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Honeywell

Final Technical Report

SYSTEM DESIGN OF A NATURAL GAS PEM FUEL CELL POWER PLANT FOR BUILDINGS

2K-70886-4 September 30, 2000

Prepared For The United States Department of Energy

Contract DE-FC02-99EE27566

Honeywell

Final Technical Report

SYSTEM DESIGN OF A NATURAL GAS PEM FUEL CELL POWER PLANT FOR BUILDINGS

2K-70886-4 September 30, 2000

PROTECTED DATA INFORMATION

This Protected Data Information was produced under Agreement No DE-FC02-99EE27566 with the U S Department of Energy and may not be published, disseminated or disclosed to others by the Government unless otherwise authorized in the Agreement until live (5} years from the date the data is produced unless express written authorization is obtained from Awardee Upon expiration of the period of protection set forth in this legend, the Government shall have unlimited rights to this data This legend shall be marked on any reproduction of this data, in whole or in part

Prepared For The United States Department of Energy

Contract DE-FC02-99EE27566

CONTENTS

Section Page

1. EXECUTIVE SUMMARY 1-1

1.1 Phase I Approach 1-1 1.2 Critical Technology Evaluation 1 -1 1.2.1 Fuel Processor Technology 1-2 1.2.2 High-Temperature Membrane Electrode Assembly (MEA) 1-3 1.2.3 Gas Compression 1-3 1.2.4 Cogeneration Unit 1-4 1.3 System Screening and Analyses 1-4 1.4 Economic Viability 1 -6 1.5 System Screening Conclusions 1-7 1.6 Recommendations for Phase II System 1-8

2. INTRODUCTION 2-1

2.1 Objective of Study 2-1 2.2 Approach 2-2 2.2.1 Task 1: Application Definition and System Screening 2-2 2.2.2 Task 2: System Definition 2-2 2.3 This Report 2-3

3. CRITICAL TECHNOLOGIES 3-1

3.1 Natural Gas Fuel Processor 3-1 3.2 High-Temperature Fuel Cell 3-4 3.2.1 Mechanisms 3-4 3.2.2 High-Temperature PEM Fuel Cell Data 3-5 3.3 Gas Compressors and Turbocompressors 3-7 3.4 Cogeneration Unit 3-10 3.4.1 Building Heating Cogeneration 3-10 3.4.2 Building Cooling Cogeneration 3-11

4. SYSTEM ANALYSIS 4-1

4.1 DOE Goals 4-1 4.1.1 Heat Rejection Greater Than 100°C 4-1 4.1.2 Thermal-to-Electrical Efficiency of 35 Percent 4-1 4.1.3 Minimal Heavily-Loaded Mechanical Subsystems 4-1 4.1.4 High Reliability During Long-Term Operation (> 40,000 Hr) 4-1 4.1.5 Installed Cost Less Than $1500/Kw 4-2 4.1.6 Operating Pressure of 1.5 Atmospheres (ATM) or Lower 4-2 4.2 System Candidate Screening 4-2 4.2.1 Baseline System Configuration and Modeling 4-2

Honeywell 2K-70886-4 Page ii

CONTENTS (Continued)

Section Page

4.2.2 System Screening Modeling Results 4-5

4.3 System Down Selection 4-7

5. ECONOMIC ANALYSIS 5-1

5.1 Baseline Economic Parameters 5-1 5.2 Power Costs, Natural Gas Cost, and Waste Heat

Utilization for Cogeneration 5-1 5.3 Fuel Cell Replacement Costs and Intervals 5-4 5.4 Comparison of Candidate Systems 5-5

6. SYSTEM DESIGN 6-1

7. CONCLUSIONS AND RECOMMENDATIONS 7-1

7.1 Recommendations for Phase II System 7-2

Honeywell 2K-70886

Figure

ILLUSTRATIONS

Page

1-1 System Model Performance: Effects of Fuel Cell Operating Temperature and Pressure on Stack Size 1-6

1-2 Effect of Utilizing Fuel Cell by-Product Heat for Cogeneration

Heat on Economic Viability 1-7

1-3 Phase II System Design 1-10

3-1 Predicted Effect of Temperature and Pressure on High Temperature PEM Fuel Cell 3-8

3-2 Honeywell's Turbocompressor Designed for Automotive

Application Fuel Cell Stack system 3-9

3-3 Single-Effect Absorption-Chilling Cycle 3-11

4-1 Generic System Diagram of a High-Temperature PEM Fuel cell

Cogeneration System for Buildings 4-3

4-2 Effect of System Pressure and Temperature on Stack Size 4-7

4-3 Effect of System Pressure and Temperature on Available Heat for

Cogeneration 4-7

5-1 Building Power and Heating Alternatives 5-3

5-2 Effect of Gas Cost, Power Cost and Cogeneration on Economic Viability 5-5

5-3 Effect of Fuel Cell Replacement Interval and Cost on Fuel Cell Cogeneration Plant Economic Viability 5-6

5-4 Candidate System Economic Viability Comparisons with Full Effect of Waste Heat Utilization for Cogeneration 5-8

5-5 Candidate System Economic Viability Comparisons Without Waste Heat Utilization for Cogeneration 5-8

5-6 Candidate System Yearly Energy Cost Savings Due to Cogeneration (50-kW Power Plant) 5-9

6-1 Phase II System Design 6-2

Honeywell 2K-70886-4 Page iv

Table

TABLES

Page

1-1 PHASE I TECHNICAL OBJECTIVES 1-1

1 -2 FUEL PROCESSOR DEVELOPERS 1 -2

1-3 SYSTEM MODEL PERFORMANCE ASSUMPTIONS 1-5

3-1 FUEL PROCESSOR DEVELOPERS 3-1

3-2 AUTHOTHERMAL AND STEAM REFORMING YIELDS

BASED ON HBT AND HARVEST DATA 3-2

3-3 FUEL PROCESSOR COMPARISON AT 3 PSIG 3-3

3-4 HIGH-TEMPERATURE PEM FUEL CELL DEVELOPERS 3-6

3-5 HIGH-TEMPERATURE MEMBRANE SIZES 3-7

3-6 AIR AND NATURAL GAS VENDORS CONTACTED 3-8

3-7 ABSORPTION CHILLER UNITS VENDOR DATA 3-12

4-1 SYSTEM CANDIDATE FEASIBILITY MATRIX TABLES 4-3

4-2 SYSTEM SCREENING MODELING PERFORMANCE

ASSUMPTIONS 4-4

4-3 SYSTEM CANDIDATE MATRIX TABLE 4-6

5-1 ECONOMIC ANALYSES ASSUMPTIONS 5-2

5-2 CANDIDATE SYSTEMS ECONOMIC ANALYSES MATRIX TABLE 5-6

H o n e y w e l l 2K7os864 Page v

1. EXECUTIVE SUMMARY

This report is a result of a co-operative program awarded to Honeywell by the Department of Energy (DOE) in 1999. The work presented here is the results of Phase I of a three-phase program as follows:

Phase I (one year): system analysis, design and definition of a fuel cell cogeneration system for a building application utilizing a high-temperature PEM fuel cell

Phase II (two years): development, assembly and test of a technology demonstration brassboard system for building cogeneration applications

Phase 111 (multi-year): field test of a 50 kW packaged prototype unit.

1.1 PHASE I APPROACH

Phase I activities involved evaluation of fuel cell stacks and balance of plant technologies for building cogeneration applications. System requirements and applications were reviewed based on the technical objectives given in Table 1-1. Data on critical technologies were acquired as available. System trade studies were performed with the goal of achieving an electrical efficiency of 35 percent utilizing a high-temperature PEM stack capable of generating a waste-heat stream near the operating temperature of the stack. Based upon candidate membrane technologies, a conceptual design was created, and a detailed system definition was developed that meets the technical objectives outlined in Table 1-1. Recommendations for the Phase II program were based on the analyses efforts presented here.

TABLE 1-1

PHASE I TECHNICAL OBJECTIVES

Phase I Technical Target System efficiency, fuel to power System Electrical Power Temperature of stack Installed Cost Operating pressure

Value 35% based on natural gas higher heating value 50 kW, Base Loaded 100to140°C $1500/kW 1.5 atm if feasible

1.2 CRITICAL TECHNOLOGY EVALUATION

The critical technologies evaluated include the fuel processor, high-temperature fuel cell, gas compression and cogeneration unit.

Honeywell 2K-70886-4 Page 1-1

1.2.1 Fuel Processor Technology

A list of fuel processor developers contacted by Honeywell is given in Table 1-2. Fuel processor performance, status of development and yield data were collected and used for system screening and analyses. System analysis revealed that steam reforming is the preferred fuel processing approach for cogeneration building applications due to both higher hydrogen concentration and technical maturity. Autothermal reforming is also considered to be viable, though less attractive than steam reforming due to more complicated controls, slightly lower efficiency, and less mature technology. For these reasons, Honeywell selected steam reforming for its baseline system design; further analyses, however, as part of the Phase II program, is warranted.

