air, Heat, and Water Management Systems:

Variable Delivery Compressor/Expander Development..................................................... 127

D. Electrically Boosted Gas-Bearing Turbocompressor for Fuel Cells.................................... 131

VII. HYDROGEN STORAGE.................................................................................................... 135

A. High-Pressure Conformable Hydrogen Storage for Fuel Cell Vehicles............................... 135

B. Advanced Chemical Hydride Hydrogen Generation/Storage System

for PEM Fuel Cell Vehicles............................................................................................ 140

APPENDIX A: ACRONYMS, INITIALISMS, AND ABBREVIATIONS.................................... 145
Fuel Cells for Transportation FY 1999 Progress Report

1

General Motors’ Zafira Fuel Cell Minivan

JoAnn Milliken

Program Manager

Patrick Davis

Program Manager

Donna Lee Ho

Program Manager

I. INTRODUCTION

Developing Advanced PEM Fuel Cell Technologies

for Transportation

On behalf of the Department of Energy’s Office of Advanced Automotive

Technologies (OAAT), we are pleased to introduce the Fiscal Year (FY) 1999

Annual Progress Report for the Fuel Cells for Transportation Research and

Development (R&D) Program. This introduction serves to briefly outline the

nature, progress, and future directions of the program. The past year has been a

very exciting one for fuel cell technology; major automotive and fuel cell

companies have announced technology breakthroughs, development vehicles,

partnerships, and new initiatives. The Department of Energy (DOE) continues to

contribute to this progress in a significant way by supporting research and

development activities that address the most critical barriers to the introduction of

commercially viable proton-exchange-membrane (PEM) fuel cell systems.

The mission of the Fuel Cells for Transportation R&D 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 United States Council for Automotive Research, which

comprises Ford, General Motors, and DaimlerChrysler. One of the objectives of

PNGV is to develop, by 2004, a mid-sized passenger vehicle capable of achieving

a gasoline-equivalent fuel economy of 80 miles per gallon (mpg) while adhering

to future emissions standards and maintaining such attributes as performance,

comfort, and affordability. PNGV has targeted PEM fuel cell power systems as

one of the promising technologies for achieving 80-mpg fuel economy in a lightweight, mid-size passenger vehicle.

While this report specifically

documents the progress made

by the Fuel Cells for

Transportation R&D

Program, we are pleased to

note the many major and

diverse fuel cell technology

advancements that have

received international

recognition throughout the year. These advancements

have taken many forms – development cars (Ford’s Fuel

Cell P2000, DaimlerChrysler’s NECAR 4, General

Zafira), stationary power advances, laboratory

announcements, and even new business ventures. For instance, the California Fuel Cell Partnership, a

program that was announced earlier this year, reflects the high level of interest by industry and state
Fuel Cells for Transportation FY 1999 Progress Report

2

governments in accelerating the development of fuel cell vehicles. The Partnership’s members represent the

confluence of interested parties, including fuel cell and automotive concerns (Ballard, DaimlerChrysler, and

Ford), the energy industry (ARCO, Shell Oil, and Texaco), and state government (California Energy

Commission and the California Air Resources Board). The Partnership has plans to place about 50 fuel cell

vehicles — cars and buses — on the road between 2000 and 2003. Aggressive plans like these demonstrate

that fuel cell technology may play a major role in our nation’s transportation future.

The Program is implemented through cost-shared contracts with automakers, automotive suppliers, and fuel

cell and component developers. Furthermore, DOE National Laboratories and universities throughout the

U.S. conduct research and development that increases the knowledge base of the emerging PEM fuel cell

technology.
Fuel Cells for Transportation FY 1999 Progress Report

3

Fuel Cell Stack Subsystem

Meeting the Challenges

An extensive gasoline and petroleum-based fuels infrastructure exists in the United States today. The

Department of Energy believes that the successful early introduction and acceptance of automotive fuel cells

is dependent on fuel-flexible fuel cell systems, systems that run on both conventional and alternative fuels.

However, to reach the goal of a commercially viable fuel-flexible fuel cell system, many technological

challenges remain.

The commercial viability of the fuel-flexible fuel cell system remains closely associated with its cost

competitiveness. Currently, the cost of the automotive fuel cell system is estimated at ten times higher than

that needed to be competitive with the internal combustion engine. To meet the challenges of lowering

system costs, the Fuel Cells for Transportation R&D Program strives to develop components with lower-cost

materials, advanced manufacturing processes, and higher operating efficiency.

In addition, technologies associated with fuel cell systems (i.e., fuel-flexible fuel processors, low-cost bipolar

plates, compact and efficient compressors, etc.) require that technological challenges be resolved. Fuel cell

system performance must be the same as, if not better than, that of current automobile engines. The on-board

fuel processor, for example, faces technological challenges in meeting response targets both for system startup and during operation. Barriers associated with complete system integration include overall performance,

weight, size, and durability.

R&D Highlights

Researchers supporting the Fuel Cells

for Transportation R&D Program made

significant progress in meeting these

challenges. In FY 1999, technological

advances were made in systems

development, in fuel-processing

technology, and in the development of

low-cost, high-volume manufacturing

processes for key components. The

following summaries represent a few

selected highlights of the progress made

under the program.

System Integration. To convert

gasoline or other petroleum-based fuels

into pure hydrogen, the fuel cell system

must include a fuel processor. During

FY 1999, Plug Power teamed with Epyx

to successfully integrate and operate a

10-kW fuel cell stack, using an

advanced, fuel-flexible fuel processor. The integration test achieved 10 kWe of electrical output and met the

project’s interim system efficiency targets while operating on low-sulfur gasoline, methanol, ethanol,

naphtha, and other fuels. Appropriate operational experience gained with this test can be incorporated into the

next phases of the project. Seven different fuels were used in the test, and all demonstrated very low

emissions. It is anticipated that Super Ultra Low Emission Vehicle (SULEV) standards should be achievable

with a gasoline fuel cell power system.
Fuel Cells for Transportation FY 1999 Progress Report

4

Cutaway View of PNNL

Microchannel Fuel Vaporizer

LANL Polarization Curves Showing Nearly Complete

Tolerance to 500 ppm CO in Reformate

Microchannel Fuel Processor. At Pacific Northwest National Laboratory

(PNNL), researchers are developing components for the onboard, automotive

production of hydrogen from liquid hydrocarbons, using a newly developed

microfabrication method to produce extremely compact hardware with high

throughputs. During FY 1999, the PNNL researchers developed and

conducted proof-of-concept demonstrations of a steam reforming microchannel

reactor. This demonstration shows the feasibility of this concept of steam

reforming of gasoline by yielding a hydrogen concentration in excess of 65%.

It is anticipated that a complete microchannel fuel processing system could

occupy less than 0.25 ft3 volume for a 50-kW application, one-tenth the size of

conventional fuel processing technology.

CO Tolerance Electrode. 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, using

methods that meet cost and efficiency targets for transportation applications.

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. As little as 10 ppm CO in reformate fuel can poison conventional

platinum catalysts in state-of-the-art fuel cells, putting very stringent performance requirements on the fuel

processor. Using newly developed catalysts and a reconfigured anode, researchers at LANL were able to

demonstrate nearly complete tolerance to 500 ppm

CO in reformate fuels. They also demonstrated that

the negative effects of 100 ppm CO in reformate on

fuel cell performance could be eliminated with as

little as 0.5% air bleed to the anode with an optimized

membrane electrode assembly (reconfigured

electrode, 0.6 mg/cm2 anode Pt loading).

CO Cleanup Catalysts. Argonne National

Laboratory is developing new catalysts for the watergas shift reaction – an important fuel processing step

that increases hydrogen content while lowering CO.

Argonne researchers developed a breakthrough

bifunctional catalyst that works effectively at a wide

range of temperatures and is not damaged by exposure

to air. Argonne also increased by a factor of three the

catalyst’s ability to react at 230oC, while

simultaneously reducing the expensive precious metal

content by 50 percent. Comparing data obtained from

Argonne’s catalyst testing with published data from commercial catalyst manufacturers indicates that this

catalyst could reduce the total volume of the water-gas shift reactor by 30 percent.
Fuel Cells for Transportation FY 1999 Progress Report

5

3M’s Three-Layer Catalyst-Coated Membrane

Low Cost MEA Manufacturing. 3M is developing an

integrated pilot process for the low-cost manufacture of

high-performance, high-quality membrane electrode

assemblies (MEAs). In a major accomplishment, 3M

demonstrated the feasibility of scaling up the fabrication of

its proprietary thin-film catalyst and the continuous

formation of three-layer catalyst-coated membrane

material, producing 15 meters of material with 99.3% of

the catalyst transferred and an excellent material

uniformity.

Low-Cost Bipolar Plate Manufacturing. Research at the

Institute of Gas Technology (IGT) and subcontractor PEM

Plates also contributed to reducing manufacturing costs

through the development of a molded composite graphite

bipolar separator plate that achieves a projected manufacturing cost of less than $10/kW while meeting all of

the DOE performance specifications. To evaluate the various steps in the molding process, PEM Plates

assembled a pilot production line with a molding capacity of five plates per hour. This pilot line will provide

an understanding of the key steps in preparation of the

composite blend, transferring the blend to the mold, forming

the plates, releasing the plates from the molds, post-molding

operations, and quality control. As a result of the molded

graphite bipolar plate development, several fuel cell stack

developers have requested plates molded to their design

specifications.

Achievements and Awards

The Vice President’s Partnership for a New Generation of

Vehicles (PNGV) Medal. Fifteen scientists from the DOE

National Laboratories, the automobile industry, and

automotive suppliers were honored at the White House on

March 17, 1999, with the PNGV Medal. The research team

was honored for several fuel processing accomplishments,

including being the first to develop and demonstrate a system

that would permit use of gasoline and other available fuels,

such as methanol, ethanol, or natural gas, in fuel cell-powered

vehicles. By developing and demonstrating a fuel-flexible

system, the scientists removed a major barrier to the

application of fuel cell technology in automobiles. The Medal winners were selected by a panel of five

judges for research involving government-industry teamwork and resulting in a significant technical

accomplishment in PNGV-related automotive technology.

R&D 100 Award. Pacific Northwest National Laboratory received an R&D 100 Award from R&D Magazine

during FY1999 for the microchannel gasoline vaporizer. Identified as one of the 100 most technologically

significant new products of the year, this unit, which consists of a microchannel reactor and a microchannel

heat exchanger, vaporizes the gasoline stream for a 50-kWe fuel processing/fuel-cell system. Heat for

Typical IGT Molded Composite Graphite

Plate Flowfield
Fuel Cells for Transportation FY 1999 Progress Report

6

Energy Partners’ 50-kW

Fuel Cell Stack Subsystem International Fuel Cells’ 50-kW Integrated System

vaporization is provided through the internal, catalytic

combustion of low-concentration hydrogen from the fuel

cell anode. The unit weighs only four pounds and occupies

a volume of only 0.01 ft3, one-tenth the volume of

conventional vaporizers.

Future Directions

While we are very encouraged by the technical progress

realized in FY 1999 under the Fuel Cells for Transportation

R&D Program, we are also well aware of the significant

challenges still ahead of us. We will continue to work

diligently and steadfastly with our government and

industry partners to address the technological barriers. In

the forthcoming year, we will research the issues of cost,

output, size, weight, and durability.

During FY 2000, researchers at Argonne National Laboratory will continue 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 completion of stack subsystems from Energy Partners and AlliedSignal and integrated systems

from Plug Power and International Fuel Cells.

The beginning of FY 2000 will also signal the start of 10 new projects. Work will begin in such areas as

autothermal fuel processing, advanced high-volume MEA manufacturing, high-temperature membrane

development, novel fuel cleanup devices, and compressor technology. Through these efforts and other

related projects, researchers in the Fuel Cells for Transportation 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.

The remainder of this report presents project abstracts that highlight progress achieved during FY 1999 under

the Fuel Cells for Transportation R&D 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.

Researchers Honored for Fuel Cell

Fuel-Processor Technology
Fuel Cells for Transportation FY 1999 Progress Report

7

 

Patrick Davis

Energy Conversion Team

Office of Advanced Automotive

Technologies

Donna Lee Ho

Energy Conversion Team

Office of Advanced Automotive

Technologies

JoAnn Milliken

Energy Conversion Team

Office of Advanced Automotive

Technologies
Fuel Cells for Transportation FY 1999 Progress Report

8
Fuel Cells for Transportation FY 1999 Progress Report

9

II. FUEL CELL POWER SYSTEM DEVELOPMENT

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) 252-4176, e-mail: podolski@cmt.anl.gov

Contractor: International Fuel Cells, South Windsor, Connecticut

Prime Contract No. DE-AC02-99EE50567

Objective

The objective of this project is to deliver to DOE a 50-kW-equivalent gasoline fuel processing system and a fully

integrated, gasoline-fueled 50-kW PEM power plant for functional demonstration testing. Although focused on

gasoline operation, the fuel processing system will utilize fuel-flexible reforming technology that can be modified to

accommodate such fuels as methanol, ethanol, and natural gas. The initial demonstration testing of each of the units

will be performed at IFC. After IFC testing, each unit will be delivered to Argonne National Laboratory for

additional operational tests by DOE.

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

Approach

• Deliver and test autothermal fuel processor.

• Deliver and test ambient-pressure integrated power subsystem.

Accomplishments

New start in late FY 1999.

Future Directions

• Advanced PEM fuel cell power plant system capable of operation on gasoline or such alternative transportation

fuels as methanol, ethanol, and natural gas

• Integrated power subsystems meeting the physical and operational characteristics necessary for automobile

applications
Fuel Cells for Transportation FY 1999 Progress Report

10

Introduction

International Fuel Cells (IFC) is committed to

the commercialization of PEM fuel cell power plants

for transportation applications. A program is in place

that addresses technology development and the

verification of each of the necessary components and

subsystems and, ultimately, 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 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

and a 50-kW PEM power plant.

Planned Approach

Fuel Processing System

The gasoline fuel processing system (FPS)

consists of an autothermal fuel reformer, a shift

converter, a selective oxidizer, a fuel desulfurizer,

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 to generate 50 kW of electrical

dc power. The gas composition produced by the FPS

will be consistent with the long-term operating

requirements of the fuel cell, including CO levels of

50 parts per million or less.

Figure 1 shows a test article that integrates the

autothermal reformer (ATR) with its associated

process heat exchangers. ATR testing has

demonstrated 98% fuel conversion with carbon-free

operation. Figure 2 shows the low-temperature shift

converter (LTSC) test article. The LTSC design is

based on over 3 million hours of operation in IFC’s

stationary power plant. It is a low-temperature

design with a CO output level of less than 1%.

Several models of each of these components have

been tested, confirming their operation while

providing opportunities for reductions in both

weight and volume. Similar development programs

are under way for the fuel desulfurizer and selective

oxidizer components.

Figure 3 shows a conceptual arrangement of the

FPS as a stand-alone test unit. The objective is to

maintain the physical arrangement of the

Figure 1. Integrated autothermal reformer test article.

Figure 2. Low-temperature shift converter test article.

CA0320

AUTOTHERMAL

REFORMER

SELECTIVE

OXIDIZER

LOW TEMPERATURE

SHIFT CONVERTER

Figure 3. Conceptual 50-kWe fuel processor system.
Fuel Cells for Transportation FY 1999 Progress Report

11

components as close to the power plant arrangement

as possible.

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, the Controller, and

associated electrical equipment.

The 50-kW Power Subsystem comprises two

25-kW PEM ambient-pressure Cell Stack

Assemblies (CSAs). Stack endurance tests on

simulated reformate with CO have been completed,

with stack performance exceeding the program goals

throughout the test period, as shown in Figure 5.

Figure 6 shows the 15% reduction in cell stack

size that has been achieved. The greater portion of

the advancement resulted from improved cell

performance. A thinner cell design has also been

developed and incorporated into the design base.

Two 25-kW CSAs are joined to achieve the

50-kW rating of the Power Subsystem.

Figure 7 is a conceptual drawing of the fully

integrated 50-kW power plant. As shown, the major

gasoline processing system components are closecoupled on the right-hand side of the picture. The

power subsystem and the thermal management and

air supply systems are located on the left-hand side.

FUEL TO

INVERTER

DC

POWER

REFORMATE

THERMAL

MANAGEMENT

SUBSYSTEM

FUEL PROCESSOR SUBSYSTEM

POWER SUBSYSTEM

AIR &

SUBSYSTEM

WATER

FPS Fuel Processor System

CSA Cell Stack Assembly

BOP Balance of Plant

FPS

CSA

AUTOTHERMAL

REFORMER

LOW

TEMPERATURE

SHIFT

CONVERTER

OXIDIZER

SELECTIVE

CELL

STACK

OTHER (Controller, etc.)

BOP

CELL

STACK

FC40463

Figure 4. Power plant schematic.

Load Time (h)

Average Cell Potential (V)

GOAL

GOAL

Figure 5. Cell stack endurance.

25 kW NET

25 kW NET

wcn16008

Figure 6. CSA advancement.
Fuel Cells for Transportation FY 1999 Progress Report

12

FUEL PROCESSING

SUBSYSTEM

POWER

SUBSYSTEM

CA0299

Figure 7. Conceptual 50-kW 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. Under this new start, IFC will

deliver to DOE a 50-kW-equivalent gasoline fuel

processing system utilizing fuel-flexible reforming

technology and a fully integrated gasoline-fueled

50-kW PEMFC power system for functional

demonstration testing.

B. Pressurized Fuel Cell Power System for Transportation

William D. Ernst

Plug Power, LLC

Latham, NY 12110

(518) 782-7700, fax: (518) 782-7914

DOE Program Manager: Donna Lee Ho

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

ANL Technical Advisor: Walter Podolski

(630) 252-7558, fax: (630) 252-4176, e-mail: podolski@cmt.anl.gov

Contractor: Plug Power, LLC, Latham, New York 12110

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

Major Subcontractor: Epyx Corporation, Cambridge, MA 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 polymer electrolyte membrane or proton exchange membrane (PEM) fuel

cell stack with balance-of-plant (BOP) components, and a 50-kWe (equivalent) fuel-flexible reformer.

• Provide test data evaluating the system for vehicle propulsion under driving cycle profiles.

OAAT R&D Plan: Tasks 5, 8, and 11; Barriers A, B, C, D, E, F, G, 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.
Fuel Cells for Transportation FY 1999 Progress Report

13

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

Accomplishments

• Successfully operated an integrated, multifuel-powered fuel cell (FC) system (at the 10-kW level) and obtained

steady-state emissions data.

• Developed capability to build large fuel cell stacks.

• Built and tested 40-kWe hydrogen-powered FC system. Demonstrated operation on Federal Urban Driving

Standard (FUDS) cycle and rapid startup of stack from ambient temperature.

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

• Develop an integrated system to increase fuel cell and fuel processor efficiency and to improve overall system

power density.

- Build and test a 50-kWe, integrated gasoline-powered fuel cell system (brassboard level).

- Build and test a tightly integrated 50-kWe gasoline-powered fuel cell system.

Introduction

There are four phases to this program. Phase I is

to develop fundamental knowledge regarding the

individual components in the fuel cell system,

culminating with the integration of a 10-kWe net

PEM fuel cell stack with a partial oxidation fuel

processor. Phase II involves the development of

components at the 50-kWe level, followed by

brassboard system integration of the various

components in Phase III. In Phase IV, a completely

integrated, compact 50-kWe system will be built that

incorporates the results of Phase III testing; this

system will be used for performance and emissions

testing.

Phase I was completed during FY 1998. Phase

II was completed during FY 1999, and Phase III is

currently in progress. In general, FY 1998 activities

were focused on fundamental hardware

development, while FY 1999 activities have been

focused primarily on system operation and

optimization.

While the fuel cells and subsystems will be

designed and developed by Plug Power, Epyx, Inc.,

will provide the fuel processor. Plug Power will

integrate the Epyx fuel processor into the overall

fuel cell system.

Phase II Program Results

During FY 1999, Plug Power developed

manufacturing techniques to enable construction of

large (up to 50 kW) fuel cell stacks. Large stacks

were built, using both stainless steel and carbon

composite plates. Improved sealing techniques

contributed significantly to the success of stack

construction. Alternative stack clamping techniques

were also developed in FY 1999.

Durability of stacks was proven out during

FY 1999. Stacks built for this DOE program have

been cycled thousands of times through pressure

swings ranging from 1 to 3 atm. A 40-kW stack was

started at room temperature and brought to 23 kW in

less than a second (Figure 1).
Fuel Cells for Transportation FY 1999 Progress Report

14

0 2 4 6 8 10 12 14 16 18 20 22 24

0

5

10

15

20

25

30

35

40

Cold Start-up Test

Stack FS-16

3 atm - 30C

10/28/98

Power (kW)

Time (seconds)

Figure 1. Startup of a 40-kW fuel cell stack.

Efforts were made during FY 1999 to optimize

stack performance. An important step toward

optimizing large stack performance is to accurately

predict performance by using smaller stacks.

Figure 2 compares the performance of several small

stacks (operated on synthetic reformate) with that of

a 10-kW stack that was operated on actual reformate

produced by the Epyx fuel processor.

Significant gains were made during FY 1999 in

the area of BOP and controls. In order for fuel cell

systems to be efficient, reactants need to be

delivered to the fuel cell stack at constant

stoichiometries throughout the stack's operating

range. The control system must be able to respond

in a load following mode.

A major portion of FY 1999's effort was to build

and test an automated test stand to deliver reactants

at near-constant stoichiometries for a 40-kWe stack.

Anode inlet pressure = 2.7 - 3.0 atm

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

Current density (A/cm2)

Mean cell voltage (V)

Test stack U-2

Test stack CV3-9

With synthetic reformate @ Plug Power

With low sulfur gas reformate @ EPYX

(5/12)

Figure 2. Comparison of stack performance with

synthetic and real reformate.

This system successfully followed a FUDS cycle in

load-following mode. The peak load transient,

illustrated in Figure 3, shows excellent agreement

between demanded and actual performance. The lag

between load demand and actual output is due to a

0.62-second instrumentation lag.

200 210 220 230 240

0

5

10

15

20

25

30

Federal Urban Driving Cycle

Stack FS-16

30 psig

10/28/98 Demanded

 Actual

Power (kW)

Time (seconds)

Figure 3. Peak load point on FUDS cycle.

Second 10-kW Integration

A second integrated test of a fuel cell and a

gasoline-powered fuel processor was carried out in

May 1999. This integration achieved all the intended

goals: attain 10 kWe output at design stoichiometry

levels, meet interim system efficiency targets (low

30% range), demonstrate multifuel (7 fuels)

operation, and gain operational experience that can

be incorporated into the Phase III and Phase IV 50-

kWe systems. The fuels tested were ethanol,

methanol, methane, Fischer-Tropsch synthetic

gasoline, M-85, low-sulfur gasoline, and California

Phase II gasoline.

The second 10-kWe integration was successful

due to the following:

• Extensive integration of the fuel cell and fuel

processor systems,

• Improved fuel processor performance [higher H2

concentration and very low CO levels (typically

<10 ppm)], and

• Increased operational experience with both

stacks and BOP.

Operational experience gained during the

10-kWe integration included effects of operating

pressures and temperatures, as well as

humidification techniques.
Fuel Cells for Transportation FY 1999 Progress Report

15

Phase III

Components developed during Phases I and II

are being integrated into a 50-kWe brassboard

system. In Phase III, the fuel cell and fuel processor

will be built on individual skids and connected

together. The interface points between the fuel cell

stack subsystem and the Epyx 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 1/4 power, (2)

the water management system will be a closed loop,

and (3) the reformate will be provided to the fuel cell

stack fully saturated. The net effects of these

conditions are better maintenance of water balance

within the fuel cells and improved power density of

the system.

Future Work

The remainder of this program will focus

primarily on systems integration and operation.

Stack development continues during Phase III in

order to achieve higher power densities and reduced

pressure drop across the stack. Two development

approaches are being taken in these efforts.

Upon completion of Phase III testing, the Phase

IV design will begin. Test results from Phase III

will be used to optimize component selection for

Phase IV. The Phase IV system will consist of 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.D. Ernst, “PEM Fuel Cell Stack Development

for Automotive Applications,” Fuel Cell

Seminar, Orlando, Fla., Nov. 17-20, 1996.

3. 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.

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

Cells,” SAE Fuel Cells for Transportation

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

1998.
Fuel Cells for Transportation FY 1999 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

DOE Program Manager: Donna Lee Ho

(202) 586-8000, fax: (202) 586-9811, e-mail: donna.ho@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, Inc., Cambridge, Massachusetts

Prime Contract No. DE-FC02-99EE50587, June 1999-June 2003

Objectives

• Develop an independent cost model for polymer electrolyte membrane (PEM) fuel cell systems for

transportation applications.

• Assess cost reduction strategies for year 2000 to 2004 development programs.

OAAT R&D Plan: Task 8; Barrier J

Approach

This five-year, multitask program will develop (1) an independent cost estimate of 1999 potential PEM fuel cell

system options and then (2) cost reduction strategies for year 2000 to 2004 PEMFC system development programs.

Annual updates to the baseline cost estimate for the subsequent four years will be provided. Integrated into the

system design and costing information will be feedback solicited from major system developers, as well as material

and component suppliers, through structured interviews.

Accomplishments

New start in late FY 1999.

Future Directions

• In the first year, a baseline cost estimate will be developed, based on best available and projected technology

and manufacturing practices. In addition, the impact of potential technology developments on system cost

reduction will be assessed.

• In the subsequent four years, annual updates to the baseline cost model and system scenarios will be made,

based on assessments of developments in PEMFC system technologies and manufacturing processes.
Fuel Cells for Transportation FY 1999 Progress Report

17

Project tasks and the work breakdown by year

are indicated in Figure 1.

The system cost model will be based on a

realistic system model developed from Arthur D.

Little’s experience in fuel cell systems and through

discussions with the DOE national laboratories and

fuel cell system developers. We are currently

working with a modeling group within Argonne

National Laboratory to calculate the state parameters

of system components, as well as energy and mass

balances for each component. The model parameters

will be selected to satisfy PNGV efficiency and fuel

utilization goals. We will then scale the various

components on the basis of technology available

now. After scaling and integrating the components,

we will then calculate the system weight and

volume. At this time, the system parameters and

model are calculated at full power. Such issues as

transient response and startup are not specifically

addressed in the design or model. As technology

evolves, we will incorporate these advances into the

system design and revise the system cost

projections. Figure 2 shows the overall process of

system design and cost modeling.

We will focus our attention on the fuel cell stack

and fuel processor subsystems, while using suppliers

to provide design and cost information for the

balance-of-plant (BOP) components.

In Task 2, we will develop a technology-based

cost model that starts with the system design and

specifications and then defines the manufacturing

processes, including development of materials and

component databases and process and equipment

databases. The manufacturing process will be scaled

to automotive volumes and will use automotive

financial and production factors. As part of the cost

modeling, we will be able to separate materials and

process costs. In Task 2, we will start the process of

identifying major areas of uncertainty in costs of

materials and process, as well as in design

parameters. This will be assessed through sensitivity

analyses and Monte Carlo simulations, as shown in

the examples in Figure 3.

In Task 3, we will continue to analyze the

impact of design parameters on cost (see Figure 4

for PNGV cost targets). For example, the impact of

operation at higher temperatures (e.g., 150oC),

allowed by new electrolyte membranes, on overall

system cost will be assessed. Higher fuel cell

temperatures will decrease heat-exchanger sizes,

increase anode tolerance to CO, and increase

performance. However, higher-temperature

operation may require the use of more expensive

stack materials. The impact of these potential

impacts on system design and cost will be estimated.

•Develop baseline

system specification

•Project technology

developments

•Assess impact on

system performance

•Identify

manufacturing

processes

Tasks 4, 5, 6, and 7:

Annual Updates

•Develop cost model

•Specify

manufacturing

processes and

materials

•Develop production

scenarios

•Baseline cost

estimate

•Perform sensitivity

analysis to design

parameters and

manufacturing

processes

•Perform risk

analysis to key

parameters

•Assess technology

evolution

•Revise Year 1 Cost

Estimates based

on technology

developments and

revised projections

•Develop baseline

system specification

•Project technology

developments

•Assess impact on

system performance

•Identify

manufacturing

processes

Task 1: PEMFC

System Technology

Synopsis

Task 2: Develop Cost

Model and Baseline

Estimates

Task 3: Identify

Opportunities for

System Cost

Reduction

Tasks 4, 5, 6, and 7:

Annual Updates

•Develop cost model

•Specify

manufacturing

processes and

materials

•Develop production

scenarios

•Baseline cost

estimate

•Perform sensitivity

analysis to design

parameters and

manufacturing

processes

•Perform risk

analysis to key

parameters

•Assess technology

evolution

•Revise Year 1 Cost

Estimates based

on technology

developments and

revised projections

Year One (1999-2000) Years 2, 3, 4, and 5

Figure 1. Project breakdown by task.
Fuel Cells for Transportation FY 1999 Progress Report

18

Figure 2. Approach to PEMFC system cost model.

Target Forecast: PRODUCT COST

Yield -.67

Raw Material Cost per kg .65

Labor Useage -.21

Scrap Credit -.04

Initial Selling Price -.03

Price Erosion -.02

Capital Investment -.02

Demand .02

-1 -0.5 0 0.5 1

Measured by Rank Correlation

Sensitivity Chart

Frequency Chart

.000

.010

.019

.029

.039

0

97.2

194

291

389

$500.00 $800.00 $1,100.00 $1,400.00 $1,700.00

10,000 Trials 160 Outliers

Forecast: Total System cost per kW

Figure 3. Examples of sensitivity analyses on cost and critical design parameters.

The following questions will be considered in

the assessment of potential opportunities for cost

reduction:

• What are the tradeoffs in stack performance and

air management system complexity and cost

arising from selection of operating pressure? Do

the benefits of operating at lower pressure

(e.g., increased blower system reliability and

simplicity), while reducing the cost of air

management, outweigh any negative impact on

system performance?

• How do the type of liquid fuel (e.g., gasoline or

methanol) and the specification of purity level

affect the system design and cost?

• How do yields in individual process steps affect

overall process yields and cost? Do certain

designs, manufacturing processes, and

measurements allow rework or recovery of

valuable components, such as membrane

electrode assemblies or separator plates?

• How do improvements in subsystem

performance (e.g., stack power density per area)

and manufacturing processes affect overall

system cost? What are the critical materials,

components, or subsystems to target for

technology development?
Fuel Cells for Transportation FY 1999 Progress Report

19

Calendar Year

Cost, $/kW

0

20

40

60

80

100

120

140

160

180

Fuel Processor

PEM Stack System

Integrated Power System

2000 2004

Figure 4 FY 2000 and FY 2004 PNGV High-Volume

Cost Targets (500,000 units/yr) for PEMFC

Power Systems for FY 2000 and FY 2004.

Deliverables

• Baseline PEMFC system configuration that

reflects projected performance for the 2004/2005

timeframe.

• Matrix of system configurations that reflects

uncertainties in performance projections,

operating parameter options, and material

developments.

• Development of cost model for PEMFC

systems.

• Baseline cost estimate for 1999 technology.

• Definition of materials, design, performance,

and manufacturing assumptions.

• Assessment of potential technology

developments and their impact on PEMFC

system cost.

• Annual updates of fuel cell stack, reformer,

balance-of-plant components, and total system

costs.

D. PEM Systems Modeling and Analysis

Rajesh Ahluwalia, E. Danial Doss, Howard Geyer, Romesh Kumar (Primary Contact), and

Michael Krumpelt

Argonne National Laboratory, Argonne, IL 60439-4837

(630) 252-4342, fax: (630) 252-4176

DOE Program Manager: JoAnn Milliken

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

Objectives

• Simulate automotive polymer electrolyte fuel cell systems and components to

- identify key design parameters and operating efficiencies

- model design, part-load, and dynamic performance

- provide results and support to fuel cell developers, the Partnership for a New Generation of Vehicles

(PNGV) technical teams, and others in the field

OAAT R&D Plan: Task 8; Barrier J

Approach

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

• Formulate component models of different fidelity

• Apply the models to issues of current interest

• Organize workshops as forums for interaction with other researchers
Fuel Cells for Transportation FY 1999 Progress Report

20

Accomplishments

• Documented GCtool with the National Energy Software Center and released Unix version for use on SUN

workstations

• Modified GCtool for the PC Windows 98 platform and provided a beta version for testing

• Developed several additional models for GCtool:

- a 2-D multinodal model of a polymer electrolyte fuel cell (PEFC)

- a transient model for an integrated fuel processor (similar to Argonne Partial Oxidation Reformer,

APOR)

- a kinetic, finite-difference chemical reactor model

• Investigated the performance and efficiency of different fuel processor configurations

• Analyzed the influence of operating pressure on the design and performance of automotive fuel cell systems

Future Directions

• Release GCtool for the PC platform

• Include cost, weight, and volume in studies of pressurized versus atmospheric pressure systems

• Refine kinetic models for the fuel processor

• Analyze fuel processor configurations for highly active catalysts in which heat transfer effects dominate

• Conduct more detailed analyses of transient and startup issues

• Continue to work with PNGV and other developers

Introduction

This work addresses three of the major technical

barriers that have been identified for the

development of vehicles powered by fuel cells.

These include fuel processor system integration and

efficiency, thermal management, and fuel cell power

system integration and management. The objective

of the work is to develop system models that can be

used to identify key design parameters and operating

efficiencies; model design, part-load, and dynamic

performance; and provide results and support to the

fuel cell developers, the relevant PNGV technical

teams, and other researchers. Modeling workshops

were conducted to get input from fuel cell

developers and disseminate the results of this work

to researchers in the field.

The GCtool software package has been

documented through the National Energy Software

Center, and a Unix version of GCtool has been

released for use on SUN workstations. GCtool is

also being adapted to the PC platform, and a beta

version is being tested internally with Windows 98

and Windows NT operating systems.

Enhancements to the model library of GCtool

include a two-dimensional, multinodal model of the

PEFC that can be used to investigate the effects of

pressure, temperature, fuel utilization, etc. in an

internally consistent manner. A transient model of an

integrated fuel processor, similar to APOR, has been

developed. A kinetic, finite-difference model of

chemical reactors of cylindrical geometry has also

been developed. These enhancements and the

analysis of the effects of operating pressure on

system design and operation are described below.

The 2-D PEFC Model

We have developed a detailed, multinodal model

of a polymer electrolyte fuel cell. This model takes

into account the Nernst potential and the ohmic,

activation, and concentration overpotentials. The

model calculates the actual cell voltage as a function

of current density, anode and cathode pressures and

temperatures, fuel and oxidant gas compositions, and

hydrogen and oxidant utilizations. By selecting

appropriate values of the exchange current densities,

membrane conductivity, and mass-transfer

coefficients, the predicted model values were

matched with experimental polarization curves. The

model could then be used to simulate cell

performance at any desired operating conditions.

This enhanced model was used to assess
Fuel Cells for Transportation FY 1999 Progress Report

21

comparative performance at different pressures,

temperatures, fuel and oxidant utilizations, etc.

The Integrated Fuel Processor Model

We have set up two fuel processor models, a

low-fidelity one and a detailed kinetic one, for

reactor geometries similar to those used in the

APOR. The low-fidelity model can simulate steadystate or transient operation in a multi-annular

geometry with arbitrary flow configurations and bed

arrangements. The model incorporates up to ten

axial nodes, with one radial node per annular

channel. The model can be executed with chemical

equilibrium, or with kinetic control of the approach

to equilibrium. Heat transfer between channels and

reactors, as well as pressure drops and heat losses,

are included.

The detailed kinetic model is a two-dimensional

(r-z) finite-difference model that can account for

non-isothermal gas flows and catalyst beds.

Processes simulated include fuel vaporization and

dissociation, water vaporization and condensation,

partial oxidation and steam reforming of the fuel, the

water-gas shift reaction, combustion, and sulfidation.

These models are being used to support the

engineering development of the APOR.

Analysis of Atmospheric Pressure Systems

For an atmospheric pressure system, assuming

equilibrium formation of methane and carbon, the

fuel processor efficiency is highest at a partialoxidation temperature (TPOX) of ~1100 K. At higher

temperatures, the efficiency suffers because of the

need for lower fuel equivalence ratios. At lower

TPOX, efficiency suffers from the excess formation of

methane.

A high-performance atmospheric pressure

system has a reforming temperature of 1100 K, a

fuel equivalence ratio of 3.4, and a water-to-fuel

mass ratio in the fuel processor of 2.2 (this may be

less than current practice), yielding a hydrogen

concentration of 44.4% in the reformate (dry basis).

For a net system efficiency of 45% at the rated

power level, the fuel cell stack must be operated

with a cell voltage of 0.8 V and with 90% hydrogen

and 50% oxygen utilizations (these utilizations may

be higher than those used in current practice).

Internal Humidification for an Adiabatic PEFC

Under these conditions, the radiator and

condenser heat loads are about equal; 65% of the

condenser cooling load is for the condensing of

water from the cathode exhaust. If the fuel cell is

internally humidified (i.e., operated as an adiabatic

stack, removing the stack waste heat by vaporizing

water), the radiator heat load shifts to the condenser.

Table 1 shows this shift in heat duties as the waterto-fuel mass ratio in the feed to the PEFC is

increased from 0.6 to 5.3.

Table 1. Effect of increasing internal humidification on

radiator and condenser heat duties and sizes.

Radiator Condenser

PEFC

mw/mf

Q

(kW)

Relative

Size

Q

(kW)

Relative

Size

0.6 28.4 1.0 25.9 1.0

2.0 20.2 0.4 34.3 1.4

5.0 2.0 0.1 53.0 2.2

5.3 0.0 0.0 55.0 2.3

The Tail-Gas Burner (Catalytic Combustor)

Depending on the level of PEFC humidification,

15–35% of the condenser duty is due to sensible

cooling of the combustor exhaust. The condenser

duty can be decreased by 15–20% by directly

cooling the depleted cathode air in the condenser and

recovering the process water. The burner exhaust

can then be discharged directly to the atmosphere

without cooling.

Furthermore, fresh air (rather than depleted

cathode air) can be used to burn the H2 in the spent

anode gas. The combination of the lower water

content and the higher oxygen concentration can

raise the combustor temperature above 575 K,

thereby improving burner performance. A side

benefit of this approach would be higher preheat for

the vaporized fuel and/or process water for the

reformer.

Ambient-Temperature Effects

The condenser is a critical component of the

adiabatic PEFC system. It must reject >50% of the

lower heating value of the fuel, and it must recover

all of the process water used in fuel reforming.

Because this condenser operates with rather small

log-mean temperature differences between the
Fuel Cells for Transportation FY 1999 Progress Report

22

process gas and the ambient air, higher ambient

temperatures would require a larger condenser for

the same duty.

A condenser designed for an ambient

temperature of 320 K (47°C, 116°F) would need to

be 60% larger than one sized for an ambient

temperature of 300 K (27°C, 81°F). Conversely, if a

system is designed for an ambient temperature of

300 K, the maximum steady-state power rating

would be decreased by 25% if the ambient

temperature rose from 300 K to 320 K. In addition,

water recovery would be inadequate for water

balance on-board the vehicle.

Startup Times for the Fuel Processor

In the relatively simplistic startup scenario

analyzed, the water-to-fuel ratio was maintained

constant, but the air-to-fuel ratio was varied to

obtain the highest heat generation, subject to

maximum allowable temperatures in the partialoxidation reactor. Since the fuel reformer consists of

various catalytic processing steps, nominal gas

hourly space velocities (GHSVs) were used to

represent the different catalyst beds. Not including

sulfur removal, the startup times for the various

catalysts are summarized in Table 2 for a "base"

case (with GHSVs comparable to today's

commercial practice for the chemical process

industry), as well as for much more active catalysts

that can be operated with much higher GHSVs.

Table 2 also shows the effects of increasing the

startup fuel flow rates beyond the full-power feed

rates. It is evident from Table 2 that much more

active catalysts (or highly improved reactor designs)

are required than those in common use today.

Table 2. Startup times (in seconds) for the various

catalyst beds in a gasoline fuel processor.

POX HTS LTS PROX

Base Case >1200 >1200 >1200 >1200

2 * GHSV 938 >1200 >1200 >1200

4 * GHSV 565 646 758 >800

10 * GHSV 351 276 320 440

20 * GHSV 285 146 172 235

10 * GHSV,

1.5 * fuel flow 47 73 108 144

10 * GHSV,

2.0 * fuel flow

28 50 77 102

Pressure Effects

Extensive analyses were conducted to

investigate the effects of pressurized versus ambientpressure system design and operation. These effects

were discussed at a workshop held in December

1998. Some of the major results of these analyses are

summarized in Table 3.

Table 3. Comparison of system design and performance

for operating pressures of 1 atm and 3 atm.

3-atm System 1-atm System

Compressor/

expander

Critical

component

Not needed

Methane and

carbon formation

Higher potential,

need higher TPOX

Lower potential,

need lower TPOX

Fuel processor

components,

relative sizes

POX = 0.33,

HTS = 0.5,

LTS = 0.5,

PROX = 0.2

POX = 1.0,

HTS = 1.0,

LTS = 1.0,

PROX = 1.0

PEFC stack

Needs active

cooling; in-cell

condensation adds

to cooling load;

cathode channels

prone to flooding

25% larger cell

active area;

potential for

membrane dryout; stack cooling

load decreased by

water evaporation

Heat rejection,

water balance

1/3 process water

recovered in

inertial separator,

2/3 in condenser

Condenser 2.8

times larger,

smaller radiator

Response to high

ambient

temperatures

Power reduction

determined by

radiator size,

~35% reduction

at 320 K

Power reduction

determined by

stack temperature

rise, 25%

reduction at

320 K
Fuel Cells for Transportation FY 1999 Progress Report

23

III. FUEL PROCESSING SUBSYSTEM

A. Advanced Fuel-Flexible Fuel Processor Development SFAA for Next

Millennium Fuel ProcessorTM for Transportation Fuel Cell Power System

William L. Mitchell, P.E.