TABLE 1-2

FUEL PROCESSOR DEVELOPERS

Developer

Argon ne GE EERC Epyx Gastec NV Haldor-Topsoe Harvest HBT Johnson-Matthey McDermott Northwest Power Pacific Northwest Shell Texaco UOP Wellman CJB

Fuel Processor Type

ATR* Steam+Adsorption Steam, ATR Steam, ATR Steam Steam ATR ATR Steam Steam/membrane ATR+Membrane ATR ATR ATR Steam

Visited by Honeywell

No Yes Yes No No Yes Yes Yes Yes No No No No Yes No

Phase II Availability

Estimated not ready Development needed Not interested Not available Not interested Yes Yes Not interested Estimated not ready Not interested Estimated not ready Not responsive Not responsive Not interested Estimated not ready

*ATR = autothermal reformer


1.2.2 High-Temperature Membrane Electrode Assembly (MEA)

High-temperature PEM technology can be classified into one of two broad categories based upon the mechanism of proton conduction within the polymer:

• A proton carrying mechanism (the vehicle mechanism, the vehicle being a water molecule)

• A lone proton migration (Grotthuss mechanism or translocation).

The conduction mechanism is very important to system design, as the vehicle mechanism requires the membrane to be saturated with liquid water while the Grotthuss mechanism does not. Hence, the vehicle mechanism requires humidification of the anode and cathode feed streams to the stack such that saturation conditions exist in the MEA; for the Grotthuss mechanism, dry anode and cathode gases can be used. For systems using a vehicle mechanism stack, pressurized operation will be required.

A list of high-temperature MEA developers contacted is given below:

3M, Arthur D. Little, Florida Solar Energy Center, Axiva NA & GmbH, Cape Cod Research, Case Western Reserve University, Dais Corp., E-Tek, Inc., Foster Miller, Inc., Fuel Cell Energy, Inc., Giner, Inc., Johnson-Matthey, Pennsylvania State University, Polymer Research Institute Syracuse University, Princeton University, University of Connecticut, University of Wisconsin, Virginia Polytechnic University, and W.L. Gore & Associates.

Useful fuel cell performance data for high-temperature PEM membranes was found to be essentially non-existent. It is noteworthy that the test conditions under which membrane developers have evaluated their membranes are very sparse and that none of the developers could or would supply either a polarization curve at the conditions required for the system or a MEA for testing. Honeywell interpreted this as a measure of the immaturity of high-temperature membranes for PEM fuel cells and was a key finding in Honeywell's decision to develop the robust system design capable of operating over a wide range of temperatures and pressures, as will be described.

1.2.3 Gas Compression

Pressurized operation is required for the vehicle mechanism stack. A turbocompressor can supply the required pressure. In operation, the motor drives the compressor, which provides pressurized ambient air to the reformer and/or fuel cell stack. The expander turbine assists the motor power consumption by recovering energy from the reformer and/or fuel cell system exhaust stream. An appropriately sized- turbocompressor is the turbine assisted motor driven compressor being designed by Honeywell for the Department of Energy under the "Turbocompressor with Variable Geometry for PEM Fuel Cells" program which is scheduled to be completed in mid-2001. The turbocompressor will be a modification of the turbocompressor used in the Honeywell 50-kW PEM fuel cell brassboard transportation system.


1.2.4 Cogeneration Unit

For building heating and hot water loads, hot water systems can be designed over a broad range of temperatures and can be characterized as follows:

• High-temperature systems: temperatures > 204°C

• Medium-temperature systems: temperatures from 82 to 204°C

• Low-temperature systems: temperatures less than 82°C

Typical PEM fuel cells operate at 80°C and below and therefore would be considered appropriate for low-temperature systems. In fuel cell systems, the waste heat generated from a fuel cell stack is in the order of 80 to 100 percent of the actual power from the stack. A liquid coolant is typically circulated through the stack to maintain temperatures in the desired range with a 5°C approach temperature. Hence, a stack operating at a nominal 100°C could supply water heat to a medium-temperature thermal distribution system in a building at 95°C.

In addition to heating loads, space cooling loads can be addressed using the coolant from a high-temperature stack. Honeywell contacted two companies, Thermax Limited and Yazaki Energy Systems, who could supply applicable units for the Phase II system demonstration.

1.3 SYSTEM SCREENING AND ANALYSES Trade studies and system analyses efforts were conducted to determine the effects

of the fuel cell type and fuel processor type on system performance and characteristics. As noted above, the vehicle mechanism requires saturated water conditions for the MEA. Hence, at high temperature (> 100°C), it became evident that the system would have to be pressurized to maintain liquid water in the MEA. Trade analyses also included the effect of stack operating temperature and pressure.

Various combinations of reformer type, stack type, operating temperatures and pressures were analyzed and modeled. The system model generated cogeneration heat, system efficiency, required fuel cell stack active area, and other heat exchanger parameters (such as required heat transfer area) for the candidate systems.

As stated above, in order to operate a high-temperature PEM fuel cell stack with a PEM that employs the vehicle mechanism for proton conduction, pressure is required to maintain water in the MEA. Hence, a turbocompressor was utilized in those system simulations where pressure is indicated. When the system is base loaded, the analysis reveals that a pressurized system is preferred regardless of the proton conduction mechanism. Pressure has the effect of reducing component sizes (especially the stack, heat exchangers, and fuel processor) and, consequently, the system cost. If the system is load following, however, a pressurized system is more complex than a low pressure

Honeywell 2K-70886-4 Page 1 -4

system and the benefits of pressure may not outweigh the complexity. Building duty cycles will be studied in Phase II.

System model performance assumptions are given in Table 1-3. As indicated earlier, the lack of fuel cell polarization curve data for high-temperature membrane required that high temperature fuel cell performance be estimated. Honeywell's approach was to use the Nernst equation and literature data on membrane conductivity to calculate performance variations away from the fuel cell performance goal of 0.35 W/cm2 at 7 psig and 120°C. With this approach, an increase in the operating pressure or temperature had the effect of increasing the cell voltage at the same current density.

TABLE 1-3

SYSTEM MODEL PERFORMANCE ASSUMPTIONS

System Net power output Fuel

50 kW @ 35 % efficiency (HHV), base loaded 143.2 kWth Natural Gas

Fuel Processor Net Fuel Processor Efficiency Fuel Processor Pressure Drop

~ 0.8 (HHV) 1 psig

Fuel Cell Power Density Polarization Curve Basis Cell Voltage at Peak Power Stack pressure drop Stoichiometry Cooling Fluid Exit Temperature/ delta-T

0.35 W/cm2 @ 7 psig (DOE Target) Projected (Experimental data unavailable) Variable, set to meet system efficiency goal 2 psig 2.0 cathode, 1.2 anode Water - stack temperature/10°C

Turbocompressor Compressor efficiency Expander (Turbine) Efficiency

0.7 0.8

The system analyses efforts indicated the following:

• The higher the operating temperature, the smaller the stack size (and system cost), as indicated in Figure 1-1.

• The higher the pressure, the smaller the stack size, regardless of whether the proton conduction mechanism is the vehicle or Grotthuss mechanism. Figure 1 -1 shows that the largest improvement is gained when the pressure is

Honeywell 2K-70886-4 Page 1 -5

increased from 3 to 30 psig. Heat exchanger and fuel processor size and cost are also reduced at pressure.

Steam reforming produces a significantly higher quality reformate stream (68 percent vs 34 percent on a wet basis at 30 psig) which will result in a lower stack size (and lower cost).

The size of the heat exchangers is reduced as the temperature is increased. This is especially true for the Grotthuss mechanism where the condenser size can be dramatically reduced due to a significant reduction in humidification requirements.

The by-product heat from the 50 kW power unit is about 35 to 50 kW depending on operating conditions and stack type. This heat is available to the cogeneration unit at approximately the stack operating condition (100, 120, or 140°C).

100 110 120

Temperature, C 130 140

Figure 1-1. System Model Performance: Effects of Fuel Cell Operating Temperature and Pressure on Stack Size

1.4 ECONOMIC VIABILITY

An economic analysis was performed to indicate the importance of various parameters including the value of the cogeneration heat. The effect of utilizing the byproduct heat from the fuel cell to replace a fired-heater for a fuel cell power cogeneration system was analyzed. Figure 1-2 indicates what the relative breakeven costs are for the above parameters. For example, a system with no by-product heat utilization placed in a


location where the electricity costs $0.08/kWhr would be economically attractive if natural gas costs were $3/MMBtu or lower. If waste heat were totally utilized, the system would be economically viable if natural gas costs were $4.25/MMBtu or lower. Hence, the value of recovering the by-product heat can be significant to economic viability.

Net Present Value Analysis

Power = 50 kW ;COGEN = 50kW

Maintenance = $0.005/kWh - S1500/kW System Cost

»

o U «

2 -3 Z

' /

t

/

/

'

/ /

/

/ /

/

Max by-product heat utilization

No by-product heat utilization

0 0 0000 0 0200 0 0400 0 0600 0 0800 0 1000 01200 0 1400 0 1600

Electricity Cost ($/kWh)

Figure 1-2. Effect of Utilizing Fuel Cell by-Product Heat for Cogeneration Heat on Economic Viability

1.5 SYSTEM SCREENING CONCLUSIONS

The following conclusions and recommendations are made based on the analysis effort:

High-temperature PEM data are not available

Stack development effort for Phase II is required

Once high-temperature stack data is available, the analysis discussed above needs to be confirmed (Phase II effort)


• The Grotthuss conduction mechanism yields the preferred system characteristics; the Grotthuss conduction mechanism is also much less technically mature than the vehicle mechanism

• Fuel processor technology is available today and can be procured for Phase II (steam or ATR)

• The immaturity of high-temperature membrane technology requires that a robust system design be developed in Phase II that is capable of operating over a wide temperature and pressure range:

• Unpressurized or Pressurized PEM (Grotthuss mechanism) at 140°C

— Highest temperature most favorable

— Lowest water requirement most favorable

— Pressurized recommended for base loaded operation

— Unpressurized may be preferred for load following

• Pressurized PEM (Vehicle mechanism) at about 100°C

— Pressure required for saturation

— Fuel cell technology currently available; stack development required

1.6 RECOMMENDATIONS FOR PHASE II SYSTEM

Based on the Phase I efforts, the following are the recommendations for the Phase II system:

• Development of a fuel cell/cogeneration demonstration system is recommended for Phase II. The system will have the flexibility of incorporating high-temperature PEM stacks.

• As it is uncertain if the 140°C-stack technology will be available, the system needs to flexible, i.e. to be capable of incorporating the vehicle mechanism stack. Hence, the system should be pressurized, but be capable of low pressure operation with necessary modifications. The Honeywell 50-kW fuel cell stack system design developed for transportation applications, used in the DOE brassboard transportation system (currently being tested at Honeywell, including the Honeywell turbocompressor) can be used as a basis for Phase II work.


• Characterization and development of the high-temperature MEA's (both 100°C vehicle mechanism and 140°C Grotthuss mechanism) is required fora detailed 50-kW system stack design.

• Development of a high-temperature stack is needed for Phase II.

• System requirements should be further defined to include duty cycle.

• It is also recommended that an advanced BCHP control system (to include fuel cell, cogeneration and real-time building loads) be developed. This effort will enable a better understanding of load profiles (electric, heat and cooling) that will allow a determination to be made as to whether the cogeneration fuel cell system should be base loaded or load following.

A generalized system diagram is given in Figure 1-3. Further details of the system and the program suggested for Phase II are given in Honeywell's Technical ProposaM. The proposal contains the following details of the system design:

System Description

System Process Flow Diagram

Preliminary Design Heat and Material Balance

Preliminary Equipment List

Operational Mode Performance Estimates:

- Grotthuss Mechanism

- Vehicle Mechanism

Fuel Processor 50-kW Design Details:

- Process, Startup, and Control Description

- Process Flow and Control Diagram

- Design Heat and Material Balance

1. Technical Proposal - Demonstration of a Brassboard High-Temperature PEM Fuel Cell Cogeneration Plant for Building Applications, Honeywell Report 2K-71136, prepared for the US Department of Energy, August 3, 2000.

Honeywell 2K-7088&4 Page 1-9

— POWER >M

COMPRESSOR

POWER-►

DC POWER M

STEM REFORMING FUEL PROCESSOR

& CO REDUCTION

FC SYSTEM EXHAUST

POWEH 1

Q j ^ -AIR

MANAGEMENT

POWER CONDITIONING

r--J\

- ►. AC POWER \

! /

-REFORM ATE—1>\ PEM FUEL CELL STACK

FC AIR

FP COOLANT TO/FROM

FPGAS - and/or -

HEAT

COGENERATION LOAD

COGEN COOLANT TOFROM

WATER/THERMAL MANAGEMENT

POWER WATER

COOLING AIR

TO/FROM

ANODE. GAS

CATHODE GAS

Figure 1-3. Phase II System Design


2. INTRODUCTION

This report is a result of a program awarded to Honeywell by the Department of Energy (DOE) on March 4,1999. The award was a result of a proposal to the DOE made in October 1998 (98-70194) in response to a Solicitation for Financial Applications (DE-SC02-98EE50526). The cooperative agreement (DE-FC02-99EE27566) was created in October 1999 with the DOE and Honeywell.

The cooperative agreement includes the following Statement of Work:

Honeywell and Energy Partners as a team will create a system design of a natural gas, high-temperature PEM fuel cell, cogeneration plant for buildings. The program will include application definition, requirements definition, and system design and definition. In addition, technical performance, technical maturity and economic viability will be emphasized for this cogeneration building application. The design will include components of sufficient technical maturity for the Phase II brassboard development and the Phase III prototype packaged system for field testing.

2.1 OBJECTIVE OF STUDY

The overall objective is to define a system design of a natural gas, high-temperature PEM fuel cell, cogeneration plant for buildings. The program includes the definition of application, requirements, and system design. In addition, technical performance, technical maturity and economic viability will be emphasized for this cogeneration building application. The design will include components of sufficient technical maturity, for the Phase II brassboard development. Phase II will consist of the fabrication/procurement, brassboard assembly, and testing of the system defined in Phase I. In Phase III, a prototype packaged system will be developed and assembled for field testing and evaluation.

The conceptual system design for the building application has the following targets:

• Heat rejection > 100°C for a broad range of cogeneration applications

• Thermal-to-electrical efficiency of 35 percent using natural gas (higher heating value)

• Minimal heavily loaded mechanical subsystems

• High reliability during long-term operation (> 40,000 hr)

• Installed cost < $1500/kW

• Operating pressure of 1.5 atmospheres (ATM) or lower.

For the Phase II, 50-kW system build, the following are considered top priorities:



• Thermal-to-electrical efficiency of 35 percent using natural gas (higher heating value)

• Potential shown for long-life stack

In addition, the Phase II system build can be considered as a base-load (50-kW) application to simplify the initial demonstration effort.

The scope of this Phase I design effort includes a screening of reformer and membrane technologies, conceptual system designs for the building application, and design of the 50-kW brassboard system for Phase II. The major technology development areas include the fuel processor and high temperature membrane. The fuel processor technology is more advanced than the membrane technology but is not yet developed to a commercial level for this application. The high-temperature PEM membrane technology is at a very early state of development. Part of the R&D effort of this program is to assess the status of this technology.

2.2 APPROACH

The work plan developed for the study included two major tasks:

• Task 1: Application Definition and System Screening

• Task 2: System Definition

2.2.1 Task 1: Application Definition and System Screening

The objective of Task 1 is to screen the appropriate technologies to create a conceptual system design that has the best potential of meeting the cogeneration application requirements. In addition to application requirements, technologies were assessed for their ability to meet DOE program requirements for a Phase II demonstration system. Various system candidates were proposed, evaluated for feasibility, modeled, and compared based on technical maturity, system performance, and economic viability. Critical technologies identified included the fuel processor, high-temperature fuel cell, air compressor and/or turbocompressor, and cogeneration unit and data collected on each.

2.2.2 Task 2: System Definition

The objective of Task 2 is a system definition of at least one of the candidate systems identified in Task 1 as the most appropriate. The emphasis of Task 2 is a system definition and design of sufficient detail such that a full size (50-kW) technology demonstration plant could be built in Phase II of the program; Phase II is a near-term project that could be initiated in 2000 to build a brassboard 50-kW to demonstrate a high-temperature fuel cell plant.

The product of the Phase I System Design leads directly to the development of the Phase II 50-kW brassboard demonstration system.


2.3 THIS REPORT

Critical technologies required for the system are reported in Section 3. Technology developers were contacted to include the fuel processor, high-temperature fuel cell, air compressors, turbocompressors, inverters, and absorption-chilling cogeneration. Appropriate data were gathered for the system analysis and design effort. Assessments of the technology maturity and viability are given.

System analysis findings are presented in Section 4. Various system candidates are identified and analyzed for their feasibility and potential. System modeling results are presented and compared for various performance parameters, including fuel cell temperature, pressure, type of membrane, and fuel processor.

Economic analysis results are presented in Section 5. Using net-present-value analysis as the measure of economic viability, the following parameters were analyzed for a fuel cell/cogeneration (cogeneration) power plant in a building application: natural gas cost, electricity cost, waste heat utilization in the building as cogeneration heat, and fuel cell replacement costs.

The system proposed for the Phase II system is briefly described in Section 6; a more complete description is given in a separate document (as the Honeywell technical proposal for Phase II).

Conclusions and recommendations are presented in Section 7.

Honeywell 2K-70886-4 Page 2-3/(2-4 blank)

3. CRITICAL TECHNOLOGIES

Technologies assessed as critical and requiring inputs for system analyses include:

• Natural Gas Fuel Processor

• High-Temperature Fuel Cell

• Gas compressors and Turbocompressors

• Cogeneration Unit

3.1 NATURAL GAS FUEL PROCESSOR

Honeywell was tasked with acquiring the fuel processor data for the system design.

Honeywell contacted various fuel processor developers to gather appropriate data and assess the availability for the Phase II system demonstration. Table 3-1 includes a list of those contacted and assessment of whether unit is available for Phase II. As indicated, a steam reforming unit (Harvest) and an autothermal unit (HBT) are available for Phase II. Yield data from each unit was acquired and is presented in Table 3-2.