Epyx Corporation/Arthur D. Little

20 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) 252-4176, e-mail: podolski@cmt.anl.gov

Contractor: Epyx Corporation/Arthur D. Little, Cambridge, Massachusetts

Prime Contract Nos. DE-RA02-97EE50443 and DE-FC02-99EE50580

Subcontractors/Partners: Modine Manufacturing (PRDA); Energy Partners (SFAA); United Catalysts, Inc (SFAA);

Corning, Inc (SFAA); STC Catalysts, Inc. (SFAA); and Dana Corporation (SFAA)

Objectives

Epyx/Arthur D. Little, Inc. (Epyx/ADL), is developing a 50-kWe fuel-flexible fuel reformer capable of processing

gasoline and alternative fuels, such as methanol, ethanol, and natural gas. Major technical issues to be addressed in

this program include advanced catalysts, CO cleanup, transient controls, and reformer startup/shutdown time.

As an extension of the integrated fuel processor, Epyx is developing and testing an advanced 50-kWe PROX device

based on proprietary catalyst technology. A major focus of fuel processor development will be gas purity when

gasoline and ethanol are used in operation. Epyx supports Plug Power in the development of a 50-kWe fuel cell

power system.

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

Approach

• 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).

• Test steady-state CO cleanup (study multiple options @ 10-kWe level) – offline on flow reactor.

• Integrate complete 10-kWe system and test at Epyx labs, using our 10-kWe system test facility.

• Aid 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, including transients, at Epyx/ADL labs.

• Provide integration assistance for testing at the prime contractor’s laboratory for 50-kWe brassboard (Phase III)

system demonstration.
Fuel Cells for Transportation FY 1999 Progress Report

24

• Aid prime contractor/system integrator in the mechanical design and packaging of the Phase III 50-kWe

system, focusing on system functionality and efficiency of operation.

• Work with a test facility to perform transient tests of the integrated Phase III system.

• Build and deliver a Phase IV 50-kWe fuel p rocessor subsystem to prime contractor for final integration. The

Phase IV system will meet PNGV weight and volume targets for the year 2004.

Accomplishments

• Demonstrated two distinct generations of fuel processor technology.

• Operated fuel processor for 1000+ hours with less than 1% CO output at firing rates between 5 and 65 kWth.

• Exceeded 2004 fuel processor efficiency targets on Phase II RFG, ethanol, methanol, and natural gas.

• Performed testing of the PNNL microchannel fuel vaporizer.

• Demonstrated 10:1 turndown and 8-min startup.

• Operated PROX during steady-state and 17-kW/s step transients with less than 10 ppm CO output.

• Demonstrated integrated 10-kWe fuel cell power system operating on gasoline at 34% efficiency.

• Measured exhaust emission levels at <<ULEV.

• Completed integration of 50-kWe Phase III fuel processor subsystem for delivery to Plug Power.

• SFAA Program – New start in FY 1999.

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

• Design and build a sub-50-kWe fuel cell system to evaluate and improve system models.

• Conduct extensive endurance testing to evaluate catalyst and hardware lifetime issues.

• Develop advanced catalyst beds and heat-exchanger designs in collaboration with subcontractors.

• Develop high-activity and low-cost catalyst and integrate with advanced heat exchangers.

Experimental Setup and Procedures

On the basis of experimental results of testing

carried out in Phase I of this program, a new

generation of fuel processor subsystem hardware

was designed, built, and tested prior to integration

into a complete fuel cell power system (1,2). Three

components comprise the fuel processor subsystem:

the fuel processor, the CO cleanup device, and the

tailgas burner/converter. The fuel processing

subsystem converts a primary fuel to a hydrogenrich gas stream, the CO cleanup subsystem removes

carbon monoxide to levels appropriate for PEM fuel

cell operation, and the tailgas burner converter

system oxidizes the waste stream from the fuel cell

anode to achieve near-zero emissions. On the basis

of results from previous integrated testing, the new

fuel processor subsystem was designed to be

operated over a thermal input power range of
Fuel Cells for Transportation FY 1999 Progress Report

25

5-65 kW. Upon completion of the fuel processor

subsystem testing and verification, a complete fuel

cell power system was integrated in the Epyx

laboratory, using a Plug Power fuel cell subsystem.

Experimental studies were carried out to permit

characterization of the entire system with regard to

efficiency, tailpipe emissions, system startup time,

thermal balances, pressure balances, hydrogen purity

effects, and required control interaction. System

sensitivity tests were performed to allow adjustment

of critical variables in order to assess the

sensitivities of other components to variations.

Fuel Processor and PROX Testing

Figure 1 shows the newly designed “Model B”

fuel processor under testing in the Epyx laboratories.

As in the previous generation of fuel processor, the

Model B contains the partial oxidation reactor

(POX) and catalytic reforming section, the water gas

shift (WGS) reactor, the sulfur-removal bed, the

system steam generator, and the air preheater. The

fuel processor assembly is 15 in. in diameter and

15 in. high, and it weighs 125 lb. With a thermal

input capacity of 65 kW and operation at 80%

efficiency, the fuel processor produces sufficient

hydrogen flow to support a 25-kWe fuel cell power

system.

Testing was carried out to determine the effect

of fuel choice, equivalence ratio, and firing rate on

fuel processor efficiency. Equivalence ratio is

defined as the actual fuel-air ratio, divided by the

stoichiometric fuel-air ratio. Fuel processor

Figure 1. Model B fuel processor.

efficiency is defined as the lower heating value of

hydrogen produced, divided by the lower heating

value of fuel into the fuel processor. Figure 2 shows

that for gasoline, methanol, and natural gas, the fuel

processor has a high efficiency over a wide range of

operating conditions. In general, in order to achieve

the year 2004 efficiency targets, it is necessary to

operate the fuel processor at equivalence ratios

between 3.5 and 4.5, depending on fuel type. When

achieving these efficiency numbers, the hydrogen

concentration in the product gas ranges between 40

and 50% (dry basis). Furthermore, fuel conversion

was greater than 99% for all cases during testing,

which minimizing the amount of hydrocarbon slip

through the system. Although not shown in

Figure 2, ethanol was tested and showed an

efficiency of 84%; a Fischer-Tropsch fuel showed

efficiencies of 79-80%.

Thermal Conversion Efficiency vs Equivalence Ratio

Epyx Model B Testing

January 20-26, 1999

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Fuel/Air Equivalence Ratio

Thermal Conversion Efficiency 

(LHV H2 out/ LHV fuel in)

Methanol - 1/20/99

Methanol - 1/21/99

Methanol - 1/22/99

Gasoline - 1/25/99

Methane - 1/26/99

2000 DOE goal

1997 DOE goa l

2004 DOE goal

Figure 2. Fuel processor conversion efficiency.

CO cleanup testing was performed in

conjunction with the fuel processor testing on a

newly designed, two-stage PROX to determine

selectivity and performance during both steady-state

and transient operation. Figure 3 shows both steadystate performance and performance over a 17-kW/s

step decrease and increase. During operation, the

fuel processor CO output level did not change

significantly, and the PROX outlet CO concentration

remained under 10 ppm at all times. The

performance was very repeatable over several

hundred hours of operation, and the PROX showed

excellent selectivity, as depicted in Figure 4. During

operation, it was difficult to determine the amount of

hydrogen loss, if any, through the PROX reactor.
Fuel Cells for Transportation FY 1999 Progress Report

26

Thermal Power Input, FPA CO, and PROX CO vs. Time

Epyx Model B. Fuel: Methanol

January 20, 1999

0

5

10

15

20

25

30

35

40

45

50

11:30 12:00 12:30 13:00 13:30 14:00

Time of Day

Thermal Power Input (kW)

0

1

2

3

4

5

6

7

8

9

10

CO Level 

FPA (%) and PROX (ppm)

Thermal Power (kW)

FPA CO (%)

PROX CO (ppm)

Figure 3. PROX performance.

40

45

50

55

60

65

70

75

80

85

90

0 5 10 15 20 25 30 35 40 45 50

Input Power (kWth)

Hydrogen% and Efficiency

Reformer Out Efficiency

Prox Out Efficiency

Reformer out H2%

Prox out H2%

Figure 4. PROX selectivity.

Integrated Fuel Cell Power System Testing

Testing was performed over a wide range of

operating conditions to determine efficiency, startup

time, and emissions of the system, as well as to

define key variables and considerations for the

Phase III and IV 50-kWe systems.

Table 1 shows selected results of a 10-kWe

system test operating on low-sulfur gasoline.

Results show 34% system efficiency over an

operational range of 25-100% power. During

operation, the fuel processor hydrogen percentage

ranged between 36 and 41% on a dry basis, with

PROX outlet CO concentrations between 2 and

14 ppm. It is important to note that the efficiency

numbers quoted do not take into account parasitic

components, such as the compressor/ expander,

which would lower the recorded values. Moreover,

the current lab system had much higher heat loss

than an integrated system would, due to lack of heat

integration, which would cause the efficiency

numbers to increase. Overall, the efficiency

numbers recorded were as expected; results were

well on the way to the Phase IV targets. The

integrated fuel cell power system was operated on

California Phase II reformulated gasoline, ethanol,

methanol, M-85, natural gas, and Fischer-Tropsch

fuels.

Also demonstrated during this testing was an

8-min startup to full electric power.

Table 1. Integrated gasoline FCPS performance.

Fuel Sulfur Free Gasoline

FUEL SFG SFG SFG

EPA INPUT POWER (kWe) 13.8 7.4 29.8

PRESSURE

Supply from FPA (psig) 38.0 38.0 38.0

CALCULATED FLOW RATE

PROX out

H2 flow (kW) 10.0 5.3 22.9

TEMPERATURE

F.C. inlet (°C) 21 21 21

COMPONENT

GC SAMPLING POSITION PROX PROX PROX

DRY VOL %

H2 (dry mol%) 38.66 36.10 40.57

DRY PPM

PROX CO (dry ppm) 14 11 2

**NOTE: 24.15 standard liters per mole is assumed (70 F, 1 atm)

Emissions were measured during system

operation for all fuels tested, using experimental

measuring equipment as previously described (1).

Table 2 shows results for system operation on lowsulfur gasoline. GC analysis shows that the major

recorded hydrocarbon emission from the system is

methane, which would further lower the NMOG

emissions from the system. It is anticipated that

SULEV emissions should be achievable with a

gasoline fuel cell power system. However, tests with

a fuel system on the appropriate driving cycles are

necessary to confirm these results.

Table 2. Integrated FCPS emissions.

2.5 kWe

(mg/gfuel)

5 kWe

(mg/gfuel)

10 KWe

(mg/gfuel)

NMHC — — —

NMOG — — —

Total HC 0.090 0.075 0.066

CO 0.063 0.003 0.004

NOx 0.226 0.093 0.120
Fuel Cells for Transportation FY 1999 Progress Report

27

Future Work

DOE SFAA: On the basis of our current in-depth

understanding of fuel processing and fuel cell

systems, Epyx shall perform a three-part program

that will yield a fully optimized fuel processing

subsystem. In the first part of the program, Epyx

will work with Energy Partners to integrate existing

hardware into a 10-kWe multifuel power system in

order 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. In

the second part of the program, Epyx will utilize

existing integrated and modular fuel processors to

perform endurance testing that will identify and

address material and catalyst degradation

mechanisms. The output of this work will feed

directly into the final fuel processor design in the

third part of the program. The major element of this

third part will be an in-depth catalysis R&D program

designed to identify high-activity, low-cost catalysts.

The new catalysts and supports will be integrated

into a fuel processor package specifically suited to

the optimized catalyst suite. The output of this

program will be a fully integrated fuel processing

subsystem that meets or exceeds 2004 PNGV

targets.

Conclusions

The design and development of a multifuel

reformer/fuel cell system for transportation

applications has been demonstrated via a 10-kWe

brassboard power system comprising a fuel

processor, a CO cleanup device, and a 10-kWe PEM

fuel cell. System testing shows that the Epyx

multifuel processor establishes efficient, integrated

fuel cell power systems operating on multiple fuels.

Specific achievements include:

• 1000+ hours of fuel processor operation with

less than 1% CO output at firing rates between

5 and 65 kWth.

• Exceeded 2004 efficiency targets on Phase II

RFG, ethanol, methanol, and natural gas.

• Demonstrated 10:1 turndown and 8-min start.

• Operated PROX during steady-state and

17-kW/s step transients with less than 10 ppm

CO.

• Demonstrated integrated 10-kWe fuel cell power

system operating on gasoline at 34% efficiency.

• Measured exhaust emission levels.

References

1. Mitchell, W.L., “Program Research

Development Announcement for Integrated Fuel

Cell Systems and Components for

Transportation and Buildings. Integrated Power

System for Transportation – Advanced Fuel

Processor Development,” Preprints of the Annual

Automotive Technology Development Customer

Coordination Meeting, U.S. Department of

Energy, Office of Transportation Technologies,

1998.

2. Mitchell, W.L., Hagan, M., and Prabhu, S.K.,

“Gasoline Fuel Cell Power Systems for

Transportation Applications: A Bridge to the

Future of Energy,” SAE Paper No. 1999-01-0535,

Society of Automotive Engineers, 1999.
Fuel Cells for Transportation FY 1999 Progress Report

28

B. Multifuel Processor for Fuel Cell Electric Vehicle Applications

Robert Privette (Primary Contact) and Tom Flynn

McDermott Technology, Inc.

1562 Beeson Street

Alliance, OH 44601-2196

(330)829-7370, fax: (330)829-7293, e-mail: rob.m.privette@mcdermott.com

Jacques De Deken and Dave King

Catalytica Advanced Technologies

430 Ferguson Drive

Mountain View, CA 94043-5272

(650)940-6339, fax: (650)968-7129

DOE Program Manager: Donna Lee Ho

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

ANL Technical Advisor: Walter Podolski

(630) 252-7558, fax: (630) 252-4176, e-mail: podolski@cmt.anl.gov

Contractor: McDermott Technology, Inc., Alliance, Ohio

Prime Contract No. DE-FC02-99EE50586, September 1999-January 2002

Subcontractor: Nextech Materials, Ltd., 720-I Lakeview Plaza Blvd., Worthington, OH 43085

Objectives

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

fuel processor will produce a hydrogen-rich gas for direct use in Proton Exchange Membrane (PEM) fuel cell

systems for electric vehicle applications.

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

Approach

• Develop preliminary design of 50-kWe fuel processor system and 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 on gasoline, methanol, natural gas, and ethanol.

• Ship fuel processor system to Argonne National Laboratory.

Accomplishments

New start in late FY 1999.
Fuel Cells for Transportation FY 1999 Progress Report

29

DOE Technical

 Targets

Performance

Characteristic

Project

Goal

Calendar

 Year 2000

Calendar

 Year 2004

Power Density, W/L 280 600 750

Specific Power, W/kg 285 600 750

CO Content, ppm 10 10 10

Lifetime, hours 5000 2000 5000

Future Directions

• Develop preliminary design of 50-kWe fuel processor

• Identify the preferred technical approach for each catalytic component and provide recommendations on the

best catalysts.

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. Advantages of a catalyst-based

autothermal reforming approach include lower

temperature, faster startup, and better materials

compatibility. Coupled with a liquid fuel

desulfurizer, the multifuel processor promises to

approach the targets established by the Partnership

for a New Generation of Vehicles (PNGV).

Background

The fuel processor will consist of a liquid-phase

desulfurizer, an autothermal reformer, high- and

low-temperature water gas shift units, a selective

oxidizing unit, and associated pumps,

compressor/expander, heat exchangers, and controls.

A general arrangement 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 sulfur in

gasoline from 30-100 ppm to less than 3 ppm. The

autothermal reformer unit, operating at an average

temperature of 800°C, will produce a hydrogen-rich

gas from the fuel feed. Two reformer approaches

will be evaluated during the program – a single

packed bed comprising a bifunctional catalyst and a

bifunctional monolith catalyst. A shift reactor,

consisting of either a single catalyst bed or

Figure 1. General arrangement drawing.

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, auxiliary equipment, and

instrumentation/controls. Catalytica Advanced

Technologies will develop the catalytic components,

including improved catalysts. NexTech, as a major

subcontractor and cost-share contributor on the

project, will contribute its expertise and technology

in the area of shift catalysis.
Fuel Cells for Transportation FY 1999 Progress Report

30

References/Publications

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

Kneidel, K. E., King, D. L., and Cooper, M.,

“Compact Fuel Processor for Fuel Cell-Powered

Vehicles,” International Congress and

Exposition, Detroit, Mich., March 1-4, 1999,

SP-1425, pp. 47-53.

2. Privette, R.M., et al., “Fuel Processing to

Military and Commercial Fuel Cell

Applications,” Proceeding of the 1998 Fuel Cell

Seminar, Palm Springs, CA, pp. 323-325,

November 16-19, 1998.

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

Richard Woods (Primary Contact) and John Cuzens

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: James Miller

(630) 252-4537, fax: (630) 252-4176, e-mail: millerj@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 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 to F3P subsystem

integration. Coordinate with fuel cell system developers, such as AlliedSignal Aerospace Corporation, in

preparation for system-level integration activities.

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

Approach

• This program includes the process and hardware design of a F3P subsystem, the assessment of alternative

materials and catalysts, the fabrication of integrated hardware assemblies, and the evaluation of alternative

carbon monoxide (CO) polishing approaches.

- The design approach selected for the prototype F3P subsystem hardware includes three assemblies – the

F

3

P assembly, the fuel vaporizer assembly, and the CO polishing assembly. A breadboard control package

was also included to allow automatic control of the hardware subsystem.

- The F3P assembly integrates the primary functions required for a fuel processor – UOB reactor, thermal

management, shift reactors, and integrated steam generation.

- The fuel vaporizer assembly integrates the function of fuel vaporization and anode off-gas combustion.
Fuel Cells for Transportation FY 1999 Progress Report

31

- The CO polishing concepts being evaluated include methanation, preferential oxidation (PROX) of CO,

and several proprietary configurations in cooperation with AlliedSignal Corporation.

• This program also includes the verification of the HLTS reactor concept, which has encompassed the evaluation

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

with improved activity at lower temperatures and higher humidity.

Accomplishments

• A process integration and hardware configuration approach was established and modeled. A process model

was used to evaluate thermal integration and chemical stability characteristics, while a heat-transfer model was

used to assess heat-transfer requirements and hardware dimensions. A preliminary hazardous operations

(HAZOP) assessment was completed to assess safety issues.

• A fabrication design package has been completed for the F3P assembly, vaporizer/anode gas oxidizer assembly,

and breadboard control assembly. The initial F3P subsystem has been fabricated and assembled.

• These F3P subsystems have been operated to assess functionality, map unit performance, qualify delivery units,

and evaluate fuel-flexibility characteristics. Over 120 hours of operation have been completed, including

approximately 60 start/stop cycles.

• Three alternative fuels have been tested – gasoline, natural gas, and methanol.

• Advanced high-temperature- and low-temperature-shift catalysts were developed and evaluated in the

laboratory and in the F3P assembly hardware.

• The HLTS reactor hardware concept was selected and integrated into a prototype F3P assembly for concept

verification testing.

• Fabrication and delivery of three additional prototype F3P subsystems was completed under parallel programs

for evaluation by an automotive manufacturer, a fuel cell system integrator, and a national laboratory.

Future Directions

• Complete performance mapping of the UOB F3P subsystem.

• Complete the control system logic, which provides for automatic control and shutdown protection.

• Assess operation of the F3P subsystem on ethanol and M-85 (85% methanol, 15% gasoline).

• Complete concept verification testing of the HLTS hardware.

• Develop a precommercial hardware design approach based on the results of the prototype F3P subsystem

activities.

Introduction

Fuel cells are considered to be a viable

alternative to the internal combustion engine in

automotive applications. Debate exists within the

automotive and development communities regarding

the appropriate fuel for fuel cell vehicles. Hydrogen

(H2) fuel provides the easiest and smallest fuel cell

system, but “on-board storage” of H2, as well as the

absence of a H2 refueling infrastructure, raises many

concerns. An alternative approach would be to use

existing liquid fuels (such as gasoline) or evolving

fuels (such as ethanol, methanol, or any of the many

synthetic liquids currently being developed). 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, that focuses on the

development and testing of a F3P subsystem for

automotive applications.

Program Overview

The cooperative agreement focuses on two

independent efforts. The greater portion of the

activity is related to the design, construction, and

testing of a prototype F3P subsystem. The second
Fuel Cells for Transportation FY 1999 Progress Report

32

effort is related to verification of the humidified

low-temperature-shift (HLTS) concept.

Figure 1 identifies the overall program scope

and structure, while indicating the progress during

FY 1999. In October 1998, HBT was beginning the

assembly of the first set of F3P components and

hardware. This unit was completed by December,

and testing was initiated during January 1999.

Activities during FY 1999 include performance

mapping of the F3P subsystem, completion of the

controller software, and defining of advanced

concepts to be incorporated into the precommercial

hardware configuration. Initial testing of the F3P

subsystem has identified advanced components and

concepts that are either being implemented into the

prototype to enhance operation or being outlined for

the precommercial hardware definition.

F

3P Subsystem Design and Hardware

Design of the F3P subsystem is based on HBT’s

noncatalyzed, under-oxidized burner (UOB)

technology. The hardware approach uses three

separate hardware assemblies to allow for the

evaluation testing of alternative components. The

three assemblies are the fuel vaporizer/anode gas

oxidizer assembly, the F3P assembly, and the CO

polishing assembly. Seven of the most critical

chemical processes of the F3P subsystem are

thermally and physically integrated into the F3P

assembly hardware. Figure 2 illustrates these

processes. The integrated hardware of the F3P

assembly provides close thermal interaction between

the UOB reaction zone, which operates at

1375-1500°C (2500-2700°F), and the lowertemperature zones of the process air preheater and

high-temperature-shift zones, which operate at

Figure 1. Overall program scope.

Water

Air

Fuel &

Steam

Mixture

Coolant

UOBTM HX Quench ZnO

HTS HRSG LTS

Water

Steam to Vap.

H2 to CO

Polishing

Unit

Figure 2. Integrated F3P assembly.

300-800°C (600-1500°F). This configuration

minimizes heat loss while maximizing reaction

temperatures.

All of the processes identified in Figure 2 are

physically integrated into the hardware illustrated in

Figure 3. The prototype F3P assembly, with

conventional, commercially available catalysts,

weighs approximately 104 kg (230 lb), which is

approximately 25% greater than its target weight of

83 kg (183 lb). Most of this excess mass comes

from high-density commercial catalyst and flange

structures used for easy disassembly and inspection.

The volume of the F3P assembly is ~ 85 L

(3 ft3). Increasing this size by the volume needed for

the vaporizer and CO polishing assemblies indicates

that the prototype hardware is approximately 30%

greater than its target volume. This experience with

the prototype hardware indicates that it should be

feasible to package the precommercial components

within their target volume of 600 W/L and target

mass of 600 W/kg.

Figure 3. Prototype F3P assembly configuration.
Fuel Cells for Transportation FY 1999 Progress Report

33

Interest in the concept of an on-board fuel

processor is very strong in the automotive and fuel

cell development communities. In parallel with our

cooperative agreement, HBT also fabricated three

additional prototype subsystems for evaluation by

others. These include an automotive manufacturer,

a fuel cell developer, and a national laboratory

supported by DOE. Results from the qualification

testing of these units are also discussed.

Subsystem Testing Results

To date, HBT has collected over 120 hours of

operational experience on the F3P subsystems

fabricated. This experience includes over 60 startstop cycles and operation on three fuels – gasoline,

methanol, and natural gas. Table 1 provides a

summary of the operating experience achieved to

date. All of this testing has been accomplished

using manual control of the subsystem because of

delays in completing the automatic sequence control

software.

This operating experience has partially mapped

the performance characteristics of the F3P subsystem

on three fuels. A summary of the achievements to

date is indicated in Table 2. Additional testing will

establish higher operating capacities on natural gas

and gasoline and push the performance envelope to

higher efficiencies through operation at a lower

stoichiometric ratio.

Testing has indicated the ability to achieve LTS

outlet CO concentrations between 1000 and

3000 ppm. Laboratory testing of a methanation

reactor has shown the ability to decrease these levels

to the 10-ppm specification of the fuel cell. Initial

testing of the PROX unit is also promising.

Additional characterization is needed to assess the

Table 1. Operating experience summary.

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

Customer HBT/DOE Auto

Mfg’er

LANL FC Devel

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

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

Runs 26 11 13 27

Operating 36 hr 18 hr 24 hr 98 hr

Fuels NG,

Gasoline

NG,

Gasoline

NG,

Gasoline,

Methanol

NG

Table 2. Summary performance mapping.

Methanol Nat. Gas Gasoline

Minimum SR 0.33 0.40 0.42 - 0.45

Efficiency <76% ~70% ~68%

Max H2, %dry 40% 33% 31%

Min CO, (LTS only) 0.3 to 0.1% 0.4 to 0.1% 0.5% to 0.1%

Tested Capacity, kWe** 38kWe 22kWe 15kWe

* Note preliminary performance based on ~120 hrs operation.

** Note Estimated Capacity based on Fuel Consumption and H2

Concentration.

selectivity of the two hardware concepts and the

process efficiency impact.

Due to delays in completing the automatic

control software, only manual startup characteristics

have been verified. Sample data from liquid-fueled

tests are shown in Figure 4. These tests indicate the

ability to achieve normal hydrogen production

within 15 to 30 min, with a cold start at low to

nominal fuel-flow rates. Similarly, hot restarts in

less than 5 min have been achieved when the shift

beds were warm. During these tests, the CO level

out of the LTS never rose above the normal levels.

Figure 6 Comparison of Start-Up Tests

Average LTS Temperatures

31.0 % H2

0.193% CO

0

50

100

150

200

250

300

0 5 10 15 20 25 30

Run Time, minutes

Temperature, C

0.001%

0.01%

0.1%

1%

10%

100%

H2 and CO, %dry

Hot Restart

Cold Starts

Figure 4. Comparison of startup tests.

Conclusions

Continued performance mapping is required to

complete the characterization of the F3P subsystem.

To date, the F3P subsystem has successfully

demonstrated operation and has approached its

performance targets. Fully integrated, advanced

design concepts are being developed that offer

improved efficiency and reduced mass and volume.
Fuel Cells for Transportation FY 1999 Progress Report

34

D. Integrated Fuel Processor Development

Shabbir Ahmed, Sheldon H. D. Lee, Candido Pereira, and Michael Krumpelt

Argonne National Laboratory, Argonne, IL 60439

(630) 252-4553; fax: (630) 972-4553

DOE Program Manager: JoAnn Milliken

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

Objectives

• Demonstrate a fuel-flexible fuel processor suitable for use on-board a fuel cell powered vehicle

- As a microreactor process train

- As an engineering-scale integrated reactor

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

Approach

• Verify fuel processor functions in a microreactor process train and operate a PEFC stack on reformate gas.

- The process train includes the reformer, H2S absorber, shift reactor(s), preferential oxidizer, and fuel cell

stack.

- The components can be studied individually or as a group.

- Alternative scrubbing technologies can be readily installed and studied.

• Design and demonstrate an engineering-scale integrated reformer that converts fuel, steam, and ambient air into

a sulfur-free, low-CO reformate gas.

- Catalyst performance is verified in a self-sustained reactor.

- Heat effects are integrated to improve hydrogen yields.

Accomplishments

• Completed setup of the microreactor process train and operating parameters for the individual reactors.

- Demonstrated that the shift reactor with the Argonne catalyst can reduce CO level from 20% to 1.5%.

- Demonstrated the reduction of CO from 20% to 0.8% by using the Argonne water gas shift and Argonne

preferential oxidation reactors.

• Operated a 7-liter integrated reactor with methanol, isooctane, and gasoline.

- The igniter coil was turned off after start-up.

- Desirable temperature profiles were achieved in all the catalyst zones.

- The reactor has been rated for 5 kWe; higher throughputs may be possible.

- Hydrogen concentrations of 32% (isooctane) to 47% (methanol) were measured.

Future Directions

• Determine operating parameters for each component in the process train and demonstrate fuel cell operation on

reformate.

- Study the effect of new-generation catalysts for the various components (reactors).

- Study the effect of alternative scrubbing technologies.

• Design an integrated fuel processor and demonstrate operation with monolith catalysts, rapid start capability,

and transient operation.
Fuel Cells for Transportation FY 1999 Progress Report

35

The objective of this work is to design, develop,

and demonstrate fuel-flexible catalytic fuel

processors based on autothermal reforming. These

reformers will be used to generate hydrogen for fuel

cells in light duty vehicles. The catalytic process

offers the advantages of greater product selectivity

and high activity at relatively low temperatures.

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.

This task is designed to obtain the “best”

operating conditions of the individual unit

operations and processes in a fuel processor. The

units are controlled so that the final reformate gas is

of sufficient quality for sustained power generation

in a polymer electrolyte fuel cell. The information

obtained from the process train is then used to

develop an integrated fuel processor design, and it is

subsequently verified at the engineering scale.

Figure 1 shows a schematic of the microreactor

process train, which can operate five reactors in

series. Vaporized fuel, steam, and air are fed into the

catalytic reformer, from which the product gas

passes through the sulfur removal bed, followed by

up to two stages of water gas shift reactors, and then

through the final CO removal unit. The CO removal

unit can be either a catalytic preferential oxidation

reactor or a CO sorption unit. The clean reformate

gas is then supplied to a polymer electrolyte fuel cell

to generate power and obtain polarization curves.

The feeds to each of the reactors can be

independently controlled. That is, the feed can be a

synthetic reformate gas from a cylinder, or

additional feed components can be added to the feed

stream from the previous reactor. Since all the

POX

Reformer S Removal

WGS1

WGS2

Pr.Ox.

Fuel Cell

Sorption

Regeneration

Gasoline

Water

Air

Air Hydrogen

(CO2, N2, H2O)

Hydrogen

(CO2, N2, H2O)

Shift

Reaction CO Removal

Figure 1. Schematic of the microreactor fuel processing

train.

reactors are located within furnaces, the reactor

temperatures can be controlled very effectively.

Each reactor is also connected to a GC/MS system,

allowing careful analysis of both the reactant and

product streams.

The microreactor fuel processing train provides

the ability to carefully study each component

individually and to fine tune its performance. A

major benefit of this configuration is the flexibility

to evaluate alternative processing stages – for

example, a CO-removal process involving a

membrane separator can easily be placed anywhere

in the sequence.

Table 1 shows some preliminary data comparing

the conversion of synthetic reformate gas in a hightemperature water gas shift reactor, a lowtemperature shift reactor, and a preferential

oxidation reactor. The feed gas composition, on the

basis of CO, CO2, and H2 only, are as shown in the

second column. When this feed gas was passed

through a high-temperature shift reactor filled with a

commercial FeCr catalyst bed at 325°C, the CO

level was reduced to 3.7%. Passing the feed gas

directly through a reactor filled with an Argonne

shift catalyst bed at 225°C reduced the CO level

from 20% to 1.5%. When the product from the

Argonne shift catalyst bed was further passed

through a reactor filled with a new preferential

oxidation catalyst maintained at 200°C, the CO level

dropped to 0.8% (on the basis of H2, CO, and CO2

only). The H2O/CO molar ratio in the feed stream

was 4, and the O2/CO ratio in the preferential

oxidation unit was 1.

Table 1. The microreactor process train was used to

evaluate the CO reduction in water gas shift

and preferential oxidation reactors.

Feed

Comm.

HTS

ANL

Shift

ANL

(Shift+PrOx)

 CO 20.0

±0.2

3.7

±2.0

1.5

±1.1

0.8

±0.4

 CO2 21.8

±0.3

35.6

±4.0

31.1

±1.2

34.4

±5.5

 H2 58.2

±0.2

60.7

±4.0

67.4

±2.3

64.9

±5.5
Fuel Cells for Transportation FY 1999 Progress Report

36

Figure 2 shows a schematic of the integrated

autothermal fuel processor. The fuel, air, and steam

feeds enter the central cylindrical zone. A small,

electrically powered igniter coil starts the reaction.

As the exothermic reaction raises the bed

temperatures, the igniter coil is turned off. The

products from the reformer section are cooled from

700°C to 350°C by injecting a small amount of

water before entering the sulfur removal section.

This zone is filled with ZnO pellets. The products

continue to flow through the shift reactor section,

where the gases are gradually cooled to exit at

200°C.

Using GCTool, a mathematical model based on

thermodynamic equilibrium, heat transfer, and

material and energy balances has been developed for

this reactor. The hardware is being used to validate

the model, and the data generated will be used to

upgrade the reactor design.

Figure 3 shows the temperature profile as the

gases flow through the reactor. The first eight

thermocouples are located in the reformer section,

and the last four are located in the outer annular

region. With appropriate heat exchange, this reactor

design avoids the sharp temperature rise typically

seen when the fuel and oxygen begin to react near

the inlet of most autothermal reforming reactors.

Varying the amount and method of water injection

helps to control the extent of cooling before the ZnO

bed.

Fuel

Water

Air

350°C

ZnO

Reforming, >700°C

WGS,

Water Gas Shift

 350-200°C

Product

Figure 2. Schematic of the Argonne integrated partial

oxidation reformer.

0

200

400

600

800

T1T3T5T7T9

T11

Thermocouple No.

Temperature, °C

052199

012999

Reforming

ZnO

WGS

0

200

400

600

800

T1T3T5T7T9

T11

Thermocouple No.

Temperature, °C

052199

012999

Reforming

ZnO

WGS

Figure 3. Temperature profiles within the integrated

reactor.

The integrated reactor was operated with

isooctane, gasoline, and methanol. Figure 4 shows

the percentages of hydrogen (30%), carbon dioxide

(12%), carbon monoxide (8%), and methane (3%)

produced from gasoline. (The balance is mostly

nitrogen). The hydrogen percentage is considerably

lower than expected because of a leak in the seals

that led to part of the reactants bypassing the

catalysts. Also, the CO percentage is high because

the water gas shift catalyst was not available.

0

10

20

30

40

10:00 12:00 14:00 16:00

Time of day hh:mm

Product Composition

% dry

H2

CO2

CO

CH4

0

10

20

30

40

10:00 12:00 14:00 16:00

Time of day hh:mm

Product Composition

% dry

H2

CO2

CO

CH4

Figure 4. Composition of the product gas obtained from

autothermal reforming of California Phase II

gasoline. (Fuel=19 mL/min, Air=1.5 scfm,

Water=16-24 mL/min).

Figure 5 shows the percentages of hydrogen and

carbon monoxide obtained from methanol. For the

shift reaction, an auxiliary copper zinc oxide catalyst

bed was used. The sharp transitions of the two

curves reflect the switching of the reformer gas

through the CuZnO bed. After passing through the

shift reactor, the product gas contained
Fuel Cells for Transportation FY 1999 Progress Report

37

0

10

20

30

40

50

13:00 14:00 15:00

Time of day hh:mm

Product Composition

% dry

H2

CO

0

10

20

30

40

50

13:00 14:00 15:00

Time of day hh:mm

Product Composition

% dry

H2

CO

Figure 5. Percentages of hydrogen and CO present in the

reformate gas from methanol. CuZnO was

used in the water gas shift reactor

(Methanol=34 mL/min, Air=0.96 scfm,

Water=31 mL/min).

47% hydrogen, 3% carbon monoxide, and 18%

carbon dioxide.

The reactor was subsequently operated with

isooctane and with the outer annular zone filled with

the Argonne water gas shift catalyst. Thirty-seven

percent (dry basis) hydrogen and 3% CO were

measured in the product gas stream. It is expected

that the hydrogen yield will substantially increase

after the leaking seals have been welded. It is also

anticipated that the CO level can be further reduced

by adjusting the temperature profile in the shift

zone.

For the future, the microreactor process train

will be used extensively to determine “best”

operating conditions of the individual reactors and to

evaluate the performance of new catalysts and newer

reformate clean-up technologies. For the integrated

reactor, we will follow the steady-state performance

studies with the demonstration of rapid-start and

transient operations. Data gathered from this reactor

will be used by GCTool to design a more compact

reactor.

E. Microchannel Fuel Processor Components

Robert S. Wegeng, Eric A Daymo, Ward E. TeGrotenhuis, Anna Lee Y. Tonkovich, Yong Wang, and

Greg A. Whyatt

Pacific Northwest National Laboratory, P.O. Box 999,

Richland, WA 99352

(509) 375-3710, fax: (509) 375-6561, e-mail: robert.wegeng@pnl.gov

DOE Program Manager: JoAnn Milliken

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

Objectives

• Demonstrate compact reactors, separation units, and heat exchangers, based on microsystems technology, for

the on-board, automotive production of hydrogen from liquid hydrocarbons.

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

Approach

• Utilize a newly developed method for process intensification to produce extremely compact hardware with high

throughputs, based on the heat and mass transport advantages realizable in engineered microstructures. The key

to this effort is the development and application of microfabrication methods for reactors, separations units, and

heat exchangers.
Fuel Cells for Transportation FY 1999 Progress Report

38

Accomplishments

• Development and proof-of-principle demonstration of a single-cell, steam-reforming microchannel reactor was

conducted during FY1999. The demonstration included vaporization of isooctane (as a gasoline surrogate) and

water in microchannel vaporizers, plus recuperation of the reformate stream in a microchannel recuperative heat

exchanger. The unit produces hydrogen in concentrations in excess of 65% (dry gas). Scale-up through the

incorporation of multiple cells suggests an overall steam reformer/heat exchanger/vaporizer unit occupying less

than 0.25 ft3 volume for the 50-kWe application.

• An R&D 100 Award was received from R&D Magazine during FY1999 for the microchannel gasoline

vaporizer, identified as one of the 100 most technologically significant new products of the year. This unit

consists of microchannel reactor and microchannel heat-exchanger cells that vaporize the gasoline stream for a

50-kWe fuel processing/fuel cell system. Heat for vaporization is provided through the internal, catalytic

combustion of low-concentration hydrogen from the fuel cell anode prior to discharge to the atmosphere. The

unit weighs 4 lb and occupies a volume of 0.01 ft 3. Validation testing of the microchannel gasoline vaporizer

was performed by Epyx at their facilities in Massachusetts during FY1999; similar testing is expected by

Hydrogen Burner Technology during late FY1999 and early FY2000.

• Manufacturing studies for microchannel reactors and heat exchangers demonstrate the potential for low

hardware cost through mass production. In particular, the microchannel gasoline vaporizer was estimated to

cost approximately $60-70 per unit when manufactured in quantities of 500,000 per year.

Future Directions

• Develop an integral steam reforming system that includes multiple-microchannel reforming reactors,

combustors, recuperative heat exchangers, and vaporizers.

• Establish a microchannel fuel processor/fuel cell test loop that provides for the investigation of fuel processing

systems, including microchannel reformers, water-gas-shift reactors, heat exchangers, and gas cleanup units.

Steady-state and transient operation with a 5-kWe fuel cell is anticipated.

• Continue industrial interactions with the microchannel gasoline vaporizer, as well as with other microchannel

reactors and heat exchangers.

• Validate mass-production techniques for microchannel reactors and heat exchangers by fabricating several

units, using low-cost mass production methods.

• Operate microchannel reactors and heat exchangers for long-duration tests.

• Adapt the current microchannel steam reformer for transportation fuels.

The development of an on-board fuel processing

system to produce hydrogen gas from liquid

hydrocarbons for fuel cell use presents a number of

technical challenges, including process

miniaturization and thermal energy integration. The

approach utilized by this project applies a new

method of process intensification, based on rapid

heat and mass transport in engineered

microstructures.

Microchannel Fuel Vaporizer

An extremely compact gasoline fuel vaporizer

(1.5 in. × 3 in. × 4 in.) for automotive fuel cell/fuel

processing systems has been demonstrated (see

Figure 1). This vaporizer, which consists of four

reactor cells and four heat-exchanger cells, is

fabricated by using micromachining techniques; it

exploits the extremely rapid heat and mass transport

rates that are possible in engineered microstructures.

The unit is able to vaporize gasoline at a sufficient

rate for a fuel processing/fuel cell system that

provides 50 kWe of electrical power.

The fuel vaporizer captures and recycles energy

from unused hydrogen in the fuel cell waste gas by

catalytically reacting it with air and then routing the

stream through microchannel heat exchangers,

within which gasoline is evaporated. Validation

testing of the microchannel gasoline vaporizer was

performed by Epyx at their facilities in

Massachusetts during FY1999; similar testing is

expected by Hydrogen Burner Technology during

late FY1999 and early FY2000.
Fuel Cells for Transportation FY 1999 Progress Report

39

Figure 1. R&D 100 Award-winning microchannel

gasoline vaporizer.

The microchannels (shown in Figure 2) are

typically 150-300 μm wide and one to several

millimeters deep, supporting heat fluxes that exceed

150 W/cm2. Despite their small size, microchannels

do not present high pressure drops for fluids.

Measured pressure drops are consistent with

calculations for laminar flow in fluids. As is shown

on the graph (Figure 3), the pressure drop through

the microchannels is actually less than one pound

per square inch (psi). The pressure drop of this

vaporizer system is dominated by that across the

engineered, monolithic catalyst, which is still quite

small (a few pounds per square inch).

The results of this fuel vaporizer project show

that catalytic microchannel reactors and heat

exchangers can be fabricated and operated in

parallel, to realize an extremely compact,

lightweight system that produces product streams

with appropriate throughput for automotive

applications. The current expectation is that a

complete microchannel fuel processing system for

the 50-kWe fuel cell, including microchannel heat

Figure 2. Engineered microchannels, typically

100-300 μm wide, 1-10 mm tall, and

1-10 cm long.

Figure 3. Experimental pressure-drop measurements

within microchannels and engineered catalyst

for microchannel gasoline vaporizer.
Fuel Cells for Transportation FY 1999 Progress Report

40

exchangers and reactors, may occupy a volume as

small as 0.3 ft3.

Experimental Validation of High

Effectiveness in Recuperative Microchannel

Heat Exchangers

High thermal efficiency for a fuel processing

system requires highly effective recuperative heat

exchangers. During FY1999, this project designed,

fabricated, and tested microchannel heat exchangers

with gas-to-gas recuperation as the objective.

Design validation was provided through fabrication

and testing of a single-cell unit that operated with

high effectiveness. This unit is designed to

recuperate the thermal energy content from the

reformate stream (as it emerges from a steam

reforming reactor).

Proof-of-Principle Demonstration of a

Microchannel Steam Reforming Reactor

In general, steam reforming is a more efficient

way to produce hydrogen from liquid fuels than

other reactions, such as partial oxidation or

autothermal reforming. Advantages include higher

hydrogen content and the elimination of nitrogen as

a diluent in the fuel stream. However, conventional

steam-reforming reactors suffer from poor heat and

mass transport, resulting in slow reaction rates and

low throughput rates per unit hardware volume.