TABLE 3-1

FUEL PROCESSOR DEVELOPERS

Developer Argonne GE EERC Epyx Gastec NV Haldor-Topsoe Harvest HBT Johnson-Matthey McDermott Northwest Power Pacific Northwest Shell Texaco UOP Wellman CJB

Fuel Processor Type ATR Steam+Adsorption Steam, ATR* Steam, ATR Steam Steam ATR ATR Steam Steam/membrane ATR+Membrane ATR ATR ATR Steam

Visited by Honeywell No Yes Yes No No Yes Yes Yes Yes No No No No Yes No

Phase II Availability Estimated not ready Development needed Not interested Not available Not interested Yes Yes Not interested Estimated not ready Not interested Estimated not ready Not responsive Not responsive Not interested

Estimated not ready * ATR = Auto Thermal Reformer


TABLE 3-2

AUTHOTHERMAL AND STEAM REFORMING YIELDS BASED ON HBT AND HARVEST DATA

REFORMER TYPE SYSTEM PRESSURE, psig Reformate Mole Fraction

H2 H20 N2 AR CH4 CO C02

Total Total Flow, gr/sec Temperature, C H2 Higher Heating Value(HHV) in Reformate, kW Feeds, gr/sec

Natural gas to Reformer reactor Fuel from Natural Gas AirtoFP Condensate to FP Fuel from Anode Gas

Feeds, HHV kW Natural gas to Reformer reactor Fuel from Natural Gas Total Natural Gas Feed [Note 1]

Total Natural Gas Feed, HHV Fuel from Anode Gas, HHV Fuel Processor Efficiency, HHV

-H2 Efficiency [Note 2] -Net Efficiency [Note 3]

ATR 3

0.326 0.263 0.288 Trace Trace 1 e-4 0.122

1.0 27.34 223.2 135.6

2.864 2.864 15.25 9.23

0.159

143.2 -

143.2 143.2 22.59

94 79

ATR 30

0.34 0.276 0.25 Trace 0.013 1e-4 0.12 1.0

24.25 251

129.6

2.864 2.864 12.16 9.23 0.15

143.2 -

143.2 143.2 21.6

90.5 75

ATR 60

0.389 0.18

0.277 Trace 0.019 1e-4

0.137 1.0

20.71 264.5 127.4

2.864 2.864 11.58 8.0

0.149

143.2 -

143.2 143.2 21.2

88.9 74

SR 3

0.7 0.05 0.03

-0.03 1e-4 0.18 1.0 8.0 225 135

2.5 0.3

-4.8

0.16

125 15

140 140 22.5

96.5 80.5

SR 30

0.68 0.12 0.02

-0.04 1e-4 0.17 1.0 7.7 247

129.3

2.54 0.26

-5.0

0.15

127 13

140 140 21.5

92.3 80

SR 60

0.65 0.17 0.03

-0.04 1e-4 0.13 1.0 7.7 253

127.4

2.58 0.22

-5.3

0.149

129 11

140 140 21.1

91 79.5

Note1:Naturalgasfeedsettocreate50kWe@ 35% HHV efficiency, composition 954%CH407%CO226%C2H607%C3 07%C4

Note 2 H2 efficiency = Total H2 in reformate/total natural gas feed * 100% Note 3 H2 in reformate used by the fuel cell/(total natural gas feed) * 100%


Of the two types of fuel processors selected, each has a hydrocarbon reaction unit, followed by CO shift reactors, and finally a selective oxidation unit to reduce the CO in the reformate product stream to 50 ppm or lower. Yields and feed requirements for the two units are represented in Table 3-3. As indicated, steam reforming has a significantly higher hydrogen percentage in the reformate product; this will result in a higher fuel cell voltage and/or a lower stack size as will be discussed below in Section 4.

TABLE 3-3

FUEL PROCESSOR COMPARISON AT 3 PSIG

H2 N2

C02 CO CH4

Sum, dry lbs Air/lb NG

lbs Water/lb NG

ATR 44.2% 38.9% 16.5%

<50ppm 0.4%

100.0% 5.3 3.2

SR 74.1% 3.7% 19.5%

<50ppm 2.5%

100.0% 0.4 2.1

Steam reforming and autothermal reforming technologies have been in practice for decades to create high-purity hydrogen from a hydrocarbon for many applications at large industrial plants. For fuel cell power systems, the specific applications have different requirements. For transportation systems, fuel processors have very challenging requirements including weight, power, volume, cost, transient and start-up targets: in particular, volume and cost goals for the transportation system are very severe at 600 W/L and $30/kW"i. However, for buildings, these requirements are significantly less challenging. The fuel processor power density for a steam reforming system is approximately 80 W/L; the cost goal for the fuel processor is an order of magnitude higher, at about ~$300-$600/kW compared with $30/kW for the transportation goal.

Steam reforming is known to have a lower power density (and therefore a higher installed volume) than autothermal reforming. For a fuel cell stationary application, steam reforming offers the advantage of having almost twice the volumetric concentration of the hydrogen in the reformate product. This can translate directly into a savings in either the fuel cell stack efficiency or the fuel cell stack size. As the fuel cell stack has the most significant impact on efficiency and costs, steam reforming is judged to have potential advantages in a stationary application.

1. Patil, P., "Energy Efficient Vehicles for a Cleaner Environment," DOE Office of Transportation Technologies, DOE/ORO/2065, March 1998.


Hydrogen Burner Technology (HBT) has built several hydrogen generation units based on its earlier Unoxidized Burner (UOB) technology for non-fuel cell applications. HBT in 1997 created a Fuel Flexible Fuel Processor (F3P) to adapt its UOB technology to a transportation application for a fuel cell system. The UOB design uses no catalyst in the hydrocarbon reforming step. In order to meet the strict volume and weight requirements, much work was undertaken on the F3P design. At the present time, HBT is devoting most of its resources to a smaller unit (<10-kW) for a stationary power plant application. In addition, it has changed its basic design in the hydrocarbon reforming reactor to include a catalyst. At the present time, while they have constructed fuel processors estimated to be in the 30 to 50-kW range, all are for liquid fuels, and are of the earlier uncatalyzed (in hydrocarbon reforming reactor) F^P design.2

Harvest Energy Technology has built and operated steam reforming fuel processors for several stationary development applications including propane, methanol, and natural gas fuel processors ranging in size from 1-kW to 15-kW hydrogen (lower heating value of product hydrogen). Harvest personnel have significant experience in commercial steam reforming hydrogen plants and in early fuel processing technology development for EPR|3, DOE and others* dating back to the early 1980's. Currently, they have supplied several sub-10 kW fuel processors to developers that are undergoing tests.

3.2 HIGH-TEMPERATURE FUEL CELL

Energy Partners was tasked to search the literature and contact all developers of high-temperature PEM fuel cells. While there appeared to be multiple developers, much of the work was with the membrane itself; data for MEA developments and fuel cell performance were sparse. A complete report on findings is given in Appendix B.

3.2.1 Mechanisms

The conduction of protons in the membrane materials occurs via two different mechanisms:

* Proton-carrying mechanism (the vehicle mechanism)

• Lone proton migration (Grotthuss mechanism or translocation).

The type of proton-conducting mechanism in a particular material depends on the protonic species it has and the crystalline structures formed by the membrane. The mechanism can change in the same material if the temperature and water vapor partial pressure change. For instance, in phosphotungstic acid, conduction occurs by Grotthuss

2. Communication between HBT and Honeywell, September 2000. 3. Minet, R., and Warren, D., "Assessment of Fuel Processing Systems for Dispersed Fuel Cell Power-

plants," EPRI Report EM-1487, prepared by KTI Corp. for EPRI, August 1980. 4. Harvest Energy Communication: design of first automated industrial hydrogen plant using IFC fuel cell

technology (1983-1984) and design of a 25-kW fuel processor for Englehard's PAFC demonstration plant (1986-1987).


mechanism at low temperatures, but changes into the vehicle mechanism at high temperatures.

Grotthuss Mechanism: In this mechanism the H+ ion is displaced along a hydrogen bond from one bond to the next. The activation energy necessary for the H+ ion transport by this mechanism is high (0.5 eV)5 and is related to the presence of the defects. This mechanism is typical for anhydrous proton conductors, which contain protonated anions. Moreover, polymers containing N-H protonic sites, conduct protons by this mechanism. In addition, anhydrous polymers blended with strong acids conduct protons by this mechanism. Their proton conductivity is not limited by the presence of water since pure acids such as sulfuric and phosphoric acids conduct protons by extensive self-ionization and self-dehydration.

Vehicle Mechanism: This mechanism requires the presence of vehicle molecules such as H2O or NH3 in the material. Mobile species H3O and NH4+ conduct protons by this mechanism. The conduction occurs via either (a) the available empty sites (defects) in a crystal or (b) counter-flow of protons and vehicles, where voids are created by thermal activation. Activation energy of this process is highly affected by temperature. This mechanism is typical for heteropolyacid hydrates such as phosphotungstic acids at high temperatures (a) and for polymers modified with inorganic acid such as Nation (b).

It is assumed that for the water-based vehicle mechanism of proton transfer, the membrane must be saturated with liquid water, as is required for the conventional low temperature PEM membranes. Hence, operation at temperatures over 100°C will require pressures that may exceed the 1.5 ATM requirement stated in Section 2.

3.2.2 High-Temperature PEM Fuel Cell Data

Energy Partners and Honeywell contacted high temperature membrane developers listed in Table 3-4.

In order to determine the relative maturity of various developers, a membrane sample was requested. Typical sizes of the membranes under development are given in Table 3-5. Although samples were requested, and Honeywell and Energy Partners were prepared to test the samples under appropriate fuel cell operating conditions, no samples were acquired: the reason is judged to be the relative immaturity of the technology.

As no appropriate fuel cell data were available (i.e., fuel cell polarization curve data at the appropriate temperatures and feed compositions), it was necessary to predict performance based on literature conductivity data and DOE's goals for high-temperature PEM fuel cells and literature data. The DOE goals, given in Appendix B, include a cell voltage of 0.7 at a power density of 350 mW/cm2; this is equivalent to 0.7 volts at 500 mA/cm2 at 120°C and 7 psig pressure. By using literature values of the effects of

5. Colomban, P., Proton Conductors, Solids, Membranes and Gels-Materials and Devices, University Press, Cambridge, Great Britain, 1992.


TABLE 3-4

HIGH-TEMPERATURE PEM FUEL CELL DEVELOPERS

DEVELOPER 3M AIST Arthur D. Little Aventis Research & Technology Axiva GmbH Axiva NA Cape Cod Research, Inc Case Western Reserve University Dais, Corp Degussa AG De Nora S p a , U de Perugia, U Montpellier II, et al DuPont Central Research & Development Ecole Polytechnique de Montreal E-Tek, Inc Foster Miller, Inc Fuel Cell Energy, Inc Giner, Inc. Hoechest-Cellanese Corporation Hoechst-Celanese Honeywell Ionic polymers

Johnson Matthey Laval University Montpellier University Pennsylvania State University Polymer Research Institute Syracuse University Princeton University Technical University of Denmark Texas A&M University U. Central Florida, Florida Solar Energy Center U. of Connecticut U. of Wisconsin Virginia Polytechnic U. & LANL W.L. Gore & Associates,Inc

Hi-T PEM TYPE N/A

org/irjorg comp UK UK UK N/A

Ionic polymer Doped polymer

N/A N/A

org/inorg comp Ionic polymer

org/inorg comp N/A

Ionic polymer Ionic polymer Ionic polymer

UK UK

org/inorg comp

N/A UK

Ionic polymer Ionic polymers Ionic polymer

org/inorg comp org/inorg comp

N/A Ionic polymers

org/inorg comp Ceramic membrane

Ionic polymers UK

NOTE BOLD = contacted UK = Unknown, N/A = not available, org /inorg comp = organic/inorganic composites


TABLE 3-5

HIGH-TEMPERATURE MEMBRANE SIZES

DEVELOPER

Cape Cod Research Virginia Polytechnic Inst. Foster Miller University of Wisconsin Princeton University Polymer Res. Ins. Syracuse Univ. Case Western Reserve University University of Connecticut Pennsylvania State University DuPont Central R&D

TYPE OF MEMBRANE

Ionic polymer NA Ionic polymer Inorganic Organic/inorganic composite Ionic polymer

Doped polymer Organic/inorganic composites Ionic polymer

Organic/inorganic composite

MAXIMUM SIZE OF MEMBRANE (CM2)

NA NA 500 7.6 5

>200

225 37 8

2

temperature on conductivity, performances were predicted for temperatures of 100, 120 and 140°C using the DOE goal of 0.7 volts at 500 mW/cm2 as the "anchor" point. In addition, as stated above for the vehicle mechanism, pressures in excess of 1.5 ATM were anticipated to maintain liquid water in the membrane. Hence, predictions for the effect of pressure were developed.

The predicted effects of pressure and temperature are given in Figure 3-1, which was used in the system design and analysis effort. While the prediction for the effect may be preliminary, the trends are believed to be correct.

3.3 GAS COMPRESSORS AND TURBOCOMPRESSORS

As indicated above, pressurized operation would be required for high-temeprature, vehicle-mechanism PEM fuel cells. Hence, data were collected for air compressors, natural gas compressors, and turbocompressors. These components are considered critical to the efficient performance of the system, but are not anticipated to require significant technology development relative to the high-temperature fuel cell. Indeed, many of the compressors are essentially off-the-shelf, or could be designed to meet the flow and pressure requirements by several vendors. Some of these vendors were contacted (see Table 3-6).


Goal Polarization Curves (High T PEMFC) Linear Curves Used for System Modeling

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

2 Current Density, A/cm

Figure 3-1. Predicted Effect of Temperature and Pressure on High Temperature PEM Fuel Cell

TABLE 3-6

AIR AND NATURAL GAS VENDORS CONTACTED

VENDOR

Quincy

Copeland

RIX

Ingersoll-Rand KNF Neuberger

AVAILABLE EQUIPMENT

Natural Gas and Air Compressors

Scroll Compressor for NG Applications Oil-Free Compressors for 0-7500 psig

7.5 hp Compact OEM oil-free Compressors

CAPABILITIES

Extensive Experience with Industrial Air Delivery. Nat. Gas Compressors new area for them. Targeted Technology for Distributed power systems Extensive Compressor Experience, undersized for our application. No NG experience Natural Gas Capable Compressors, but they are undersized for our application.

OTHER USES

Currently Developing new unit for this application May/June release Refrigeration and Air Conditioning


If pressurized operation is required, or is found to be beneficial to the system performance, then it is usually advantageous to use a turbine to capture some of the expansion energy, offsetting the energy used to compress the air.

An appropriately sized turbocompressor is the turbine-assisted, motor-driven compressor being designed for the Department of Energy under the "Turbocompressor with Variable Geometry for PEM Fuel Cells" program scheduled to be completed in mid-2001. The turbocompressor will be a modification of the turbocompressor used in the Honeywell 50-kW PEM fuel cell brassboard transportation system. The modifications include a new, wider flow range compressor and a turbine incorporating variable geometry, in addition to a new, compact, and lightweight motor controller. The performance of the unit to be used in the transportation system has been fully mapped, and over 300 hours of operation have been demonstrated. A picture of the transportation unit is provided in Figure 3-2.

Figure 3-2. Honeywell's Turbocompressor Designed for Automotive Application Fuel Cell Stack system

In operation, the motor drives the compressor, which provides pressurized ambient air to the reformer and/or fuel cell stack. The expander/turbine assists the motor power consumption by recovering energy from the reformer and/or fuel cell system exhaust stream. The turbine has the capability of operating up to a temperature of 290°C. The motor controller is capable of driving the compressor with up to 9 kW of continuous power to a speed of 110 krpm, delivering sinusoidal currents to the motor from a nominal 300 VDC source. In addition, the controller is capable of regenerating power out of the motor and supplying power back to the power distribution system when the turbine is driven with excess power.

Honeywell ™ - «

This turbocompressor is unique when compared to other air compression systems. The turbine, compressor and permanent-magnet motor are mounted on a single, highspeed shaft that is supported on a foil air-bearing system. The air bearing system provides a contamination-free air stream by eliminating conventional oil-lubricated bearings. Additionally, mounting all components on a single shaft creates a compact, lightweight, high-performance package that allows for packaging flexibility. This approach eliminates the typically bulky and complex gearboxes and motor drives used in conventional positive displacement machines. The parts count is also lower compared to conventional positive displacement machines, increasing reliability and facilitating reduced production cost.

The compliant-foil, air bearings are hydrodynamic self-sufficient bearings and do not require a source of pressurized air. The bearing system consists of two journal bearings to support radial loads, and two thrust bearings to support axial loads. Honeywell has been using compliant-foil, air bearing technology since 1957. This technology has been incorporated in over forty-five aircraft platforms, as well as in ground-based applications. Honeywell is the world's leader in foil air bearing machines, producing over 15,000 turbomachines that have accumulated over 300 million operating hours. Well-documented experience shows that Honeywell foil bearing machines withstand well over 100.000 start/stop cycles and can operate continuously for years.

3.4 COGENERATION UNIT

The US consumed almost 93 quadrillion BTU's (Quads) in 1996, of which commercial buildings accounted for almost 15 Quads. Of this quantity, 47 percent of the consumed energy was for thermal loads: 22 percent space heating, 18 percent space cooling, and 7 percent water heating. The other 53 percent is primarily electrical loads (lighting, office equipment, cooking, etc.). Hence, if the waste heat from a fuel cell power plant can be effectively utilized for the thermal loads, nearly half of the energy consumption of commercial buildings could be relieved.

3.4.1 Building Heating Cogeneration

For heating and hot water loads, hot water systems can be designed over a broad range of temperatures and can be characterized as follows:

• High-temperature systems: temperatures > 204°C

• Medium-temperature systems: temperatures from 82 to 204°C

• Low-temperature systems: temperatures > 82°C6

Typical PEM fuel cells operate at 80°C and below, and therefore would be considered appropriate for low-temperature systems. In fuel cell systems, the waste heat generated from a fuel cell stack is in the order 80 to 100 percent of the actual power from

6. Orlando, J., Cogeneration Design Guide, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 1996.


the stack. A liquid coolant is typically circulated through the stack to maintain temperatures in the desired range. A 5°C approach temperature of the coolant from the stack is considered typical (i.e., the coolant stream exits the fuel cell stack 5°C or less from the nominal stack operating temperature). Hence, a stack operating at a nominal 100°C could supply water heat to a medium-temperature thermal distribution system in a building at 95°C.

3.4.2 Building Cooling Cogeneration

As indicated above, a significant quantity of a building's primary energy use is to supply electricity to generate cooling. Waste heat from a fuel cell can be utilized for space cooling via the use of absorption chiller units. Absorption chilling is a mature technology, with companies selling units worldwide.

A typical single-effect absorption chiller unit is represented in Figure 3-3. The cogeneration mechanism employed is absorption chilling via a modular chiller with cooling capacity in the ten to thirty refrigeration ton (TR) range. If larger capacities are required in the future, these units can be combined in assemblies to achieve the desired effect. The advantages of using an absorption chiller include increased efficiency for the fuel cell system, space savings due to compact design, low maintenance due to the absence of any moving parts, lack of noise or vibrations, and benign environmental impact.