To address the potential application of

engineered microstructures to steam reforming,

preliminary catalyst screening investigations were

conducted during FY1998. These experimental

studies confirmed the rapid intrinsic kinetics

(<50 ms) for the steam reforming of automotive

fuels and demonstrated the scientific feasibility of

applying this miniaturization approach to steamreforming reactors.

Efforts during FY1999 included the design,

fabrication, and experimental demonstration of a

single-cell, microchannel steam reforming reactor.

For testing this unit, a breadboard system was

assembled that included compact microchannel heat

exchangers for vaporizing fuel (isooctane) and

water, a very small catalytic combustor, an integral

microchannel catalytic reactor/heat exchanger for

steam reforming, and a microchannel recuperative

heat exchanger for recuperating energy from the

reformate stream. As indicated in Figure 4, which

Figure 4. Proof-of-principle demonstration of steam

reforming in catalytic microchannel reactor

(experimental data, first hour of testing).

shows data from the first hour of testing of this unit,

this system was operated at one bar pressure, at

650-700°C, with 100% conversion of the fuel feed.

Residence time in the system was quite small, about

2.3 ms, and conversion and selectivity to hydrogen

was consistently around 90%. Dry gas content

contained >65% hydrogen for all test runs.

Microchannel Fuel Processing System

Implications

Current developments suggest that a

microchannel fuel processing system, including

reformers, water-gas shift reactors, and gas cleanup,

could be developed for the PEM fuel cell, with an

overall system efficiency of up to 45% and a fuel

processing system volume of less than 1 ft3. While

high efficiency for a total fuel cell/fuel processor

system requires reasonable hydrogen utilization

within the fuel cell, system studies have confirmed

that overall system efficiency is not strongly

sensitive to this parameter, because unused

hydrogen can be recycled to the fuel processor to

provide for additional reforming. The expectation is

that a compact steam-reforming unit can provide

high efficiency and high power densities for the

overall system.

Publications

Drost, M.K., C.J. Call, J.M. Cuta, and R.S. Wegeng,

“Microchannel Integrated Evaporator/Combustor

Thermal Processes,” Journal of Microscale

Thermophysics Engineering, Vol. 1, No 4,

pp. 321-333, 1997.
Fuel Cells for Transportation FY 1999 Progress Report

41

Martin, P.M., D.W. Matson, and W.D. Bennett,

“Microfabrication Methods for Microchannel

Reactors and Separations Systems,” Joint

AICHE/DECHEMA Special Topical Meeting:

Process Miniaturization – Second International

Conference on Microreaction Technology, March

1998.

Tonkovich, A., C. Call, D. Jimenez, R. Wegeng, and

M. Drost, “Microchannel Heat Exchangers for

Chemical Reactors,” Heat Transfer – Houston 1996

(AICHE Symposium Series 310), pp. 119-125.

Tonkovich, A., J. Zilka, D. Jimenez, M. Lamont,

and R. Wegeng, “Microchannel Chemical Reactors

for Fuel Processing,” Joint AICHE/DECHEMA

Special Topical Meeting: Process Miniaturization –

Second International Conference on Microreaction

Technology, March 1998.

Tonkovich, A., C. Call, and J. Zilka, “The Catalytic

Partial Oxidation of Methane in a Microchannel

Chemical Reactor,” Joint AICHE/DECHEMA

Special Topical Meeting: Process Miniaturization –

Second International Conference on Microreaction

Technology, March 1998.

Tonkovich, A., J.L. Zilka, M.J. Lamont, Y. Wang,

and R.S. Wegeng, “Microchannel Reactors for Fuel

Processing Applications. I. Water Gas Shift

Reactor,” accepted for publication in Chemical

Engineering Science, 1998.

Wegeng, R., and M. Drost, “Developing New

Miniature Energy Systems,” Mechanical

Engineering, Vol. 116, pp.82-85. American Society

of Mechanical Engineers, Sept. 1994.

Wegeng, R., M. Drost, T. Ameel, and R.

Warrington, “Energy Systems Miniaturization

Technologies, Devices, and Systems,” Proceedings

of the International Symposium on Advanced Energy

Conversion Systems and Related Technologies,

RAN 95, Dec. 1995.

Wegeng, R., C. Call, and M. Drost, “Chemical

System Miniaturization,” PNNL SA-27317, AICHE

1996 Spring National Meeting, New Orleans, La.,

Feb. 1996. [Also available on the world wide web

at: http://www.pnl.gov/edo/license/programs/

fliers/microfly.stm]]

Wegeng, R., and M. Drost, “Opportunities for

Distributed Processing Using Micro Chemical

Systems,” Invited Plenary Speech, Joint

AICHE/DECHEMA Special Topical Meeting:

Process Miniaturization – Second International

Conference on Microreaction Technology, March

1998.
Fuel Cells for Transportation FY 1999 Progress Report

42

F. On-Board Hydrogen Generation Technology

James Hedstrom, Nick Vanderborgh (Primary Contact), Michael Inbody, Byron Morton, Mike

Banaszek, JinKi Hong, Lois Zook, and José Tafoya

MS J576, Los Alamos National Laboratory, Los Alamos NM 87545

(505) 667-6651, fax: (505) 665-6173

DOE Program Manager: JoAnn Milliken

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

Objectives

• Explore the effects of various fuels and fuel impurities on the performance of on-board hydrogen generation

technology integrated into PEM fuel cell systems through

- Measurement of automotive-scale (50-kW) fuel processor performance and durability

- Measurement of the effects of real reformate on gas cleanup devices

- Measurement of fuel cell stack anode performance under realistic operating conditions

OAAT R&D Plan: Task 4; Barriers E and F

Approach

• Develop an automotive-scale fuel processor test facility with the ability to integrate gas cleanup devices and

fuel cell stack components

- Precision measurement of flow, pressure, temperature, and chemical species

- Transient control and measurement

- Operation on hydrocarbon and alcohol fuels, with ability to blend test impurities into fuels and fuel

mixtures

• Install and characterize the operation of two automotive-scale fuel processors:

- Integrated fuel processor system from Hydrogen Burner Technology for studies of integrated system

performance

- Modular fuel processor system from Epyx for studies of individual component performance

• Study the effects of fuel processor operation on fuel cell stack anode performance:

- Measure stack anode CO tolerance with and without air injection

- Examine the design options and penalties between operation with PROX and/or stack air injection

- Characterize fuel cell stack anode response to high-concentration CO pulses

- Characterize effects of fuel processor output on fuel cell stack thermal management

Accomplishments

• Designed and fabricated fuel processor test facility

- Received Fuel-Flexible Fuel Processor from Hydrogen Burner Technology

- Awaiting shipment of Modular Pressurized Flow Reactor fabricated by Epyx

• Designed and fabricated 25-kW electrochemical test facility

• Measured fuel cell stack anode CO tolerance with and without air bleed

• Measured fuel cell stack anode response to high-concentration CO pulses

• Examined PROX and stack air injection efficiency options
Fuel Cells for Transportation FY 1999 Progress Report

43

Future Directions

• Complete installation of test fixtures in fuel processor test facility:

- Complete experiment automation

- Complete installation of emissions analysis instrumentation

• Verify fuel processors and fuel processor test facility with operation on CNG :

- Verify reactant management, pressure control, and emissions instrumentation to achieve accurate heat and

mass balances

- Verify controls operation

- Measure CO transients, both normal and within operational stages

• Study fuel processor operation on petroleum-based fuels to evaluate effects of major constituents:

- Evaluate requirements to achieve stable and efficient hydrogen generation rates

• Measure fuel processor transient operation, including startup/shutdown and variations in flow rates

• Integrate fuel cell stack testing with fuel processor operation to evaluate system integration effects of fuels

Introduction

This report describes our FY99 technical

progress in on-board hydrogen generation

technology research. The goal of this research is to

explore the effects of various fuels and fuel

impurities on the performance of on-board hydrogen

generation devices and consequently on the overall

performance of the PEM fuel cell system.

Fuels and fuel impurities may affect fuel

processor operation, efficiency, reformate gas

composition, transient performance, lifetime, and

durability. The effects will be investigated through

experiments with fuel processor hardware in a newly

developed fuel processor test facility. The effects of

fuels and fuel impurities on fuel processor operation

cascade to affect the performance and operation of

gas cleanup devices integrated with the fuel

processor. The performance and operation of gas

cleanup devices on real reformate from the installed

fuel processors will be investigated. Fuels and fuel

impurities ultimately affect the performance and

operation of the fuel cell through their effects on the

anode feed stream composition and contaminants

and their variation with time. These effects are

investigated by testing representative fuel cell stacks

with simulated reformate streams and also by

eventual integration within the fuel processor test

facility.

Below we describe our progress on the

development of a fuel processor test facility and the

installation of two vendor-provided fuel processors,

the development of an ele ctrochemical test facility,

and results from testing fuel cell stacks on simulated

reformate.

Fuel Processors and Fuel Processor Test

Facility

The fundamental tools for our research on the

effects of fuels and fuel impurities on on-board

hydrogen generation technology are our fuel

processor test facilities, beginning with two

automotive-scale fuel processors. These two

automotive-scale fuel processors will serve

complementary roles in our laboratory.

The first fuel processor, the Fuel-Flexible Fuel

Processor (F3P) from Hydrogen Burner Technology

(Long Beach, CA), is an integrated fuel processor

that incorporates a partial oxidation reformer, a

high-temperature shift reactor, a zinc oxide sulfurremoval bed, a low-temperature shift reactor, an

integral steam generator, and a combustion-driven

fuel vaporizer. Control hardware and software are

included. This fuel processor will be used to study

the effects of fuels and fuel impurities on a

thermally integrated system where the interactions

between components are close-coupled. Studies

involving transient operation, startup and shutdown,

and integration with gas cleanup devices and fuel

cell stacks are also planned for this system. The fuel

processor, shown in Figure 1, was received from

Hydrogen Burner Technology in June 1999; it is

being installed in the fuel processor test facility,

with testing to begin in the last quarter of FY99.
Fuel Cells for Transportation FY 1999 Progress Report

44

Figure 1. The Fuel-Flexible Fuel Processor (from

Hydrogen Burner Technology) at Los Alamos.

The second fuel processor, the Modular

Pressurized Flow Reactor (MPR) from Epyx

(Cambridge, MA), incorporates the sequential unit

operations of a partial oxidation reformer, a steam

reformer, a high-temperature shift reactor, a zinc

oxide sulfur-removal bed, a low-temperature shift

reactor, and heat exchanger components in

individual sections. This modular configuration can

be seen in the isometric drawing of the reactor

(Figure 2). This fuel processor allows for detailed

studies of the effects of fuels and fuel impurities

within each component. Multiple temperature and

gas sample ports allow profiling of each stage. The

modular components permit the modification of the

configuration and the changing of catalysts. Epyx

has completed fabrication of the reactor and

conducted initial testing of the reactor components.

The reactor is scheduled to be shipped to Los

Alamos in the fourth quarter of FY 1999.

The fuel processor test facility was designed to

provide the balance-of-plant framework for these

fuel processors, together with the necessary

analytical instrumentation and supervisory control to

characterize their operation and performance. The

balance-of-plant systems include the fuel supply and

fuel vaporizer, process air supply and preheater,

deionized water supply, steam supply, anode off-gas

simulation gas supplies, coolant supply for the heat

exchangers, and fuel processor exhaust treatment

and back pressure system. These systems are

Figure 2. Isometric drawing of the Epyx Modular

Pressurized Flow Reactor.

designed for accurate reactant management and

emissions management so that accurate heat and

mass balances can be measured during operation.

Supervisory control hardware and software allow for

transient control and operation of the fuel

processors.

The next step in this task is to complete the

installation of the fuel processors in the test facility

and to complete automation of the experiments. The

operation of the fuel processors and test facility will

be verified through operation on methane and

compressed natural gas. The reactant management,

pressure controls, and emissions measurements will

be verified to obtain accurate heat and mass balances

on the systems. Transient behavior will be

characterized both for normal operation and for

transitions between operating power levels.

Following these initial characterizations on natural

gas operation, fuel processor operation on

petroleum-based fuels will be characterized to

evaluate the effects of fuel composition and

contaminants. The goals of these tests are to identify

fuel processor operating conditions for stable,

efficient hydrogen generation and to investigate the

effects of fuel composition on durability and

lifetime. Future work will involve integrating gas

cleanup devices, such as a PROX, with the fuel

processor and incorporating a fuel cell stack into the

system.
Fuel Cells for Transportation FY 1999 Progress Report

45

Fuel Cell Stack Anode Performance

Fuel cell stack testing was conducted to identify

effects of fuel processor operation on fuel cell stack

anode performance. The capabilities of the LANL

stack test facility allow testing of stacks on synthetic

reformate; the gas flow rate and composition can be

varied to replicate fuel processor and gas cleanup

device behavior. Trace contaminants such as CO can

be introduced in either steady state or transient

conditions. Fuel cell stack performance then can be

measured for a variety of fuel processor operating

conditions, including different fuel options.

Alternatively, a stack can be tested on actual

reformate, derived from one of the fuel processor

units. Because today the scale of the fuel processor

is larger than the scale of test hardware, such

integration tests require sample splitting, using only

a fraction of the fuel processor output for stack

testing.

A full fuel cell stack was obtained from a

supplier. This 68-cell stack has an active area of

123 cm

2

 and is rated at 4 kW. The bipolar plates are

coated stainless steel and have an embossed flow

field. Such hardware can lead to low-cost

manufacturability. Some testing was completed on

the full stack, but most results presented here were

obtained with a short (10-cell) stack. This stack was

fitted with commercial MEAs. A photograph of the

stack as installed in the Fuel Cell Test Stand is

shown in Figure 3.

Of particular interest were anode effects that

influenced the stack’s pe rformance. One such test

was a CO tolerance test. The results are shown in

Figure 4. With 1.5% air injection, this stack can

operate to over 200 ppm CO without a serious loss

in cell voltage. With no air injection, this stack can

Figure 3. Short stack in test stand.

0

0.2

0.4

0.6

0.8

1

1.2

0 50 100 150 200 250 300

1.5% Anode Air Injection

No Air Injection

Average Cell Voltage, V

Anode CO Concentration, ppm

Anode Flow 39% H2 - 29% N2 - 17% CO2 Stoich =5

Cathode Flow 100% Air Stoich = 10

30 /30 psig 81 deg C

600 mA /cm2

Figure 4. CO tolerance tests on short stack.

tolerate a concentration up to 20 ppm CO. Tests

were also completed to determine if CO2 had adverse

consequences (e.g., by flooding the anode structure).

Exchanging the same number of moles of N2 with

CO2 and then reversing the procedure showed no

performance loss with carbon dioxide.

Parametric studies were completed to determine

the efficiency variation observed with changing the

air injection strategy—injecting air into the PROX

or into the anode of a particular stack. PROX

performance was obtained by testing a PROX built

to support Energy Partners (see III H, Reformate

Cleanup Technology, Figure 2).

The results of the efficiency study are shown in

Figure 5. The efficiency presented here is defined as

the fuel cell power divided by the LHV of hydrogen

in the PROX inlet stream. It is assumed that all

oxygen injected into the system and not combined

with CO is consumed by hydrogen oxidation, an

Figure 5. Effect of efficiency caused by changing air

injection strategies.
Fuel Cells for Transportation FY 1999 Progress Report

46

efficiency loss mechanism. The PROX air flow is

the total air flow into all stages of the PROX. For

this stack, highest efficiency is achieved by injecting

1.5 % air into the anode and 5.65% air into the

PROX. The PROX air feed rate results in a PROX

outlet CO concentration of 50 ppm. The actual result

for any given stack depends on tole rance to CO with

a given amount of anode air injection.

The stack supplier indicates that the proper

moisture level is essential to obtain good

performance. The net water balance for the stack is

defined in Figure 6 and plotted as a function of

anode stoichiometry for various cathode thermal

conditions. The cathode temperature increase within

the stack is controlled by setting the inlet

temperature (with the inlet steam condenser) and

then adjusting the stack coolant temperature to

achieve the desired cathode outlet temperature. With

a small cathode temperature rise, the stack tends to

accumulate water because the difference in absolute

humidity between cathode entrance and exhaust

ports is small. Likewise, a large cathode temperature

rise results in a dry stack exhaust region and a

decline in actual relative humidity below 100%.

Lowering the anode flow rate maintains more humid

conditions because less moisture is removed as part

of the anode flow stream.

The stack performance for these same test

conditions is shown in Figure 7. The best

performance for this stack is seen to occur when the

anode stoichiometry is between 1.2 and 2.0 and the

cathode temperature rise is between 5 and 10o C.

When the stack is very wet (Dt=0) the cell voltage

drops rapidly when the anode stoichiometry is

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0 1 2 3 4 5 6

Tin = 75 Dt=0

Tin = 75 Dt=5

Tin = 70 Dt=10

Tin = 65 Dt=15

Average Cell Voltage, V

Anode Stoichiometry

Anode Flow 36% H2 - 29% N2 - 17% CO2 

Cathode Flow 100% Air Stoich = 8.0

20 /20 psig

Cathode Thermal Conditions

Figure 6. Variation of stack performance with variation

in fluid dynamics of anode compartment.

-4

-2

0

2

4

0 1 2 3 4 5 6

Tin = 75 Dt=0

Tin = 75 Dt=5

Tin = 70 Dt=10

Tin = 65 Dt=15

Net Water Balance/ Water Produced

Anode Stoichiometry

Anode Flow 36% H2 - 29% N2 - 17% CO2 

Cathode Flow 100% Air Stoich = 8.0

20 /20 psig

WET

DRY

Cathode Thermal Conditions

Figure 7. Effect on performance resulting from water

management strategies.

decreased below 2.0, as no moisture is being

removed from that side of the membrane as well.

The dry stack also does not perform well, but it does

improve in performance as the anode stoichiometry

decreases as less water is being removed.

Contemporary stack design offers two general

approaches for reactant delivery control:

(1) prescribed flow channels, leading to improved

and simplified reactant dynamics at the expense of

greater manufacturing complexity; and (2) open

flow channels, leading to somewhat more complex

requirements for reactant gas dynamics, but

probably with far less complex manufacturing. The

test article supplied is of this second type.

Several experiments are also reported that use

data collected on a test fixture supplied by another

company. Tests shown here reflect results when a

large-concentration/finite-duration pulse of CO is

admitted to the anode compartment. The experiment

is to establish stable operating conditions

(reformate-air), promptly inject a CO contaminant

stream of 600 ppm for 60 s, and then revert to the

original CO-free test conditions. (Such an event

might replicate an upset in reformer control systems,

for example.)

Data are shown in Figure 8. The lower left-hand

trace shows the CO introduction. The heavy line

shows the computer control signal, and the lighter

line represents the measured CO concentration,

sampled at the stack anode inlet. The difference in

data represents the response time of the reactant

control hardware. Two data sets are shown. One is

done with a continuous 2% (of the total flow) air

bleed—a standard anode test condition. The second

shows results with no air injection. As can be seen,
Fuel Cells for Transportation FY 1999 Progress Report

47

0

0.2

0.4

0.6

0.8

1

0

1000

2000

3000

4000

5000

0 100 200 300 400 500

Cell Voltage, Volts

CO Concentration, ppm

Normalized Time, sec

Anode Flow 39% H2 - 46% N2 - 0% CO2 Stoich =1.5

Cathode Flow 100% Air Stoich = 2.5

30 /30 psig

Pulse 5

N2 dilution with 2% air

Pulse 6

N2 dilution with no air

Air Injection Started

CO ppm

800 mA/cm2

Figure 8. Response of a stack to high-concentration

pulses of carbon monoxide. Two experiments

are shown, with and without 2% air bleed. The

35-cell stack showed no adverse long-term

consequences.

the results are quite different. In both cases,

performance loss of approximately 50% is observed.

Air bleed results in a case where the performance

decay is less rapid and the loss somewhat less

severe. At the termination of the pulse, recovery is

rapid with air bleed and essentially nonexistent in

the absence of air bleed. (The abrupt change in slope

of voltage with time data in the recovery plots is an

artifact of the cell load control system.)

The LANL team also assembled a new

electrochemical-testing fixture, which permits

advanced diagnostics of devices up to the 25-kW

level. A schematic of this testing instrument is

shown in Figure 9. A new feature is a unique digital

valve that permits rapid, flexible, computercontrolled pressure-flow metering of hydrogen and

hydrogen-containing gaseous mixtures.

In summarizing the anode-performance

experiments, the following conclusions are apparent:

1. CO Control: An appropriate reactant injection

strategy is necessary to achieve the best anode

performance. This is a system-level control issue

involving the extent of CO tolerance in the

anode and the design of the PROX hardware.

Optimization is component-dependent.

2. CO2 Performance Loss: A modern MEA shows

no adverse consequences with significant, longterm exposure to carbon dioxide.

3. Reactant Flow: Successful stack designs can be

built with a variety of fluid dynamic solutions,

F M

MF

M

HEA

E X CHAN

COOL

W A T

TEMPER AT

C O N TRO

H X

C V

MF

P

D I

F ILT E

PUMP

H V

H V

F M

D F

P T

V 1

O2

D I

S UP P L

MAKE

TAN

HT1

T 1

P 2

HYDROG

VEN

A N O

I N

CATH

O U A N O

O U

ELE C T RO L Y

P R

P R

OXYGE

VEN

POWE

R

S UPPL

Y

HYDROGEN

C O N T A

SHU

H 2

PRV

PRV

O 2

H2DE

FUS

KNOCKDRU

C O N D E

C K

N

PUR

PUR

S Y ST E

POWE

S UPPL

V

SHT

H X

V 1

V

P T

T 2

C T

PS1 PS2

LEV

LEV

C O N TRO

A N O

I N

CATH

O U A N O

O U

FUEL

CATH

I N

COOL

I N

COOL

O U

+ -

LOA

LEV

LEV

C O N TRO

AIR

H Y D R O

S UP P L

V V

V

V

V

DI

VA

P

V3

V

P R

V 1

V 1

H2DE

V 1

C K

MF

H X

Figure 9. Schematic of new electrochemical test stand.

including both open flow areas and prescribed

(channel) flow areas.

4. CO Pulse Experiments: Stacks continue to

perform, even in the presence of extraordinary

CO contamination levels. Recovery requires

thorough removal of CO (e.g., by air oxidation

of that species).

5. Stack Diagnostics: Data analysis (not shown) of

the time response of performance loss can be

used to evaluate the quantity of reactive anode

catalyst.

Although quality test fixtures (PEM fuel cell stacks)

were necessary to achieve these results, it is not the

authors’ intent to compare performance among

different vendors. Both of the test fixtures are

prototypical and may or may not represent other

hardware from the same vendor. Data are selected to

represent the types of experiments now under way at

LANL, to support DOE's activities in fuel-cells-fortransportation technology. A more appropriate view

is that the stack component is just one element in the

overall system—the optimization of the engine is the

necessary goal.

FY 2000 Technical Plans

Future activities are focused on stack testing

with the use of actual reformate gaseous mixtures

generated by means of the fuel processing hardware

at Los Alamos. Testing will emphasize

documentation of effects of specific components

resulting from the fuel processing hardware. Both
Fuel Cells for Transportation FY 1999 Progress Report

48

large-concentration and trace-concentration

constituents will be explored.

We will also experiment with the effects of cold

storage temperatures of PEM systems, such as might

occur with a vehicle stored outdoors in cold

climates. Studies will examine similar constituent

effects and evaluate improved start-up options.

We will continue to advance the technology

leading to improved diagnostics of the stack

component within these indirect fuel cell engines.

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

Remediation in an Automotive PEM Fuel Cell Power Plant

Nguyen Minh (PM) and Tim Rehg (Co-PI)

AlliedSignal Aerospace Equipment Systems

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

Torrance, CA 90504-6099

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

Rehg: (310) 512-2281, fax: (310) 512-3432, e-mail: Tim.Rehg@AlliedSignal.com

Di-Jia Liu (Co-PI)

AlliedSignal Des Plaines Technology Center

50 E. Algonquin Road

Des Plaines, IL 60017-5016

(847) 391-3703, fax: (847) 391-3750, e-mail: Di-Jia.Liu@AlliedSignal.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: AlliedSignal Aerospace Equipment Systems, Torrance, California

Prime Contract No. DE-FC02-99EE50578, September 1999-November 2001

Objectives

• Develop, implement, and demonstrate a new CO-removal system for use in PEMFC systems that provides high

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 ppm.

OAAT R&D Plan: Task 7; Barrier E

Approach

• In a 27-month program, AlliedSignal 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.

Following the initial 12-month R&D phase, these approaches will be evaluated critically for selection 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 synthetic reformate, as well as on reformate

obtained from a Hydrogen Burner Technology fuel processor.
Fuel Cells for Transportation FY 1999 Progress Report

49

• The program consists of four major tasks:

- Research and development on two potentially viable approaches to the in-line removal and treatment of

CO.

- Selection 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

• New start in late Fiscal Year 1999.

Fuel Cell Stack System

(excludes fuel processing/delivery system)

(includes fuel cell ancillaries: i.e., heat, water, air management systems)

Characteristic Status DOE Technical Target

Peak Power (kW) 50 50

Stack System Efficiency @ 25% Power (%) 44-55 55

Stack System Efficiency @ Peak Power (%) 45-52 44

Power Density (W/L) 282-322 350

Specific Power (W/L) 295-430 350

Precious Metal Loading (g/kW) 0.9-2.6 0.9

Future Directions

• Conduct in-depth R&D and analysis for approach selection and brassboard application.

• Construct a prototype for performance evaluation.

Introduction

Because of its inherent advantages, including

high efficiency, low noise and chemical emissions,

and low operating temperature, the PEMFC

continues to benefit from intense development

efforts for its potential application in automobiles.

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. Therefore, the use of

reformers to convert more conventional and readily

available hydrocarbon fuels, such as gasoline or

methanol, to hydrogen is considered a more viable

alternative at present. Unfortunately, a typical

reformate consists of a mixture of gaseous products

that includes CO at concentration levels near 1%;

the detrimental effect of CO, even at the parts-permillion (ppm) concentration level, 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

– residing in the fuel line, between the fuel processor

and the fuel cell – that significantly decreases 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 PROX). These

techniques suffer from various disadvantages,

including high cost and complexity, high parasitic

hydrogen consumption, and intolerance to large CO

transients without complicated and expensive

control processes.

Objective and Approach

The goal of this program is to develop and

demonstrate a novel CO-removal system that

provides high CO-removal efficiency with an

increased tolerance to CO input variation in an

easily controllable manner. 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 is based on the use of a
Fuel Cells for Transportation FY 1999 Progress Report

50

 PEM FUEL

CELL

STACK

AIR, WATER, AND THERMAL

MANAGEMENT

FUEL PROCESSOR

&

CO REDUCTION

AIR

COOLANT

REFORMATE

CATHODE

GAS

ANODE

GAS

GASOLINE OR OTHER

HYDROCARBON FUEL

COOLANT

CO REMOVAL

SYSTEM

D.C. POWER

OUT

WATER

Figure 1. CO removal system in a reformer-fueled PEMFC power system.

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 with changing 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 will be investigated.

Initial proof-of-principle experiments for both

approaches have been successfully demonstrated in

our laboratory. Shown in Figure 2 are preliminary

data that confirm our first approach. During the

CO-removal phase of the experiment, a synthetic

reformate with a CO concentration greater than

1400 ppm was passed through the device and, as

shown in the figure, >95% of the CO was removed

selectively from the reformate stream. The device

regeneration process can be repeated continually

with no apparent loss in CO-scrubbing efficiency.

Shown in Figure 3 are preliminary data that

demonstrate the underlying concepts of the second

approach. Again, CO is selectively removed from

the synthetic reformate. As the figure indicates, a

CO-removal device based on Approach 2 can be

operated in a discrete mode. With an increase in the

frequency of operation, a continuous depletion of

CO in the reformate can be obtained.

The most promising of the two techniques will

be selected for implementation and testing in a

brassboard device. The device will be designed for

0

200

400

600

800

1000

1200

1400

1600

0 500 1000 1500 2000 2500 3000 3500

Elapsed Time (Seconds)

CO (ppm)

A

B

C C C

D

Figure 2. Demonstration of periodic CO removal with

rapid device regeneration, using approach #1.

At Point A, the CO-containing reformate was

directed into the CO removal device prior to

reaching the in-line CO detector. Point B

denotes the device’s removal from the

reformate stream, indicated by the rapid

increase in CO concentration. During C, the

device was readied for the next cycle

(regeneration process not shown). At Point D,

no CO was detected; the apparent presence of

CO is due to detector offset.

removal of CO from a continuous reformate stream

sized for a 10-kW PEMFC stack with an input CO

concentration level of up to 8000 ppm. The

prototype will later be delivered to Argonne

National Laboratory for further testing.
Fuel Cells for Transportation FY 1999 Progress Report

51

0

100

200

300

400

500

600

0 10 20 30 40 50 60 70

Time (min)

CO Concentration (ppm) in effluent

CO

A

B

Figure 3. Demonstration of periodic CO removal, using

approach #2. The device can be operated in

either a discrete (A) or a continuous (B) mode.

Reference

Ferrall, J., et. al., “Parametric Analyses for an AirReformate Proton Exchange Membrane (PEM) Fuel

Cell Vehicle Application,” Proceedings of the 1998

Fuel Cell Seminar, Palm Springs, CA, pp. 323-325,

November 16-19, 1998.

H. Reformate Cleanup Technology

Michael Inbody (Primary Contact), José Tafoya, Byron Morton, James Hedstrom, Barbara Zelenay,

JinKi Hong, Mike Banaszek, and Nicholas Vanderborgh

MS J576, Los Alamos National Laboratory, Los Alamos NM 87545

(505) 665-7853, fax: (505) 665-9507

DOE Program Manager: JoAnn Milliken

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

Objectives

• Develop gas cleanup technology for removal of contaminants from the fuel processor outlet stream to optimize

fuel cell stack performance

• Develop improved reactor cleanup designs to meet PNGV goals by

- Improving device efficiency

- Optimizing for fuel cell engine system

- Increasing the ability to accommodate automotive transients

- Improving cost, volume, weight, and durability metrics.

OAAT R&D Plan: Task 3; Barrier E

Approach

• Investigate catalysts, catalyst supports, and catalyst performance for gas cleanup applications

• Refine PROX concept and design

- Modify reactor design, controls, and sensors for optimal performance and to meet performance

requirements

• Test PROX designs and concepts in LANL PROX Experimental Test Facility
Fuel Cells for Transportation FY 1999 Progress Report

52

- Quantify contaminant removal and transient performance on simulated reformate

- Develop and refine control strategies under simulated operating scenarios

• Test PROX designs and concepts in fuel processing systems

- Address system integration issues and operation on real reformate streams

- Develop 10-kWe PROX for Energy Partners PEM system

- Integration 50-kW PROX with HBT and Epyx fuel processors in LANL fuel processing lab

• Develop modeling and analysis tools

- Support reactor design, experimental analysis, optimization, and control algorithm development

Accomplishments

• Implemented a new PROX/catalytic reactor design that permits compact operation with a 2% CO inlet stream

• Developed a PROX for the Energy Partners PEM fuel cell system

- Designed, fabricated, thoroughly evaluated, and delivered

- Reconfigured reactor design to manage higher inlet CO concentration

- Demonstrated low outlet CO (< 10 ppm)

- Demonstrated operation at reduced oxygen stoichiometry and with reduced hydrogen consumption

- Demonstrated decreased sensitivity to fluctuations in inlet CO concentration

- Demonstrated ability to accommodate transients

• Conducted catalyst evaluations

• Conducted PROX transient response studies

• Addressed DFMA issues through planned workshop and PROX design and testing

Future Directions

• Continue PROX transient experiments to investigate control strategies and provide modeling data

• Continue catalyst investigation and evaluation

- Evaluate rugged supports for use in PROX automotive applications

- Evaluate catalysts for reducing size of the PROX catalyst volume

• Investigate compact devices for controls, gas mixing, sensors, and actuators to reduce overall PROX volume

and cost, thereby enabling new, compact fuel processing hardware

• Integrate PROX with fuel processing systems at LANL

- Operate stacks on “real” vs. synthetic reformate

- Address PROX/POX system integration issues, including synergy and transients

- Investigate durability issues

- Investigate reformate cleanup by processing of additional contaminants in real reformate stream

- Investigate effects of fuel-processing contaminants on PROX performance

• Explore technology transfer opportunities.

Introduction

This report describes our FY 1999 technical

progress in research on reformate gas cleanup

technology. The goal is to advance catalytic gas

cleanup technology to remove contaminants from

the fuel processor outlet stream, thereby improving

fuel cell stack performance. The initial focus of

research has been the removal of the contaminant,

CO, from reformate streams by preferential

oxidation (PROX) cleanup technology. Our research

and designs have expanded to implement additional

mechanisms for CO removal and to address other

reformate contaminants, but we still describe the

devices that accomplish this by the generic name

“PROX.” To develop a PROX from the current

laboratory device into an automotive device requires

improvements in efficiency and transient capability,
Fuel Cells for Transportation FY 1999 Progress Report

53

as well as meeting automotive requirements for cost,

volume, weight, and durability.

The approach taken to meet the PROX

automotive requirements requires investigating

catalysts and catalyst supports, refining the PROX

concept and design, and incorporating improved

catalysts into a reactor design with the required

controls and sensors. We verify these PROX designs

through benchmark testing on simulated reformate

in our PROX experimental test facility and through

integration with fuel processing systems via

industrial collaborations or, in the future, integration

with prototypical fuel processor systems in LANL

laboratories.

Below, we describe our implementation of a

new PROX design, development of a PROX for the

Energy Partners PEM system and its performance,

experiments in catalyst testing and PROX transient

studies, and progress toward manufacturability of

PROX devices.

Implementation of New PROX Design

Much of the experimental work on gas cleanup

has been conducted with a new design of the PROX

hardware. The motivation for this new design

resulted from new specifications for the Energy

Partners natural gas PEM fuel cell system and the

need to develop a flexible, modular catalyst test

reactor as our laboratory tool for gas cleanup

research.

The modular design allows rapid addition and

removal of a single stage. The design is compact

because of integrated air injection and mixing within

Figure 1. PROX stage components. Outer shell is shown

by the two stages in the foreground. A catalyst

cartridge is shown in the center background,

with a HEX insert in the right background.

a heat exchanger built into the device’s exterior. The

transient response of the device is improved through

reduction of the mass of the internal components and

by regenerative heat transfer features. The design

incorporates manufacturable components while still

maintaining experimentalease and flexibility of use

for laboratory investigations.

The parts are fabricated from drawn, precision,

thin-wall stainless steel tubing. Only the external

tubing has the necessary thickness to achieve the

pressure rating; the internal components are

lightweight and demonstrate improved transient

response.

One key design feature is the use of an easily

replaceable catalyst cartridge that can accommodate

catalysts in the form of monoliths, pe llets, foams,

and screens. Another key design feature is the use of

a replaceable heat exchanger insert that facilitates

quick exchange of different heat exchanger

configurations for interstage cooling. The end result

is a flexible and multipurpose design in which any

stage can be configured as a PROX stage, a filter

stage, a shift reactor stage, or a reformer stage. This

design serves well for cleanup experiments that use

realistic flow rates and process conditions.

Importantly, it is fully capable of handling

hydrogen-containing gaseous mixtures under a

variety of testing conditions.

Development of PROX Subsystem for Energy

Partners

We designed, fabricated, thoroughly evaluated

and delivered a PROX subsystem to Energy Partners

(West Palm Beach, Fla.). The PROX subsystem

was designed for integration into a natural-gasfueled PEM fuel cell system being integrated by

Energy Partners. The new PROX design described

above was implemented for this PROX device. The

initial configuration of the PROX included three

active catalyst stages designed to manage a

maximum inlet concentration of 1% carbon

monoxide at a maximum reformate flow of

45 kWth, based on the LHV of methane.

The modified PROX device, shown in Figure 2,

incorporated the balance-of-plant components to

make the system self-contained. Air mass flow

controllers within the stand control the air injection.

Proportional control valves regulate the coolant flow

through each interstage heat exchanger. Pressure and

temperature instrumentation are also included. The
Fuel Cells for Transportation FY 1999 Progress Report

54

Figure 2. PROX subsystem for Energy Partners PEM

fuel cell system.

data acquisition and control interface uses hardware

from National Instruments, and the operating

software was written using National Instruments’

LabVIEW. Figure 2 shows the test stand framework

incorporating the PROX subsystem. The PROX is

mounted on the left. The mass flow controllers, flow

control valves, and data acquisition hardware are

mounted on the right. The open test stand design

allows easy access for modifying the hardware and

altering the PROX reactor design (for example, to

change the catalyst). Thus, this test apparatus is

built for experimental convenience rather than

compactness.

We conducted proof testing of the PROX

subsystem at Los Alamos, during which time we

trained personnel from Energy Partners in standard

operation procedures. The proof testing served to

identify the PROX stage-operating map to meet the

design requirements for the Energy Partners fuel cell

stack. For the tests, we simulated methane partial

oxidation reformate with an inlet CO concentration

of 1% at two total flow rates, 35 kWth and 15 kWth,

based on the LHV of methane. Figure 3 shows the

0

1000

2000

3000

4000

5000

6000

7000

8000

0.5 1 1.5 2 2.5 3 3.5 4

35 kW Stage 1

35 kW Stage 2

35 kW Stage 3

15 kW Stage 1

15 kW Stage 2

15 kW Stage 3

 CO Concentration (ppm)

Oxygen Stoichiometry

Power Level 15-35 H2 kWch

Inlet CO Concentration 10000 ppm

Stage 1 Outlet

Stage 2 Outlet

Stage 3 Outlet

Figure 3. Outlet CO concentration from each stage of

PROX as function of overall oxygen

stoichiometry.

outlet CO concentration from each stage of the

PROX as a function of oxygen stoichiometry. Here

we define oxygen stoichiometry as

actual CO

O

O

N

N

















= ⋅

&

&

2

2

f 2

where O2N& is the oxygen molar flow from the air

injection and NCO

&

 is the carbon monoxide molar

flow at the PROX inlet. An overall oxygen

stoichiometry for a PROX stage sums the oxygen

molar flows up to and including that stage. The ideal

operating point for a PROX would be an overall

oxygen stoichiometry of 1, where just enough

oxygen is added to oxidize quantitatively the carbon

monoxide. Where oxygen stoichiometries are higher

than 1.0, operating conditions are such that oxygen

consumes hydrogen in addition to carbon monoxide,

an efficiency penalty. Figure 4 shows the outlet CO

concentration from the PROX as a function of

overall oxygen stoichiometry. At the two indicated

flow rates, the outlet CO concentration drops below

50 ppm, our target level, for oxygen stoichiometries

ranging from 4 to below 3.

The PROX subsystem subsequently was

installed in the Energy Partners natural gas PEM

fuel cell system, where it was used in the successful

demonstration of electricity production from a

natural gas system.

Reconfiguration of PROX Subsystem

Results from catalyst testing in a duplicate

version of the Energy Partners PROX led to the
Fuel Cells for Transportation FY 1999 Progress Report

55

0

20

40

60

80

100

2.5 3 3.5 4

 CO Concentration (ppm)

Oxygen Stoichiometry

Power Level 15-35 H2 kWch

Inlet CO Concentration - 10000 ppm

35 kW Stage 3 Outlet

15 kW Stage 3 Outlet

Figure 4. Detail of PROX outlet CO concentration as a

function of overall oxygen stoichiometry.

concept for a new approach to reduce both the outlet

CO concentration and oxygen stoichiometry. Test

data obtained during the Energy Partners

experiments showed a new design requirement, to

manage higher levels of CO than first planned.

Based on these results, the PROX subsystem for

Energy Partners was reconfigured and rebuilt for

operation with an inlet concentration of 2% CO.

The modifications included (1) the addition of a

particulate inlet filter to assure dust-free sample inlet

flow; (2) addition of a compact low-temperature

shift reactor stage; (3) modifying the catalyst design

in the PROX reactor stages; and (4) a new code for

the control computer.

We conducted benchmark testing of the

reconfigured PROX subsystem before shipping it

back to Energy Partners. Operating conditions

observed during Energy Partners’ fuel cell system

experiments were reproduced in the LANL PROX

Test Facility. Figure 5 shows the resulting outlet CO

concentration for each stage of the PROX for

simulated methane POX reformate at 4 total flows

and specified POX equivalence ratios and

steam-to-carbon ratios. A 2% CO inlet concentration

was utilized for all of these experiments. PROX

operating conditions were determined that led to an

outlet CO concentration of less than 10 ppm CO

under all test conditions. Note: at the 20-kWth flow

rate, three PROX stages are sufficient to achieve the

<10-ppm CO level. Figure 6 shows the PROX outlet

CO concentration as a function of the overall oxygen

stoichiometry and shows greater detail of the low

outlet CO concentration (< 10 ppm) for each flow

rate. The graph also shows that the overall oxygen

0

5000

10000

15000

20000

1 2 3 4 5

40 kWch Methane

35 kWch Methane

30 kWch Methane

20 kWch Methane

Stage Outlet CO Concentration (ppm)

Prox Sampling Location

Prox Inlet

Stage 1 Outlet

Stage 2 Outlet

Stage 3 Outlet

Prox Outlet

Figure 5. Outlet CO concentration from each stage of

the PROX.

0

100

200

300

400

500

600

700

800

0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

40 kWch Methane

35 kWch Methane

30 kWch Methane

20 kWch Methane

Prox Outlet CO Concentration (ppm)

Overall Oxygen Stoichiometry

Figure 6. PROX outlet CO concentration as a function

of the overall oxygen stoichiometry.

stoichiometry required to achieve these low outlet

CO concentration values has been reduced below 1.3

for all four flow rates. This represents a significant

reduction in the hydrogen consumption and, thus, an

improvement in the overall efficiency of the fuel cell

system.