Heat In Generator

I Heat Ex

Cooling , Water —j*n Absorber

In

r,--"'

High Pressure Gas

Condenser High Pressure Liquid

Cooling Water Out

Evaporator

Expansion Device

Thermal Compressor

Low Pressure Gas j ^

Chilled Water

Low Pressure Liquid

Figure 3-3. Single-Effect Absorption-Chilling Cycle

Typical single-effect systems have coefficient of performance (COP) in the 0.6 to 0.7 range. This compares with COP values of 0.9 to 1.2 for double-effect systems. While the double-effect systems achieve higher efficiencies, the initial costs are also greater to pay for extra components, including an extra generator. The COP values for vapor-compression refrigeration systems generally range from 2 to 6.75. However, these systems require a higher grade of energy to power them (electricity versus recovered heat). Therefore, it is important to take into account the cost of the input energy when comparing these two types of systems. As the cost to produce the needed mechanical energy for cooling in the vapor-compression system is greater than the cost to utilize the heat


needed in an absorption chilling system, absorption-chilling is often a very viable economic option.

Honeywell contacted two companies, Thermax Limited and Yazaki Energy Systems. Data from two units are presented in Table 3-7.

TABLE 3-7

ABSORPTION CHILLER UNITS VENDOR DATA

Model Chilled Water Flow, Ib/hr Inlet T, F (C) Outlet T, F(C) kW cooling Rated Qc,Tons Cooling Rated Fuel Cell Coolant Flow, Ib/hr MAX T, F(C) Inlet T,F(C) Outlet T, F(C) kWCOGEN @ Rated Cooling tower water Flow, Ib/hr Inlet T,F(C) Outlet T, F(C) kW Cooling tower load @ Rated Power Required Absorbent pump @ rated, watts Coefficient of Performance =cooling capacity/heat input Physical Data Length, ft Width, ft Height, ft Weight, lbs

Thermax THW-LT-3

40,004 53.6(12) 44.5(7)

107 30

50,886 —

195(91) 185(85)

149

66,032 85(29)

97.88(37) 249

300

0.72

7.0 4.1 6.2

6600

Yazaki WFC-10

13,196 57.2(14) 48.2(9)

35 10

18,895 212(100) 190.4(88) 181.4(83)

50

32,091 85(29) 94(34)

85

30

0.70

3.3 3.0 6.5

1606


4. SYSTEM ANALYSIS

The system analysis efforts are presented in this section. The DOE goals are presented and discussed based on the analysis and screening findings. Various system candidates are identified and analyzed for their feasibility and potential. System modeling results are presented and compared for various performance parameters including fuel cell temperature, pressure, type of membrane, and fuel processor.

4.1 DOE GOALS

The DOE technical goals for the program include:


• Thermal-to-electrical efficiency of 35 percent using natural gas (based on higher heating value)

• Minimal heavily-loaded mechanical subsystems


• Installed cost less than $1500/kW

• Operating pressure of 1.5 atmospheres (ATM) or lower

4.1.1 Heat Rejection Greater Than 100°C

As discussed in Section 3 in the paragraph on Cogeneration Units, by operating the PEM fuel cell stack above 100°C, the cogeneration unit will enable the use of medium-temperature thermal distribution for utilizing the fuel cell waste heat. In addition, fuel cell temperatures of 100°C and higher enable the use of absorption chilling for space-cooling in buildings.

4.1.2 Thermal-to-Electrical Efficiency of 35 Percent

This goal will be specifically designed for in the analyses.

4.1.3 Minimal Heavily-Loaded Mechanical Subsystems

By minimizing complicated mechanical components, the system reliability and maintenance costs should be minimized.

4.1.4 High Reliability During Long-Term Operation (> 40,000 Hr)

This goal suggests that an operating life of about 5 years is required before major equipment replacements. For this study, it will be assumed that the technology must be developed to meet the goal.


4.1.5 Installed Cost Less Than $1500/Kw

This goal is currently seen as necessary to have marketability for buildings and will be addressed in Section 5.

4.1.6 Operating Pressure of 1.5 Atmospheres (ATM) or Lower

This goal, as discussed in Section 4, may be inconsistent with the operational goal of 100 to 140°C of the fuel cell stack, depending on the type of fuel cell ion-transfer mechanism. It will be addressed in this section.

4.2 SYSTEM CANDIDATE SCREENING

In order to identify and define a promising system to meet the DOE goals, various system candidates were proposed, evaluated for feasibility, modeled, and compared based on technical maturity, system performance, and economic viability. The system performance of the candidates are presented here.

4.2.1 Baseline System Configuration and Modeling

The baseline system configuration is represented in the generic system diagram for the BCHP application as presented in Figure 4-1. The most critical components are the fuel processor, the high-temperature stack, and the cogeneration unit. In evaluating the most appropriate design, various system candidates were postulated including two types of fuel processors, two types of high-temperature stacks, and three operating temperatures and three operating pressures. Various combinations of reformer type, stack type, operating temperatures and pressures, analyzed and modeled using ASPEN PLUS, are presented in Table 4-1. Also indicated in the table are the output parameters such as efficiency, stack size, etc., calculated from the system. The system model generated cogeneration heat, system efficiency, required fuel cell stack active area, and other heat exchanger parameters (such as required heat transfer area).

As stated above, in order to operate a high-temperature PEM fuel cell stack with a PEM that employs the vehicle mechanism for proton conduction, pressure is required to maintain water in the MEA. Hence, a turbocompressor was utilized in those system simulations where pressure is indicated. When the system is base loaded, the analysis reveals that a pressurized system is preferred, regardless of the proton-conduction mechanism. Pressure has the effect of reducing component size (especially the stack, heat exchangers, and fuel processor) and, consequently, the system cost. If the system is load following, however, a pressurized system is more complex than a low pressure system, and the benefits of pressure may not outweigh the complexity. The "not feasible" identification in Table 4-1 indicates that the operating pressure for the given operating temperature of the stack is not sufficient to maintain liquid water in the MEA when the vehicle mechanism is the conduction mechanism in the membrane. Not surprisingly, the Grotthuss mechanism does not suffer from this problem since humidification is not required.


POWER-^

COMPRESSOR

DC POWER 1

FUEL PROCESSOR &

CO REDUCTION

POWER—I

AIR MANAGEMENT

POWER CONDITIONING

r — J \ - f c AC POWER \ ^ /

-REFORHATE—(> PEM FUELCELL STACK

COGENERATION LOAD

~TT FC COOLANT

WATER/THERMAL MANAGEMENT

s f -

WBTEH POWER TT COOLING

TO/FIIOM

I I Figure 4-1. Generic System Diagram of a High-Temperature PEM

Fuel cell Cogeneration System for Buildings

TABLE 4-1

SYSTEM CANDIDATE FEASIBILITY MATRIX TABLES

Stack Type

Grotthuss Grotthuss Grotthuss Grotthuss Grotthuss Grotthuss Grotthuss Grotthuss Grotthuss

Vehicle Vehicle

Temperature <°C)

100 100 100 120 120 120 140 140 140 100 100

Pressure (psig)

3 30 60 3

30 60 3 30 60 3

30

Cogeneration Heat

Calculated Calculated Calculated Calculated Calculated Calculated Calculated Calculated Calculated Not feasible Calculated

Total Efficiency


Stack size


Outher Heat Exchanger Parameters



TABLE 4-1

SYSTEM CANDIDATE FEASIBILITY MATRIX TABLES (Continued)

Stack Type

Vehicle Vehicle Vehicle Vehicle Vehicle Vehicle Vehicle

Temperature (°C)

100 120 120 120 140 140 140

Pressure (psig)

60 3 30 60 3 30 60

Cogeneration Heat

Calculated Not feasible Calculated Calculated Not feasible Not feasible Calculated

Total Efficiency


Stack size


Outher Heat Exchanger Parameters


System model performance assumptions are given in Table 4-2. As indicated earlier, the lack of fuel cell polarization curve data for high-temperature membrane required that high temperature fuel cell performance be estimated as discussed in Section 3. With this approach, an increase in the operating pressure or temperature has the effect of increasing the cell voltage at the same current density.

TABLE 4-2

SYSTEM SCREENING MODELING PERFORMANCE ASSUMPTIONS

System: Net power output Fuel Fuel Processor: Net Fuel Processor Efficiency Fuel Processor Pressure Drop Fuel Cell: Power Density Polarization Curve Basis Cell Voltage at Peak Power Stack pressure drop Stoichiometry Cooling Fluid Exit Temperature/ AT Turbocompressor: Compressor efficiency Expander (Turbine) Efficiency

50 kW @ 35 % efficiency (HHV), base loaded 143.2 kWth Natural Gas

~ 0.8 (HHV) 1 psig

0.35 W/cm2 @ 7 psig (DOE Target) Projected (Experimental data unavailable) Variable, set to meet system efficiency goal 2 psig 2.0 cathode, 1.2 anode Water - stack temperature/10°C

0.7 0.8


4.2.2 System Screening Modeling Results

Twenty-two system candidates were modeled to compare the relative merits of the proposed candidates, as indicated in Table 4-3. The system analyses efforts indicated the following:

• The higher the operating temperature, the smaller the stack size (and system cost), as indicated in Figure 4-2.