Following the benchmark testing at Los Alamos,

the reconfigured PROX was transferred to Energy

Partners and again incorporated into their natural gas

fuel processor–fuel cell system experiment. Figure 7

shows a data snapshot taken during the initial
Fuel Cells for Transportation FY 1999 Progress Report

56

1.0

1.2

1.4

1.6

1.8

2.0

0

20

40

60

80

100

16200 16300 16400 16500 16600 16700 16800 16900 17000

EP Prox Test - Inlet CO and Outlet CO vs time

25 kWth methane flows

Inlet CO (%)

Outlet CO (ppm)

Inlet CO (%)

Outlet CO (ppm)

Elapsed Time (sec)

Figure 7. Data snapshot taken of PROX inlet and outlet

CO concentrations with the fuel processor

operating at 25-kWth total flow rate.

checkout of the PROX in the Energy Partners

laboratory. The graph shows the PROX inlet and

outlet CO concentrations as a function of time, with

the reformer operating at a steady-state 25-kWth

total flow rate. During this time snapshot, the PROX

outlet CO concentration remains below 50 ppm,

even though the inlet CO concentration varies

considerably. Here, we are demonstrating that the

improved PROX approach results in a greatly

reduced sensitivity to fluctuations in the inlet CO

concentration. The fuel processor in this system was

not fitted with an active low-temperature shift

reactor and thus shows periodic variation in the

PROX inlet CO concentration. A system with a lowtemperature shift reactor would be expected to yield

far smaller fluctuations in the PROX inlet CO

concentration.

Catalyst Investigations

We continue investigations of catalysts and

catalyst supports to document catalyst performance

and to generate data for kinetic modeling. These

studies provide the research base for improving

PROX performance and design. The catalyst

evaluation studies utilize the new PROX design in a

two-stage configuration—these tests are done using

full-scale flow rates. The first stage is a gas mixing

and conditioning stage, while the second is the

catalyst, which modifies the composition of the

sample stream.

Catalysts tested during the year have included

formulations made with platinum, ruthenium, and

palladium. Catalyst support types have included

pellet, monolith, and ceramic foam supports. Also,

experiments were instrumented to measure

temperature and species profiles throughout the

catalyst volume to obtain data for modeling studies.

PROX Transient Operation

We also continue experiments that measure the

transient response of the PROX, including new

options for faster transient operation. Both the

50-kWe PROX system developed last year and the

new, reconfigured PROX design have been used for

these transient experiments. The experiments are

now focused on the new PROX design because of its

demonstrated faster transients, coupled with

experimental flexibility.

Experiments in progress study fluctuating inlet

CO concentrations and control of those fluctuations,

as well as PROX transient response and control

during transients in overall reformate flow rates,

which occur when fuel cell system power levels

change. The goal for these experiments is to develop

a simplified control strategy for PROX transients.

Work under way seeks new approaches that may

eliminate the need for an online CO sensor.

PROX Design for Manufacturing

We are also investigating design-formanufacturing engineering, where the goal is to

cooperate with new partners in the design and

prototype fabrication of a compact, transientcapable, durable PROX device. As part of that

process, Larry Blair, the Los Alamos Fuel Cells for

Transportation Program Manager, will organize a

workshop during the year 2000.

Our activities on this task have focused on

manufacturable automotive components. This work

includes testing manufacturable components in the

PROX, designing catalyst components with reduced

size and weight and of rugged design, testing LANL

PROX concepts in real-world situations (such as

within a cooperative activity with Energy Partners),

and developing design tools that lead to system

design optimization. Also, we are investigating

options for transient control, via new concepts built

into the reactor design. Here, the goal is to eliminate

an online CO sensor, reduce the overall sensor count

in the fuel cell system, and reduce the actuator count
Fuel Cells for Transportation FY 1999 Progress Report

57

for air injection and temperature control. There are

several design directions that appear to lead toward

such goals.

Future Directions (FY2000)

The future direction for this work on reformate

cleanup technology is to improve options for

catalytic cleanup technology, moving toward ever

more compact, reliable, and cost-effective reactor

designs. This includes continuing development of

PROX transient experiments, with the goal of

investigating control strategies and developing input

data for transient modeling. We will continue

catalyst investigations and evaluations and will work

with catalyst developers on rugged catalyst

structures for more transient-capable and compact

hardware. To meet automotive requirements for cost

and volume, we will investigate and develop

compact devices for controls, gas mixing, sensors,

and actuators.

We also plan to integrate the PROX with fuel

processing systems in our laboratory. This

experimental integration work is aimed at operation

of combined Autothermal/Shift/PROX components

containing cleanup devices used to provide

reformate for PEM stack testing. Such tests will be

critical in studying the effects of fuels and fuel

composition.

I. Evaluation of Partial Oxidation Fuel Cell Reformer Emissions

Stefan Unnasch

ARCADIS Geraghty & Miller, Inc.

555 Clyde Avenue, P.O. Box 7044

Mountain View, CA 94039

(650) 254-2413, fax: (650) 254-2496, e-mail: sunnasch@acurex.com

DOE Program Manager: Donna Ho

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

ANL Technical Advisor: Walter Podolski

(630) 252-7558, fax: (630) 252-4176, e-mail: podolski@cmt.anl.gov

Contractor: ARCADIS Geraghty & Miller, Inc., Mountain View, California

Prime Contract No. DE-FC02-99EE50585, September 1999-September 2000

Objectives

• Determine the emissions from partial oxidation/autothermal fuel processors for PEM fuel cell systems.

• Determine whether emission standards for automobiles and light-duty trucks can be met by a fuel cell vehicle

with a multifuel reformer.

• Evaluate performance of catalytic burners in controlling startup emissions.

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

Approach

• Quantify cold startup and normal operating emissions from a partial oxidation reformer before and after anodegas-burner treatment.

• Test four fuels – gasoline, methanol, ethanol, and natural gas – as well as different catalyst formulations.
Fuel Cells for Transportation FY 1999 Progress Report

58

• Test both Epyx and Hydrogen Burner Technology, Inc. (HBT), fuel processors.

Accomplishments

• New start in late FY 1999.

Future Directions

• Complete emissions testing in FY 2000.

Introduction

This project will determine the emissions from

partial oxidation/autothermal fuel processors for

PEMFC systems. Both Epyx Corporation and

Hydrogen Burner Technology, Inc. (HBT), fuel

processors will be tested. The cold startup and

normal operating emissions of NOx, CO, and CO2,

methane, nonmethane hydrocarbons, carbonyl group

compounds (aldehydes), and speciated hydrocarbons

(light end hydrocarbon group components and

mid-range hydrocarbon group components) from a

partial oxidation reformer (POX), before and after

treatment by an anode gas burner, will be quantified.

Different anode gas burner catalyst formulations and

four fuels (gasoline, methanol, ethanol, and natural

gas) will be tested. The project will determine

whether a fuel cell vehicle with a multifuel reformer

can meet emission standards for automobiles and

light-duty trucks.

Background

The operating requirements for both the HBT

and Epyx systems are similar. Emissions from the

fuel cell system arise in two operating modes,

startup and normal partial oxidation (POX)

operation. During startup, the fuel processor burns

fuel at near-stoichiometric conditions. Cold-start

emissions from a cold combustor are much higher

than those from a system that has been warmed up.

Target times for startup are less than 30 seconds.

However, the emissions produced during this brief

period can be substantially higher than those during

the remaining, much longer portion of a driving

cycle. Pollutant emissions from startup include

NOx, unburned hydrocarbons and other organic

compounds, CO, and formaldehyde. Organic

compounds – including hydrocarbons, alcohols, and

aldehydes – are referred to in California, and

regulated as, “nonmethane organic gases” (NMOG).

This distinction is convenient when dealing with

oxygenated fuels, such as reformulated gasoline

(RFG), which contains 11 percent methyl tertiary

butyl ether (MTBE) or other oxygenated

compounds, as well as methanol and ethanol.

During normal operation, the fuel processor

operates under very rich conditions, with a

stoichiometric air/fuel ratio below 0.4. Under these

conditions, virtually no NOx is formed, although the

formation of ammonia is possible. Most

hydrocarbons are converted to carbon oxides (or

methane, if the reaction is incomplete); however,

trace levels of hydrocarbons can pass through the

fuel processor and fuel cell. Carbon monoxide in

the product gas is reduced by the shift reactors and

preferential oxidizer (PROX), so the feed

concentration to the fuel cell can be less than

20 ppm. The fuel cell may also convert CO to CO2,

thereby further reducing exhaust CO levels. 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

if these compounds are not efficiently eliminated in

the catalytic burner.

Figure 1 shows estimated NMOG emissions,

taken from the ARCADIS Geraghty & Miller study

for CARB, for compressed-natural-gas- (CNG-) and

gasoline-fueled POX systems. The figure illustrates

the importance both of startup emissions in

Figure 1. Estimated exhaust emissions for POX/PEMFC

systems.
Fuel Cells for Transportation FY 1999 Progress Report

59

determining total driving cycle emissions, and of

catalyst performance with respect to the ability to

reduce NMOG emissions. For example, if catalyst

efficiency is reduced from 85 to 20 percent, a

gasoline-fueled POX reformer/PEMFC can no

longer meet the California SULEV standard for

NMOG emissions, with the exceedence caused by

startup emissions.

Purpose

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 Epyx fuel-flexible fuel

processors.

Approach

Emissions will be tested under conditions

simulating cold start and normal operation; anode

gas burner catalyst performance for reducing

NMOG emissions will be evaluated, and the

performance of alternative catalyst formulations and

anode burner combustion approaches for reducing

NMOG emissions will be tested. The results will

consist of emissions data obtained under the various

anode gas burner configurations and operating

conditions tested for NOx, total hydrocarbons

(THC), methane, CO, CO2, speciated hydrocarbons,

alcohols, aldehydes, and ammonia. A preliminary

emission sampling system is shown in Figure 2. The

data will be presented on a grams-per-unit fuel basis,

as well as a predicted grams-per-mile (g/mi) basis.

Comprehensive final reports will be prepared that

evaluate the reformer and anode gas burner

configurations and the fuels tested. The results will

be compared with proposed low emission standards,

including the EPA Tier 2 and California SULEV

standards.

Concentrations of O2, CO2, CO, NOx, and THC

will be monitored with continuous emission

Air

Exhaust

Burner

FFFP Product Gas

Start-Up Exhaust

Simulated

 Cathode Gas

N2

NMOG Cat 2

Δ 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.

monitors (CEMs). Measuring emissions from a

POX system requires a wide range of analyzer

capabilities. During startup, emissions will be in the

10–1000-ppm range for NOx, CO, and

hydrocarbons. During fuel cell operation, these

levels will drop to less than 10 ppm. Ambient-level

CEMs will be employed for NOx and hydrocarbon

measurements. Hydrocarbon speciation analysis

will be performed by collecting integrated gas

samples (in Tedlar bags) and analyzing them via gas

chromatography (GC) for the hydrocarbon species

required by the California NMOG calculation.

Emission testing is expected to start in October

1999 and to be completed in FY 2000. A final

report will be issued upon completion.
Fuel Cells for Transportation FY 1999 Progress Report

60

J. Catalytic Partial Oxidation Reforming Materials and Processes

Michael Krumpelt (Primary Contact), S. Ahmed, R. Wilkenhoener, J.D. Carter, Y. Shi

Argonne National Laboratory, Argonne, IL 60439

(630) 252-4553; fax: (630) 972-4553

DOE Program Manager: JoAnn Milliken

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

Objectives

• Develop catalyst for the partial oxidation reforming of hydrocarbon fuels for fuel cells in transportation

- Improve catalyst formulation to increase activity and selectivity

- Elucidate mechanism

- Support catalyst on monoliths

OAAT R&D Plan: Task 3; Barrier E

Approach

• Catalyst performance is evaluated in microreactors under carefully controlled conditions:

- Pure hydrocarbons, oxygen/carbon ratio, water/carbon ratio, temperature

- Elucidate mechanism by studying segments of the reforming reaction sequence

• Explore new materials

- That have some theoretical basis for promoting the desired reaction

- That match the properties of catalysts demonstrating high activity and selectivity

• Catalyst technology development:

- Investigate synthesis techniques that lead to higher activity, promote stability, and are suitable for

manufacturing

- Develop monolith catalysts suitable for transportation applications

Accomplishments

• Developed new catalyst formulation and synthesis technique

- Increased activity such that 60% (dry, N2-free) hydrogen was achieved at 600°C

- Increased catalyst surface area by a factor of 4

- Demonstrated higher space velocity (10X) capability, leading to compact reformer

Future Directions

• Continue fundamental studies of catalyst to improve performance through the understanding of material effects

on reaction mechanism

• Advance catalyst formulation and preparation

- Materials, synthesis methods, and structured supports

The objective of this work is to develop

catalysts for the autothermal reforming of

hydrocarbon fuels for use in fuel cell vehicles. It has

been demonstrated that a new class of catalysts

developed at Argonne has the ability to convert

various hydrocarbon fuels into a hydrogen-rich gas
Fuel Cells for Transportation FY 1999 Progress Report

61

at temperatures of less than 750°C. This project

undertakes to improve the catalyst’s activity and

selectivity; to elucidate the reaction mechanism,

which will lead to better catalysts; and to develop

monolith catalysts that are suited for use in mobile

applications.

The catalyst development work is pursued from

a number of directions. For example, the catalyst

formulation is varied to study the changes in

catalytic properties that result from different

materials, their phases, the proportions and the

resulting effects of material interactions, etc.

Changing the synthesis technique alters the material

properties because of modifications in the phase and

structure, as well as in the surface area, of the

catalyst.

The concept for the Argonne partial oxidation

reforming catalyst was derived from our experience

with solid oxide fuel cell materials, where the anode

material is chosen on the basis of (among other

things) the ability to conduct oxide ions. Also,

Vayenas et al. [1,2] showed that when an applied

chemical potential exceeded a threshold value, the

rate of oxidation reactions jumped several orders of

magnitude, as shown in Figures 1 and 2. Extending

this phenomenon, called the non-Faradaic

Electrochemical Modification of Catalytic Activity

(NEMCA), we have demonstrated that catalysts

based on these oxide-ion-conducting materials show

remarkable activity for the partial oxidation of

hydrocarbons and exhibit good selectivity for

hydrogen and carbon dioxide in the product.

The Argonne partial oxidation catalyst uses a

combination of a metal on the oxide ion conductor

(substrate) to achieve the desired reaction. In order

to determine the effect of the metal loading on the

substrate, experiments were conducted in a

Figure 1. Schematic of the fuel cell reactor.

Figure 2. Effect of VWR on the rate of CO formation;

Catalyst C4.

microreactor with isooctane as the fuel, oxygen

(O2/C8=4), and steam (H2O/C8=8), with the reactor

maintained at 800°C. Figure 3 shows the product

gas distributions obtained by changing the loading

of metal A. The hydrogen percentage was found to

be maximum at a weight loading of 0.5 wt.%.

However, the variations in product distribution with

loadings between 0.2 and 1.03 are quite small.

A number of material combinations and

synthesis techniques have also been tried to increase

the catalyst activity. Figure 4 compares the

percentages of hydrogen obtained from a new

catalyst material synthesized by a new method to

that obtained with a formulation from the previous

year. The new method produced a catalyst with a

surface area that was 4 times larger, at 30 m2/g.

0

10

20

30

40

50

60

70

80

Product Composition, % 

(dry, N2-free)

0 0.2 0.5 0.72 1.03

Loading with A, wt. %

H2

H2 a/WGS

CO2

CO

CH4

Temperature: 800°C

0

10

20

30

40

50

60

70

80

Product Composition, % 

(dry, N2-free)

0 0.2 0.5 0.72 1.03

Loading with A, wt. %

H2

H2 a/WGS

CO2

CO

CH4

Temperature: 800°C

(Fuel:C8H18, O2/ C8H18=4, pressed pellets)

Figure 3. Effect of metal A loading (on a substrate), on

product gas distribu-tions during autothermal

reforming of isooctane. (H2 a/WGS means the

H2 percentage after the CO is converted in a

water gas shift reactor)
Fuel Cells for Transportation FY 1999 Progress Report

62

Figure 4. Newer catalyst material and synthesis methods

give 60% hydrogen at 600°C.

The combination of new material and higher

surface area has led to a more active catalyst. This is

demonstrated by the fact that the new catalyst

produced 60% hydrogen (dry, N2-free) at 600°C

(Figure 4), compared to the older catalyst, which

produced similar H2 concentrations at over 750°C.

The improved catalyst activity is reflected in the

fact that complete conversion can now be achieved

at a much higher space velocity. Figure 5 shows the

product gas distributions obtained as a function of

the gas hourly space velocity (GHSV, based on

gaseous reactants at 25°C and catalyst volume). The

reactor was maintained at 700°C. At the low space

velocity of 3000 hr-1 , 62% hydrogen was measured

in the product gas. When the space velocity was

increased by an order of magnitude, to 30,000 hr-1,

the catalyst was still able to complete the conversion

of isooctane, although the level of by-product

hydrocarbons (mainly methane) was increased and

the hydrogen percentage dropped to 55%. It is very

likely that the trend toward higher HC and lower H2

percentages can be reversed by raising the

temperature slightly, and this will be investigated

further. The fact that the space velocity can be

increased 10-fold while maintaining conversion is

very promising because it predicts that the reformer

volume can be reduced by a factor of 10.

The catalyst development work has led to a new

catalyst material that has shown remarkable activity

0

10

20

30

40

50

60

70

0 5000 10000 15000 20000 25000 30000 35000

GHSV, 1/hr

Product Composition, % 

(dry, N2-free)

H2

CO

CO2

HC's

C8H18 Reforming:

O2/C8H18 = 4

T = 700°C

Figure 5. Effect of space velocity on product gas

distributions obtained from partial oxidation

reforming of isooctane.

and selectivity for the partial oxidation reforming

reaction. Fundamental studies in progress have led

to advances in the catalyst formulations, and to

synthesis methods that indicate more active and

selective catalysts are possible. These advances, in

turn, point to the ability to reform at lower

temperatures and in smaller reformers.

These studies on the fundamental aspects of

material interactions and their effects on the reaction

mechanism will be pursued further to gain a better

understanding of the process. The work on

alternative synthesis techniques will be continued to

develop faster methods that produce more rugged

catalysts with larger surface area.

For transportation applications, it is desirable to

use monolithic catalysts. We are investigating

several methods (e.g., catalyst monoliths, catalysts

supported on monoliths, etc.) to establish the best

way to make catalyst forms that achieve the

robustness of monoliths without compromising the

catalytic properties.

References

1. C.G. Vayenas and S. Bebelis, Catalysis Today,

51 (1999), 581.

2. I.V. Yentekakis, Y. Jiang, S. Neophytides, S.

Bebelis, and C.G. Vayenas, 2nd European Solid

Oxide Forum, Oslo, 1996, p.131.
Fuel Cells for Transportation FY 1999 Progress Report

63

K. Alternative Water-Gas Shift Catalyst Development

Romesh Kumar (Primary Contact), Deborah J. Myers, Christopher R. Kinsinger, J. David Carter,

Theodore R. Krause, and Michael Krumpelt

Argonne National Laboratory, Argonne, IL 60439-4837

(630) 252-4342, fax: (630) 252-4176

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 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, such as

ceria, under reformate conditions)

- Exploit such reaction pathways as

* + CO  COad * = active surface site

M2O3 + H2O  2MO2 + H2

2MO2 + COad  M2O3 + CO2

Accomplishments

• Improved catalyst activity by a factor of >3 while reducing precious metal content by a factor of 2

• Demonstrated high catalyst activity over the entire conventional HTS and LTS operating temperatures (i.e.,

from 230°C to 400°C)

• Demonstrated that the catalyst retains high activity even after prolonged exposure to air at 550°C

• Determined kinetic parameters and estimated preliminary reactor sizes to be much smaller than with

conventional HTS and LTS catalysts

• Scaled up the supported catalyst fabrication process to synthesize 2-kg batches

Future Directions

• Explore other oxide/metal combinations, such as MnOx/Mo, for reduced cost, higher activity

• Determine source of poor catalytic activity obtained for nonprecious metals

• Decrease loading of total catalyst and precious metal on high-surface-area support

• Test catalyst under real reformate conditions and investigate potential poisoning by contaminants (e.g., sulfur)
Fuel Cells for Transportation FY 1999 Progress Report

64

Introduction

The water-gas shift reaction,

CO + H2O → CO2 + H2

is used to convert the bulk of CO in the 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) takes place 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.

Commercial HTS and LTS catalysts require

activation by careful pre-reduction in situ; once

activated, they lose their activity very rapidly if they

are exposed to air. Further, the HTS catalyst is

inactive at temperatures <300°C, while the LTS

catalyst degrades if heated to temperatures >250°C.

For the automotive application, with its highly

intermittent duty cycle, it is important to develop

alternative water-gas shift 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

We are developing metal-support

combinations to promote a bifunctional mechanism

of catalyst action. In this approach, the metal to

adsorb the CO is selected as one with an

intermediate CO adsorption strength (i.e., an

adsorption energy of 20–50 kcal/mol). The support

serves to adsorb and dissociate the H2O. This is

typically a mixed-valence oxide with redox

properties (such as ceria) under the highly reducing

conditions of the reformate. This mechanism may be

represented as,

* + CO  COad * = active surface site

M2O3 + H2O  2MO2 + H2

2MO2 + COad  M2O3 + CO2

Figure 1 shows the CO adsorption energies

of the Periodic Table Group IV to Group XIV

metals. The metals with CO adsorption energies of

20 to 50 kcal/mol are shown in Figure 1; these

metals were the ones tested as a shift catalyst

component. Similarly, the candidate supports with

mixed valence are the oxides of transition metals

(Fe, Cr, Mn, V, but not Ni, which is a methanation

catalyst and which also forms the volatile nickel

carbonyls) and the lanthanides (La, Ce, Sm, etc.).

Note that ZnO would not fit this approach, because

its role in the commercial Cu-ZnO shift catalyst is

not bifunctional. Other non-bifunctional supports

could include zeolites, for example.

Au

Ru Ge

Mo

Ni

Fe

Pd

Pt

Rh

Co Cu, Ag

0

20

40

60

80

100

120

140

160

180

2 4 6 8 10 12 14 16

Periodic Table Group

CO Adsorption Energy (kcal/mol)

Figure 1. The CO adsorption energy of several Group

IV to Group XIV metals.

Recent Progress

Table 1 shows the results of testing the metals

identified in Figure 1 with various candidate support

materials. High shift activity was observed only with

noble metals.

Tests of the candidate catalyst’s activity were

conducted with simulated reformate, using a

microreactor setup as shown in Figure 2.

The reactor was operated as an integral reactor

for activity determinations. The logarithm of the

change in CO concentration relative to its

Table 1. High catalytic activity was obtained only with

noble metals.

Metal

Number of

Supports

Relative

Activity

Ag 2 Poor

Co 1 Poor

Cu 2 Medium

Fe 1 Poor

Pt 5 High

Ru 2 High

(but CH4)

Pt-Cu 1 High

Pt-Ru 1 High
Fuel Cells for Transportation FY 1999 Progress Report

65

N2, 30.8

H2, 48.9

CO, 0.994

CO2, 19.3

H2O (S/C=6.5)

VAP

MICROREACTOR

IN

FURNACE

GC

SAMPLE

PORT

CO, CO2

ANALYZERS

REACTOR

BYPASS

Figure 2. Schematic diagram of the microreactor test

apparatus.

equilibrium value, when plotted versus the inverse

of the reactant flow rate, shows a linear behavior.

The slope of this line is proportional to the reaction

kinetics (i.e., the activity of the catalyst). Most of the

tests were conducted at 230°C, except the tests to

determine activation energies, for which the

temperatures ranged up to 400°C.

Figure 3 shows that over the past year we have

increased the activity of the catalyst (at 230°C) by

more than a factor of 3, while at the same time the

catalyst’s precious metal content has been reduced

by one-half.

The activity of the catalyst was unaffected by

exposure to air and to high temperatures in air, as

shown in Fig. 4.

The catalyst also showed high activity over the

temperature range from 230 to 400°C. The change in

product composition as a function of temperature is

shown in Figure 5. The product composition

0

1

2

3

4

0 20 40 60 80 100 120 140 160

1/Total Flow Rate (min/mol)

ln[(Ci-Ceq)/(Co-Ceq)]/g cat

May 99

0.57 wt% Pt, 50 m2/g

February 99

0.48 wt% Pt, 25 m2/g

June 98

1.2 wt% Pt, 17 m2/g

Triangles - Cu/ZnO (UC G66B)

Figure 3. Improvements in catalyst activity from June

1998 to May 1999.

0.0

0.4

0.8

1.2

1.6

2.0

0 50 100 150

1/Wet flow rate

ln[(Ci-Ceq)/(Co- Ceq)]/g cat 

Initial Activity

Exposed to air at 230° for 16 hrs.

Exposed to air at 550°C for 16 hrs.

Figure 4. Catalyst retains high activity even after

exposure to air at 550°C for 16 h.

7.38

0.2

0.5

1.0

1.9

7.39

7.1

4.9

2.2

2.2

0.010.00.00.00.1

0

10

20

30

40

Reactant

Comp.

231 280 340 401

Reactor Temp. (°C)

Product Composition

 (% on wet basis)

CO Equil. CO H2 CO2 CH4

Figure 5. The Argonne catalyst is active from 230°C to

400°C, the range covered by the commercial

HTS and LTS catalysts.

approaches the equilibrium CO concentration at

higher temperatures, reaching nearly the equilibrium

value at 401°C.

The catalysts discussed above were in powder

form and were made by the glycine nitrate or like

processes. We have also successfully supported the

catalyst on high-surface-area γ-alumina, making the

catalyst form more rugged while simultaneously

reducing the net Pt loading (see Figure 6).

Fabrication of the supported catalyst has been

reproducibly scaled up to 2-kg batch sizes.

The Argonne catalyst can reduce the shift

reactor volumes significantly, if the reactor can be

designed to exploit the high intrinsic activity of the

catalyst (i.e., to operate with no diffusion

limitations). Table 2 shows a comparison of the

calculated shift reactor volumes for the commercial

HTS and LTS catalysts, as well as for the Argonne

catalyst, used at the two distinct temperatures shown

in the table. The calculated reactor volumes were
Fuel Cells for Transportation FY 1999 Progress Report

66

0

400

800

1200

1600

2000

2400

2800

0 20 40 60 80 100 120 140 160

1/Wet flow rate (min/mol)

ln[(Ci-Ceq)/(Co-Ceq)]/L Cat

Powder, 19 m2/g

55.4 wt% on Al2O3

50.5 wt% on Al2O3

0.34 wt% Pt, 124 m2/g

Figure 6. Catalyst retained high activity when supported

on γ-alumina, even with reduced Pt loading.

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 Table 2, 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-

kW fuel cell system. In comparison, with the

Argonne catalyst operated at 400°C and 300°C, the

total required catalyst volume is 13.5 L, amounting

to a 30% reduction.

Table 2. The Argonne catalyst can reduce shift reactor

volumes significantly.

Commercial

Catalyst

Argonne

Catalyst

HTS LTS HTS LTS

Tin, °C 400 200 400 300

Tout, °C 455 227 455 327

COin, % 11.4 4.3 11.4 4.3

COout, % 4.3 1.0 4.3 1.0

Vol., L 5.5 13.7 0.8 12.7

Total, L 19.2 13.5

Accomplishments

• Kinetic parameters have been determined for the

Argonne catalyst to enable reactor design and

analysis.

• Preliminary reactor sizing calculations show that

significant reductions in reactor volumes may be

achievable with the Argonne catalyst.

• Tolerance of the Argonne catalyst to air and to

high temperatures in air has been verified.

• The catalyst has been supported on high-surfacearea γ-alumina to reduce platinum loading while

maintaining high activity.
Fuel Cells for Transportation FY 1999 Progress Report

67

IV. FUEL CELL STACK SUBSYSTEM

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

Fuel Cell Stack System

Tim Rehg (Primary Contact) and Nguyen Minh (Program Manager)

AlliedSignal Aerospace Equipment Systems

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

Torrance, CA 90504-6099

(310) 512-2281, fax: (310) 512-3432, e-mail: Tim.Rehg@AlliedSignal.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: AlliedSignal Aerospace Equipment Systems, Torrance, California

Prime Contract No. DE-FC02-97EE50470, October 1997-December 1999

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 Epyx Corporation.

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 iteratively conducted 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 CO tolerance.

- PEM stack R&D to advance technologies toward 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.
Fuel Cells for Transportation National Laboratory Annual Progress Report

68

Accomplishments

• Demonstrated two feasible concepts for CO management on a laboratory scale, based on regenerable adsorption

bed techniques.

• Characterized a new anode electrocatalyst.

• Demonstrated CO tolerance and MEA performance to meet second 10-kW stack objectives.

• Demonstrated 28 days of stable performance with coated aluminum bipolar plates.

• Upgraded stack system testbed with a reformate simulator.

• The first 10-kW-class stack has been built and tested. This 130-cell stack produced 18 kW on hydrogen/air and

15 kW on 10-ppm CO gasoline reformate/air.

• A 73-cell stack was subjected to a 100-hour life test, running continuously on CO-containing reformate.

• Completed the conceptual system design for a 50-kW fuel cell stack system.

• 50-kW brassboard system design is in process. Component performances have been specified, and major

component procurement has begun.

• 50-kW brassboard controls/interfaces work has begun. Dynamic transient data are being collected, and dynamic

simulation is under way.

• The stack engineering design and component procurement have been completed for the second 10-kW subscale

PEM fuel cell stack.

Fuel Cell Stack System

(excludes fuel processing/delivery system)

(includes fuel cell ancillaries: i.e., heat, water, air management systems)

Characteristic Status DOE Technical Target

Peak Power (kW) 50 50

Stack System Efficiency @ 25% Power (%) 44-55 55

Stack System Efficiency @ Peak Power (%) 45-52 44

Power Density (W/L) 282-322 350

Specific Power (W/kg) 295-430 350

Precious Metal Loading (g/kW) 0.9-2.6 0.9

Future Directions

• The second 10-kW-class PEM stack build and test is scheduled for September 1999.

• Brassboard 50-kW net PEM fuel cell stack system to be delivered to Argonne National Laboratory at the

conclusion of the project.

• Continue collaboration with Argonne National Laboratory 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 500,000 units/yr).

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 that of the ICE. Meeting these

requirements is a significant technical challenge that

requires an integrated systems approach. This effort

encompasses the technical and developmental

activities required to incorporate innovations
Fuel Cells for Transportation FY 1999 Progress Report

69

necessary to develop a 50-kW fuel cell stack system

to meet the requirements set forth by the DOE. In

this reporting period, AlliedSignal is progressing

from Phase I to Phase II of the program.

System Analysis

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.

A conceptual system design for a 50-kW fuel

cell stack system has been completed (Figure 2),

using ASPEN PLUS and internally developed

AlliedSignal modeling tools.

Both pressurized and near-ambient systems have

been evaluated. The analysis revealed that a nearambient system will require a stack with ~200%

more electrochemically active surface area than that

of a stack in a pressurized system to simultaneously

meet the power and efficiency goals. Consequently,

AlliedSignal has adopted a pressurized system for

the brassboard.

The 50-kW brassboard system design is

currently in process. Component performances have

been specified, and major component procurement

has begun. Dynamic transient data are being

collected, and dynamic simulation is under way to

support the controls/interfaces work.

FUEL PROCESSOR

AIR

MANAGEMENT

PEM

FUEL CELL

STACK

CAOG

ANOG

AIRFP

FUEL ANIN

AIR

FUELCMB

AIRFC

T1EX

AIRBLEED

CNDFP

CAIN

CLIN

WATER AND THERMAL

MANAGEMENT

CLEX

CLEXA

1OL

CAEX

ANEX

AIRCND

AIR WH

EXHSTV

AIRCND

AIR WH

FUELFP

Figure 1. PEM FC stack system diagram.

Figure 2. Conceptual system design, preliminary

package.

Stack Technology Development

Our technology development efforts are divided into

the areas of CO management technology

development, MEA technology development, and

stack technology development. The CO management

technology development has been transitioned to a

separate DOE contract, described elsewhere in this

report (see III G).

In the area of MEA technology development, we

have characterized a new anode electrocatalyst and

demonstrated long-term (200+ hours) stability of

cell performance with an improved gas diffusion

layer (GDL). We have also demonstrated (Figure 3)

that our cells can tolerate 100 ppm CO

contamination without appreciable performance loss.

A variety of materials are under investigation in

our work on low-cost, advanced bipolar plate

materials. Among these are coated metals and

conductive composites.

A coated aluminum bipolar plate has been tested

for 28 days of continuous operation with no

observable loss in performance (Figure 4). Fuel cell

testing of full-size coated aluminum plates is in

progress. We also plan to use conducting composite

bipolar plates in our upcoming second 10-kW stack

build.

The first 10-kW stack has been built and tested

(Figure 5). This stack gave a specific power of 0.69

kW/kg and a power density of 1.32 kW/L.

The stack engineering design and component

procurement have been completed for the second

10-kW subscale PEM fuel cell stack (Figure 6).
Fuel Cells for Transportation National Laboratory Annual Progress Report

70

Figure 3. Effect of air bleed on CO poisoning.

Figure 4. Coated aluminum bipolar plate performance

following 28 days of operation.

Figure 5. First 10-kW-class stack.

Figure 6. 10-kW stack designs. Comparison of Stack 1

(left) and Stack 2 (right) designs.

Improvements for this second stack build will

include a new flowfield with lower stoichiometry

capability, conducting composite bipolar plates, 13%

increase in active cell area, and substantial

improvements in stack weight, volume, and

manufacturability.

Conceptual studies on a next-generation stack

have also begun.
Fuel Cells for Transportation FY 1999 Progress Report

71

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

Design for Operation on Reformate Used in Vehicle Power Systems

Jay Neutzler (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: neutzler@energypartners.org

DOE Program Manager: Donna Ho

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

ANL Technical Advisor: William Swift

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

Contractor: Energy Partners, L.C., West Palm Beach, Florida

Prime Contract No. DE-FC02-97EE50476, September 30, 1997-December 31,1999

Objectives

• Develop low-cost bipolar collector plates through improvements in materials and processes.

• Evaluate and optimize MEA configurations with enhanced CO tolerance and low platinum loading.

• Achieve stable and usable performance with steady-state CO levels of 10 ppm and transient levels of 100 ppm.

• Attain 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.

• Integrate and demonstrate a small-scale fuel processor/PROX/fuel cell power system.

• 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 PEM ten-cell stack with reformate capability and ten additional

bipolar plates manufactured by the compression molding process.

• Phase II: Demonstration of a high-efficiency, reformate-tolerant 50-kWnet fuel cell stack subsystem utilizing

injection-molded bipolar plates (with compression-molded plates as an alternative), excluding power

conditioning and fuel processor. Delivery to Argonne National Laboratory for independent testing and

verification.

Accomplishments

• Bipolar plates

- Completed compression-molding development for high performance:

- Achieved high performance, low cost (< $10/kW) with new injection molding of advanced

molded composite bipolar plates, 100% recyclable, with < 20-sec cycle time/part/machine on

232-cm

2

 plates.
Fuel Cells for Transportation National Laboratory Annual Progress Report

72

• Demonstrated hydrogen and reformate fuel cell stack performance:

- Scale-up of 50-kWnet automotive reformate design Model NG3000, comparable to previous

20-kWgross Model NG2000.

- Completed over 1000 hours of endurance testing.

- Freeze-tolerant testing with coolant temperature down to negative 10°C.

- “Road- tested” 20-kW Model NG2000 (hydrogen FC stack), concluding with Virginia Polytechnic

Institute and State University placing second in the “FutureCar Challenge.”

• Acquired fuel processors and gas cleanup units for subscale system analysis and integration:

- Epyx POX fuel processor rated at 45 kWth on natural gas

- Johnson Matthey fuel processor rated at 5,000 L/h hydrogen production on methanol

- Los Alamos National Laboratory preferential oxidation unit

- Johnson Matthey Demonox gas cleanup unit (integrated with fuel processor)

• System optimization and analysis:

- Trade-off studies to increase efficiency of performance at temperature extremes.

- Reduced componentry with thermally integrated system approach.

- Water balance achievable.

Fuel Cell Stack System

(excludes fuel processing/delivery system)

(includes fuel cell ancillaries: i.e., heat, water, air management systems)

Characteristic Status DOE Technical Target

Peak Power (kW) 50 50

Stack System Efficiency @ 25% Power (%) 55-57 55

Stack System Efficiency @ Peak Power (%) 44-50 44

Power Density (W/L) 350 (predicted) 350

Specific Power (W/kg) 350 (predicted) 350

Precious Metal Loading (g/kW) 1.17 0.9

Future Directions

• Continue evaluations of new MEA materials for reformate performance.

• Injection mold large-scale blank bipolar plates (1000 cm2).

• Injection mold net-shaped bipolar plates with all features (500 cm2).

• Deliver reformate-tolerant 10-cell stack.

• Finish fabrication, assembly, controls, and testing of 50-kWnet stack subsystem 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

focuses on a systems approach, broken down into

three discrete areas: bipolar collector plates, PEM

fuel cell stack, and integrated system analysis.

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 uses compression-molded

graphite composite plates in all of its fuel cell stacks.

Given the advances made in fillers, binders, and

processes, these plates have properties comparable
Fuel Cells for Transportation FY 1999 Progress Report

73

to those of pure graphite, with the exception of

somewhat lower conductance. However, because of

its long processing time and high energy

consumption, compression molding is not suitable

for automotive-style mass production.

Energy Partners is developing the materials and

processes suitable for injection molding (patents

pending). After computer simulations have shown

the feasibility of this concept, we have injectionmolded several samples of blank plates as well as a

sample with channels embossed on its surface.

Figure 1 illustrates a 500-cm2 compression-molded

plate (lower), a 232-cm2 injection-molded plate

(left), and a sample of injection-molded flow

channels (right and upper left insert).

Preliminary results are very encouraging. A part

can be produced in less than 20 seconds (as

compared to 40 minutes required for compression

molding). Conductivity of the injection-molded

plates is somewhat lower than that of compressionmolded plates, but still within the DOE

specifications. Table 1 presents the bipolar plate

status with comparison to the DOE requirements.

We were able to produce intricate features (array of

channels) with both compression- and injectionmolding techniques, while keeping flatness and

parallelism within the tolerances. Advanced

composites, processes, and equipment have the

potential to yield improvements in time/equipment,

Figure 1. Compression- and injection-molded bipolar

plates.

Table 1. Bipolar plate status and properties.

Plate Property

Compression

(complete)

Injection

(in progress) DOE Specs.

Bulk >320 S/cm >110 S/cm > 100 S/cm

conductivity 4-point probe method

<30 mΩ-cm2<50 mΩ-cm2Surface

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-sec

<< 2 x 10 –6

cm3/cm2-sec

< 2 x 10 –6

cm3/cm2-sec

Crush strength ~14,000 psi >8,000 psi None

Flexibility

(modulus)

1.35 x 106psi >1 x 106psi None

Flexural

strength

6,000-6,500

psi

6,500-9,000 psi None

Material cost ~$7.5/kW ~$7.5/kW None

Estimated

manu-factured

cost

$146/kW <$10/kW $10 /kW

Production

cycle time

< 40 min < 20 sec None

Recyclability No 100% None

Durability

@ 60oC

>5,000 h >5,000 h None

Dimensions:

 Total plate

 Active area

 Thickness

 Weight

In Production

500 cm2

300 cm2

<3.0 mm

~ 7 oz

Development

232 cm2

150 cm2 

<3.0 mm

< 3 oz

None

Material

density

2.0-2.2 g/cm31.95-2.0 g/cm3 None

cost, durability, dimensional stability, and

recyclability without sacrificing performance.

PEM Fuel Cell Stack

For the past year, the focus has been on

evaluating short fuel cell stacks and full-scale stacks,

addressing performance and system integration

issues. The program baseline is the advanced

hydrogen PEM fuel cell stack NG2000, rated at 20

kWgross. It now has a reformate-tolerant equivalent

(NG2000R). The new NG3000 is designed

specifically for reformate, with automotive design

criteria specified by the program (50 kWnet); it has a

larger active area (594 cm2) and manifolds designed

for the flows required. Testing has shown the

performance of the NG2000 and NG3000 designs to

be comparable (Figure 2).

Both of these designs are flexible, ranging from

2 to 250 cells. They operate between 0.2 to 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 over 1000 hours on

a 10-cell stack. Figure 3 shows that at a steady state,

the stack voltage declines over a period of time

(dotted lines). However, this is recoverable by
Fuel Cells for Transportation National Laboratory Annual Progress Report

74

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 2. Comparison of NG2000 and NG3000 stacks

on hydrogen and on reformate.

0 

2 

4 

6 

8 

10 

stack potential (V)

0 200 400 600 800 1000 1200 

operating hours

Figure 3. Durability of 10-cell stack @0.80 A/cm2 at

60°C and 100% humidification on H2/air.

simply running a polarization curve (or “exercising”

the cell).

In keeping with DOE goals, to prove automotive

design concepts on actual hardware, freeze-tolerance

testing was performed by reducing the stack liquid

coolant temperature down to negative 10°C. The

polarization curves, illustrated in Figure 4, show

performance when held for 15 minutes at each

temperature. The stack was held at negative 10°C

for approximately one hour while operating. This

preliminary test shows excellent response, which

facilitated further systems analysis.

Further understanding and concepts were gained

through the “FutureCar Challenge” program with

Virginia Polytechnic Institute & State University

and Texas Tech University (Figure 5). Virgina Tech

placed second in the 1999 competition.

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)

Performance Curve: Freeze Tolerant

Test

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.(ohms-cm2):.

Current Density(mA/cm2):

60 C 50 C 40 C 30 C 20 C 10 C 5 C 0 C -10 C

Figure 4. Freeze tolerance performance on H2/air at

1.2/2.0 stoich.

Figure 5. NG2000 stack installed in Virginia Tech’s

competition vehicle (Chevy Lumina).

Small-Scale Fuel Processors

Energy Partners has completed over 100 hours

of Epyx POX fuel processor testing without any

significant drops in performance or efficiency.

Operation has been performed at various power

levels, from 6 kWth to 45 kWth. A summary of

reformate compositions on a dry basis at different

operating conditions is presented in Table 2. The

thermal output is based on the lower heating value

(LHV) of methane. The reformate compositions are

presented in volume percent.

Table 2. Reformate composition from Epyx fuel

processor (vol%).

kWth H2 CO2 O2 N2 CH4 CO*

20 38.2 12.9 0.24 44.3 1.27 2.04

25 40.9 14.2 0.30 41.8 0.67 1.52

30 41.2 14.2 0.18 42.3 0.09 1.92

40 41.9 13.2 0.29 41.3 0.11 2.36

45 40.7 11.9 0.31 42.2 0.96 2.10

* CO concentration before LTS reactor.
Fuel Cells for Transportation FY 1999 Progress Report

75

Currently, over 50 hours of testing have been

conducted on the Epyx fuel processor and the Los

Alamos National Laboratory PROX integrated

system. Energy Partners has been working closely

with Epyx and LANL to reduce the carbon

monoxide (CO) concentration to levels below

100 ppm. LANL modified and installed a lowtemperature-shift (LTS) reactor into the first stage of

the PROX. With the modifications, the PROX was

able to operate comfortably with the oxygen

stoichiometric ratio well below 3 (~2.7), as

illustrated in Figure 6. This leads to very little

hydrogen being burned in the PROX. An analysis of

reformate at the inlet and outlet of the PROX

showed less than 2% of the hydrogen-in was

oxidized in the PROX. A photograph of the Epyx

fuel processor and LANL PROX integrated test

stand is shown in Figure 7.

0

100

200

300

400

500

600

700

800

900

1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3

Oxygen Stoichiometric ratio

CO at Prox outlet, ppm

Power: 30 kWth

CO at Prox inlet: 1.85%

Figure 6. CO concentration at PROX outlet.

Figure 7. Epyx fuel processor and LANL PROX.

In addition to subscale testing of the natural gas

fuel processor from Epyx, testing of a methanol fuel

processor from Johnson Matthey was also conducted

at Energy Partners over the past year. Currently,

over 60 hours of durability testing have been

performed without a significant drop in

performance. The Demonox gas cleanup unit,

developed by Johnson Matthey, performed

flawlessly — virtually no CO was detected during

steady operations. CO levels of less than 10 ppm

were detected during transient operations.

Integrated System Analysis

Over a thousand simulations were conducted,

using various system configurations and operating

conditions. Optimization included such factors as

operating pressure, which affects system power

density; achieving a zero system water balance;

resolving thermal dissipation needs; and maximizing

system controls and integration and overall system

efficiency. Simulation information

was exchanged with Arthur D. Little, and realistic

values of the compressor-expander efficiency were

used in the simulation to estimate net fuel cell

system efficiency. Based on DOE-PRDA efficiency

targets, the maximum allowable parasitic power

consumption (radiator fan, pumps, etc.) was

estimated from simulations and components were

subsequently identified, resulting in a fuel cell

system exceeding DOE performance goals, as shown

in Table 3.

Table 3. Energy Partners’ status vs. DOE program goals.

Characteristic EP Status (7/99) DOE Goals

System efficiency

 @50 kWnet (wo/FP)

 @12.5 kWnet (wo/FP)

44-50%

55-57%

>=44%

>=55%

Net power density 350 W/l (est.) 350 W/l

Net specific power 350 W/kg (est.) 350 W/kg

Cost ($) <100/kW (est.) 100/kW

Durability >1000 h 2000 h

Emissions <<Tier 2 <<Tier 2

Transient performance

(10% to 90%)

~0 s 3 s

Precious metal loading

(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
Fuel Cells for Transportation National Laboratory Annual Progress Report

76

Operating conditions were optimized to result in

the smallest heat-exchanger equipment size while

maintaining water balance. The resulting system is

shown in Figure 8. A control strategy has been

developed to maintain neutral water balance over the

entire system operating range (kW) and under

different ambient conditions (patent pending).

Simplified humidification techniques based on

optimized thermal integration (from simulations) are

being verified experimentally.

Rapid start-up from an extreme ambient

temperature of -40oC is possible under Energy

Partners’ system design. As shown in Figure 9, the

system is almost up to full power in 2-3 minutes.

Experimental results from freeze-tolerance tests

(explained earlier) were used in the simulations. The

quick start-up feature is the result of optimum

utilization of feed gas thermal energy and fuel cell

stack thermal dissipation (patent pending).

Figure 8. Resulting 50-kWnet automotive system.

0

10

20

30

40

50

60

0 1 2 3 4 5 6 7

Time (min)

FC Gross Power (kW)

-40

-23.33

-6.66

10.01

26.68

43.35

FC Stack Temperature (C)

Figure 9. Cold start-up simulated response of Energy

Partners' 50-kWnet system.

Conclusion

Energy Partners is developing an automotive

fuel cell power system that will meet the DOE

performance goals. Significant progress has been

made in 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:

F. Barbir, B. Balasubramanian, and J. Neutzler,

Trade-off Design Study of Operating Pressure and

Temperature in PEM Fuel Cell Systems, Symp. on

Thermodynamics and the Design, Analysis and

Optimization of Energy Systems, ASME Winter

Annual Meeting, Nashville, Tenn., Nov. 1999.

F. Barbir, B. Balasubramanian, and J. Neutzler,

Optimal Operating Temperature and Pressure in

PEM Fuel Cell Systems in Automotive Applications,

accepted for the 218th National Meeting of the

American Chemical Society, New Orleans, La.,

Aug. 1999.

F. Barbir, J. Braun, and J. Neutzler, Properties of

Molded Graphite Bi-Polar Plates for PEM Fuel

Cells, presented at the 3rd International Symposium

on New Materials for Electrochemical Systems,

Montreal, Canada, July 1999.

F. Barbir, J. Braun, and J. Neutzler, Effect of

Collector Plate Resistance on Fuel Cell Stack

Performance, in Proton Conduction Membrane Fuel

Cells II, S. Gottesfeld and T.F. Fuller (eds.), Proc.

Vol. 98-27, pp. 400-406, The Electrochemical

Society, Pennington, N.J., 1999.

V. Gurau, F. Barbir, and H. Liu, TwoDimensional Model for the Entire PEM Fuel Cell

Sandwich, in Proton Conduction Membrane Fuel

Cells II, S. Gottesfeld and T.F. Fuller (eds.), Proc.

Vol. 98-27, pp. 479-503, The Electrochemical

Society, Pennington, N.J., 1999.

F. Barbir, J. Neutzler, W. Pierce, and B. Wynne,

Development and Testing of High Performing PEM

Fuel Cell Stack, Proc. 1998 Fuel Cell Seminar, Palm

Springs, Calif., pp. 718-721, 1998.

F. Barbir, Trade-offs in Ambient/Pressurized

PEM Fuel Cell Systems, presented at the SAE Fuel

Cells for Transportation TOPTEC, Cambridge,

Mass., March 1998.
Fuel Cells for Transportation FY 1999 Progress Report

77

J. Braun, M. Fuchs, J. Neutzler, and R. Ross,

Development of Bipolar Collector Plates for Mass

Production PEM Fuel Cells, presented at the SAE

Fuel Cells for Transportation TOPTEC, Cambridge,

Mass., March 1998.

C. Direct Methanol Fuel Cells

Piotr Zelenay, Xiaoming Ren, Sharon Thomas, Huyen Dinh, John Davey, and Shimshon Gottesfeld

(Primary Contact)

Los Alamos National Laboratory, Los Alamos, NM 87545

(505) 667-6832, fax: (505) 665-4292

DOE Program Manager: JoAnn Milliken

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

Objectives

Develop materials, components, and operating conditions for direct methanol fuel cells (DMFCs) that would prove

the potential of DMFCs for transportation applications in terms of power density, energy conversion efficiency, and

cost. Specifically,

• Continue to optimize anode catalyst layers to enhance cell performance;

• Prove that low fuel utilization can be resolved with combination of ionomeric membrane of good protonic

conductivity and optimized stack operation conditions; and

• Prove stability of all cell components – primarily anode catalyst – in longer-term operation under these

combined requirements.

OAAT R&D Plan: Task 14; Barriers B, F, H, and I

Approach

• Operate DMFC cells and stacks near 100°C with a variety of membrane/electrode assemblies, 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 short stacks operating near 100°C.

Accomplishments

• Five-cell methanol/air LANL stack, originally built by LANL for portable power applications (with DARPA’s

support), was reconfigured to operate at 100°C and 30 psig air, generating power density on the order of 1 kW

per liter of active stack volume.

• Fuel utilization near 90% was demonstrated in the five-cell DMFC stack at the expected design point of 0.45V.

Future Directions

• Further lowering of precious catalyst loading.

• Possible (budget permitting) scale-up of stack to the 0.5-1.0 kW level.
Fuel Cells for Transportation National Laboratory Annual Progress Report

78

The objective of the direct methanol fuel cell

effort at LANL, sponsored by DOE/OAAT, has been

to develop materials, components, and operating

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 has the

potential to offer 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 vehicle, and

good potential for zero-emission vehicle (ZEV)

characteristics.

In our work this year, we have focused on the

first demonstration of a DMFC short stack, based on

LANL unique stack hardware, operating near 100°C

on methanol and (30-psig) air. Our demonstrated

five-cell stack (45 cm

2

 active area), shown in

Figure 1, had a pitch of only 1.8 mm per cell, at the

same time allowing operation with pressure drops

across the stack as low as a few inches of water.

Figure 2 demonstrates the performance achieved

Figure 1. Five-cell DMFC stack, built this year utilizing

novel LANL hardware that enabled, together

with optimized MEAs, achievement of

maximum power output of 1 kW per liter o f

active stack volume.

Current Density (A cm-2)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Stack Voltage (V)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Power Density (kW L-1

)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Figure 2. Five-cell DMFC stack: methanol/air

performance at 100°C (active area 45 cm2, cell

width 1.8 mm).

from that five-cell stack in terms of voltage-current

and power-current characteristics. Maximum power

generated by the stack under these conditions was

50 W. The active part of the stack volume was close

to 40 cm

3

; thus, maximum power density exceeded

1 W cm

-3

, or 1 kW L-1. This is certainly a

respectable level, reaching an order of power density

similar to those achieved from reformate/air PEM

fuel cell stacks.

Table 1 highlights the other highly important

feature we have demonstrated for this small DMFC

stack. The table provides details of methanol massbalance measurements performed for the stack in

operation at 0.45 V per cell. In contrast to a

prevailing perception that fuel utilization in DMFCs

is low (because of significant methanol crossover

through the membrane electrolyte), Table 1 reveals

methanol utilization of 82% with an anode feed of

1 M methanol, and as high as 99% (5% error bar)

when the methanol feed concentration is lowered to

0.75 M. This high fuel utilization was achieved by

optimizing electrode structure, rather than by any

significant membrane modification. Therefore, high

fuel utilization can be reached in DMFC stacks even

before development of alternative membrane

technology. This is an important insight regarding

prospects and the potential time line for

demonstrating and implementing DMFC technology

in transportation applications, where energy

conversion efficiency is of prime significance.

Finally, to address the issue of cost, this year we

have further pursued the target of lowering catalyst

loading in DMFCs while maintaining performance.

Figure 3 illustrates results obtained with relatively
Fuel Cells for Transportation FY 1999 Progress Report

79

Table 1. Fuel utilization, i.e., (cell current)/(cell current + crossover current), derived from a detailed methanol balance

in a LANL five-cell methanol/air stack. (The table shows that, in this stack, which utilized a commercially

available ionomeric membrane, fuel efficiencies as high as 99% could be achieved when operating at 0.45 V

per cell. The high fuel utilization is achieved with appropriate electrode design.)

CFEED

(M)

CEXHAUST

*

(M)

MFEED

(μmole s-1)

MEXHAUST

(μmole s-1)

MOX

(μmole s-1)

MX-OVER

(μmole s-1)

IX-OVER

(A cm-2)

ε

(%)

0.75 0.57 385.5 234.0 150.9 0.6 0.002 99±5

1.00 0.79 522.8 334.3 154.0 34.5 0.089 82±4

* Determined in the electrochemical crossover measurement in a separate cell.

Current Density (A cm-2)

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Voltage (V)

0.0

0.2

0.4

0.6

0.8

~60%Pt / ~40%Ru (A-16, 2.1 mg Pt/cm2)

37%Pt / 18%Ru / 45%C (A-"C", 1.2 mg Pt/cm 2)

30%Pt / 24%Ru / 46%C (T-1, 2.0 mg Pt/cm 2)

19%Pt / 14%Ru / 67%C (T-2, 2.0 mg Pt/cm 2)

100°C

Current Density (A cm-2)

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Power Density (W cm -2

)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

100°C

Figure 3. Voltage–current and power–current plots for single cell DMFCs utilizing lower Pt loading. The best DMFC

result obtained this year with our MEAs was 5 mgPt W-1 (5 gPt kW-1), at 100°C, for operation on

methanol/water feed to the anode and 30 psig air to the cathode.

low loading of Pt. The highest effective catalyst

activity demonstrated was 5 mg Pt W-1 (5 g Pt kW-1),

counting the total loading in the cell (i.e., anode +

cathode Pt loading). This is better by a factor of two

than our demonstrated catalyst activity in DMFCs

last year and thus constitutes a further step toward

lowering the DMFC catalyst cost. In our estimate,

the state of the art can be roughly summarized as a

ratio of about 3 between DMFC loading and (overall

system) reformate/air precious metal loading. While

certainly significant, and a target for further effort,

this gap in precious metal loadings is smaller than is

usually perceived.

The technical achievement of the DOE/OAATsponsored efforts at LANL, targeting potential

transportation applications of DMFCs, is substantial.

On the basis of short stack results, in terms of power

density and energy conversion efficiency, the DMFC

is today comparable with an on-board methanol

reforming system. There is a remaining gap in

precious-metal catalyst demand, with the DMFC

requiring 5 g Pt kW-1vs. about 2 g Pt kW-1 needed

today for an on-board reforming system. However,

we believe that this gap can be narrowed, and we

will devote a significant part of our DMFC effort in

FY 2000 to this goal. Our effort will focus on

further optimization for higher-temperature cell

operation and further anode catalyst work. We also

plan, budget permitting, to extend our DMFC work

in FY 1999 to fabrication and testing of stacks in the

range of 0.5-1 kW, operating near 100°C.
Fuel Cells for Transportation National Laboratory Annual Progress Report

80

D. Efficient Fuel Cell Systems

Mahlon S. Wilson, Steffen Moeller-Holst, Daniel M. Webb, and Christine Zawodzinski

Materials Science and Technology Division, MST-11, MS D429,

Los Alamos National Laboratory, Los Alamos, NM 87545

(505) 667-6832, fax: (505) 665-4292, e-mail: mahlon@lanl.go

DOE Program Manager: JoAnn Milliken

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

Objectives

• Develop a high-performance, simple, low-parasitic-power, low-cost fuel cell system.

OAAT R&D Plan: Task 13; Barriers B, C

Approach

• Utilize direct liquid water hydration of the membrane electrode assemblies (MEAs).

• Operate the cathodes at near-ambient pressures to minimize parasitic power losses.

• Operate the stack in an “adiabatic” configuration.

Accomplishments

• Designed new 300-cm2 active-area cell hardware to optimize operation of the “adiabatic” stack configuration.

• Scaled up to a 26-cell, 300-cm2 active-area near-ambient-pressure stack that supplies more than 1.5 kW under

nominal load.

• Demonstrated system efficiencies, using the 1.5 kW stack, that exceed 55% (LHV of hydrogen). Parasitic

power losses are only 1.4% of the stack output (does not include the fan for water recovery from the condenser,

which is expected to be approximately 1%).

• Attained stack volumetric power densities of 365 W/L (based on the area of the graphite bipolar plates and a

55% efficiency level).

Future Directions

• Refine and optimize system, stack components, and operation/control.

• Demonstrate a water self-sufficient system (incorporate condenser, etc.).

• Determine performance enhancement with sea-level operation).

• Increase power density to 500 W/L (on a bipolar plate area basis).

Historically, most fuel cell system development

efforts have emphasized the use of pressurized

reactants, primarily because of the improved

performance with the increase in the oxygen partial

pressure on the cathode. However, a relatively

powerful and sophisticated compressor is then

required to supply the pressurized air for the fuel cell

stack. To partially offset the substantial power

requirements of the compressor, an expander located

on the cathode effluent can be used to recover some

of the compression work. Even so, the parasitic

power draw on the system can be significant. For

example, a hydrogen fuel cell system with a

compressor/expander, recently demonstrated by a

major fuel cell developer, incurred parasitic power

losses of about 20%, primarily due to the 30-psig
Fuel Cells for Transportation FY 1999 Progress Report

81

compressor. Naturally, a 20% power loss

profoundly affects the overall system efficiency.

Therefore, one of our major objectives is to

operate the air-side of the fuel cell stack at nearambient pressure, because even relatively modest

pressures can result in a surprisingly high power

requirement. This is illustrated in Figure 1, which

depicts the parasitic power losses incurred with an

ideal adiabatic compressor as a function of the

cathode inlet air pressure. Even a seemingly modest

2 psig incurs a 3% loss in this example; in reality, a

loss as high as 10% might be expected because of

blower inefficiencies.

For this reason, it is desirable to operate at air

pressures of only several inches of water. This

precludes the ability to humidify the air before the

fuel cell stack, because of the additional pressure

drop due to a humidification module and an air flowfield design that can tolerate two-phase flow.

However, introducing dry air to the fuel cell stack

requires the use of an alternative membrane

humidification scheme; here, we adapt a method that

was developed previously in this program to directly

humidify the fuel cell membrane electrode assembly

(MEA) with liquid water.1 The humidification is

accomplished by the introduction of an anode

wicking backing that conveys liquid water in the

anode flow-field plenum directly to the membrane,

as depicted in Figure 2.

The technique of using direct liquid hydration of

the MEAs has a number of advantages for a simple,

low-cost fuel cell system; it utilizes “ordinary”

MEAs and bipolar plate technologies and eliminates

0

2

4

6

8

10

0 1 2 3 4 5 6 7

Conditions: 

0.7 V/cell, 

3 x Stoich. Airflow 

(33% utilization)

Compressor Power / Stack Power (%)

Cathode Pressure (psig)

Adiabatic Comp

Figure 1. Contribution of an ideal adiabatic compressor

to the parasitic power loss as a function of

cathode inlet pressure.

CATALYZED 

MEMBRANE 

(MEA)

HYDROPHOBIC 

GAS DIFFUSION 

BACKINGS

ANODE 

SIDE

H2 CATHODE 

SIDE

HYDROPHILIC 

WICKING 

THREAD

O 2

H2O

GAS FLOW 

CHANNELS

Wicking X-sec

WATER 

CHANNELS

Figure 2. Schematic depicting the use of an anode

wicking backing to convey water from the

anode flow-field directly to the MEA.

the need for a number of auxiliary components. The

approach supplies liquid water to all regions of the

MEA to improve performance at higher stack

temperatures and/or at lower cathode air pressures.

Direct liquid hydration also separates the functions

of gas supply and membrane hydration, which

substantially simplifies the overall system as well as

its control. The fine wicking threads are simply

sewn into a conventional hydrophobic carbon cloth

backing, using a computer controlled embroidery

machine to accurately place the wicking thread in

the desired configuration.

One benefit of operating a well-humidified fuel

cell stack with a dry, cool cathode air inlet is that the

airstream becomes heated and water vapor becomes

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. Evaporation is a very effective heat-transfer

mechanism, and the waste heat is transferred to the

air as generated and where generated. Since the air

inlet is at room temperature and the effluent is at

60-70°C, 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 the stack,

thereby preventing condensation from occurring

within the flow-field channels. This general scheme

of nonisothermal operation with in situ evaporative

cooling has been appropriately described as an

“adiabatic” stack in Argonne National Laboratory’s

system modeling efforts.
Fuel Cells for Transportation National Laboratory Annual Progress Report

82

This past year, 300-cm2 active area cells were

designed for an adiabatic stack based on 6" × 10.5"

graphite bipolar plates. New design features were a

narrower active area and external manifolding of the

reactants. The narrower width decreases the span

between tie-bolts, and hence the deflection of the

endplates, while also providing shorter cathode

channels. Externally manifolding the reactant

supply simplifies plate design and fabrication, as

well as sealing and alignment.

A number of single cells were assembled and

tested in an effort to optimize performance. Of

paramount interest was obtaining a cathode-side

pressure drop of about 4" H2O at three times

stoichiometric air flow. At much less pressure, the

air supply did not appear to be uniform, but at much

more the airflow through the anticipated 1.5-kW

stack would not be sufficient with the 12-V blowers

we had on hand. Naturally, a single cell would not

heat up as much as a stack; nonetheless, it was

desirable to optimize around realistic stack

temperatures. To compensate, the end plates were

heated to 60 or 70°C, although the temperature

profile would undoubtedly be different than that

which would be attained in the midst of a stack. A

configuration was settled upon that provided the

target 300 mA/cm2 at 0.7 V/cell and three times

stoichiometric air flow at 4" H2O for the single cell.

Cell resistances were about 0.13 Ω-cm

2

.

A 26-cell stack was assembled using this plate

design. A small 12-V diaphragm pump was used to

supply the hydration water to the anode side of the

stack, and a slightly larger version was used to

recirculate the hydrogen to flush out accumulated

water. A picture of the system is provided in

Figure 3. Shown are all of the relevant components:

stack, blower, water trap/reservoir, and hydrogen

and water pumps. Manifold pressures were higher

than anticipated from the single-cell results, even

Adiabatic

STACK

BLOWER

Hydrogen

Pump

Water

Pump

Water Trap/

Reservoir

Figure 3. Components of the 1.5-kW adiabatic stack fuel

cell system.

though adequate compression of the stack was not

achieved, as indicated by hydrogen leakage from the

plates and cell resistances that were about 0.02 Ωcm

2 too high. Nevertheless, the stack was operated

sufficiently long for some degree of break-in.

A data set obtained at that point indicated a stack

voltage of 17.41 V (0.67 V/cell, or a voltage

efficiency of 57% based on LHV of hydrogen) and a

current of 87 A, for 1.51 kW gross power. The

water balance indicated that 25.5 mL/min of water

was evaporated to the air-stream, which corresponds

to about 1000 W of evaporative cooling (260 W lost

to ambient). The water-vapor-saturated effluent air

was at 61°C, which yields a stoichiometric flow of

only 2.2. The 6" H2O manifold pressure was already

at the limit of the capabilities of the blower. For

whatever reason, the pressure drop was higher than

anticipated by the single-cell work, so we could not

attain the target 3X stoichiometric flow.

Nevertheless, since our parasitic power load for the

blower and hydrogen and water pumps was only

21.6 W (1.43% parasitic power), the system

efficiency still met the target of 55% (LHV) while

providing a net system power of 1.49 kW.

These numbers, however, do not include the

parasitic power requirements for a fan to cool a

condenser to enable water self-sufficiency. Based

on last year's effort, this would incur roughly an

additional 1 % parasitic power. Also, the hydrogen

leakage (approximately 10% of the total flow) may

have influenced the heat balance to some degree.

The specific power of the adiabatic stack at

these performance levels is about 365 W/L on a

graphite plate area basis and about 490 W/L on an

active area basis. These numbers are not

dramatically different from those attained with

pressurized systems. From a balance-of-plant

perspective, the adiabatic system would appear to

have significant cost and simplicity advantages over

a pressurized system.

The next step was to increase the compression of

the stack to eliminate the leaks and attain single-cell

resistance levels. This was achieved by retorquing

the tie-bolts while clamping the stack in a large

press. As hoped, leakage and cell resistances

dropped to the desired levels and stack performance

increased correspondingly (about 20 mV per cell),

but so did the manifold pressure, to about 10" H2O,

well beyond the desired pressure range. As a result,

the next step will be to dismantle the stack and

machine down the air-flow channels further to
Fuel Cells for Transportation FY 1999 Progress Report

83

decrease the pressure drop and allow three times

stoichiometric flow at an efficient pressure drop. It

is hoped that this will provide the 300 mA/cm2

current densities at 0.7 V/cell that would provide a

comfortable cushion to accommodate the condenser

fan parasitic power and still attain 55% net system

efficiency.

Elements of the full 1.5-kW system require

further refinement. The current stack sealing

materials are readily available but do not appear to

be the best choice. Other operating conditions need

to be investigated, and the system has not been

refined or tuned to any degree.

The purpose of operating the stack at or below

three times stoichiometric air flow is to elevate the

temperature of the water-vapor-saturated air to a

level that facilitates water recovery in a condenser.

Roughly two-thirds of the water vapor needs to be

condensed and recovered for system self-sufficiency.

Last year, we assembled a plastic flat-plate

condenser that we demonstrated to provide overall

heat-transfer coefficients and fan power

requirements similar to those of a conventional

water/air radiator for equivalent amounts of heat

transfer. Next, we need to integrate a similar flatplate condenser (last year's is too large for a 1.5-kW

stack) into the stack system in order to demonstrate

water self-sufficiency for the full system while

achieving the target system efficiency.

All of the above results were obtained in our

laboratories, which are at an altitude of 7,300 ft

above sea level (2,250 m), where the ambient

pressure is only 0.76 atm. Because of the

compounding effect of the water vapor pressure,

oxygen partial pressures within the stack can be as

much as 60% lower than at sea level. Furthermore,

blowers etc. are only about half as effective as at sea

level. As a result, determining sea-level

performance and efficiency is of interest because of

the possibly substantial improvements. The results

are also of more relevance than our high altitude

data for most potential applications.

Finally, power density is of considerable interest

for transportation applications. The simplest method

of realizing increases is by decreasing the thickness

of the bipolar plate. Currently, our web thicknesses

are rather generous. Time permitting, an interesting

exercise would be to see if about one-third thinner

plates could be used, which should push the specific

power over 500 W/L (although sea-level operation

alone may also achieve this).

Reference

1. M.S. Wilson, C. Zawodzinski, and S. Gottesfeld,

“Direct Liquid Water Hydration of Fuel Cell

Membranes,” in Proton Conducting Membrane

Fuel Cells II, Vol. 98-27, pp. 424-434, The

Electrochemical Society, 1998.
Fuel Cells for Transportation National Laboratory Annual Progress Report

84
Fuel Cells for Transportation FY 1999 Progress Report

85

V. PEM STACK COMPONENT COST REDUCTION

A. High-Performance, Low-Cost Membrane Electrode Assemblies for PEM

Fuel Cells and Integrated Pilot Manufacturing Processes

Mark K. Debe (Primary Contact) and Judith B. Hartmann

3M Co.

3M Center, Building 201-2N-19

St. Paul MN 55144-1000

(651) 736-9563, fax: (651) 737-2590, e-mail: mkdebe1@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) 252-4176, e-mail: millerj@cmt.anl.gov

Contractor: 3M Company, St. Paul, Minnesota

Subcontractor: Energy Partners, Inc., West Palm Beach, Florida

Prime Contract No. DE-FC-02-97EE50473, September 1997-December1999

DE-FC02-99EE50582 (Proposed), September 1999-December 2001

Objectives

• Demonstrate the feasibility for continuous manufacture of high-performance, high-quality membrane electrode

assemblies (MEAs) for polymer electrolyte membrane (PEM) fuel cells, based on a nontraditional catalyst

support system.

• Develop highly CO-tolerant anode catalysts based on the proprietary catalyst system.

• Develop a continuously produced, low-cost electrode backing medium with optimized properties for use with

the proprietary MEA.

• Develop a set of high-performance, matched PEM fuel cell components and integrated manufacturing processes

to facilitate high-volume, high-yield stack production (New Contract).

OAAT R&D Plan: Task 13; Barriers A and B

Approach

• Phase I (primary contractor only) had five primary areas of development:

- Demonstration of the continuous manufacturing feasibility of the nanostructured thin film support,

- Demonstration of a continuous process for Pt catalyst deposition on the nanostructured supports,

- Development of a continuous process for forming 3-layer membrane electrode assemblies with the

proprietary catalyst and commercial membranes,

- Development of new multicomponent catalyst compositions and structures for highly CO-tolerant anodes,

based on the nanostructured support, and

- Development of conductive, porous web-based electrode backing materials with optimized properties for

use with the 3-layer membrane electrode assemblies.

• Phase II consists of demonstrating scale-up potential for fabricating the CO-tolerant anode catalysts and

targeting performances of prototype manufactured MEAs in subcontractor fuel cell stacks.
Fuel Cells for Transportation FY 1999 Progress Report

86

• Phase I of the new contract will focus on the development of high-performance, matched components and pilot

manufacturing processes, building on the results of the first contract. Tasks include:

- Develop anode catalyst compositions and structures with higher reformate tolerance,

- Investigate catalyst compositions and structures to produce higher activity cathodes,

- Scale up the pilot manufacturing process for continuous fabrication of catalyst-coated membrane

assemblies,

- Develop continuously produced electrode backing media, and

- Develop integrated manufacturing processes for fabrication of membrane electrode assemblies.

• Phase II of the new contract will involve stack fabrication and testing of matched component systems, in

cooperation with the subcontractor. The primary tasks are:

- Evaluate matched component system performance in subcontractor stack tests and

- Fabricate and deliver a 10-kW stack.

Accomplishments

• Completed multiple deposition coating runs, producing over 1700 ft of proprietary catalyst support material,

which exceeded target limits for process control.

• Completed conversion of the proprietary catalyst support material to the nanostructured form on 500 m of web

material and coating with Pt.

• Demonstrated feasibility for continuous formation of 3-layer catalyst-coated membrane material, producing 15

meters with <0.7% of nontransferred catalyst and excellent down-web uniformity.

• Prepared and tested over 25 new catalyst anode compositions for CO tolerance, including a new ternary

composition with CO tolerance similar to that of PtRu.

• Completed assessment of 24 new porous conductive composite materials produced by continuous web

processing means for use as diffuser current collectors.

• Evaluated multiple membrane electrode assemblies in subcontractor prestack tests.

• Demonstrated feasibility for continuous manufacturing of optimized anode catalyst coatings on proprietary

catalyst support films.

Future Directions

• Complete Phase II of existing contract, evaluation of full-sized MEAs in subcontractor stacks.

• Work on Phase I of the new contract is expected to begin in September 1999.

Introduction

The membrane electrode assembly (MEA) is the

core component set of a PEM fuel cell stack. For

large-scale volume fabrication at the costs and

quality targets required by transportation

applications, very high yields and in-line control of

continuous processes based on cost-effective

materials will be required. The objective of this

work has been to demonstrate the feasibility of highvolume manufacturing of a novel 5-layer MEA for

PEM fuel cells, based on a proprietary thin-film

catalyst and support system. Specifically, the targets

are to demonstrate a continuous process with low

cost and high volume potential for fabrication of

MEAs with ultra-low loadings of catalyst on

commercial membranes, develop anode catalyst

compositions and structures optimized for CO

tolerance, and develop continuously produced, lowcost carbon-containing electrode backing media with

properties optimized for use with the thin-film

catalyst support. In the FY 1998 Contractors’

Program Report, the proprietary thin catalyst support

system was discussed, a batch-processed 3-layer

MEA with ultra-low (0.04 mg/cm2 total anode and

cathode) catalyst loadings was illustrated, and

polarization curves were presented that

demonstrated cathode-specific activities of the

proprietary catalyst of 150 A/mg-Pt at 0.5 V under

60 psig O2.
Fuel Cells for Transportation FY 1999 Progress Report

87

Process Scale-Up Feasibility

During the current period, the Phase I tasks were

completed that demonstrated the feasibility for

scaling up the fabrication of the proprietary thin-film

catalyst and catalyst-coated membrane as a

continuous process.

The first development task area focused on

scale-up of the nanostructured support film. Figure

1 illustrates an example of continuously coated

material prior to conversion to the nanostructured

phase. Multiple coating experiments totaling over

1700 feet of coated substrate were conducted that

met or exceeded the target thickness control of +5%

at the targeted web speeds.

Conversion of the support material in Figure 1

to the nanostructured support film phase was also

demonstrated as a continuous process by two

methods. In one method, over 1500 feet of web was

converted and the target conversion rate achieved.

Task 2 of Phase I, to demonstrate coating of the

catalyst onto the thin-film proprietary support as a

continuous process, was also concluded in this

period.

Figure 2 shows a scanning electron micrograph

of a cross-section of the continuously produced

catalyst-coated nanostructured films.

The third task of Phase I was to demonstrate

feasibility for the continuous fabrication of a

catalyst-coated membrane (CCM), using a

commercial membrane and the proprietary

nanostructured catalyst film material from the first

and second tasks. The work completed under this

Figure 1. Roll-good coated nanostructure support

material.

Figure 2. SEM cross-section of nanostructured catalyst

film.

task included five catalyst transfer experiments with

Nafion 115. Approximately 50 meters of 3-layer

CCM was produced at the target speed while

obtaining data on the catalyst transfer parameters.

Approximately 15 meters of 3-layer CCM was

produced with excellent results, with < 0.7%

untransferred catalyst. Figure 3 is a photograph of

CCM produced in the successful transfer run.

Down-web uniformity of the 3-layer CCM

shown in Figure 3 was examined by cutting 50-cm2

electrode area samples from the web at

approximately 10-ft intervals (between 5 ft and

45 ft) and measuring fuel cell performance. Figure 4

Figure 3. 3-layer catalyst-coated membrane as a rollgood.
Fuel Cells for Transportation FY 1999 Progress Report

88

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

FC983: 16'7" From End, 24% Compression

FC992: 28'5" From End, 31% Compression

FC995: 43'3" From End, 24% Compression

FC996: 4'10" From End, 25% Compression

FC1000: 5'3" From End, 27% Compression

FC1004: 24'5" From End, 25% Compression

012799_FCSUMMARY - [Graph1]

75/115/65C

30/30psig H2/O2

800/400SCCM

0.5cc/min

0.7V SP

 FC983 85.dat

 FC995 75.dat

 FC996 171.dat

 FC1000 78.dat

 FC1004 36.dat

 ###

Cell Voltage (volts)

J (amps/cm 2)

Figure 4. Fuel cell performance versus down-web

position.

shows a superposition of the potentiodynamic

polarization curves obtained from the sampling

process. The very good reproducibility of the fuel

cell performance validates the uniformity of the

continuous roll-good produced CCM.

The fourth task of Phase I of the current contract

has been directed at development of proprietary

catalysts based on nanostructured films for

optimized CO tolerance. The new type of catalyst

support and facile catalyst deposition methods allow

the obtaining of new catalyst stoichiometries and

physical structures. The ability to control the

composition and structure, then rapidly characterize

and evaluate fuel cell performance, has allowed fast

screening of multiple material and process

parameters. Over the course of the current contract,

40 binary, 120 ternary, and 14 quaternary

compositions have been made and tested for CO

tolerance in some 200 MEAs. The target was to

demonstrate less than 20 mV loss at 0.7 V under 100

ppm CO, compared to pure hydrogen/air (30 psig)

for 16 hours with no air bleed and low anode

catalyst usage. This was nearly demonstrated for a

PtRu-based system. Performance was further

improved with 0.5% air bleed and 50 ppm CO, as

shown in Figure 5. Under 24 psig H2/air, the pureH2 and CO-containing polarization curves are

identical, with only 0.12 mg/cm2 anode loading.

The materials for the above task were produced

by a batch process. The second task of Phase II of

the current contract was directed at demonstrating

the feasibility of scaling up the process to

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 0.2 0.4 0.6 0.8

Purifier 

50 ppm CO 0.5% Air Bleed

j (amps/cm 2)

85/115/23C H

2

/Air

24/24 psig 300/1600sccm 0.25cc/min

FC839 50cm

2

 Nafion 112 P6NR

PtRu based about 0.12 mg/cm

2

Figure 5. Comparison of 50-ppm CO and pure H2.

fabricate the CO-tolerant anode catalyst developed

in the batch process. During this

period, a scale-up in the process rate by a factor of

100 was successfully demonstrated as feasible. The

process parameters were studied in over 100

deposition runs to determine sensitivity of fuel cell

performance and material properties to process

conditions. It has been found that CO tolerance is a

strong function of one process parameter variation,

and the effect of this parameter on material

properties has also been determined. Similarly, it

has been found that CO or reformate tolerance is

very dependent on water management and operating

pressure conditions.

The fifth task under Phase I was directed at

developing a continuously produced porous,

conductive composite material for use as a diffuser

current collector (DCC). In this reporting period,

work continued on material and process screening of

a proprietary technology (7 new composites),

selected fuel cell evaluations (20), and evaluation of

a new composite approach (17 composites

fabricated). Of all the new composite constructions,

one has demonstrated performance equivalent to that

of a preferred commercial DCC, producing 0.6

A/cm2 at 0.6 V on ambient-pressure air with Nafion

112. Transfer of this composite approach to a

continuous process remains to be done.

Testing of MEAs prepared with CCMs made by

continuous processes like that in Figure 3 has begun

at our subcontractor, Energy Partners. The first task

of Phase II of the current contract is directed at

evaluating 150-cm2 MEAs in single cells. Initial

testing of MEAs has focused on understanding “fit

and function” parameters and test station/protocol

differences that affect measured fuel cell

performances. The proprietary 3M catalyst
Fuel Cells for Transportation FY 1999 Progress Report

89

electrodes have different water management

properties from conventional dispersed carbon

particle supported catalysts. Understanding how to

optimize their performance with the subcontractor’s

proprietary flow fields is necessary before

proceeding to full-sized stack testing. These first

tasks are nearly completed.

New Contract Work

Our development program has been driven by

assessment of the significant manufacturing

challenges that must be met to achieve the PNGV

goals. Considering the 5-layer MEAs, bipolar

plates, and gaskets/seals, a 50-kW stack may involve

as many as 3,000 layers produced by a variety of

process steps. With this many components and

process steps, the yield requirements can only be

met with a philosophy of six-sigma quality

throughout the entire set of manufacturing

processes. Furthermore, the processes must be highvolume. For example, if we assume 10 m2

 of MEA

per 50-kW stack and a target of 500,000 units/year,

the MEA production rate would have to be ~150

ft2/minute. The manufacturing approach must be

capable of cost-effectively providing such levels.

The new contract effort will build on the

feasibility demonstrations of the first contract and

will focus on the development of cell and stack

component sets matched for optimum performance

and high-volume production by well-understood,

integrated manufacturing processes to meet these

challenges. It includes further development of

nanostructured anode catalyst compositions and

structures with higher reformate tolerance and of

continuously produced electrode backing media.

Catalyst compositions and structures to produce

higher-activity cathodes will be investigated. The

pilot manufacturing process for continuous

fabrication of catalyst-coated membrane assemblies

will be scaled up, and integrated manufacturing

processes for fabrication of membrane electrode

assemblies will be developed. The best candidates

for the matched components system will be selected

at the end of the first phase of the new contract, on

the basis of component characterization and cell

performance tests and manufacturability. In the

second phase, the performance of the selected

matched component systems will be evaluated in

subcontractor stack tests, and a 10-kW stack will be

fabricated and delivered to ANL.

B. Low-Cost, High Temperature, Solid Polymer Electrolyte Membrane for

Fuel Cells

Robert Kovar (Primary Contact) and Richard M. Formato

Foster-Miller, Inc.

350 Second Avenue

Waltham, MA 02451-1196

(781) 684-4114, fax: (781) 290-0693, e-mail: bkovar@foster-miller.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) 252-4176, e-mail: millerj@cmt.anl.gov

Contractor: Foster-Miller, Inc., Waltham, Massachusetts

Prime Contract No. DE-FC02-97EE50478, July 1998-June 1999
Fuel Cells for Transportation FY 1999 Progress Report

90

Objectives

• Demonstrate a new class of low-cost, high-temperature solid polymer electrolyte composite membranes, which

are useful in automotive (PNGV) 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 (MEAs):

• 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.

• Develop fabrication methods for the high-temperature composite membranes (using the selected ICP and

substrate). The ICP and substrate must be combined to form an interpenetrating network (IPN).

• Develop an appropriate electrode structure and corresponding processing methods for MEA fabrication.

• Evaluate and refine the MEA structure for use in HTSPEM fuel cell systems.

Accomplishments

• Selected methods for synthesis and scale-up of ICPs, using the most promising commercially viable candidate

base polymer, polyphenylsulfone (PPSU, Radel R).

• Selected methods for synthesis and characterization of poly-p-phenylene benzobisoxazole (PBO) polymer,

identified as the most promising polymeric substrate material.

• Continued to develop and refine the processing methods (imbibition/pressing etc.) for fabrication of the

ICP/substrate combination into microcomposite membranes.

• Developed first-generation MEAs, using the above microcomposite membranes.

• Conducted single-cell PEM fuel cell testing. The Foster-Miller HTSPEM-based MEAs have already

demonstrated performance curves similar to state-of-the-art perfluorinated ionomers.

Future Work

• Continue development of low-cost, high-temperature aromatic-based ICPs that show long-term fuel cell

stability.

• Continue development of substrates with microstructure suitable for IPN formation.

• Continue development of electrode structure and corresponding application method(s).

• Continue single-cell fuel cell testing, including analysis of fuel cell performance curves to optimize operating

conditions.

• Supply high-temperature MEAs for independent testing (LANL, ANL, etc.)

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

shortcomings of today's Nafion-based solid polymer

electrolyte fuel cells (SPEFC, H2/O2-driven). The

HTSPEM will cost less, improve power density, and

reduce sensitivity to carbon monoxide in hydrogen

fuel. It may also alleviate water-management

problems, which limit the efficiency of present-day

Nafion-based fuel cells. Utilizing this new
Fuel Cells for Transportation FY 1999 Progress Report

91

membrane technology will provide a clean, quiet,

efficient, lightweight, and high-density power source

useful over a wide range of applications, from

portable computers to next-generation vehicles.

Fabrication and Evaluation of HTSPEMs

Both the ICP and PBO components selected to

make the composite membranes were scaled up to

allow batch-type membrane production methods.

Composite membranes were prepared by FosterMiller (as discussed in last year’s annual summary

report) by using selected PBO/ICP combinations.

Sulfonated PPSU (by Foster-Miller) was used as the

ICP, and PBO (by Foster-Miller) was used as the

substrate material. Once fabricated, the HTSPEMs

were fully characterized, and the most promising

specimens were made into MEAs. These MEAs

were then evaluated at various operating conditions

in single-cell test hardware.

The composite membranes prepared by FosterMiller were sent to Giner, Inc., to determine selected

transport and physical/chemical properties.

Properties of the Foster-Miller membranes were

measured and compared with those of Nafion 117

as a baseline. Recent composite membrane results

are listed in Table 1. The most important properties

are high ionic conductance (low area specific

resistance) and limited fuel crossover. The low-cost,

high-temperature (aromatic) ICPs do not yet exhibit

acceptable long-term stability. The issue of stability

is being addressed through a newly awarded

program sponsored by the DOE fuel cells for

buildings program (Ron Fiskum). The composite

membranes were evaluated for the following set of

properties:

• Thickness (dry and wet).