• The higher the pressure, the smaller the stack size, regardless of whether the proton-conduction mechanism is the vehicle or Grotthuss mechanism. Figure 4-2 shows that the largest improvement is gained when the pressure is increased from 3 to 30 psig. Heat exchanger and fuel processor size and cost are also reduced at pressure.

• Steam reforming produces a significantly higher quality reformate stream (68 percent vs. 34 percent on a wet basis at 30 psig) which will result in a lower stack size (and lower cost).

• The size of the heat exchangers is reduced as the temperature is increased. This is especially true for the Grotthuss mechanism where the condenser size can be dramatically reduced because of significantly lower humidification requirements.

• The by-product heat from the 50 kW power unit is about 35 to 50 kW depending on operating conditions and stack type, as presented in Figure 4-3. This heat is available to the cogeneration unit at the stack operating condition (100, 120, or140°C).

• The higher temperature candidates have slightly less heat available to cogeneration ,as some of the heat is used to heat the anode and cathode reactants to the operating temperature of the stack. The exception to this is the 100°C, 60 psig case, where the conditions of the cathode exit are such that some of the product water condenses; the associated heat of condensation is removed from the stack via the fuel cell coolant stream, which is then available for cogeneration

• The higher pressure candidates generally have higher parasitic power requirements which require the stack to operate at slightly higher voltages. This translates into slightly lower waste heat from the stack that is available to cogeneration heat.

• As noted above, the vehicle stack type requires temperature and pressure conditions to maintain liquid water in the stack. This limited the cases available to modeling to temperatures of 100-110°C and pressures of 30 and 60 psig. For the 100°C cases, the stack sizes were comparable to those of the Grotthuss mechanism. However, the cogeneration heat was less because part of the cogeneration heat was used to humidify the stack feed.

Honeywell 2K-70886-4 v Page 4-5

TABLE 4-3

SYSTEM CANDIDATE MATRIX TABLE

Candidate System #

1 5a 5b 15a 15b 15c 16a 16b 16c 3a 3b 3c 13 6b 6c 17a 17b 17c 7a 7b 11a 11b

Fuel Processor Type

Autothermal Autothermal Autothermal Autothermal Autothermal Autothermal Autothermal Autothermal Autothermal

Steam Reforming Steam Reforming Steam Reforming Steam Reforming Steam Reforming Steam Reforming Steam Reforming Steam Reforming Steam Reforming

Autothermal Autothermal Autothermal Autothermal

Fuel Cell Stack Type

Grotuss Grotuss Grotuss Grotuss Grotuss Grotuss Grotuss Grotuss Grotuss Grotuss Grotuss Grotuss Grotuss Grotuss Grotuss Grotuss Grotuss Grotuss Vehicle Vehicle Vehicle Vehicle

System Temperature

100 100 100 120 120 120 140 140 140 100 120 140 100 120 140 100 120 140 100 100 110 110

System Pressure

3 30 60 3

30 60 3

30 60 3 3 3 30 30 30 60 60 60 30 60 30 60


110 120

Temperature, C 140

Figure 4-2. Effect of System Pressure and Temperature on Stack Size

Effect of Pressure & Temperature on Available COGEN Heat [ATR Fuel Processor, Grotthuss Stack]

60

50 HI O O O o O 40

to °*

« 3 20 < 10

T=100C T=120C T=140C Stack Temeprature, T

Figure 4-3. Effect of System Pressure and Temperature on Available Heat for Cogeneration

4.3 SYSTEM DOWN SELECTION

The following conclusions are made based on the analysis effort:

• Once high-temperature stack data is available, the analysis discussed above needs to be confirmed (Phase II effort)



• While the Grotthuss type stack offers the best system, the vehicle mechanism is more mature

• Steam reforming is chosen as the preferred fuel processor technology primarily due to it's higher hydrogen reformate composition (vol percent) and it's effect on the fuel cell stack



Highest temperature most favorable Lowest water requirement most favorable Pressurized recommended for base loaded operation Unpressurized may be preferred for load following

• Pressurized PEM (Vehicle mechanism) at about 100°C

Pressure required for saturation Fuel cell technology currently available; stack development required

Of the two stack technologies available, the Grotthuss mechanism offers the best potential for meeting the program goals, if the technology can be realized. As noted above, the pressurized Grotthuss stack would have the lowest stack size, and therefore system cost, when considering a baseload fuel cell system requirement. However, if the system is made to cycle over various load points, the unpressurized system could have advantages in system simplicity and perhaps cost. This requires further analyses as the system loads are better defined. Better definition of system loads is anticipated as part of the proposed Phase II activity to develop a building level control system for the cogeneration system.

Of the two fuel processsor technologies, both are considered applicable to a building cogeneration application. While the ATR technology might offer a lower packaged volume, the SR technology could offer a slightly lower stack size. More analyses in Phase II would help to discriminate the best choice.


5. ECONOMIC ANALYSIS

The DOE goals that relate to the overall economic viability of a system include the following:

• Installed cost less than $1500/kW


This section will present an analysis of economic viability using net-present-worth as the basis. An economic analysis was performed to indicate the importance of various parameters including the value of the cogeneration heat. The effects of power costs, natural gas costs, utilization of waste heat for cogeneration, and fuel cell replacement interval to economic viability will be presented. In addition, an analysis of the relative cost of replenishing water for the system vs. recycling water will be discussed.

5.1 BASELINE ECONOMIC PARAMETERS

The FC PAYBACK model was prepared by Honeywell and calculates the net present value of the fuel cell cogeneration power plant. Economic parameter data assumed are given in Table 5-1. Parameters assumed for the analyses were similar to those used in other analyses.1 2

5.2 POWER COSTS, NATURAL GAS COST, AND WASTE HEAT UTILIZATION FOR COGENERATION

Analysis was done comparing a building where a fuel cell power plant is installed that meets the DOE goal of $1500/kW and generates useful waste heat that could be utilized for cogeneration in a building. Two options are compared as indicated in Figure 5-1:

• A conventional building, where power is taken from the grid and natural gas is used as cogeneration heat (space heating and/or water heating)

• A cogeneration fuel cell system, where the fuel cell supplies the building's power and waste heat can be utilized for cogeneration

1. D.R. Brown, "PEM Fuel Cells for Commercial Buildings", prepared by Pacific Northwest National Laboratory for office of Building Technology, State and Community Programs, November 1998.

2. A.D. Little, "Fuel Cells for Building Cogeneration Applications - Cost/Performance Requirements and Markets", prepared for Building Equipment Division Office of Building Technologies US Department of Energy, January 1995.

Honeywell 2K708864 rf Page 5-1

TABLE 5-1

ECONOMIC ANALYSES ASSUMPTIONS

Stack Replacement Cost

Fixed Maintenance cost Variable Maintenance Cost Electrical Conversion Efficiency Annual Availability System Operating Life Stack Replacement Years Discount Rate General Inflation Rate Electricity Escalation Rate Natural Gas Escalation Rate Property Tax Rate Income Tax Rate Depreciable Life Water Heater Efficiency System Size Capacity Factor Total Cost

Calculated for Each Case

30 $/kW/yr 1.4 $/MWhr 35% 95% 10 years 3; 5; 7 years 10% 3% 3% 3% 2% 40% 7 years 80% 50kW 0.75

Calculated for each case


Natural Gas

H ►

Grid

Boiler

AC Power

P

Boiler Heat

(^boiler

Building

Conventional Building A

Non-recoverable Energy

Natural Gas

H

Av Was

Fuel Cell Power Plant

ailable ste Heat

Non-u Waste

A-C Power

□

Boiler

Co-

generation

tilized Heat i f

Boiler Heat

\J boiler

Co-gen Heat ^

QCG

Building

Fuel Cell Powered Building with Cogeneration

Figure 5-1. Building Power and Heating Alternatives

For this analysis, the following were assumed:

• Power 50 kW

• Heat 50 kW

• Electrical Efficiency 36 percent


Cogeneration Efficiency 72 percent

• Initial Installed Cost

• Maintenance Cost

• Stack Replacement

• Replacement Cost

• Utilities:

Natural Gas

$1500/kW

$0.005/kWh

None

NA

Variable Power Variable

The plot shown in Figure 52 indicates what the relative breakeven costs are for the above parameters. For example, a system with no byproduct heat utilization placed in a location where the electricity costs $0.08/kWhr would be economically attractive if natural gas costs were $3/MMBtu or lower; if waste heat were totally utilized, the system would be economically viable if natural gas costs were $4.25/MMBtu or lower. Hence, the value of recovering the byproduct heat can be significant to economic viability. Although this net present value (NPV) calculation requires some refined consideration to be accurately used, it gives a good preliminary indication as to how viable a market could be. For instance, the proposed NPV representation presented in Figure 52 indicates that in a location like Los Angeles, California, where the natural gas costs about $6.7/MMBtu and the electricity costs $0.145/kWh3 , the cogeneration solution would be a very attractive option.

5.3 FUEL CELL REPLACEMENT COSTS AND INTERVALS

An important parameter for system economic viability is the fuel cell lifetime. A DOE durability goal given for hightemperature fuel cells is 20,000 hours, or about 2

1/2

years. For the analyses, the following were assumed:

» Power 1 Heat

► Electrical Efficiency

► Cogeneration Efficiency

* Initial Installed Cost

» Maintenance Cost 1 Stack Replacement

50 kW

50 kW

36%

72%

Variable

$0.005/kWh

Variable

3. A.D. Little, "Fuel Cells for Building Cogeneration Applications Cost/Performance Requirements and Markets", prepared for Building Equipment Division Office of Building Technologies US Department of Energy, January 1995.