• Ion exchange capacity (IEC, meq/g).

• Water content (%).

• Area specific resistance (ASR, Ω·cm

2

).

• N2 gas permeability at 23oC (cm3·mil/ft2·h·atm).

• Dimensional stability.

The most important of these properties are

discussed below, including a summary of recent

results in ionic conductivity, area specific resistance,

and nitrogen gas permeability. Table 1 results

confirm that by varying the processing methods, we

can achieve the composite membrane target values:

IEC > 1.5 meq/g), ASR < 0.20 Ω·cm

2

), and gas

permeability (GTR) < 150 cm3·mil/ft2·h·atm). Note,

however, that the water contents of the composite

membranes are much higher than the target value

(target < 50%, currently >>100%). Future work has

been proposed to reduce the ICP water content while

maintaining low resistance. It is important to note

that, even at these high water contents, our crossover

values are similar to (or lower than) that for

Nafion 117 membranes. Therefore, reducing water

content will result in significantly lower GTR, with

the added benefit of improved hydrated mechanical

strength.

Ion Exchange Capacity and Water Content

As shown in Table 1, we have developed several

composite membranes that have exceeded the target

IEC of 1.5 meq/g, which is considered necessary for

adequate ionic conductance. Some composite

membranes showed very low resistance values, even

at IECs of less than 1.5 meq/g. The water content of

our composite membranes, which are based on

SPPSU ICP (measured IEC = 1.9 meq/g, measured

water content = 174%) normally ranges from 100 to

150%. This is far in excess of the target value of

50% or lower. In future programs, Foster-Miller will

work to develop ICPs (new and modifications of

existing ones) that show the required combination of

low resistance and reduced water content. If

successful, this approach will result in a number of

synergistic improvements in composite membrane

properties.

Ionic Conductivity and Area Specific Resistance

Foster-Miller continues to generate composites

with low values of area specific resistance.

However, we have not yet been able to obtain the

theoretical composite conductivity values. The best

samples fabricated (to date) exhibit two to five times

higher ASRs than expected. Clearly, the fabrication

method for producing the composites must be

improved if we are to realize the full combination of

substrate benefits (strength and thin cross-section).

The ASR value for FMI 167-19CW of 0.119 Ω·cm

2

is almost one-half (48%) that of Nafion 117! Work

continues on developing composites with improved

ASR by improving ICP/PBO synthesis and

composite membrane processing methods.
Fuel Cells for Transportation FY 1999 Progress Report

92

Table 1. Data from Foster-Miller’s composite membrane.

Thickness (mil)

Serial Number Dry Wet

IEC

(meq/g)

Water

Content

(%)

Resistance

(Ω·cm

2

)

a

N2, Permeability

@ 23°C

(cm3·mil/ft2·h·atm)

Dim.

Stability

(% area

change)

Nafion Control 7.1 8.7 0.90 38 0.229 148.3 –20

FMI 126-AY2 1.9 3.0 1.69 139 0.220 NTbnil

FMI 126-AY3 1.4 2.4 1.56 111 0.230 NT nil

FMI 126-82BE 1.0 1.5 0.91 143 0.140 15% of N117;

1 M Me(OH)

nil

FMI 167-11CR 1.3 2.0 1.26 118 0.125 43.2 nil

FMI 167-15CU 2.5 5.8 1.52 164 0.150 161.0 nil

FMI 167-19CW 1.1 2.0 1.70 131 0.119 154.2 nil

FMI 167-36DS 1.5 2.5 1.06 108 0.208 89.2 nil

FMI 167-52EV 2.5 3.5 0.84 121 0.285 76.2 nil

FMI 167-55EX 2.0 3.0 1.00 127 0.285 61.4 nil

a

Contact pressure = 500 psi, bonded Pt black electrodes (H+ form, 23°C). 492-DOE-97210-1

b NT = Not tested/no data available.

Gas Permeability [Nitrogen]

Nitrogen (N2) gas diffusion measurements were

obtained on all film samples, as well as on baseline

controls (N117). Testing was performed according

to ASTM tests D-1424 and D-618(A) at a

differential pressure of 25 psi and a temperature of

73°F. Prior to measurements, all samples were fully

hydrated by boiling in DI water for 1 h. As shown in

Table 1, sample FMI167-11CR shows both an

improved ASR (45% less of N117) and an improved

GTR (71% less than N117). The other samples,

although not as good, show similar trends.

Optimization of the SPPSU (Radel R) ICP water

content (currently 174%!) will certainly reduce the

GTR even more, as well as having the added benefit

of improved mechanical properties (when hydrated).

Dimensional Stability

The dimensional stability (in plane area change

of the fully hydrated composite membrane) of all the

PBO-based composites is outstanding. No samples

tested showed any noticeable dimensional changes

in the plane of the membrane! This is impressive,

considering that the sulfonated Radel R films (no

substrate used) showed excessive swelling and

dimensional change (ranging from 84 to 153%).

Foster-Miller remains confident that, given the

exceptional strength of the PBO substrate, the

mechanical properties of the composites will be well

in excess of state-of-the-art fuel cell membranes

(e.g., Nafion 112, Gore-Select).

Produce HTMEAs and Complete Single-Cell

Fuel Cell Tests

After property evaluations, the composite

membranes were developed into MEAs, which were

used in single-cell fuel cell tests. Standard platinum

black electrodes (4 mg/cm2 Pt loading) were

thermally bonded onto the FMI films and tested in

an H2/air fuel cell. To date, the best performance

was obtained on sample 167-55EX. The MEA

fabricated with FMI sample 167-55EX was placed in

fuel cell hardware, and performance data were

collected initially at 80°C, and subsequently at 90°C

and 100°C. Hardware limitations prevented data

collection above 100°C. Testing at these

temperatures was completed at a pressure of 30 psig,

even though minor cross-cell leakage was detected.

The data were compared with those for an MEA

fabricated with Nafion 117, which had the same

electrode structures as the 167-55EX-based MEA.

At temperatures above 100°C, the Nafion MEA

began to lose its mechanical properties, and

measurements were difficult to obtain, in agreement

with LANL experience (1).

Performance data collected at each temperature

range are shown individually in Figures 1-3. The

gradual increase in cell resistance with temperature

increase indicates a loss of water in the films during

operation. FMI sample 167-55EX exhibited higher

performance than that of the baseline Nafion 117

film. At a temperature of 80°C, the FMI sample

exhibited a 50-mV improvement in H2/O2
Fuel Cells for Transportation FY 1999 Progress Report

93

Figure 1. Comparative FMI membrane performance at

80°C (iR-included).

Figure 2. Comparative FMI membrane performance at

90°C (iR-included).

performance at a current density of 1000 mA/cm2; at

90°C, ~100 mV. At an operating temperature of

100°C, the performance of the FMI film at a current

density of 1000 mA/cm2 was 558 mV. The Nafion

MEA did not sustain its performance at this current

density and temperature.

Figure 3. Comparative FMI membrane performance at

100°C (iR-included).

Reference

1. T. Zawodzinski, Los Alamos National

Laboratory, personal communications (undated).

FY1999 Publications/Presentations

1. R. Formato, R. Kovar, P. Osenar, and N.

Landrau, “Composite Solid Polymer Electrolyte

Membranes,” U.S. Patent Pending.

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,” Virginia

Polytechnic Inst. and State Univ., Blacksburg,

Va., accepted for publication by ACS, 1999.

3. R. Formato, R. Kovar, P. Osenar, and

N. Landrau, “Novel Ion Conducting Materials

Suitable for Use in Electrochemical

Applications and Methods Related Thereto,”

U.S. Patent Pending.
Fuel Cells for Transportation FY 1999 Progress Report

94

C. Nanopore Inorganic Membranes as Electrolytes in Fuel Cells

Marc A. Anderson

Water Chemistry Program

University of Wisconsin – Madison

660 North Park Street

Madison, WI, 53706

(608) 262-2674, fax: (608) 262-0454, e-mail: nanopor@facstaff.wisc.edu

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

Objectives

• Develop inorganic membranes with high proton conductivity.

• Develop methods for depositing platinum on mesoporous ceramic electrolytes.

• Deposit crack-free films of ceramic electrolyte membranes on mesoporous electrodes.

• Fabricate and test an entire proton exchange ceramic membrane fuel cell (PECMFC).

OAAT R&D Plan: Task 13; Barriers A and B

Approach

• Develop and characterize ceramic membranes with high proton conductivity.

• Support these membranes on catalytically active porous supports.

• Design and construct a fuel cell prototype based on these materials.

Accomplishments

This work started in late FY 1999. To date, we have studied a number of candidate ceramic materials and have

selected a few, which have been characterized with respect to proton conductivity and pore structure.

Future Directions

Prepare supported thin ceramic films, using porous conductive media that have been coated with a catalyst.

Introduction

Proton exchange membrane (PEM) fuel cell

technologies based on organic polymer membranes

(perfluorosulfonated polymer, sold under the trade

name of “Nafion”) are unlikely to meet system

requirements for PEM fuel cell cogeneration

systems. The lower operating temperatures required

in using these perfluorosulfonic membranes leads to

increased costs because of excess platinum

requirements and the tendency of the cell anodes to

be fouled by CO poisoning. Also, as operating

temperatures are raised, organic polymer membranes

are unable to retain water, leading to poor proton

conductivity.

Proton Conductivity

In the first phase of our project, we have studied

the temperature and relative humidity (RH)
Fuel Cells for Transportation FY 1999 Progress Report

95

dependence of conductivity in three different

ceramic membrane materials: SiO2, TiO2, and Al2O3.

[1].

Proton conductivity was determined as a

function of both RH and temperature. Figure 1

shows the impedance spectra of theTiO2 chip at

25°C for different RH values. The membrane

resistance was considered to be the intersection of

the arc with the Z(Real) axis, a value that was

independent of the different applied bias voltages,

applied on top of the oscillating potential. Similar

behavior was obtained for Al2O3 and SiO2. Data in

Figure 2 show that the conductivity for all three

oxides improves with increasing relative humidity.

The conductivity of SiO2 and TiO2 improves by

three orders of magnitude when the RH increases

from 33% to 97%. However, between 58% and 81%

RH, the conductivity increases sharply, by two

orders of magnitude. The conductivity of alumina

has a linear dependence on relative humidity; from

33% to 81% RH, it increases by only one order of

magnitude. At 25°C, the largest value of

conductivity, 1.1 × 10-3 Ω

-1

·cm

-1, is observed in the

TiO2 sample. Concerning the ability of our ceramic

materials to hold water, the results listed in Table 1

show that conductivity values do not correlate with

water content under the conditions of 81% RH and

25°C. This is true whether our results are considered

0.0E+00

2.5E+04

5.0E+04

7.5E+04

1.0E+05

1.3E+05

1.5E+05

0.0E+00 2.5E+04 5.0E+04 7.5E+04 1.0E+05 1.3E+05 1.5E+05

Z

real

 (W)

Zimginary (W)

33% R.H.

58% R.H.

0

200

400

600

0 200 400 600

81% R.H.

97% R.H.

10kHz

100 kHz

100kHz

10 MHz

Figure 1. Dependence of conductivity on relative

humidity. This example corresponds to TiO2.

Both Al2O3 and SiO2 show the same behavior.

(l 33% RH; n 58% RH; Δ 81% RH; u 97%

RH).

0.00E+00

2.00E-04

4.00E-04

6.00E-04

8.00E-04

1.00E-03

1.20E-03

1.40E-03

1.60E-03

1.80E-03

2.00E-03

0 20 40 60 80 100 120

% R.H.

s (S.cm-1)

SiO2

TiO2

Al2 O3

Figure 2. Dependence of conductivity on relative

humidity. Data obtained at 25°C.

Table 2. Water content and stability in samples

hydrated at 25°C under 81% RH. Data

obtained from thermogravimetric analysis.

% Weight Loss (a) Water Content

Sample 100 °C 200 °C

Temp. of

DTG min.

(°C)

Molec./

nm2 (b)

mmol/

cm3 (c)

SiO2 23.7 0.6 76 22 20

TiO2 21.2 1.8 80 64 26

Al2O3 18.2 4.8 85 23 25

Nafion 13.2 2.8 60 -- 15

Nafion (d) 29.5 -- -- -- 21

(a) Samples equilibrated at 81% RH.

(b) Internal specific surface area.

(c) Volume of chip.

(d) 100% RH Nafion.

on the basis of sample volume or specific surface

area. The only correlation that we find with

conductivity among all of these materials, including

Nafion, is the degree of surface acidity, which can

be related to the pK of surface protonation. Surface

acidity is also reflected in the isoelectric pH (pHiep)

of the material: SiO2 = 2.0 < TiO2 = 4.5 < Al2O3 =

9.0. Nafion, on the other hand, has very acidic

functional groups.

Figure 3 shows that, at 81% relative humidity,

the conductivity for all three oxides increases with

temperature in the range of 10 to 92°C. At the higher

temperatures, the conductivity still increases in the

order σ Al2O3 < σ TiO2 < σ SiO2. The observed

values are 2.0 × 10-3, 3.9 × 10-3, and 4.0 × 10-3 Ω

-1

cm

-1 for Al2O3 (92°C), TiO2 (80°C), and SiO2

(92°C), respectively. In our experiments, the RH is
Fuel Cells for Transportation FY 1999 Progress Report

96

0.0E+00

1.0E-03

2.0E-03

3.0E-03

4.0E-03

5.0E-03

0 25 50 75 100

Temperature (oC)

s (S.cm-1

)

SiO2

TiO2

Al2O3

Figure 3. Dependence of conductivity with temperature.

Data obtained at 81% RH.

controlled by using saturated salts and the % RH for

these salts depends on temperature, so the

conductivity for the systems at 80 and 92oC may

correspond to a RH value lower than 81%, and it is

probably underestimated. Figure 3 also shows that,

in the case of SiO2, the conductivity increases

linearly with temperature, while for TiO2 and Al2O3,

it increases exponentially. However, the activation

energies calculated from these data are very similar

for the three materials: 15.8, 17.0, and 17.1 kJ·mol-1

for SiO2, TiO2, and Al2O3, respectively. Reported

values of activation energy for Nafion range from 17

to 29 kJ·mol-1. [2-4].

Following Sumner [5] and Zawodzinski [6], the

conductivity of Nafion does not depend as strongly

on RH as does that of our ceramic materials. At

room temperature, the values reported by Sumner

[5] range from 1 × 10-2Ω

-1

 cm

-1 at 45% RH to

4 × 10-2Ω

-1

 cm

-1 at 70 % RH. At higher

temperatures, the conductivity does not increase at

the same rate as it does with relative humidity; the

value reported for Nafion at 79°C and 42% RH is

1.3 × 10-2Ω

-1

 cm

-1

. Moreover, Zawodzinski [6]

reported that the water content in Nafion, in terms of

water molecules per sulfonate group, does not

change significantly when the temperature is raised

from 30 to 80°C in samples equilibrated with water

vapor, and that the membrane takes up less water as

the temperature is raised. We therefore assume that

the same behavior can be expected under conditions

of higher temperature and relative humidity. If we

extrapolate Sumner’s data to the same conditions

used in our study, we find that the conductivity of

Nafion is not higher than 3.7 × 10-2 Ω

-1

 cm

-1. In the

case of our ceramic chips, the conductivity increases

significantly with both RH and temperature. Our

values at higher RH and temperature are less than an

order of magnitude lower than that observed for

Nafion, but our materials can be easily obtained as

0.5-μm thin supported films, whereas Nafion

membranes are about 160 μm thick. Therefore, the

actual ohmic resistance of such films would be of

the same order of magnitude as that of Nafion, or

lower, in a given device.

Conclusions

Monolithic, self-supporting ceramic chips can

be prepared from different materials via the sol-gel

route. These chips are mesoporous and present

surface areas ranging from 120 to 489 m

2

 g

-1 , and

they have high porosities. These ceramic chips retain

more water than do Nafion membranes, and they

lose this water at higher temperatures. The proton

conductivities of these chips are highly dependent

on relative humidity, being 1 to 2 orders of

magnitude lower than that of Nafion. Because the

chips can be obtained as supported thin films that

are at least 300 times thinner than Nafion, we

believe that they are a potential candidate for

electrochemical applications in fuel cells.

References

1. F.M. Vichi, M.T. Colomer, M.A. Anderson,

Electrochem. Solid State Lett., 2, 313 (1999).

2. K.D. Kreuer, Solid State Ionics, 97, 1 (1997).

3. F.N. Büchi and G.G. Scherer, J. Electroanal.

Chem, 404, 37 (1996).

4. K. Uozaki, K. Okazaki, and H. Kita, J.

Electroanal. Chem., 287, 163 (1990).

5. J. Sumner, S. Creager, J. Ma, and D.

DesMarteau, J. Electrochem. Soc., 145, 107

(1998).

6. T.A. Zawodzinski, Jr., and S. Gottesfeld,

Extended Abstr. of the Electrochemical Society

Meeting Canada, Fall 1992.
Fuel Cells for Transportation FY 1999 Progress Report

97

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: spectragjf@aol.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) 252-4176, e-mail: millerj@cmt.anl.gov

Contractor: Spectracorp Ltd., Lawrence, Massachusetts

Subcontractor: Energy Partners, West Palm Beach, FL

Prime Contract No. DE-FC02-97EE50474, September 1997 – December 1999

Objectives

• Improved performance and cost reduction in polymer electrolyte membrane (PEM) fuel cells through the

optimization of the carbon-based gas diffusion electrode (GDE) material. A matrix of numerous variations in

the composition and processing of carbon-fiber-based papers will be fuel-cell-tested and analyzed to determine

the effect of performance-enhancing, lower-cost materials and processes. Base paper properties will be

correlated with fuel cell performance, and a manufacturing feasibility study and limited production runs will be

conducted on the most promising materials in terms of cost and performance.

OAAT R&D Plan: Task 13; Barrier B

Approach

• Change the various parameters in carbon/carbon GDE, such as pore size distribution, electrical and thermal

conductivity, and physical strength, by varying fiber types and lengths, heat treatment temperatures, density,

and thickness (over 30 variants).

• Correlate the variants to fuel cell performance by using cell testing and analysis – first short-term, and then

long-term for the more promising variants.

• Produce the optimized paper(s) in production volumes and make them available for evaluation by laboratory

and industry partners.

Accomplishments

• 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. Correlation of these properties (such as air flow vs. density, resin

content, thickness, and pore size) was performed.

• 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 and eliminated

nonperforming variants.
Fuel Cells for Transportation FY 1999 Progress Report

98

• Combinations of the most promising material variants were produced to explore the limit of potential cost

reduction while maintaining excellent cell performance.

Future Directions

• Long-term testing on the best-performing GDE variants from initial screening will commence shortly.

• Large-volume cost and manufacturing analysis (including possibility of continuous manufacturing) is under

way for the most promising GDE variants.

• A small production run of the best-performing GDE variants will be made.

Introduction

The objective of this program is to optimize the

physical structure of porous carbon papers for use as

gas diffusion electrodes in membrane electrode

assemblies for fuel cells. This optimization will be

directed toward maximizing cell and stack

performance with regard to such characteristics as

mass transport (H2O removal), appropriate electrical

conductivity, and reduced cost versus current stateof-the-art materials.

Manufacture and property characterization was

conducted on the full GDE matrix (30+ variants), a

fuel cell baseline was established, and initial cell

screening was conducted on the GDE variants.

Representative cell testing results can be seen in

Figure 1.

0.4

0.5

0.6

0.7

0.8

0.9

1

Cell Voltage (VDC)

0 200 400 600 800 1000 1200 1400 1600

Current Density (mA/sq.cm.)

Figure 1. Representative polarization curves from GDE

matrix.

As can be seen in Figure 1 (and as was

expected), some variants exhibited excellent

performance, while other variants (stretching the

limits on several paper variables in order to define

the performance envelope) exhibited quite poor

performance.

Figure 2 shows the performance of the baseline

material (1N) at several different pressures.

Excellent performance is maintained at lower

pressure, demonstrating the feasibility of lower-cost

materials used in atmospheric-pressure fuel cells.

Much of the expense of existing carbon fiber

paper GDEs derives from the processes used in the

manufacture of the finished product. In particular,

the high heat treatments (>2,000°C) – carried over

from phosphoric acid fuel cell technology – add

considerable expense to the material and may not be

0.2

0.4

0.6

0.8

1

Cell Voltage (VDC)

0 200 400 600 800 1000 1200 1400 1600

Current Density (mA/sq.cm.)

1N (0psig)

1N (15psig)

1N (30psig)

Figure 2: Polarization curves at different cell pressures.
Fuel Cells for Transportation FY 1999 Progress Report

99

necessary, because of the less caustic environment

of the PEM cell. Figure 3 shows promising results

from a preliminary examination of lower-cost

treatments.

0.4

0.5

0.6

0.7

0.8

0.9

1

Cell Voltage (VDC)

0 200 400 600 800 1000 1200 1400 1600

Current Density (mA/sq.cm.)

LOW COST 2

LOW COST 1

BASELINE

Figure 3. Polarization curves for low-cost GDE.

Combinations of the best-performing and

lowest-cost GDE variants from the initial cell

screening have been manufactured and will be

included in long-term testing at Energy Partners,

which is to commence shortly.

Initial cost reductions present no manufacturing

hurdles; small production-run quantities will be

produced. Long-term cost reductions will require

changes in the manufacturing process (possibly to

continuous manufacturing). Analysis of the

manufacturing possibilities, based on examination of

the cell testing data, has begun and should yield a

paper cost of <$10/m2 in large volumes, a reduction

of over 50% from current cost figures.
Fuel Cells for Transportation FY 1999 Progress Report

100

E. Optimized Electrodes for PEM Operation on Reformate/Air

Thomas A. Zawodzinski (Primary Contact), Francisco Uribe, Jayson Bauman, Tommy Rockward,

Bernd Meuller, Markus Vogt, Thomas Springer, Judith Valerio, and Shimshon Gottesfeld

Electronic and Electrochemical Materials and Device Research Group

Los Alamos National Laboratory

(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 PEFCs under conditions appropriate for reformate/air operation, via methods

that allow cost and efficiency targets to be met for transportation

OAAT R&D Plan: Task 13; Barrier A

Approach

Simultaneously achieving the following cell characteristics, through applied R&D:

• Minimum air injection for CO cleanup

• Minimum catalyst loading

• Minimum losses due to dilution at high fuel utilization

• Highest possible performance at 0.8 V

Accomplishments

• Dilution effects. Achieved improved operation at high utilization, in line with predictions from new diagnostics.

• CO tolerance. Reduction in both precious metal loading (0.5->0.2 mg/cm2) and in air bleed (2.5% or lower vs.

4% for 100 ppm) since July 1998 review.

- New catalyst in reconfigured anode shows promise for reaching full tolerance with <5% air bleed to

500 ppm in reformate, using 0.3 mg/cm2 anode catalyst.

- New, reconfigured MEA allows us to tolerate 100 ppm in reformate with only 0.5% air bleed.

- Testing of transient response of cells under various conditions; improved recovery from transient increase

in CO, using air bleed.

- Testing with segmented cell indicates stepwise propagation of poisoning down the channel.

• Impurities other than CO. Effects of ammonia, methane, olefins, and hydrogen sulfide on performance were

studied. Ammonia and hydrogen sulfide caused substantial performance loss. However, in each case, a

cleanup method was demonstrated.

• Cathode Performance. The cell performance at 0.8 V was studied. Performance improvements, relative to that

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.

Future Directions

• Change emphasis to reflect need to increase cell voltage – more cathode work.

• Cathode work: overall goal is to increase achievable current density at 0.8 V.

• Improve cathode catalysts.
Fuel Cells for Transportation FY 1999 Progress Report

101

• Vary catalyst layer and backing compositions to improve hydration.

• Experiment with elevated temperature operation/alternative hydration methods.

• Obtain guidance from cathode modeling.

• Anode work: overall goal is to minimize effects of dilution and CO.

• Improve anode catalysts, reconfigure anodes, and increase effectiveness of air injection for ever higher CO

tolerance.

• Improve catalyst layer composition to further minimize dilution effects, increase fuel utilization.

• Further clarify long-term effects of higher levels of CO.

• Practical studies: break-in effects, cold start, new fabrication approaches.

Introduction

The requirements for overall polymer electrolyte

fuel cell (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, because the former

entails higher cell voltages (and thus, some focus on

the PEFC cathode); higher cell voltages also may

provide some “relief” in the context of the

stringency of CO-tolerance requirements. The scope

of this project has broadened slightly to include both

of these items. We seek to address these needs by

developing an understanding of electrocatalysis and

transport issues related to reformate feed and by

using this understanding to guide the development,

testing, and demonstration of improved electrodes

for reformate operation. We test the single cells

under steady-state and transient exposure to various

levels of CO. We have also tested cells exposed to

various other impurities expected in a reformate

stream. Finally, we have carried out preliminary

work aimed at improving fuel cell cathode

performance.

Dilution Effects

We encountered substantial performance losses

in 50-cm2 single cells as we lowered the anode

stoichiometric flow rate below 1.3 (approx. 77%

fuel utilization). Operation of a fuel cell using a

feed stream with 40% hydrogen under the target

conditions of 90% utilization results in a hydrogen

concentration of 6% near the cell outlet.

Accordingly, we investigated the effect of dilution

of the anode stream on cell performance. To

decouple the dilution effect from utilization effects,

we operated in small single cells, using high flow

rates, to approximate a “zero utilization” condition.

Results of such tests for a series of different

dilutions are shown in Figure 1.

We also include a result for which the

humidification was varied. The improved

performance at lower humidification led us to

believe that gas access to the electrode could be a

decisive factor. Accordingly, we systematically

varied the gas diffusion layer (GDL), looking at

several thicknesses and hydrophobicities, and tested

the deviation of the cell response from the ideal,

Nernstian behavior expected for simple dilution

effects. We found, surprisingly, that the best

performance was obtained for a GDL with a thick

microporous layer on one side of the backing. On

the basis of this finding, we tested a larger cell under

high utilization conditions and found that this

enabled good performance on simulated reformate

with 83% utilization (Figure 2), thus overcoming a

previously observed barrier.

Figure 1. Polarization curves showing the effect of

diluting the anode feedstream under “zero

utilization” conditions.
Fuel Cells for Transportation FY 1999 Progress Report

102

Figure 2. Polarization curves comparing operation on

neat H2 (upper curve) and 40% H2 (lower

curve). Cell conditions: 0.2 mg/cm2 Pt each

on anode and cathode, other operating

conditions as in Figure 1.

CO Tolerance

We have continued to progress toward the

simultaneous goals of enhanced CO tolerance with

minimum air injection and minimum catalyst

loading. We showed that certain new catalysts

allowed us to approach a high level of tolerance to

500 ppm CO. Figure 3 shows this result.

We also showed that the effects of 100 ppm CO

in reformate could be eliminated by as little as 0.5%

air bleed with an optimized MEA (reconfigured

anode, 0.6 mg/cm2 anode Pt loading). In short-term

tests, we can simultaneously lower catalyst loading

to 0.2 mg/cm2 and achieve complete tolerance to

Figure 3. Polarization curves showing the combined

effects on new catalyst and reconfigured

anode, providing near complete tolerance to

500 ppm CO in reformate.

100 ppm CO with <2.5% air bleed. Our best results

to date, shown in Figure 4, indicate that we can

reach full tolerance to 100 ppm in reformate with

0.5% air. Industrial collaborators are currently

testing our reconfigured anodes.

In another set of tests, we have extensively

studied the effects of transient excursions in CO

levels, characterizing the response of cells as a

function of flow rate, temperature, catalyst loading,

and type. Perhaps the most technologically

significant result is our finding that injection of air

can dramatically improve the recovery, from

excursions in CO level from 20 to 100 and back to

20 ppm CO, as shown in Figure 5.

Impurities Other than CO

Various impurities or products of the reforming

process could be present at the fuel cell anode. We

demonstrated the deleterious effects of hydrogen

sulfide (Figure 6) and ammonia on fuel cells,

together with methods of cleanup. We also showed

that the presence of methane and ethylene in the

anode flow stream had little effect on the cell

performance.

Cathode Performance

To meet efficiency requirements for operation

on reformed gasoline, the cathode performance must

be improved at high cell voltages. We began a

serious investigation of this problem with several

studies, two of which are highlighted here.

Operation at high cell voltages necessarily

implies operating with little water production at the

Figure 4. Series of polarization curves with various

levels of air injection used to achieve CO

tolerance.
Fuel Cells for Transportation FY 1999 Progress Report

103

Figure 5. Rapid recovery from a transient increase in

CO level, achieved with air injection. Plot

shows response of 3 different anode catalysts

to CO in H2 varied from 20 ppm to 100 ppm

and back to 20 ppm. Other cell conditions as

in Figure 1.

Figure 6. Plot showing effect of exposure of cell to

3ppm H2S as a function of time, with and

without upstream trapping method. Other cell

conditions as in Figure 1.

cathode. We previously showed that dry conditions

led to poorer oxygen reduction reaction (ORR)

kinetics. Figure 7 shows the decline in steady-state

current with time after changing 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

shown in Figure 7. Clearly, the application of such a

pulse provided improved steady-state performance.

The nature of the improvement is under

investigation.

We also studied the relative ORR activity of

various alloy catalysts in the cell. Results are shown

in Figure 8. Thus far, PtNi and PtCr cathode

catalysts have been the most active.

Figure 7. Response of the cell with time (bottom curve)

after changing the cell voltage from 0.5 V to

0.8 V and effect of pulsing the cell voltage

(top curve) between 0.8 V (99% of the time)

and 0.2 V (1%).

Figure 8. Polarization curves for a series of different

cathode catalysts.
Fuel Cells for Transportation FY 1999 Progress Report

104

F. New Alloy Electrocatalysts and Electrode Kinetics

Philip N. Ross, Jr.

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

• Conduct research on the kinetics and mechanism of the electrode reactions in low-temperature fuel cells.

• Develop new electrocatalysts, using a materials-by-design approach.

OAAT R&D Plan: Task 13; Barrier A

Approach

• Study the kinetics of fuel cell electrode reactions by means of modern electroanalytical methods. Study the

reaction mechanisms by using state-of-the art in-situ spectroscopic techniques.

• Use ultra-high vacuum methods of surface preparation and surface analysis to form tailored surfaces, and

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

• Collaborated with LANL and BNL in testing of the prototype E-TEK Pt-Mo alloy catalysts in PEM fuel cells

fed with simulated reformate. Achieved milestone of 50–100-mV higher cell voltage than with Pt-Ru catalyst

with reformate containing 20 ppm carbon monoxide (no air bleed).

• Obtained the first results for a Pd-based catalyst.

Future Directions

• Determine CO tolerance of tailored electrodes consisting of thin films (1-10 monolayers) of Pd on the closepacked single crystal surfaces of Nb, Ta, and Mo.

• Pursue Pt-skin structures as novel air cathode electrocatalysts.

Introduction

During the past fiscal year, we collaborated with

E-TEK to synthesize a carbon-supported Pt-Mo

catalyst having performance approaching that

predicted for alloy nanoclusters that have the

Pt75Mo25 bulk alloy surface. We established a

performance milestone for prototype Pt-Mo catalyst:

less than 50 mV loss at 0.6 A/cm2 (80oC, 3 atm) with

H2/25%CO2/20 ppm CO, using 0.5 mgPt/cm2. We

collaborated with Los Alamos National Laboratory

(LANL) and Brookhaven National Laboratory

(BNL) in testing the prototype E-TEK Pt-Mo alloy

catalysts in PEM fuel cells fed with simulated

reformate. Prototype carbon-supported Pt-Mo

catalyst from E-TEK met the performance milestone

by the end of the 1st quarter. We determined the CO

tolerance of ternary Pt1-x-yMxM′y electrodes prepared
Fuel Cells for Transportation FY 1999 Progress Report

105

by plasma immersion ion-implantation (PIII) of M′

in Pt-M binary alloy. The systems to be studied were

M = Ru, Mo, and M′ = Sn. The results with Sn

implanted in Pt75Ru25, Pt77Mo23, and Pt85Mo15 to the

levels of 10–15 at.% Sn were disappointing; the

presence of Sn in the surface either had no effect or

actually decreased the CO tolerance. We decided

not to continue the study of ternary Pt1-x-yMxM′y

systems at this time, meeting our milestone of a

Go/No Go decision by mid-year.

Thin films of Pd on early-period transition

metals (e.g., Nb, Ta, W) are reported to have

dramatically reduced binding of CO when adsorbed

in UHV, probably because of strong intermetallic

bonding between Pd and the transition metal

substrate. Electrochemical properties of these

systems have never been investigated. This

electronic interaction may create a “weakly

adsorbed” state of CO on the Pd that can be oxidized

at low potentials, thus producing a CO-tolerant

surface. Pd metal itself is essentially as active a

catalyst for H2 electrooxidation as is Pt. Electronic

effects in electrocatalysis are frequently postulated

but rarely proven to exist. In theory, however, such

effects present an important opportunity that we

must seek to utilize.

Preliminary results in the study of Pd thin-film

(1–10 ML, 1 ML = 1 monolayer) electrodes appear

promising. We were able to control the film

thickness in the 1–10-ML region. As shown in

Figure 1, a 1-ML film of Pd on Pt(111) showed

slightly increased activity [with respect to that for

clean Pt(111)] for H2 electrooxidation, and

significantly greater activity than a multilayer Pd

film [i.e., bulk Pd(111)]. Pt(111) was chosen as a

“control” substrate, but even in this case, an

electronic effect was observable. The theoretically

more interesting substrates, the hexagonal close

packed (hcp) surfaces of Ta and W, have been

prepared and are ready for use.

In previous research directed toward improved

air electrodes for phosphoric acid fuel cells, we had

sought to utilize what we termed a “skin effect” to

produce a more active state of Pt for oxygen

reduction. The skin effect arises from strong surface

segregation of Pt in certain alloys — in particular,

Pt3Co and Pt3Ni. At equilibrium (in vacuum), the

surface of these alloys is pure Pt (i.e., a monolayer

“skin” of Pt), with the second layer nearly pure Co

-0.2 0.0 0.2 0.4 0.6 0.8 1.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0.05 M H2SO4

278 K

1600 rpm

20 mV s -1

 5 ML Pd on Pt(111)

 1 ML Pd on Pt(111)

j/mA cm-2

E/V RHE

2.8 3.0 3.2 3.4 3.6 3.8

0.1

1

18 kJ mol-1

9 kJ mol-1

 Pt(111)

 1 ML Pd on Pt(111)

 5 ML Pd on Pt(111)

103T

-1 /K-1

j

0/mA cm -2

Figure 1. H2 oxidation/evolution polarization curves on

Pt(111) and epitaxial thin films of Pd on

Pt(111). Note uniquely lower activation

energy for the 1-ML Pd film vs. either bulk

Pt(111) or epitaxial multilayer Pd.

or Ni. The electronic state of the Pt skin is shifted

from that of a bulk Pt surface, which results in

enhanced oxygen reduction kinetics with respect to

pure Pt. However, in hot phosphoric acid fuel cell

cathodes, the skin structure of the alloy nanoclusters

was found to be unstable, and the enhanced activity

was lost relatively quickly (after about 100 hr). At

lower temperatures, and in the less aggressive

medium of polymer electrolyte, the skin structure

may be more stable.

Studies of the oxygen reduction activity and

stability of the skin structure on Pt3Co and Pt3Ni

bulk alloys in polymer electrolyte are in progress,

using our unique rotating ring-disk electrode

methodology coupled with ex-situ surface analysis

techniques. It is fundamentally important in the

pursuit of this concept to determine the stability of

elements like Co and Ni in PEM, even when they

are covered by a “skin” of Pt. We have also initiated

studies of other possible skin-effect bimetallic

systems for Pt, using thin films (<4 ML) of Pt

evaporated onto a metal M that — in the Pt-M alloy

— is predicted (from ab initio calculations) to form

a Pt-skin structure.
Fuel Cells for Transportation FY 1999 Progress Report

106

Publications

Refereed Journals

1. Grgur, B., N. Markovic, and P. Ross, “Electrooxidation of H2, CO and H2/CO Mixtures on a

Well-Characterized PtRe Bulk Alloy Electrode

and Comparison with Other Pt Binary Alloys,”

Electrochim. Acta 43 (1998) 3631.

2. Markovic, N., B. Grgur, C. Lucas, and P. Ross,

“Electrooxidation of CO and H2/CO Mixtures on

Pt(111) in Acid Solutions,” J. Phys. Chem. B

103 (1999) 487.

3. Mukerjee, S., S. Lee, E. Ticianelli, J. McBreen,

B. Grgur, N. Markovic, P. Ross, J.

Giallombardo, and E. De Castro, “Investigation

of Enhanced CO-Tolerance in PEM Fuel Cells

by Carbon Supported PtMo Alloy Catalyst,”

Electrochem. and Sol. State Lett., 2 (1999) 12.

4. Grgur, B., N. Markovic, and P. Ross, “The

Electrooxidation of H2 and H2/CO Mixtures on

Carbon Supported Pt-Mo Alloy Catalysts,” J.

Electrochem. Soc., 146, 1613, 1999.

Books, Book Chapters, and Refereed Conference

Proceedings

1. Ross, P., “The Science of Electrocatalysis on

Bimetallic Surfaces,” in Electrocatalysis, J.

Lipkowski and P. Ross, Eds., J. Wiley and Sons,

New York, N.Y., 1998, pp. 43-74.

2. Grgur, B., N. Markovic, and P. Ross, “On the

Mechanism of CO-Tolerance of Pt-Mo Alloy

Electrocatalysts,” in Proton Conducting

Membrane Fuel Cells II, S. Gottesfeld and T.

Fuller, Eds., The Electrochemical Society,

Pennington, N.J., Proc. Vol. 98-27, 1999, pp.

176 – 187.

Other Publications

1. Markovic, N., Grgur, B., and P. Ross, “Electrooxidation of H2, CO and H2/CO Mixtures on

Well-Characterized Pt-Ru, Pt-Sn, and Pt-Mo

Alloy Surfaces,” in 9

th Int. Conf. Sol. State

Protonic Conductors., Bled, Slovenia (Aug. 17-

21, 1998), Extended Abstracts, pp. 243-44.

2. Ross, P., J. Giallombardo, and E. De Castro,

“Preparation and Testing of a New CO-Tolerant

Electrocatalyst for PEM Fuel Cells,” 1998 Fuel

Cell Seminar Abstracts, Courtesy Assoc.,

Washington, D.C., 1998, pp. 560-61.
Fuel Cells for Transportation FY 1999 Progress Report

107

G. Cathode Catalysts

Dan DuBois (Primary Contact) and Jim Ohi

Basic Sciences Center, National Renewable Energy Laboratory

1617 Cole Boulevard

Golden, CO 80401

(303) 384-6171, fax: (303) 384-6150, e-mail: dan_dubois@nrel.gov

DOE Program Manager: JoAnn Milliken

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

Objectives

• Develop new electrocatalysts for oxygen reduction.

• Develop rapid throughput method for electrocatalyst discovery.

OAAT R&D Plan: Task 13; Barrier B

Approach

• Synthesize libraries of bimetallic complexes in which the coordination environment of the metals and the

distance between the metals are systematically varied:

- Synthesize bridging ligands (triphosphine and carboxylate for 1999).

- Develop rapid throughput synthesis of bimetallic complexes.

• Adapt screening method used in previous work to study oxygen reduction.

Accomplishments

• Prepared bridging ligands containing tridentate phosphine and carboxylate groups.

• Developed rapid throughput synthetic methods for preparing bimetallic complexes.

• Integrated rapid screening method (using cyclic voltammetry) with rapid throughput synthetic method. This

integrated approach permits rapid identification of active catalysts from reaction mixtures. Screening method is

both general and quantitative.

• Prepared more than 1200 bimetallic complexes and screened them for oxygen reduction. Approximately 20

hits were observed, which indicates that bimetallic complexes are a promising class of compounds for further

study.

Future Directions

• Now that the feasibility of the basic approach has been demonstrated, increased emphasis will be placed on the

design of the bridging ligands.

• Two classes of bridging ligands will be studied in the next year, bis(diphosphine) and bis(Schiff base)

compounds.

Introduction

The major objective of this research is to use a

rapid throughput approach to identify new

electrocatalysts for oxygen reduction. The

electrochemical reduction of O2 to water is an

important reaction in all low-temperature fuel cells.

In hydrogen fuel cells, it is the oxygen electrode that

has the largest overpotential. For methanol fuel
Fuel Cells for Transportation FY 1999 Progress Report

108

cells, highly selective oxygen reduction catalysts

could also reduce or eliminate the energy loss

associated with methanol crossover. For these and

other reasons, the development of new catalysts for

oxygen reduction is important for efficient and

practical low-temperature fuel cells. Although

significant effort has been devoted to development

of better oxygen reduction catalysts than platinumbased catalysts, none have been found.

In the research outlined below, we describe the

application of a new experimental approach, called

“combinatorial” or “rapid throughput” chemistry,

1,2

to the discovery of new catalysts for oxygen

reduction. The main difference between the rapid

throughput approach and more traditional catalyst

discovery methods is the use of rapid synthetic

methods, coupled with rapid screening methods.

The objective is to be able to prepare and evaluate

large numbers of compounds for evaluation as

catalysts. Compared to more traditional approaches,

the rapid throughput approach should permit at least

100 times as many compounds to be evaluated.

In the past year, we began a study of bimetallic

homogeneous compounds that will permit a

systematic approach to catalyst development.

Bimetallic complexes were chosen because it is

known that such complexes facilitate the fourelectron reduction of oxygen to water more readily

than do mononuclear complexes.3 The rapid

synthesis of arrays of bimetallic complexes was

demonstrated. This was accomplished by adding

two weakly solvated metal complexes to ligands

specifically designed and/or selected to promote the

binding of two metals. These reaction mixtures

were screened by cyclic voltammetry without

separation of the different complexes that resulted

from this synthetic approach. Proper analysis of the

resulting data permitted the complexes responsible

for catalytic activity to be identified from reaction

mixtures.

Bridging ligand syntheses

Figure 1 shows ligands that we prepared and

used to synthesize bimetallic complexes. The two

ends of the first three bridging ligands are tridentate

binding units, which can be the same (e.g., L3) or

different (e.g., L1). Different ends result in different

coordination environments around each metal

center, allowing features that control redox

potentials and reaction pathways to be varied. The

ligands in Figure 1 also permit variation of the

distance between the two metal sites. This distance

is thought to be important in oxygen reduction.

Library synthesis

Synthesis of the bimetallic complexes consisted

of adding a stoichiometric amount of mixtures of

two weakly solvated metal ions (shown in Table 1)

to solutions of the bridging ligands. For example,

we followed the reaction of one equivalent of

[Ni(CH3CN)6]

2+ and one equivalent of

[Fe(CH3CN)6]

2+ with one mole of the symmetrical

bridging ligand, L3, by 31P NMR spectroscopy. The

result was the formation of a mixture of three

compounds, Fe-L3-Ni, Fe-L3-Fe, and Ni-L3-Ni, in

a roughly statistical 2:1:1 ratio, as expected.

Whenever two different metals are used with a

symmetrical bridging ligand, three bimetallic

L 3

P

P

PEt2

PEt2

PEt2

PEt2

L 1

N

P

COO

-

PEt2

PEt2

COO

-

N

P

NMe2

NMe2

PEt2

PEt2

L 2

O

-

C

O

O

-

C

O

O

-

C

O

O

-

C

O

COO

-

COO

-

L 4

L 5 L 6

Figure 1. Bridging ligands.
Fuel Cells for Transportation FY 1999 Progress Report

109

Table 1. Metal complexes.

[M(CH3CN)6](BF4)2

M = V, Cr, Mn, Fe, Co, Ni, Ru

[Cu(CH3CN)4](PF6)

[Pd(CH3CN)4](BF4)2

[Pt(COD)(CH3CN)2](BF4)2

[V(O)SO4]

.

3H2O

Mn(NO3)2

In(NO3)3

Ag(BF4)

compounds should result. This situation is shown

schematically in Table 2.

The number three in this matrix indicates those

reaction vessels expected to contain three bimetallic

compounds. If the two aliquots of the same metal

solution are added to L, then pure M-L-M

complexes will be obtained. This result has also

been confirmed by NMR spectroscopy. These pure

compounds are indicated by the numeral 1 for the

diagonal elements of the matrix. It is clear that the

array contains all possible M-L-M ́ compounds,

where M and M ́ can either be the same or different.

Most of the reaction vessels will contain mixtures.

We have used approximately 20 different metal

complexes for preparing arrays of compounds. This

results in 210 different bimetallic complexes

[(N+1)!/(N-1)!2! where N = 20] for each

symmetrical bridging ligand (e.g., L3) and 400

compounds (N2) if the two ends of the bridging

ligand are different (e.g., L1). To date, we have

prepared more than 1200 compounds by using this

approach.

Table 2. Reaction matrix.

M1 M2 M3 M4

M1 1 3 3 3

M2 3 1 3 3

M3 3 3 1 3

M4 3 3 3 1

Screening of bimetallic complexes

The screening process consisted of performing

multiple cyclic voltammograms on the arrays of

reaction vessels discussed in the preceding

paragraph. A cyclic voltammogram was performed

on each reaction mixture (or reaction vessel) under

(1) nitrogen, (2) oxygen, (3) oxygen and acid, and

(4) acid with nitrogen purge. A positive result or

“hit” has one criterion: for acidic solutions, the ratio

of the catalytic current in the presence of oxygen (ic)

to the current observed for the complex under study

in the absence of oxygen (id) must be greater than 4

(ic/id > 4). This corresponds to a second-order rate

constant of approximately 20 M-1 s

-1 under our

screening conditions. For example, if compound

M3-L-M3 is active, then all of the reaction mixtures

shown in column 3 and row 3 of Table 2 should

show catalytic activity, with the diagonal elements

having approximately twice the activity of the offdiagonal elements in row and column 3. These

matrix elements are highlighted with light gray. If a

mixed compound, say M1-L-M2, is active, then the

two off-diagonal elements, M1M2 and M2M1 (dark

gray) will show activity, but no diagonal elements

will be active. Using this screening approach, it is

possible to screen between 50 and 100 compounds

per day, obtaining quantitative information under a

variety of reaction conditions. More than 1200

compounds have been evaluated, and it is possible to

unambiguously identify the species responsible for

the catalytic activity. Approximately 20 of these

1200 compounds have demonstrated sufficient

catalytic activity to be classified as hits. The rapid

throughput approach has allowed us to confirm that

bimetallic complexes are an active class of

compounds for oxygen reduction, and for a broader

range of compounds than had been previously

studied.

Compounds selected for further study or socalled “promising candidates” must meet two

criteria. The ic/id ratio must be greater than 4, and

the onset potential of the catalytic wave must be

within 0.5 V of the thermodynamic potential. The

compounds studied to date operate at onset

potentials too negative to meet our second criterion.

We will continue to apply this approach in searching

for promising candidates for oxygen reduction..

The rate-determining step in the rapid

throughput approach is the synthesis of bridging

ligands that allow for a systematic variation in the

coordination environments and the distance between

the metals. The careful design of such ligands is

important for a systematic search of these bimetallic

complexes using the rapid throughput approach.

Such a systematic search of bimetallic complexes

would not be feasible in a reasonable time frame,

using more traditional synthetic approaches.
Fuel Cells for Transportation FY 1999 Progress Report

110

References

1. Baum, R. Chem. Eng. News 1996, 74(7), 28-73.

2. Reddington, E.; Sapienza, A.; Gurau, B.;

Viswanathan, R.; Sarangapani, S.; Smotkin, E.

S.; Mallouk, T. E. Science 1998, 280, 1735.

3. Collman, J. P., Rapta, M., Bröring, M., Raptova,

L., Schwenninger, R., Boitrel, B., Fu, L., and

L'Her, M. J. Am. Chem. Soc. 1999, 121, 1387-

1388.

H. Development of a $10/kW Bipolar Separator Plate

Michael Onischak, Leonard G. Marianowski (Primary Contact), Scott Thielman, and Qinbai Fan

Institute of Gas Technology, Des Plaines, IL 60018

(847) 768-0590, fax: (847) 768-0916

DOE Program Manager: Donna Lee Ho

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

ANL Technical Advisor: Walter Podolski

(630) 252-7558, fax: (630) 252-4176, e-mail: podolski@cmt.anl.gov

Contractor: Institute of Gas Technology, Des Plaines, Illinois 60018

Prime Contract No. DE-FC02-97EE50477, September 1997-March 2000

Subcontractors:

PEM Plates, LLC, Elk Grove Village, IL 60007

AlliedSignal Inc., Torrance, CA 90504

Stimsonite Corporation, Niles, IL 60714

Superior Graphite Corporation, Chicago, IL 60638

Objectives

• Evaluate the IGT molded graphite bipolar separator plate’s performance and endurance in fuel cell stacks.

• Evaluate mass production of molded plates by building a pilot production molding line with a capacity of

5 plates per hour.

OAAT R&D Plan: Task 13; Barrier B

Approach

• Design, build, and operate the 5-plate-per-hour pilot production molding line at PEM Plates, LLC.

• Produce molded bipolar plates from the pilot line for the IGT and AlliedSignal fuel cell stack tests.

• Assemble fuel cell stacks at IGT to establish the functional performance and endurance of molded plates in

stack environments.

• AlliedSignal to test the molded plates from PEM Plates in fuel cell stacks of their design

Accomplishments

• Built pilot production line facility and equipment, producing plates for IGT and samples for several fuel cell

stack developers.
Fuel Cells for Transportation FY 1999 Progress Report

111

• IGT operated multiple cell stacks (4-, 7-, and 20-cell stacks) with molded plates from PEM Plates.

• A 20-cell IGT stack, with plates produced by PEM Plates, has remained in operation for over 2200 hours, with

excellent performance.

• Confirmed that $10/kW cost target is within reach with cost of separator plate materials at $4/kW; however,

molding costs under $6/kW depend upon bipolar plate design.

Future Directions

• Demonstrate operational functionality of molded plates as part of multicell fuel cell stack for heat management,

sealing, stacking stability, and water management.

• Design higher-capacity production molding line with process modifications.

• Prepare to supply commercial fuel cell stack developers with molded separator plates of their bipolar plate

designs.

Introduction

The overall objectives of this program are to

develop a $10/kW-manufactured-cost, molded

bipolar separator plate and to advance the

technology to commercial production rates. On the

basis of the performance success of the IGT molded

composite graphite bipolar separator plate, PEM

Plates, LLC, was formed to mold plates for

developers worldwide. PEM Plates, LLC, is a joint

venture of Stimsonite Corporation and ENDESCO

Services.

In the first phase of the DOE program

completed last year, several resins, graphite types,

and additives were evaluated for their fuel cell

property enhancement characteristics. Several types

of graphite blends were evaluated; the hydrophilic

graphite blend selected was a proprietary blend

supplied by our subcontractor, Superior Graphite

Corp. This blend, molded into the IGT IMHEX®

bipolar plate, yielded volume conductivities that

were three times the DOE-specified target of

100 S/cm. The criteria for all components were

chemical inertness, low cost, long-term availability,

low flammability, and no leachates to poison the

catalyst or membrane.

Bipolar Plate Measured Properties

Dies for IGT bipolar separator plate molds were

made with flow fields for an anode and with watercooling channels on the opposite side for a cathode

(Figure 1). Measurements of the electrical,

chemical, and physical properties of the molded

plates have met or exceeded DOE’s specified

targets, as shown in Table 1.

Figure 1. Typical molded graphite plate flow field.

Table 1. Bipolar plate properties.

Property Measured Value

Conductivity

(goal >100 S/cm)

250–350 S/cm

Corrosion

(goal <16 μA/cm2)

<5 μA/cm2

H2 permeability <2 x10-6 cm

3

/cm2-s

(dry, nonporous plates);

bubble pressure >15 psig

(wet, porous plates)

Crush strength >3000 psi

Flexibility 3–6% deflection at midspan

Total creep ~1% @ 200 psi, 100 °C

Material cost ~ $4/kW

Manufactured cost <$10/kW
Fuel Cells for Transportation FY 1999 Progress Report

112

The DOE target of 100 S/cm for conductivity,

measured by ASTM C-661, was typically exceeded

by a factor of three. The corrosion-rate target of

16 μA/cm2 in hydrogen, air, and oxygen

atmospheres was determined in an aqueous solution

of 2 ppm fluoride, using ASTM G5, at 90°C, pH~4.

The IGT molded composite blend yielded measured

rates below 5 μA/cm2. Hydrogen permeability was

measured as a function of molding pressure for

either dense, nonporous molded plates or plates

molded with some degree of porosity. The

hydrogen permeability rate for the dense, nonporous plates was 2 x 10-6

 cm

3

/cm2-s at 90°C and

30 psi,, well below the specified 16 x10-6 value.

In addition, IGT measured the strength,

flexibility, and creep characteristics of the plates,

anticipating a magnitude of 200 psi for fuel cell

holding forces, nonuniformity of gasketing and stack

assembly, plus handling and packaging actions from

the production line. These values (Table 1) are

expected to be within a reasonable safety factor.

The plates also have retained their properties after

being subjected to immersion in boiling water and to

freeze-thaw cycles.

Multicell Fuel Cell Stack Performance

In Phase 1 of the DOE program, IGT molded

bipolar separator plates with active areas of 50 cm2

and 300 cm2 for property measurements, as well as

for single-cell performance testing. The single fuel

cell performance was compared to operation in stateof-the-art machined graphite plates under identical

conditions. Performance was nearly identical to that

of the state-of-the-art machined graphite (about 3%

lower performance, ~15 mV @ 400 mA/cm2, mainly

due to the slightly higher surface resistance of the

present molded plates, as shown in Figure 2).

The performance shown in Figure 2 was very

stable over the 2000 hours of testing that was

conducted as a continuous, 24-hour-per-day test. In

this period, weekly diagnostic and open-circuit

measurements were made.

Following the 50-cm2 testing, full-size 300-cm2

active area plates were tested, and the same

performance and endurance were obtained, thereby

confirming the scaleup of the molded graphite

plates.

In Phase 2 of the DOE program, the molded

graphite plates were evaluated in a short-stack

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)

@800mA/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 

Plate

Figure 2. Comparison of IGT molded graphite cell with

machined graphite.

environment. The single-cell tests established

excellent molded plate performance, but these cells

operate isothermally. Operation of fuel cell stacks

involves non-isothermal conditions, with attention to

active cooling, proper sealing, type of seals, and

clamping forces. All of these functionality issues

address the durability of the molded bipolar plate.

Full-size anode and water-cooled cathode

molded bipolar plates were molded for IGT by PEM

Plates. These plates were assembled and tested at

IGT in 4-, 7-, and 20-cell fuel cell stacks.

AlliedSignal will test the molded plates in their

design later in 1999.

The operating performance of the 20-cell IGT

stack, 1.5 kW, is shown in Figure 3 up to 2200 hours

of operation. The stack was operated at near

ambient pressure and at a temperature of 60°C for

most of the 2200 hours of operation. Another period

to establish endurance at 80°C is planned.

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: 60 oC

Pressure: Ambient

Fuel: H2 @ 1.6 Stoics

Oxidant: Air @ 4.0 Stoics

Current Density: 400 mA/cm2 

Figure 3. Life test of IGT 20-cell molded bipolar plate

fuel cell stack.
Fuel Cells for Transportation FY 1999 Progress Report

113

Cost Studies and Commercial Production

The updated cost analysis indicates that the

materials used in the molded plate in commercial

quantities comes to about $1.46 per pound. Using

the DOE goals for power density and active area per

kilowatt, this cost translates to about $4.10/kW.

Manufacturing costs are judged to be within $6/kW,

so that the total molded separator plate cost should

be under $10/kW, depending on the complexity of

the design.

The molded separator plate information

developed in this work is applicable to almost any

size and shape of bipolar plates; that is, molding to

any final net shape is possible, with no finishing

steps necessary. However, designs with complicated

features may cost more to manufacture.

PEM Plates, LLC, has built the pilot production

line, with a molding capacity of 5 plates per hour, to

evaluate the steps in molding. The pilot line

addresses the key steps of preparation of the

composite blend, transferring to the mold, forming

of the plates, releasing from the molds, post-molding

operations, and QA/QC operations.

Several fuel cell stack developers have evaluated

the quality of the molded graphite bipolar plate and

have requested bipolar plates to be molded. PEM

Plates operates on a strictly confidential basis with

developers independent of IGT.

I. Layered PEM Stack Development

Michael Pien, Ph.D.

ElectroChem, Inc.

400 W. Cummings Park

Woburn, MA 01801

(781) 938-5300, fax: (781) 935-6966

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) 252-4176, e-mail: millerj@cmt.anl.gov

Contractor: ElectroChem, Inc., Woburn, Massachusetts

Prime Contract No. DE-FC02-97EE50475, October 1, 1997-September 30, 1999

Objectives

• Develop a low-cost bipolar PEM separator plate design for light vehicle transportation applications, on the basis

of a layered structure composed of low-cost, commercially available, mass-produced materials.

OAAT R&D Plan: Task 13; Barrier B

Approach

• Perform a stepwise development of a layered bipolar plate structure that incorporates stainless steel, porous

graphite, and polycarbonate in a reliable and easy-to-manufacture structure:

- Select materials and fundamental fabrication technologies that are inherently low-cost yet have suitable

precision to guarantee reliable stack assembly.

- Develop bonding techniques between dissimilar materials that are compatible with the environment

associated with PEM fuel cell and light vehicle applications.
Fuel Cells for Transportation FY 1999 Progress Report

114

• Validate the plate design and continued improvements through the construction and testing of a series of

laboratory-scale fuel cell stacks:

- Develop and test several 50-cm2 stacks that validate the basic design and materials compatibility.

- Scale up and test several 232-cm2 stacks that validate the best designs for full-scale applications.

• Perform a manufacturing cost and performance analysis in support of the suitability of this technology for light

vehicle transportation applications.

Accomplishments

• Developed and tested an inherently low-cost, layered bipolar plate design that uses commercially massproduced materials. Projected plate costs are estimated to be $10/kW or less when produced in volume.

• The bipolar plate design exhibits a low internal resistance loss, leading to a potential loss of only 8 mV at a

current density of 1 A/cm2. This leads to only a 1% loss resulting from internal resistance.

• Validated corrosion resistance of the design by prolonged operation and chemical testing of the product water.

No significant corrosion was observed.

• Endurance testing (over a period of six months) demonstrated performance equivalent to conventional lowporosity graphite plates.

• Established reliability and performance of gasket-free design and assembly process for 232-cm2 stack.

• Extended layered plate design to successful operation and extended testing of 232-cm2 bipolar and cooling

plates. Prolonged testing has already passed 6300 A·h, with no signs of degradation.

Future Directions

• Maximize cost savings from the design by using molded graphite and polycarbonate components.

• Develop molded components and automated handling processes to validate cost projections.

Introduction

The principal hardware element in a PEM fuel

cell is the bipolar separator plate, which in

conventional designs also constitutes the largest

single cost item in a fuel cell system. The bipolar

separator plate must perform a number of important

tasks simultaneously and still remain 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 from

which to inexpensively produce 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.

Our Approach

Our approach has been to fabricate separator

plates from several materials, thereby relaxing

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 a

layered design (b). The principal components of the

new design are porous graphite, polycarbonate

plastic, and stainless steel.

Porous graphite is used in this design because

the gas impermeability of the completed plate is

provided by the stainless steel and polycarbonate.

Because the graphite can be porous, the basic

material cost is greatly reduced. Commercially

available processes exist for the rapid fabrication of

porous graphite parts by molding. Alternatively,

porous graphite blocks can be produced at modest

cost and easily machined with gang cutters.

Polycarbonate is the most chemically resistant

of the high-volume manufactured plastics. With a

safe operating temperature well above that of PEM
Fuel Cells for Transportation FY 1999 Progress Report

115

Non-porous

(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 conventional fuel

cell separator plate vs. ElectroChem’s layered

structure. Monolithic plate is made of

expensive nonporous graphite or composite.

ElectroChem design uses 3 primary materials

chosen for low cost, high performance, and

ready availability.

fuel cells, its chemical resistance to attack is

sufficient for many years of operation. It is easily

molded into the shapes necessary to provide reliable

gaskets and manifolds. This permits efficient

channeling of the reactants and coolants to each of

the cells throughout the stack.

Stainless steel (SS) has been examined

repeatedly as a primary material for separator plate

fabrication. The steel surface is intentionally spaced

from the highly reactive surface region of the MEA

by the porous graphite plate. Furthermore, the steel

sheet is kept flat and stress-free (not stamped to

form gas channels), which reduces the tendency for

corrosion. Using the steel as a flat featureless

surface, with only a few holes for manifolding of

reactants, makes its fabrication by a low-cost

shearing/stamping process efficient. It also lets the

thickness of the steel, the heaviest component of the

plate, be minimized for weight reduction.

Because the bipolar plates are now fabricated

from several components, the required intricate gas

flow channels are easier to design in. Post-mold

machining is avoided entirely; the gas manifolding

channels can be more easily introduced in several

components and then assembled, while sealing

surfaces are reliably maintained.

The Technical Challenges

The primary technical challenges in this

approach were

1. Providing a reliable, low-resistance contact

between the graphite and stainless steel, with

minimal stress and long life.

2. Achieving reliable seals, to avoid crossover and

leakage.

3. Minimizing corrosion and contamination to

maintain stack performance and life.

Initial Test Results: Initial testing of the basic

design on small, 50-cm2 cells worked well, and the

three primary materials selected all performed well

under extended life testing. These early tests were

accomplished using relatively thick components to

enable passive cooling. Extended life test results are

shown for the stacks tested, indicating that the

materials selected provided performance that

matched that of conventional solid graphite plates.

No corrosion was observed.

Sealing and Bonding: These small initial cells

all used fairly rigid conductive adhesives to make

the contact between the graphite and stainless steel.

Furthermore, a strong adhesive was used to enable

bonding between the polycarbonate and stainless

steel. The process required several steps, but the

results were encouraging, and the fundamental cost

of the materials was acceptably low. However, as

the design was scaled to 232-cm2 active area,

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 0.2 0.4 0.6

Current Density (A/cm2)

Cell Voltage

Figure 2. Comparison of 50-cm2 layered cell’s

performance (data points) with standard

performance range obtained from solid

graphite separator plates (solid lines). All data

were collected at 50 psi.
Fuel Cells for Transportation FY 1999 Progress Report

116

thermally induced stresses between components

became more evident. The larger pieces showed

significant curling, and the separation between

contact layers was unacceptable.

Stress Analysis: The stress problem was

analyzed by means of computer modeling. As

expected, the thickness of the components strongly

influenced the stress level, with the thinner

components generating lower stress. Unexpectedly,

it was found that the stress did not scale significantly

with part size between 50 and 232 cm2. We

concluded that the contact layer between the

graphite and SS needed to be far less rigid.

Improved Design: A new approach was taken

to making a contact layer that has provided superior

results. Besides being stress-free, the electrical

contact between the graphite and SS has very low

resistance. This same contact layer also provides an

adequate seal between the polycarbonate and SS to

avoid leakage and crossover. Part thickness was

also dramatically reduced, so that the total separator

plate thickness is now 3.6 mm. This design was

assembled and tested at the full-scale 232-cm2 size,

complete with 6 active cells and 2 cooling plates,

with test results shown below.

Plate Resistance Measurements: To verify that

the plate design is of low resistance, high DC current

(0.5 A/cm2) was passed through the plates, and the

potential drop was measured. From these

measurements, the internal resistance of the

separator plates was determined to be 8.2 mΩ/cm2.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.0 0.1 0.2 0.3 0.4 0.5

Current density, A/cm2

Cell voltage

Figure 3. Comparison of 232-cm2 layered cell’s

performance (data points) compared with

standard performance data obtained from solid

graphite separator plates (solid line). All data

were collected at 30 psi.

This translates into a resistive loss during high

power operation (1 A/cm2 at 0.8 V/cell) of

approximately 1%, thereby meeting the

requirements for light vehicle applications.

Corrosion Resistance: All testing was

performed with pure oxygen, both to demonstrate

high-power-density performance and to maximize

corrosion effects. Our results indicated that no

significant corrosion occurred, as evidenced either

by visible effects on the SS or by ion content of the

product water.

Manufacturing Technology: The process for

fabrication of the layered bipolar plates lends itself

to low-cost mass production using techniques,

equipment, and processes used across several

industries. Although the plates comprise several

pieces that require individual fabrication and

handling, each step is quite low-cost and rapidly

executed. As part of this program, a cost analysis is

being carried out and continuously refined,

specifically for volume production associated with

the auto industry.

Some of the results of this analysis are shown in

Figures 4 and 5. 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, using commercially available

materials, with reasonable assumptions made about

cost savings from volume production techniques.

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 4. Specific power analysis of layered separator

plus cooling plates for a 50-kW stack

operating at 0.8 V/cell.
Fuel Cells for Transportation FY 1999 Progress Report

117

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 5. Cost analysis results of layered separator

plates plus cooling plates for a 50-kW stack

operating at 0.8 V/cell (based on production of

100,000 units/yr).

Future Challenges

A key element in our design involves looking

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 and are

well-engineered, and economies of scale can be

achieved rapidly with minimal investment.

Meanwhile, this material combination can also

be obtained in small volumes at modest cost and can

be machined inexpensively to provide parts that

already cost less than their nonporous graphite

equivalents. These less expensive parts can be

readily introduced into fuel cells when

manufacturing volumes are still small, yet they can

provide substantial cost savings at every level of

production volume.

Full exploitation of the cost savings from this

design will be provided by the use of molded

graphite and polycarbonate components. Future

work should include the development of molded

components and automated handling processes to

validate cost projections.

J. Corrosion Test Cell for Metallic Bipolar Plate Materials

Kirk Weisbrod, Don Prier II,* and Nick Vanderborgh

Los Alamos National Laboratory, MS J576

Los Alamos, NM 87545

(505) 665-7847, fax: (505) 667-0600

(* Southern University, Baton Rouge, LA 70813)

DOE Program Manager: JoAnn Milliken

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

Objectives

Develop tools to characterize the corrosion characteristics of metallic bipolar plate materials:

• Perform potentiometric measurements to rapidly characterize dissolution behavior.

• Design, build, and evaluate a test cell that adequately mirrors the environment encountered by bipolar plate

material in a PEM cell.

OAAT R&D Plan: Task 13; Barrier B

Approach

• Use potentiometric scans to characterize dissolution behavior.

• Develop and demonstrate a corrosion test cell that adequately evaluates performance.
Fuel Cells for Transportation FY 1999 Progress Report

118

Accomplishments

• Performed initial screening of readily available metallic materials.

• Developed and tested a corrosion test cell.

Future Directions

• Test sample materials, as requested by the fuel cell community.

• Provide the corrosion test cell design to potential users, as requested.

Introduction

Development of low-cost bipolar plate materials

is a significant challenge for commercialization of

PEM fuel cells for transportation applications. Some

of the key constraints for selection of bipolar plate

materials were outlined by Borup.1For metallic

options, manufacturing cost is generally minimal.

Corrosion resistance is a major challenge. Primary

objectives of the test cell are to (a) measure the

change in electrical resistance across the bipolar

plate and (b) characterize the soluble ions formed

that may be absorbed by the ionomer membrane.

Experimental Approach

The interfaces between a large number of cells

in a stack may be represented by the two cells given

schematically in Figure 1.

Figure 2 illustrates a cross section of the

corrosion test cell. The ionomer membrane is

replaced with a 0.001 N H2SO4 solution containing

2 ppm F-. The catalyst layer, an ELAT electrode

(0.5 mg Pt/cm2, 20% Pt on C), establishes an

Catalyst 

Layer

Ionomer 

Membrane

Catalyst 

Layer

Carbon 

Backing

Bipolar 

Plate

Carbon 

Backing

Ionomer 

Membrane

Catalyst 

Layer

Catalyst 

Layer

Corrosion Cell Section

Figure 1. Two-cell cross-section. The central region

represents components in the corrosion test

cell. The cell is a two-membrane test fixture

designed to establish reproducible test

conditions surrounding the central plate.

Bipolar Plate 

Sample

Reference 

Electrodes

Aluminum Plug 

Teflon Faced

Polycarbonate 

Blocks

Carbon 

Backing 

Layer

Pt Screen

Pt on 

Carbon

Heater

H2 

Supply

Air 

Supply

0.001 N H2SO4 

3 ppm Fluoride

Figure 2. Operating schematic of the bipolar plate

corrosion test cell.

electrochemical potential between the metal

components and the electrolyte. Platinum screens

pass electric current through the backing layers and

bipolar plate. Electrical potential between

components is recorded to monitor oxide growth.

Hydrogen and air are supplied to the anode and

cathode faces, respectively.

Results and Discussion

Potentiometric studies were performed at a pH

of 3. The dissolution rate of aluminum is quite high,

as expected (Figure 3). POCO graphite (AXF-5Q)

also has a high dissolution rate at 1 V vs. NHE.

Sealing the plate decreases the rate of dissolution to

the equivalent of 150 μM/10,000 h. Since the test

pH is lower than that expected in a fuel cell, the

dissolution rate is higher than expected in actual

operation.

Titanium nitride coatings on titanium and nitride

implanted in titanium both decrease the corrosion

rate to the lowest rate observed in this study.

Figures 4 and 5 illustrate how the addition of nickel

and chromium to stainless steel alloy did not
Fuel Cells for Transportation FY 1999 Progress Report

119

Figure 3. Polarization curves for aluminum, 316 SS, and

titanium: 0.001 N H2SO4, 2 ppm F-, 80°C,

deaerated with N2, 0.1 MV/s scan rate.

Figure 4. Electrodissolution rate for selected metal

samples at anode potential: 0.1 V vs. NHE

after 5 h: 0.001 N H2SO4, 2 ppm F-, 80°C,

deaerated with N2.

decrease the corrosion rate at a pH of 3. Nickel

dissolution at low pH appears to enhance the overall

dissolution rate. At a pH of 5-6, the effect may not

be as significant.2

Corrosion test cell results were obtained for

aluminum, 316 SS, titanium, and Hastelloy C-276.

Reference electrode potentials indicated that the

bipolar plate was exposed to conditions similar to

those within an operating fuel cell (Figure 6).

Figure 5. Electrodissolution rate for selected metal

samples at cathode potential: 0.96 V vs. NHE

after 5 h: 0.001 N H2SO4, 2 ppm F-, 80°C,

deaerated with N2.

Figure 6. Cell potential transients with 316 SS bipolar

plate: 0.001 N H2SO4, 2 ppm F-, 80°C; anode -

H2 at 1 atm, cathode – air at 1 atm.

Changes in pH with time are reflected by the

reference potential. High dissolution rates for

aluminum led to high contact resistance and soluble

ion concentrations. 316 SS experienced intermediate

performance and may be acceptable for shorter-term

applications.3 Titanium and Hastelloy C-276 both

showed minimal increases in contact resistance

against carbon paper. Lower cation concentrations

were measured in solution for C-276 than for

316 SS.
Fuel Cells for Transportation FY 1999 Progress Report

120

Table 1. Change in anode and cathode bipolar plate

resistance in corrosion cell at 1 A/cm2.

Voltage

Bipolar Plate Change

Material Time (h) (mV/1000 h)

Aluminum

Anode 87 172.4

Cathode 87 839.1

316 SS

Anode 700 8.6

Cathode 700 30.0

Titanium

Anode 1546 -0.6

Cathode 1546 -1.3

Hastelloy C-276

Anode 740 -9.5

Cathode 740 0.0

Testing to date indicates that the corrosion test

cell is a useful tool in characterizing the change in

oxide resistance and formation of soluble ions under

conditions that closely represent fuel cell conditions

at the anode and cathode. Confirmation of trends in

actual fuel cell operation is desirable.

References

1. R.L. Borup and N.E. Vanderborgh, “Design and

Testing Criteria for Bipolar Materials for PEM

Fuel Cell Applications,” Mat. Res. Soc. Symp.

Proc., Vol. 393, pp.151-155 (1995).

2. C. Zawodzinski, Los Alamos National

Laboratory, personal communication (undated).

3. S. Cleghorn, X. Ren, T. Springer, M. Wilson,

C. Zawodzinski, and S. Gottesfeld, “PEM Fuel

Cells for Transportation and Stationary Power

Generation Applications,” Hydrogen Energy

Progress XI, Proc. WHE Conf., Stuttgart,

Germany, June 23-28, 1996, pp. 1637-45.
Fuel Cells for Transportation FY 1999 Progress Report

121

VI. AIR MANAGEMENT SUBSYSTEMS

A. Turbocompressor for PEM Fuel Cells

Mark K. Gee

AlliedSignal Aerospace Equipment Systems

2525 W. 190th Street, MS-36-2-93084

Torrance, CA 90504

(310) 512-3606, fax: (310) 512-4998, e-mail: mark.gee@alliedsignal.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: AlliedSignal Aerospace Equipment Systems, Torrance, California

Prime Contract No. DE-FC02-97EE50479, October 1997-May 2000

New Start FY 1999, July 1999-February 2001

Objectives

Design, develop, and demonstrate a low-flow turbocompressor for PEM light-duty vehicles powered by PEM fuel

cells.

OAAT R&D Plan: Task 13; Barrier D

Approach

• Use of automotive and aerospace turbomachinery technology for low cost and low weight/volume.

• Use of contamination-free and zero-maintenance compliant foil air bearings.

• Use of a high-efficiency, low-cost two-pole toothless motor.

Accomplishments

• Numerous start/stop cycles with no appreciable wear.

• Stable operation at full turbine temperature.

• Compressor and turbine mapping showed performance close to predicted values.

• Compressor mapping with inlet guide vanes and vaneless diffuser showed improved performance at lower flow

rates.
Fuel Cells for Transportation FY 1999 Progress Report

122

Compressor/Expander Turbocompressor Subsystem

(compressor/expander subsystem includes the compressor and expander units; excludes heat exchangers, motors,

and controllers); status presented below is based on a 250°C flow inlet temperature to the expander

Characteristic Status DOE Technical Target

Flow Rate at 50 kWe (g/s)

Compressor 76 64-76

Expander 82 68-82

Peak Efficiency at 80% Flow Rate (%)

Compressor 71 80

Expander 80 90

Pressure Ratio as a Function of Flow Rate Below DOE

Guidelines

1.3 @10% to

3.2 @ 100% flow

Net Shaft Power Required at Max. Flow (kWe) 5.1 @ 85% flow,

est. 7-8 at full flow

4.3

Subsystem Volume (L) 10 (includes motor) 4

Subsystem Weight (kg) 8.1 (includes motor) 3

Future Directions

• Complete power consumption evaluation.

• Complete layout design, incorporating components for optimal performance across the full fuel cell operating

range.

• Complete analysis, design, fabrication, and testing of components for increased turbine inlet temperature.

• Perform a test study of performance vs. cost, using the compressor mapping results with the inlet guide vanes

and vaneless diffuser, to determine if variable compressor and turbine geometry is viable.

• If the above trade study warrants, complete analysis, design, fabrication, and testing of turbocompressor with

variable compressor and turbine geometry.

• With the turbocompressor, complete analysis, design, fabrication, and integrated testing of a vehicle-ready

motor controller.

The objective of this work is to develop an airpressurization system to pressurize a light-duty

vehicle fuel cell system. The turbocompressor

(Figure 1) is a motor-driven compressor/expander

that pressurizes the fuel cell system and

subsequently recovers energy from the high-pressure

exhaust streams. Under contract to the U.S.

Department of Energy, AlliedSignal has designed

and developed a motor-driven compressor/expander

and evaluated performance, weight, and cost

projection data. Compared to positive displacement

technology, the turbocompressor approach offers

potential for high efficiency and low cost in a

compact, lightweight package.

As shown in Figure 2, the turbocompressor

consists of a compressor impeller, an

expander/turbine wheel, and a motor magnet rotor

incorporated on a common shaft; the system

operates at a maximum design speed of 104 krpm on

compliant foil air bearings. The air bearings are

Figure 1. Photograph of turbocompressor.

lubrication-free, in addition to being lightweight,

compact, and self-sustaining; no pressurized air is

required for operation. The turbocompressor works
Fuel Cells for Transportation FY 1999 Progress Report

123

 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. Turbocompressor details.

by drawing in ambient air through the motor/bearing

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.

The turbocompressor has operated for more than

200 hours at varying conditions, with and without

motor operation. To date, the full design speed of

104 krpm has been reached with the motor.

Other work completed includes the analysis,

design, fabrication, and testing of compressor inlet

guide vanes and a vaneless diffuser to widen the

compressor operating range. The testing shows

progress toward meeting the 1.6 pressure ratio at

2 lbm/min, in addition to a more constant pressure

ratio and efficiency for a given corrected speed.

Future work will include completion of the motor

consumption measurements with the compressor

low-flow components. A layout incorporating the

compressor inlet guide vanes and vaneless diffuser

and an increased-inlet-temperature turbine are also

to be completed. From the layout, a detailed design

of the increased-inlet-temperature turbine will be

completed, fabricated, and tested.

Awarded in March 1999, the new program for a

turbocompressor with variable geometry for PEM

fuel cells includes four tasks. The first task is a trade

study to define the optimal turbocompressor

configuration, based on earlier work noted above.

Next, the existing turbocompressor will be modified

to the preferred configuration, as determined by the

trade study. In the previous programs, an industrial

controller was utilized. For a vehicle demonstration,

a more compact, variable-speed controller will be

developed. Testing of the optimal

turbocompressor/motor controller also will be

performed.
Fuel Cells for Transportation FY 1999 Progress Report

124

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, MA

Prime Contract No. DE-FC02-97EE50487

Objectives

Design, develop, and demonstrate a scroll compressor-expander module (CEM) 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 CEM.

• To meet the flow requirements for 50-kW fuel cells, the second-generation design has increased displacement

and higher speed with respect to the first-generation CEM.

• A second-generation prototype has been fabricated and is undergoing testing.

• As a final step in the development, the CEM will be integrated with a fuel cell system.

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 that involve no direct surface-to-surface contact

- Two central drive design concepts that eliminate drive belts

- Improved orbiting drive with rolling-element bearings for better orbiting scroll alignment.

• Second-generation CEM has been designed, fabricated, and successfully tested up to 80% of design flow.
Fuel Cells for Transportation FY 1999 Progress Report

125

Compressor/Expander Scroll Subsystem

(compressor/expander subsystem includes the compressor and expander units; excludes heat exchangers, motors,

and controllers); status presented below is based on a 150°C flow inlet temperature to the expander

Characteristic Status DOE Technical Target

Flow Rate at 50 kWe (g/s)

Compressor 76 64-76

Expander 82 68-82

Peak Efficiency at 80% Flow Rate (%)

Compressor 71 80

Expander 81 90

Pressure Ratio as a Function of Flow Rate Exceeds DOE

Guidelines

1.3 @10% to

3.2 @ 100% flow

Net Shaft Power Required at Max. Flow (kWe) 5.2 (est.) 4.3

Subsystem Volume (L) 27 4

Subsystem Weight (kg) 36 3

Future Directions

• Demonstrate compressor-expander in a fuel cell system.

• Develop hybrid compressor technology for size/weight reduction while maintaining superior performance

characteristics.

Phase I of the scroll compressor-expander

module (CEM) development culminated in the

successful demonstration of a scroll CEM capable of

pressurization and energy recovery for a 28-kW fuel

cell.

The first-generation prototype, shown in

Figure 1, is powered through the orbiting drive,

which transforms rotational motion to orbiting

motion.

The compressor and expander are mounted on

either side of the drive. Expander power is

transferred to the compressor mechanically through

grid

Expander

Fixed Scroll

Compressor

Fixed Scroll

Compressor

Orbital Drive

Transmission

Expander

Drive

Shaft

Oil Sump

Figure 1. First-generation scroll compressor-expander

module.

the drive. The orbiting drive is oil-lubricated;

however, oil is prevented from being introduced into

the compressor airflow by two sets of oil seals with

vented intermediate space.

The first-generation prototype was tested at flow

rates up to 42 g/s and compressor discharge

pressures up to 32 psig, operating at a peak

efficiency (taking drive losses and parasitic loads

into consideration) of 70%. The expander peak

efficiency was 80% (see Figure 2).

The main goals of the Phase II work are to:

• Increase flow rate.

• Improve integration of oil and cooling systems.

• Eliminate belt drive.

• Further demonstrate reliability.

• Integrate CEM with a fuel cell system.

The work included construction of a “back-toback” (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 130 hours.
Fuel Cells for Transportation FY 1999 Progress Report

126

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90

Percent Flow

Efficiency (%)

Compressor Efficiency

Expander Efficiency

Compressor Volumetric Efficiency

Expander Volumetric Efficiency

Figure 2. Compressor and expander efficiencies

(Phase I).

In addition, the first prototype CEM was

modified to demonstrate (1) integration of the oil

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

to improve CEM reliability have been demonstrated

successfully.

Extended reliability testing has been done to

verify durability of the first-generation orbiting drive

design. About 500 test hours have been

accumulated without incident at machine speeds up

to 3,450 rpm.

The second-generation CEM has been designed

and fabricated, and testing of the machine is

proceeding. The second-generation CEM is shown

in Figure 3. Design changes, compared with the first

generation, include:

• 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.

Initial testing of the second-generation machine

up to 80% of design flow is complete. This initial

testing has verified the performance projections of

Figures 4 and 5.

Figure 3. Second-generation scroll CEM.

Figure 4. Second-generation scroll CEM operating

envelope.

0

1

2

3

4

5

6

0 10 20 30 40 50 60 70 80

Flow (g/s)

Power (kW)DOE Guideline

Pressure

Max Pressure

Figure 5. Second-generation scroll CEM projected shaft

power.

Demonstration of the CEM integrated into a fuel

cell system is currently in process. This work is

being done with Energy Partners. The work will

show the viability of the scroll compressor for

automotive fuel cell applications and allow testing of

system control issues.
Fuel Cells for Transportation FY 1999 Progress Report

127

The performance envelope of the secondgeneration scroll CEM is shown in Figure 4. The

scroll technology allows for a wide flow range while

maintaining system pressure level.

The efficiency of scroll technology for fuel cell

pressurization is shown in Figure 5. The figure

shows shaft power projections for DOE Guideline

pressures and for the projected maximum pressure

curve of Figure 4. When operating according to

DOE Guidelines, the scroll CEM uses a very modest

amount of the net fuel cell stack power over the

entire flow range.

C. Fuel Cell Power System - Critical Components for Transportation

Development of Compact Air, Heat, and Water Management Systems:

Variable Delivery Compressor/Expander Development

Jeremiah J. Cronin, Principal Investigator

VAIREX Corporation

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 1997-December 1999

Objectives

The primary objective is to develop a second-generation integrated compressor expander motor suitable for

installation in 50-kW fuel cell vehicles.

• Expand, through research and development, the performance envelope of the variable delivery piston

technology for use as a fuel cell air compressor and expander. Focus performance improvements in the areas of

operating speed, compressor power consumption, and expander power recovery, as well as the volume and

weight of both devices.

• Define development pathway for an application-specific integrated compressor expander motor (ICEM) that

will satisfy cost, weight, and volume as well as performance goals for a fuel-cell-powered production vehicle.

OAAT R&D Plan: Task 13; Barrier D

Approach

The phased approach to the development of a satisfactory air system for use in an automotive environment is in its

second phase. In the initial phase, the concept of independent control of pressure across a fuel cell power range was

demonstrated. The hardware demonstrated the ability to select any pressure ratio at will, from 1.0 to 3.2. The 3.2

pressure ratio was also demonstrated over a 10:1 turndown in mass flow.

Moving beyond demonstration of variable-delivery piston machinery capability, this phase will:
Fuel Cells for Transportation FY 1999 Progress Report

128

• Compare alternative technology approaches (piston vs. screw) across a representative air delivery requirement

for an automotive fuel cell. Use real device data as input to a hypothetical fuel cell stack and examine where

differences occur.

• Compare each compressor’s characteristic efficiency behavior.

• Provide air systems in support of the FutureCar Program

• Design a Generation 2 variable-delivery compressor and expander. Build upon the results of testing and

evaluation of the first-generation ICEM. Model and optimize the various sub-entities that are required for a

successful Generation 2 air system.

Accomplishments

• Demonstrated approximately 30% more mass flow from approximately two-thirds the previous compressor’s

volume.

• Demonstrated a 25-30% reduction in compressor power consumption from the previous-generation compressor

for comparable pressure settings and mass deliveries.

• Designed a drive core that is common to both compressor and expander devices.

• Modeling of Generation 2 alternative designs has resulted in a reduction in both volume and dynamic mass by

one-third, from the previous generation. It has also resulted in approximately 50% parts count reduction.

• Established (a) that both piston (zero clearance device) and screw compressors (clearance device) can have

similar efficiencies, but in very different operating regimes, and (b) determined that the optimal application of

either technology depends upon the duty cycle of the fuel cell as used in a vehicle.

• Demonstrated the ability of the Generation 1 piston compressor design to handle large amounts of liquid water,

not just vapor.

Compressor/Expander Piston Subsystem

(compressor/expander subsystem includes the compressor and expander units; excludes heat exchangers, motors,

and controllers); status presented below is based on a 250°C flow inlet temperature to the expander

Characteristic Status DOE Technical Target

Flow Rate at 50 kWe (g/s)

Compressor 76 64-76

Expander 82 68-82

Peak Efficiency at 80% Flow Rate (%)

Compressor 70 80

Expander 50 90

Pressure Ratio as a Function of Flow Rate Variable; can exceed

DOE Guidelines

1.3 @10% to

3.2 @ 100% flow

Net Shaft Power Required at Max. Flow (kWe) 5.4 (est.) 4.3

Subsystem Volume (L) 48-65 4

Subsystem Weight (kg) 27 3

Future Directions

• Demonstrate a compressor operating envelope that supports a 50-kW net fuel cell power system.

• Continue to reduce power consumption.

• Continue to reduce dynamic mass, inertia(s), overall component weights, and costs.

• Conduct testing of expander configuration and demonstrate energy-recovery strategies.

• Complete thermal analysis and identify areas for reduction of heat in the compressor and retention of heat in the

expander.
Fuel Cells for Transportation FY 1999 Progress Report

129

• Determine pathway to manufacture, achieving technical targets within cost constraints acceptable to automotive

industry.

The Generation 1 compressor/expander

demonstrated that pressure ratios in excess of 3.5

could be generated in one stage. The Generation 2

compressor has successfully demonstrated the same

performance, but it has done so at a consistent

25-30% lower power consumption.

Figure 1 shows the Generation 2 compressor’s

power consumption data to date for representative

pressure ratios from 1.5 to 3.2. Figure 2 shows the

projected power consumption of the Generation 2

ICEM while following the DOE guidelines for

pressure and temperature at the respective mass

flow.

Means to reduce friction in various parts of the

system are being evaluated in this phase. Test

fixtures (see Figure 3) have been fabricated and used

extensively for examining parts and materials

performances before incorporation into the

individual assemblies.

VAIREX Gen 2 Piston Compressor 

0 

2 

4 

6 

8 

10 

12 

0 20 40 60 80

Mass Flow {g/sec}

Test Data through 5-27-99

Compressor Shaft Power {kW}

P/p=1.5

P/p=2.0

P/p=2.5

P/p=3.2

Figure 1. Power consumption data to date, Gen. 2

ICEM.

VAIREX Gen 2 I-CEM

PROJECTED POWER CONSUMPTION 

Includes an 85% efficient motor/controller loss

0

1

2

3

4

5

6

7

8

9

0 10 20 30 40 50 60 70 80

Air Flow {gram/sec}

Power Consumption (kW)

1.0

1.5

2.0

2.5

3.0

3.5

Pressure Ratio

Pressure Ratio

Power Consumption

Figure 2. Projected power consumption.

Figure 3. Test fixture.

With the use of advanced seal materials, the zero

clearance piston devices are being operated without

lubrication.

Modeling, testing, and design efforts on the

Generation 2 ICEM have reduced the volume and

mass of the compressor and expander hardware by

one-third. Figure 4 shows the previous and current

generations of compressors, for size comparison.

Development work on the expander has resulted

in developing a unique valving configuration. A

nationally renowned laboratory has tested it over a

large range of Reynolds numbers prior to

implementation. The results of this testing have

provided a high degree of confidence in the

projected expander performance.

Figure 4. Compressor size comparison, new generation

vs. old.
Fuel Cells for Transportation FY 1999 Progress Report

130

The study of zero clearance compressors vs.

clearance compressors determined that the pressure

ability of the VAIREX piston compressor device has

the capability to provide higher pressure at low

mass-flow rates. This would allow an appropriate

match to automotive duty cycles, resulting in lower

power consumption in the region where the

automobile spends the majority of its time. Since the

air system is parasitic to the fuel cell, this would be a

significant advantage in vehicle power system

architecture trades. Figure 5 compares the maximum

pressure capability of the two different technologies

when configured as a compressor/expander air

system. The Federal Urban Driving Schedule

(FUDS) indicates that U.S. automotive vehicles

spend the vast majority of their life (70%+) below

the 30% load level. The majority of their time is

spent within the bracketed area shown in Figure 5.

To optimize vehicle fuel efficiency, the

automotive fuel cell and all of its support hardware

must maximize its collective performance in this

same region while remaining able to achieve

maximum performance when needed.

Evaluation of the two technologies, configured

as an integrated compressor and expander air

system, was performed to investigate power

consumption differences for a hypothetical fuel cell.

The pressure vs. mass flow of the twin screw with

throttling (TSCE w/Throttle), indicated in Figure 6,

was duplicated by the VAIREX piston

compressor/expander. Using test data from this

phase, the power consumption of both air systems, at

the same mass flow and pressure, is expressed as a

percentage of the hypothetical fuel cell’s gross

power output. For example, if the 30% output point

of the fuel cell was 30 kW and one air system used

10 kW to operate at that powering level, that would

represent a specific power consumption of 33%. If

another air system required 20 kW to operate at that

Pressure Supplied to Fuel Cell Stack

36 kW net Fuel Cell (54 g/s)

1.0

1.5

2.0

2.5

3.0

3.5

0.0% 33.3% 66.7% 100.0%

Net Fuel Cell Power Level

Pressure Ratio

VDCE

TSCE System w/Throttle

TSCE System

Prefered Area

Figure 5. Pressure capability, twin screw vs. VAIREX

piston.

Projected Specific Power Consumption for ICEM

Twin Screw Comp/Exp vs. VAIREX Piston Comp/Exp

An 85% efficient Motor/Controller Included

0%

5%

10%

15%

20%

25%

30%

35%

0% 20% 40% 60% 80% 100%

Percent of Fuel Cell Gross Output

1.0

1.5

2.0

2.5

3.0

3.5

Twin Screw Comp/Exp

VAIREX Gen 2 Comp/Exp

Pressure Profile

Figure 6. Power consumption, twin screw vs. VAIREX

piston.

same point, it would have a specific power

consumption of 66%. The piston approach is clearly

appropriate in terms of power consumption for the

predominant automotive cycles. (See Figure 6.)

Figure 7 shows the Generation 2 compressor

component being tested and delivered at the end of

this development phase. The manifold configuration

shown in Figure 7, in addition to its normal

functions of intake and exhaust of compressed air,

also provides a shroud for highly effective forced

cooling of the piston chambers. The expander

configuration is exactly the same as the

compressor’s. Only the valving accommodating the

variable-pressure control function will be different.

Current efforts involve the implementation and

testing of the expander valving system.

Figure 7. Compressor with manifolds.
Fuel Cells for Transportation FY 1999 Progress Report

131

The compressor and the expander will be

integrated with an available drive motor, as shown in

Figure 8, and tested in this phase.

Figure 8. Motor/compressor/expander integrated for

testing.

References and Publications

1. Cronin, J. “Assessment Report – Twin-Screw

Compressor vs. VDCE,” May 1998.

2. Cronin, J., and S. Milburn, “Relationship

between Vehicle Duty Cycle and Air Systems,”

presented at the Fuel Cell Vehicle Technology

Conference, The Institute of Transportation

Studies, University of California, Davis. April

28-29, 1998.

3. Cronin, J. “Variable Displacement Compressor

Development,” Poster Presentation at the

Automotive Technology Development

Customers’ Coordination Meeting. Oct. 27-30,

1997.

D. Electrically Boosted Gas-Bearing Turbocompressor for Fuel Cells

G. Fonda-Bonardi and P. Fonda-Bonardi

Meruit, Inc., 1450 23rd St., Santa Monica, CA 90404-2902

(310) 453-3259, fax: (310) 828-5830, e-mail: fbarch@concentric.com

Eric Sonnichsen

Test Devices, Inc., 6 Loring St., Hudson, MA 01749

(978) 562-6017, fax: (978) 562-7939, e-mail: esonic@testdevices.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: Meruit, Inc., Santa Monica, CA 90404-2902

Prime Contract No. DE-FC02-97EE-50480, August, 1998-July, 1999

Subcontractor: Test Devices, Inc., Hudson, MA 01749

Objectives

• Develop and test a Rayleigh step gas-bearing set for small turbomachinery.

• Develop a 70-g/s PEM cell turbocompressor with an integral, high-speed electric motor to supply any required

boost.

OAAT R&D Plan: Task 13; Barrier D
Fuel Cells for Transportation FY 1999 Progress Report

132

Approach

• Design and manufacture a gas-bearing test object modeling a turbocompressor.

• Test the gas-bearing test object according to established test protocol.

• Design the 70-g/s turbocompressor.

• Choose the matching high-speed electric boost motor and power supply.

• Manufacture and test the boosted turbocompressor test object.

Accomplishments

• Designed and fabricated the gas bearing test object; created the test protocol.

• Modeled bearing performance in static, steady-state, and transient conditions.

• Predicted performance to be extremely stiff with an idle stiffness of about 20,000 lb/in., strong damping of

oscillations, and no harmful resonant frequencies.

• Statically tested gas bearings, verifying the predicted zero-speed stiffness of 2,500 lb/in.

• Designed an efficient compressor wheel with extended turndown ratio.

Future Directions

• Continue dynamic testing of the gas bearing.

• Continue turbocompressor design concurrently with the bearing testing program.

Introduction

To use the warm (~180°F), low-pressure

(~30 psia) PEM cell exhaust flow to achieve a fuel

cell air compression of ~45 psia requires very

efficient bearings to support the rotor of a small,

efficient turbocompressor. Accordingly, the PRDA

DE-FC02-97EE-50480 PRDA contract has two

major tasks: the first task is to build and test an

experimental gas thrust bearing designed to

represent the bearing in a turbocompressor for the

DOE standard 50-kW automotive fuel cell; if, and

only if, the proposed thrust bearing performs as

expected, the second task is to design, build, and test

a complete turbocompressor for 50-kW fuel cell

service, including a built-in electric motor for

makeup power (if needed) and presumably for

startup.

Meruit proposes to use proprietary radial

(journal) and thrust gas bearings that would use less

than 1% of the compressor mass flow for lubrication

and cooling. Meruit has modeled the gas bearing's

performance under static, steady-state, and transient

conditions; designed and built a bearing test object;

and statically tested the bearings. Dynamic testing

will proceed in August and September of 1999; here,

we present some of the computed findings.

Technical Progress and Accomplishments

to Date

Meruit, Inc. has completed the following subtasks as

part of Task 1:

1. Preliminary design of a turbocompressor

suitable for the DOE 50-kW target fuel cell; the

bearing test object simulates the size, mass, and

moments of inertia of the shaft, bearings, turbine and

compressor wheels, and integral electric motor

(collectively, the “rotor”).

2. Determination of the parameters relevant to the

design of the test article, which are:

Maximum speed: 85,000 rpm

Idle speed: 55,000 rpm

Radial bearing

Diameter: 20.73 mm (0.8165 in.)

Rubbing speed: 121.5 m/s (398 ft/s)

Thrust bearing

Diameter: 62.25 mm (2.451 in.)

Tip speed: 277.1 m/s (909 ft/s)

Rotor weight: 1,115 g (2.45 lb)
Fuel Cells for Transportation FY 1999 Progress Report

133

3. Modeling bearing performance: The

computation of the expected thrust bearing stiffness

at several running speeds is shown in Figure 1. As

the rotor moves in its clearance, the thrust bearing

creates a restoring force toward the center of its

clearance, which in the case of the small

turbocompressor designed here is on the order of

0.001 inches per side. Because the air pressure

expected from the compressor varies with speed, the

bearing’s stiffness also varies: it is stiffer at higher

air pressures (i.e., at higher speeds). In Figure 1,

expected force and stiffness developed by the gas

bearing in the test object at different speeds are

shown. The X-axis represents displacement Z from

dead center as a proportion of the clearance B2; for

example, when the rotor has traveled to 90% of the

available clearance, the restoring force generated by

the gas bearing is about 21 lb at 55,000 rpm (turbo

idle) and 48 lb at 85,000 rpm (full speed).

The predicted forces and displacement allows

for calculation of a spring constant, or stiffness: it

turns out that air in the recesses of the Meruit gas

bearing is quite stiff, with a k-factor of about

2,500 lb/in. at zero speed, at least 18,000 lb/in. of

displacement at idle, and 41,000 lb/in. at full speed.

Since the rotor is expected to weigh about 2.45 lb,

the gas bearing should be stiff enough to support the

rotor in normal automotive service.

When “floating” in the gas bearing, the rotor may

be thought of as a mass suspended on very stiff

springs, and it may be subject to resonance frequency

effects that might make the bearing unstable in a

critical speed range or when subjected to transient

accelerations. Although Meruit predicts that the

proposed gas bearing will strongly damp any

reasonable vibration, collisions must be considered.

Figure 1. Computed thrust bearing stiffness.

Figure 2 shows a typical response of the suspended

mass to a sudden deceleration of the housing from a

collision speed of 5 mph to zero in a distance of

0.5 ft (corresponding to the crumpling of the bumper

and perhaps some sheet metal) for various rotating

speeds of the turbocompressor (resulting in various

values of the stiffness). The deceleration is assumed

to occur with a sine-like variation, as shown on the

lower curve. The top curve shows the displacement

of the mass from the center of the stroke toward

contact with the thrust bearing face, where the

displacement is initial clearance B2. A collision of

this strength will not cause contact for all speeds

above 30% of the design speed of 85,000 rpm

(i.e., never, if the idling speed of the

turbocompressor is higher than this). The curves are

spaced by intervals of approximately 10% of

maximum stiffness, which is not linear with

displacement or rotating speed.

If contact occurs, the natural frequency of the

spring-mass system is excited, causing oscillations

after contact is released; the oscillations decay with a

characteristic damping coefficient. We have not yet

investigated the details of the release of contact,

which depends on the characteristics of the

contacting surfaces; an experiment recommends

itself.

4. Modeling turbocompressor rotor dynamics: In

the steady-state case, the natural frequency for small

amplitudes is wn

= k / m (see Table 1), where

rpm and wn are converted into comparable units of

frequency (Hertz): f = RPM/60, and f

n =wn

/ 2 p,

and r = f / f

n

 .

Figure 2. Computed response to 5-mph collision.
Fuel Cells for Transportation FY 1999 Progress Report

134

Table 1. Turbocompressor rotor dynamics.

rpm f fn r

85,000 1416.67 412.92 3.43

80,000 1333.33 392.42 3.39

75,000 1250.00 371.94 3.36

70,000 1166.67 350.22 3.33

65,000 1083.00 329.05 3.29

60,000 1000.00 302.03 3.32

55,000 916.67 275.64 3.33

The ratio r is large and almost constant, meaning that

if the housing is made to vibrate in the axial direction

with amplitude Z, the rotor will respond synchronously

with the spin with an amplitude of approximately 1.1

Z, and the relative displacement will be approximately

0.1 Z. It is exceedingly unlikely that the spinning rotor

could ever induce an axial vibration of the housing of

any amplitude comparable with B2; therefore, the

steady-state response appears to be entirely

satisfactory. It is equally unlikely that any external

excitation of the housing by vehicle (e.g., engine)

vibrations and associated harmonics would have

components near the natural frequency f

n

. Hence, all

natural frequencies appear to be far from the

corresponding running speed, so that no resonances

are expected.

5. Designed and fabricated the bearing test object.

6. Defined the test protocol for the measurement of

static and dynamic characteristics of the test article.

7. Tested the bearing statically, finding the

predicted zero-speed stiffness.

8. Designed an efficient compressor wheel with the

desired pressure ratio and extended turndown

performance.

Future Activities

Meruit will:

1. Continue dynamic testing of the gas bearing.

2. Continue modeling compressor and turbine

wheels to find a matched set for the best overall

performance.

3. Build and test (when bearing wheel performance

issues are settled) the turbocompressor test

object. For further information, please refer to

the cited references.

References

1. G. Fonda-Bonardi, “Gas Bearing for High-Speed

Turbomachinery,” paper presented at the July

1999 ASME Fluids Engineering Conference,

San Francisco, Calif. (FEDSM99-7327).

2. G. Fonda-Bonardi, “Meruit Turbocompressor

PRDA: Gas Bearing Experimental Results,” DOE

PRDA FC02-97EE-50480, June 20, 1999.

3. G. Fonda-Bonardi, “Meruit Turbocompressor

PRDA: Turbocompressor Design and Test,” DOE

PRDA FC02-97EE-50480, June 2, 1999.

4. G. Fonda-Bonardi, “Gas Bearing for High-Speed

Turbomachinery,” paper presented at the July

1998 ASME Fluids Engineering Conference,

Washington, D.C. (FEDSM98-5120).

5. G. Fonda-Bonardi, “Meruit Turbocompressor

PRDA: 1998 Program Review,” DOE PRDA

FC02-97EE-50480, June 20, 1998 (includes Apps.

A, B, and C).
Fuel Cells for Transportation FY 1999 Progress Report

135

VII. HYDROGEN STORAGE1

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

Richard Kunz (Primary Contact) and Andy Haaland

Thiokol Propulsion

P.O. Box 707, M/S 254

Brigham City, UT 84302-0707

(435) 863-8799, fax: (435) 863-6223, e-mail: kunzrk@thiokol.com

DOE Program Managers: Sigmund Gronich and JoAnn Milliken

(202) 586-1623, fax: (202) 586-5127, e-mail: sigmund.gronich@hq.doe.gov

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

ANL Technical Advisor: Walter Podolski

(630) 252-7558, fax: (630) 252-4176, e-mail: podolski@cmt.anl.gov

Contractor: Thiokol Propulsion, Brigham City, Utah

Prime Contract No. DE-FC02-97EE-50484, September 30, 1997-March 31, 2000

Subcontractors: Aero Tec Laboratories, Ramsey, NJ, and Southern Research Institute, Birmingham, AL

Objective

Develop and demonstrate key enabling technologies for on-board conformable high-pressure hydrogen storage for

fuel-cell-powered light vehicles.

OAAT R&D Plan: Task 1; Barrier I

Approach

Phase I: Component Development and Integration

• Composite structural capability development

- Demonstrate required pressure capability of conformable tanks for high-pressure hydrogen storage

- Optimize design, materials, and processes to enhance structural efficiency

• Liner technology development

- Develop materials and processing capability for plastic liners for conformable hydrogen tank

- Design and fabricate liners for integration and testing

• Integration and testing

- Integrate liner and composite technology development through fabrication of plastic-lined,

composite overwrapped conformable prototype tanks

- Perform burst and permeation testing

Phase II: Safety and Durability Testing

• Fabricate 12 full-scale conformable hydrogen tanks

• Perform qualification safety testing

 

1

The Hydrogen Storage System Development projects are co-funded by the DOE Office of Transportation

Technologies and the Office of Power Technologies Hydrogen Program.
Fuel Cells for Transportation FY 1999 Progress Report

136

Accomplishments

• Completed liner process development and fabricated full-scale conformable liners for tank fabrication

• Fabricated full-scale tanks on plastic liners and validated tank structural capability through hydroburst testing

• Performed liner material permeation testing at high and low temperature and under biaxial strain

• Performed mechanical property testing of candidate liner materials to determine processability and estimate

cycle life capability

• Identified and tested additional candidate liner materials

• Fabricated subscale and full-scale tanks with candidate liner materials to verify processability and burst/cycle

performance

• Initiated subscale and full-scale tank cycle testing and integrated leak testing

Future Directions

• Down-select to one baseline liner material and one backup liner material

• Fabricate twelve full-scale tanks and perform Phase II qualification safety testing.

Introduction

Several challenging technical issues confront

on-board high-pressure hydrogen storage for fuel

cell powered vehicles. Because the energy density of

hydrogen is significantly less than that of

conventional fuels, larger tanks are required for

equivalent range. Furthermore, because the

geometry of traditional high-pressure cylinders

generally does not conform to the available space on

the vehicle, packaging issues arise. 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 (Figure 1) uses

multiple cells, the number and shape of the cells

being 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.

The tanks are designed for a service pressure of

5,000 psi with a burst safety factor of 2.25,

consistent with existing standards for high-pressure

Figure 1. Thiokol’s conformable storage concept.

vehicle fuel tanks. The full-scale tank under

development is a two-cell configuration that fits in

an envelope 12.8 in. x 21.2 in. x 27.9 in. The tank

has a water volume of 17.9 gal and a capacity of

3.4 lb of hydrogen at a nominal service pressure of

5,000 psi. The conformable tank provides 23% more

capacity than would two cylinders in the samevolume 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 were defined

Cylinders in a rectangular envelope

Cylinders in a rectangular envelope

End View
Fuel Cells for Transportation FY 1999 Progress Report

137

in cooperation with Ford Motor Co. and Directed

Technologies, Inc., and are consistent with space

constraints on Ford’s P2000 fuel cell vehicle.

Structural Capability Development

Successful structural tests of subscale prototype

tanks during FY 1998 led to design, fabrication, and

testing of full-scale tanks during the current fiscal

year. The plastic liners for the full-scale tanks

(Figure 2) were designed by Thiokol and fabricated

by Aero Tec Laboratories (ATL) by using the

rotational molding process. Cross-linked

polyethylene (XLPE) was used for the initial liners.

Fabrication process development was performed to

optimize filament winding on the non-cylindrical

plastic liners. Winding patterns and tow tensions

were determined to minimize fiber slippage at the

dome transitions, ensuring adequate load transfer.

Figure 2. Full-scale plastic liner with aluminum polar

boss.

The tanks were designed for a minimum burst

pressure of 11,250 psi, consistent with a 5,000-psi

service pressure and a 2.25 burst factor, based on

finite element analysis of the tank configuration.

Two tanks were filament-wound using Toray’s

M30S carbon fiber with Thiokol’s TCR® prepreg

resin system (Figure 3). Both tanks were hydrobursttested; they burst at 11,600 psi and 12,150 psi,

respectively. Structural failure initiated in the hoop

overwrap and cell sidewalls (Figure 4), consistent

with the designed failure mode.

A third tank was fabricated to the same

composite design, using liners composed of Kynar

Flex, a PVDF polymer formulated for rotational

Figure 3. Full-scale conformable tank.

Figure 4. Full-scale conformable tank following

hydroburst test.

molding. This tank, which was hydroburst at a

pressure of 13,725 psi, also exhibited the desired

hoop failure mode.

The above-described testing validates the

capability of the conformable tanks to meet the

pressure requirements for hydrogen storage.

Refinements to the design and fabrication of the fullscale tanks are being developed to improve overall

carbon fiber structural performance. Advanced

analytical techniques are under development to more

accurately predict structural response to pressure
Fuel Cells for Transportation FY 1999 Progress Report

138

loading. This will lead to the ability to optimize the

tank structure within the constraints imposed by the

filament-winding process.

Liner Material Selection

Current tank development efforts are focused on

material and processing issues relevant to the

development of plastic liners. The liner serves as a

permeation barrier to the stored hydrogen, as well as

a mandrel for filament-winding the load-carrying

composite overwrap. Rotational molding was

selected as the processing method for prototyping

and low-volume liner production. ATL initially

conducted an extensive liner material assessment,

considering key properties of permeability,

processability, density, mechanical properties,

material compatibility, and cost of 35 polymer

formulations. Based on this evaluation and on

preliminary data, three polymer classes – XLPE,

nylons, and PVDF – were chosen for further

screening.

Because hydrogen permeation is a key selection

criterion for the liner material, Southern Research

Institute (SRI) developed a unique permeation test

fixture for this program. The setup can test

permeability of sample coupons to a pressure

differential of 5,000 psi at ambient, high, and low

temperatures, as well as under biaxial strain. Initial

permeability screening tested unstrained,

rotationally molded coupons at ambient temperature

for XLPE, Nylon, and PVDF (Figure 5). A

permeability value of 10-14 mol/(m·s·Pa) is estimated

to provide a tank half-life of 6 months for a 0.15-in.-

thick liner.

Permeation testing at high and low temperatures

and under biaxial strain has been performed on

Nylon-6 at SRI to evaluate the effects of in-service

conditions on permeation. At 180°F, the

permeability increased by approximately one order

of magnitude above ambient; at -40°F, permeability

declined by one order of magnitude. No measurable

influence was observed with the specimen under 1%

biaxial strain, which is representative of strain

conditions at service pressure. A full-scale

conformable tank with an XLPE liner is now

undergoing integrated leak testing to determine the

correlation with coupon permeability data.

-17

-16

-15

-14

0 1 2 3 4 5

Delta Pressure (ksi)

XLPE

Nylon-6

 Nylon-11

 Kynar PVDF

 Kynar Flex PVDF

Figure 5. Hydrogen permeability of candidate polymers

at ambient temperature.

The liner also largely limits tank cycle life.

Fatigue failures are generally characterized by

leakage at a liner through-crack. Mechanical

property testing of rotationally molded coupons for

candidate liner materials is ongoing to estimate tank

cycle life. Tensile data collected over a range of

strain rates are used in a viscoelastic cumulative

damage model.1 Tank finite element analysis results

are then used with the damage model to estimate

liner cycle life (Figure 6). This approach has been

1

10

100

1000

10000

100000

1000000

Figure 6. Cycle life estimates for various liner materials.
Fuel Cells for Transportation FY 1999 Progress Report

139

effective in screening candidate liner materials and

in identifying the material property parameters that

most influence cycle life. Subsequent pressure cycle

testing of both cylindrical and conformable tanks

has demonstrated excellent correlation with model

predictions.

Liner Evaluation

Coincident with material screening via

permeation and mechanical property testing, liner

evaluation has been conducted by fabrication and

testing of both subscale cylindrical and full-scale

conformable tanks with candidate liner materials.

Tanks fabricated using both Nylon-6 and Kynar

developed liner cracks at low pressure following

composite cure. The Nylon-6 liners exhibited

brittle-type behavior and a large degree of porosity.

The Kynar liners were apparently degraded by the

composite cure cycle.

XLPE-lined tanks have performed well in both

burst and cycle testing. It was found that the

mechanical properties and cycle life behavior of

XLPE liners could be improved by preconditioning

to the composite cure temperature prior to tank

fabrication (see Figure 6). The Kynar flex tanks

have also performed very well in both burst and

cycle testing. Evaluation of Nylon-12 as a potential

liner material is still in progress.

Future Plans

On the basis of analysis and testing to date,

XLPE, Kynar Flex, and Nylon-12 remain potential

candidates for liner materials. Further evaluation of

these materials will lead to the selection of one

baseline and one backup to carry into Phase II

qualification testing. Because of the lack of a

current industry standard for safety, durability, and

performance testing of hydrogen tankage for fuel

cell vehicles, qualification tests will be based on the

current NGV22 standard for natural gas vehicles.

Performed using full-scale two-cell conformable

tanks, the tests will include burst, pressure cycling,

environmental cycling, flaw tolerance, drop impact,

accelerated stress rupture, and bullet impact.

Previous test results on both subscale cylinders

and full-scale conformable tanks will be used to

guide the material selection and design of tanks for

qualification testing. In supporting programs,

conformable tanks have been successfully tested to

the NGV2 standard for burst; pressure cycling at

ambient, high, and low temperature; and flaw

tolerance. Drop impact testing has revealed the need

for additional damage protection because of the

inherent sensitivity of carbon fiber composites to

impact damage. An external foam protection system

is currently under development and will be

incorporated into the design.

Publications/References

1. K.L. Laheru, “Development of a Generalized

Failure Criterion for Viscoelastic Materials,” J.

of Propulsion and Power, AIAA, Vol. 8, No. 4,

July/August 1992.

2. “Basic Requirements for Compressed Natural

Gas Vehicle (NGV) Fuel Containers,” American

National Standard ANSI/IAS NGV2-1998.

3. R.K. Kunz, R.P. Golde, and B.M. McQuivey,

“High Pressure Conformable Hydrogen Storage

for Fuel Cell Vehicles,” Proceedings, 10th

Annual U.S. Hydrogen Meeting and Exhibition,

Vienna, Va., April 7-9, 1999, sponsored by

National Hydrogen Association.

4. R.P. Golde, R.K. Kunz, and M.J. Warner, “The

Shape of Things to Come,” SAMPE Journal,

March/April 1999.
Fuel Cells for Transportation FY 1999 Progress Report

140

B. Advanced Chemical Hydride Hydrogen Generation/Storage System for

PEM Fuel Cell Vehicles

Dr. Ronald W. Breault, Christopher A. Larsen, Jonathan Rolfe, and Andrew W. McClaine

Thermo Power Corporation

45 First Avenue

Waltham, MA 02454-9046

(781) 622-1046, fax: (781) 622-1025, e-mail: rbreault@tecogen.com

DOE Program Managers: Sigmund Gronich and JoAnn Milliken

(202)586-1623, fax:(202)586-5127, e-mail: sigmund.gronich@hq.doe.gov

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

ANL Technical Advisor: Walt Podolski

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

Contractor: Thermo Power Corporation, Tecogen Division, Waltham, MA

Prime Contract No. DE-FC02-97EE50483, October 1997-April 2000

Objectives

The objective of this program is to develop a prototype, 50-kW electric power equivalent hydrogen supply system

utilizing an innovative chemical hydride/organic slurry technology. The system goals are to construct a hydrogen

storage system with a gravimetric power density of greater than 3355 W·h/kg and a volumetric power density of

greater than 929 W·h/L.

OAAT R&D Plan: Task 1; Barrier I

Approach

The program covers a 30-month period that comprises two phases. During the first 15-month phase, Thermo Power

optimized the hydrogen generation efficiency of the proposed process, utilizing a laboratory-scale reactor unit

(1-kW equivalent). In the second phase, Thermo Power will be fabricating and evaluating the performance of a

prototype hydrogen supply system for 50-kW fuel cell systems. The approach we are following to accomplish the

objectives of this program is to:

• Investigate and select metal hydride and organic slurry materials to achieve maximum specific energy.

• Optimize the hydride/organic selection for minimum weight and high stability.

• Develop a system for quick, complete activation of the hydride with minimum weight.

• Establish a thermal management design for a prototype system, including heat dissipation and use.

• Design and fabricate a 50-kW-equivalent prototype system.

• Evaluate and optimize performance of the prototype system.

• Complete hydrogen supply system integration into simulated power sources and performance evaluation.

Accomplishments

The accomplishments of this program during its first year, beginning in October 1997, are as follows:

• Evaluated a wide selection of chemical hydrides and oils to use as slurries.
Fuel Cells for Transportation FY 1999 Progress Report

141

• Selected lithium hydride for the chemical hydride and a light mineral oil as the slurry liquid. With the use of

some carefully selected dispersants, Thermo Power developed a procedure to form a slurry of the mixture. The

slurry is transportable and stable, and it protects the chemical hydride from accidental or incidental contact with

moisture in the air.

• Developed a hydrogen generation system that produces hydrogen from the chemical hydride slurry and water.

The generator is reliable, controllable, and capable of supplying hydrogen under moderate pressures. It

produces hydrogen on demand and can be scaled to larger sizes as required.

During the second year of the program, through June 1999, Thermo Power has:

• Completed the design of a thermal management system to handle the heat released during the reaction between

the chemical hydride and water.

• Completed the design and fabrication of a prototype 50-kW electric-power-equivalent hydrogen generator.

Future Directions

The balance of Year 2 will see the production and testing of the prototype reactor. The system will provide actual

operating experience and an in-depth understanding of the realistic and practical application of the technology, as

well as revealing areas that require further efforts in design, selection of materials, and process control. Work will

be done to optimize the system and to improve subsystems requiring additional attention. The design will be

specifically for a PEM fuel cell application.

Introduction

To supply high-purity hydrogen for fuel-cellpowered vehicles, Thermo Power Corporation is

working on the use of a chemical hydride/organic

slurry as the hydrogen carrier and storage medium.

At the point of use within the vehicle, high-purity

hydrogen will be produced by reacting the hydride

slurry with water. The chemical hydride slurry

approach for hydrogen storage is attractive because:

• The organic slurry system can moderate the

reaction rate of the hydrolysis process,

minimizing the possibility of runaway reactions

such as had occurred in other efforts. In the

event of a spill, the reaction of the chemical

hydrides with environmental moisture would

result in slow release of hydrogen. This would

be a hazard comparable with a spill of liquid

hydrocarbons for today’s vehicles.

• The pumpable organic slurry can be accurately

metered, depending on hydrogen demand,

pressure, and temperature, to provide safety and

reaction control not otherwise possible.

• The use of a simple low-pressure chemical

hydride slurry storage system provides

volumetric densities approaching that of

cryogenic hydrogen storage.

During the past nine months, the program has

focused on the issues of (1) developing a thermal

management design and (2) designing and

fabricating a prototype 50-kWe equivalent hydrogen

generator.

Thermal Management

During the hydrolysis reaction, heat evolves that

is equivalent to 37% of the energy contained in the

hydrogen stream. Thus, when the reactor is working

at its full 50-kW electrical output, it evolves 37 kW

of heat. Unfortunately, because of the mineral oil in

the slurry, the temperature of this heat energy must

be limited to near 100°C to prevent damage to the

mineral oil and contamination of the hydrogen

product. Disposing of this heat is a difficult problem

given the size and weight restrictions for the system.

Care must be taken to create a small, lightweight

heat exchanger for the system.

In accomplishing this task, Thermo Power

evaluated four systems:

1. The direct heat-exchange system considers heat

exchange from the reactants through the reactor

wall to a water jacket surrounding the heat

exchanger. This first design weighs too much,

and it is bulky.

2. The water-bathed reactor directly mixes the

reactants with the cooling water. The advantage
Fuel Cells for Transportation FY 1999 Progress Report

142

of this system is that heat is not transferred

through a fixed surface, reducing the weight of

the heat-exchange system. Unfortunately, the

cooling water cannot be separated from the

waste products with a reasonable weight or

volume.

3. The auger-aided, water-vaporizing reactor

accomplishes the cooling water/ waste product

separation thermally. Excess water is injected

into the reaction zone to be vaporized by the

heat of reaction. The water is then condensed in

water-vapor-to-air heat exchangers. This system

works, but the heat-exchanger size is a bit larger

than desired. The design of the 50-kW reactor

will be based on this design (see Figure 1).

4. The packed-bed vapor-condensing design

focuses on the condensation of water vapor. It

uses a dense packed bed to extract heat and

water from the hydrogen stream. The packed

bed is cooled by water pumped through a waterto-air heat exchanger. This system may have

some benefits, but it is expected to weigh more

than the third design with direct vapor-to-air

heat exchangers.

Granular

Products

H2

Auger Drive Motor

Steam Condenser

H2O Pump

Hydride

Slurry

Auger/

Reaction

Chamber

Slurry

Solid/Gas

Separation

H2/Water Separation

Water

Figure 1. Auger-aided water-vaporization heat-transfer

system

Design and Fabricate Prototype System

The goal of Task 5 is to design and fabricate a

high-purity 50-kWe H2 system capable of operating

for 15 min at 50 kWe (3 kg H2/hr). From the results

of the previous tasks, Thermo Power has selected

the mixed reactor, water-vaporizing reaction system

for its simplicity and ability to satisfy weight and

volume goals of 3350 W·h/kg and 930 W·h/L. This

design evaporates water to absorb the heat of

reaction. During operation, pumps meter slurry and

water into the reaction zone. An auger continually

clears the injection zone and mixes the two reactants

to ensure a quick, complete reaction. A short paddle

section of the auger ensures an adequate residence

time in the reactor, allowing heat to transfer from the

hot products to the excess water used for cooling.

The dry products of the reaction are pushed into a

hydroxide storage tank. Hydrogen and water vapor

produced by the reaction are cooled in the vapor-toair heat exchanger. This exchanger condenses the

water vapor and returns it to the water tank. The

product hydrogen stream is filtered and dried before

use in a fuel cell. Figure 2 is a picture of the

completed hydrogen generator.

Hydride

Slurry Tank

H2 Generator

Heat

Exchanger

Figure 2. 50-kWe hydrogen generation system.

The system mass and volumetric design

summary are provided in Table 1. The pilot system

is compared with the design system. The differences

between the pilot and the ultimate design are caused

by the need to design for additional safety for the

prototype system.
Fuel Cells for Transportation FY 1999 Progress Report

143

Table 1. System design summary.

Ultimate

Design Pilot Design

Wt. Vol. Wt. Vol.

(kg) (L) (kg) (L)

Hydride 103 76 103 76

Hardware 76.5 374.2 141.5 379.2

W·h/k

g

W·h/

L

W·h/k

g

W·h/

L

Value 3362 1341 2468 1326

Goal 3355 929 3355 929

Publications/References

1. R.W. Breault, J. Rolfe, and A. McClaine,

“Hydrogen Transmission/ Storage with a

Chemical Hydride/ Organic Slurry,” 9th

Canadian Hydrogen Conference, Vancouver,

B.C., Feb. 7-10, 1999.

2. R.W. Breault, J. Rolfe, and A. McClaine,

“Hydrogen for the Hydrogen Economy,” 24th

Coal Utilization and Fuel Systems Conference,

Clearwater, Fla., March 8-11, 1999.

3. R.W. Breault and J. Rolfe, “Chemical Hydride

Hydrogen Storage Canisters for DOD Fuel Cell

Applications,” 10th National Hydrogen

Association Conference, Tysons Corner, Va.,

April 7-9, 1999.

4. R.W. Breault, C. Larson, and J. Rolfe,

“Hydrogen for a PEM Fuel Cell Vehicle Using a

Chemical-Hydride Slurry,” 10th National

Hydrogen Association Conference, Tysons

Corner, Va., April
Fuel Cells for Transportation FY 1999 Progress Report

144
Fuel Cells for Transportation FY 1999 Progress Report

145

APPENDIX A: ACRONYMS, INITIALISMS, AND

ABBREVIATIONS

ADL Arthur D. Little, Inc.

AIAA American Institute of Aeronautics and Astronautics

ANL Argonne National Laboratory

ANSI American National Standards Institute

APOR Argonne Partial Oxidation Reformer

ASR area specific resistance

ASTM American Society for Testing and Materials

ATL Aero Tec Laboratories

ATR autothermal reformer

BNL Brookhaven National Laboratory

BOP balance-of-plant

BTB back-to-back

CARB California Air Resources Board

CCM catalyst-coated membrane

CEM continuous emission monitor or compressor expander module

CNG compressed natural gas

CO carbon monoxide

CSA Cell Stack Assembly

DARPA Defense Advanced Research Projects Agency

DCC diffuser current collector

DI deionized

DMFC direct methanol fuel cell

DOE U.S. Department of Energy

ELATTM solid polymer electrolyte electrode

FC fuel cell

F

3

P fuel-flexible, fuel-processing or fuel-flexible, fuel-processor

FPS fuel processing system

FUDS Federal Urban Driving Schedule

FY Fiscal Year

GC gas chromatographic or gas chromatography

GC/MS gas chromatography/mass spectroscopy

GDE gas diffusion electrode

GDL gas diffusion layer

GHSV gas hourly space velocity

GTR gas transmission rate, gas permeability

H2 hydrogen

HAZOP hazardous operations

HBT Hydrogen Burner Technology

HLTS humidified low-temperature shift

HTS high-temperature water-gas shift reactor or high-temperature shift

HTSPEM high-temperature solid polymer electrolyte membrane

IAS International Approval Services

ICE internal combustion engine

ICEM integrated compressor expander motor

ICP ion-conducting polymer

IEC ion exchange capacity
Fuel Cells for Transportation FY 1999 Progress Report

146

IFC International Fuel Cells

IGT Institute of Gas Technology

IPN interpenetrating network

LANL Los Alamos National Laboratory

LHV lower heating value or low heat value

LMTD log-mean temperature difference

LTS low-temperature water-gas shift reactor or low-temperature shift

LTSC low-temperature shift converter

M-85 85% methanol and 15% gasoline

MEA membrane electrode assembly or membrane/electrode assembly

MPR Modular Pressurized Flow Reactor

MTBE methyl tertiary butyl ether

NEMCA non-Faradaic Electrochemical Modification of Catalytic Activity

NG natural gas

NGV natural gas vehicle

NMOG nonmethane organic gas(es)

NMR nuclear magnetic resonance

NOx oxides of nitrogen

NREL National Renewable Energy Laboratory

OAAT Office of Advanced Automotive Technologies (DOE)

ORR oxygen reduction reaction

PBO poly-p-phenylene benzobisoxazole

PC personal computer

PECMFC proton exchange ceramic membrane fuel cell

PEFC polymer electrolyte fuel cell

PEM polymer electrolyte membrane or proton exchange membrane

PEMFC PEM fuel cell

PIII plasma immersion ion-implantation

PNGV Partnership for a New Generation of Vehicles

PNNL Pacific Northwest National Laboratory

POCO a subsidiary of UNOCA, originally the graphite division of Pure Oil

Company

POX partial-oxidation reformer or partial oxidation reactor

PPSU polyphenylsulfone

PRDA program research and development announcement

PROX preferential oxidizer or preferential oxidation

PVDF polyvinylidene fluoride

QA/QC quality assurance/quality control

R&D research and development

RFG reformulated gasoline

RH relative humidity

SAMPE Society for the Advancement of Material and Process Engineering

SFAA solicitation for financial assistance application

SOTA state-of-the-art

SPEFC solid polymer electrolyte fuel cell

SPPSU sulfonated PPSU

SRI Southern Research Institute

SS stainless steel

SULEV super-low-emission vehicle (California standard)

TCR Thiokol Composite Resin

THC total hydrocarbon(s)
Fuel Cells for Transportation FY 1999 Progress Report

147

TSCE twin-screw compressor expander

UHV ultrahigh vacuum

ULEV ultralow-emission vehicle

UOB Under-Oxidized Burner

UOP formerly known as Universal Oil Products

USCAR U.S. Council for Automotive Research

WGS water gas shift

XLPE cross-linked polyethylene

ZEV zero-emission vehicle