Honeywell 2K708864 Page 54

Replacement Cost

Utilities:

— Natural Gas

— Power

Parameter

$7/MBtu

$0.12/kWh

The effects of replacement cost and intervals are presented in Figure 53. To meet the DOE goals of a $1500/kW system cost and a 2

1/2 year life, the allowable stack

replacement cost is $200/kW. If the cost of the stack replacement were to double ($200/ kW to $400/kW), the replacement time would have to roughly double also to maintain the same NPV value at $1500/kW system installed cost.

Residential Utility NPV Simulation

♦ Winter s Summer * TU max ♦ TU = 0%

0.14 0.16

Electricity Cost (S/kWh)

Figure 52. Effect of Gas Cost, Power Cost and Cogeneration on Economic Viability

5.4 COMPARISON OF CANDIDATE SYSTEMS

Several of the candidate systems were compared based on the NPV economic viability. The candidates and operational variables, including fuel processor, stack type, temperature and pressure, are given in Table 52. The differences in the candidate systems resulted in different fuel cell stack sizes and cogeneration heat. The effects are presented here.


Allowable System Cost vs Replacement Times

Replacement Times (years)

Figure 5-3. Effect of Fuel Cell Replacement Interval and Cost on Fuel Cell Cogeneration Plant Economic Viability

TABLE 5-2

CANDIDATE SYSTEMS ECONOMIC ANALYSES MATRIX TABLE

Candidate System #

1 5a 5b 15a 15b 15c 16a 16b 16c

Fuel Processor Type

Autothermal Autothermal Autothermal Autothermal Autothermal Autothermal Autothermal Autothermal Autothermal

Fuel Cell Stack type

Grotthuss Grotthuss Grotthuss Grotthuss Grotthuss Grotthuss Grotthuss Grotthuss Grotthuss

System Temperature

100 100 100 120 120 120 140 140 140

System Pressure

3 30 60 3

30 60 3

30 60


In order to estimate the system installed cost for each candidate, several assumptions were made:

• The market will support 245,000-kW power of installed systems yearly, or approximately 4900 50-kW units/year

• The system installed cost can be represented by the combination of the fuel cell stack, the fuel processor, the power inverter (dc- to ac power), the cogeneration unit, and other balance-of-plant components

• Costs are estimated for a high volume production of 4900 50-kW units, or the equivalent, per year

• High volume costs for system components excluding the high-temperature fuel cell stack are approximately $500/kW at the 4900/year volume

• 50-kW peak power

• Cogeneration capability = 50-kW

• Stack uses 600-cm2/cell

• High-temperature MEA and stack component costs are similar to those of low-temperature membranes and the costs, when volume production achieved, are significantly lower than today's costs; e.g., low temeprature membrane cost will be reduced by approximately a factor of 10 ($600/m2 to $60/m2)

• 2 V2 year stack replacement interval

• Labor cost = 20 percent of material costs

• Fees, profit, installation costs = 30 percent of material and labor costs

• Capacity factor = 0.754

The results of the NPV analysis are plotted in Figure 5-4, which includes the full utilization of the waste heat for cogeneration. Figure 5-5 is given to show the comparisons when waste heat is not utilized. As shown, the effect is to change some of the relative positions of some of the candidates due to the energy savings of the cogeneration unit. This is further illustrated in Figure 5-6, which gives the yearly savings in natural gas costs for a baseline of $6/MMBtu.

While there are differences between the candidates, it should be noted that the analyses were done with many assumptions, including the performance of the high temperature fuel cell. Hence, all comparative results should be viewed as preliminary until data can be acquired and the analysis verified.

4. Capacity factor is defined as the fraction of the maximum kW-hrs yearly produced; for the 50-kW power-plant defined here, capacity factor = Yearly kW-hrs / (50*8760) kW-hrs

Honeywell 2K-70886-4 * Page 5-7

Grotthuss Candidate Systems NPV Lines

3 psig, 100 C 30 psig, 100 C 60 psig, 100 C 3 psig, 120C 30 psig, 120 C 60 psig, 120 C 3 psig, 140C 30psig, HOC 60 psig, 140 C

0.02 0.03 0.04 0.05 0.06

Electricity Cost (S/kWh)

0.07 0.08

Figure 5-4. Candidate System Economic Viability Comparisons with Full Effect of Waste Heat Utilization for Cogeneration

Grotthuss Candidate Systems NPV Lines

~~*~3psig, 100 C —*— 30 psig, 100 C • ^ " 6 0 psig, 100 C ~ * ~ 3 psig, 120 C ~ * — 30 psig, 120 C "~+~~60psig, 120 C

3 psig, 140 C ~™*"—30 psig, 140C

60 psig, 140 C

0.03 0.04 0.05 0.06 0.07 0.08 Electricity Cost ($/kWh)

0.09 0.10

Figure 5-5. Candidate System Economic Viability Comparisons Without Waste Heat Utilization for Cogeneration


Fuel Cell with Full Cogeneration: Yearly Savings

3 psig, 30 psig, 60 psig, 3 psig, 30 psig, 60 psig, 3 psig, 30 psig, 60 psig, 100 C 100 C 100 C 120 C 120 C 120 C 140 C H O C H O C

Figure 5-6. Candidate System Yearly Energy Cost Savings Due to Cogeneration (50-kW Power Plant)

Honeywell 2K-70886-4 Page 5-9/(5-10 blank)

6. SYSTEM DESIGN

The system analysis and screening evaluation resulted in the identification of the following components for the most promising system:

• Steam reforming fuel processor

• Grotthuss mechanism fuel cell stack operating at 140°C

• Means to deliver system waste heat to a cogeneration unit

However, due to the relative immaturity of the high-temperature Grotthuss stack technology, a system for Phase El demonstration should be capable of utilizing the vehicle-mechanism stack, which requires pressurization. Hence, a robust system design for Phase II is advised for Phase II to be capable of operating both the vehicle mechanism and Grotthuss mechanism. For this reason, a turbocompressor, such as Honeywell's Fuel Cell Turbocompressor, is included to provide the air for the fuel cell and recover energy from the pressurized stack gases.

A generalized system diagram is given in Figure 6-1. Further details of the system are given in Honeywell's Technical ProposaM. The proposal contains the following details of the system design:

• System Description

• System Process Flow Diagram

• Preliminary Design Heat and Material Balance

• Preliminary Equipment List

• Operational Mode Performance Estimates:

• Grotthuss Mechanism

• Vehicle Mechanism

• Fuel Processor 50-kW Design Details:

• Process, Startup, and Control Description

• Process Flow and Control Diagram

• Design Heat and Material Balance

1. Technical Proposal - Demonstration of a Brassboard High Temperature PEM Fuel Cell cogeneration Plant for Building Applications, Honeywell Report 2K-71136, prepared for the US Department of Energy, August 3, 2000.


POWER»

COMPRESSOR

— POWER ►

DC POWER ^

STEM REFORMING FUEL PROCESSOR

& CO REDUCTION

FC SYSTEM EXHAUST

POWER 1

AIR MANAGEMENT

POWER CONDITIONING

r — ' \ f c AC POWER \ n /

PEM FUEL CELL STACK

COGENERATION LOAD

CATHODE

COOLANT TO/FROM

WATERfTHERMAL MANAGEMENT

POWER WATER

COOLING

TOFROM

1 Figure 61. Phase II System Design


7. CONCLUSIONS AND RECOMMENDATIONS

The following conclusions are made based on this analysis effort:

• High-temperature PEM data are not available

• Stack development effort for Phase II is required

• System results are by definition preliminary, mostly due to the immaturity of the high-temperature stack; other components of the system are relatively well defined


• Fuel processor technology is available today and can be procured for Phase II (steam or ATR)



— Highest temperature most favorable

— Lowest water requirement most favorable

— Pressurized recommended for base loaded operation

— Unpressurized may be preferred for load following

• Pressurized PEM (vehicle mechanism) at about 100°C

— Pressure required for saturation

— Fuel cell technology currently available; stack development required

The system analysis and screening evaluation resulted in the identification of the following components for the most promising system:

• Steam reforming fuel processor

• Grotthuss mechanism fuel cell stack operating at 140°C

• Means to deliver system waste heat to a cogeneration unit


• Pressurized system utilizing a turbocompressor for a base-load power application. If duty cycling is anticipated, the benefits of compression may be offset due to complexity of control. In this case (and even in the base loaded case), the turbocompressor can be replaced with a blower for low-pressure operation.

7.1 RECOMMENDATIONS FOR PHASE II SYSTEM

Based on the Phase I efforts, it is recommended that a balanced system and technology developmental program be undertaken in Phase II to include the following:

• Development of a fuel cell/cogeneration demonstration system is recommended. The system will have the flexibility of incorporating high-temperature PEM stacks.

• As it is uncertain if the 140°C-stack technology will be available, the system needs to flexible, i.e., to be capable of incorporating the vehicle mechanism stack. Hence, the system should be pressurized, but be capable of low pressure operation with slight modification. The Honeywell 50 kW fuel cell stack system design developed for transportation applications, used in the DOE brassboard transportation system (currently being tested at Honeywell, including the Honeywell turbocompressor) can be used as a basis for Phase II work.

• Characterization and development of the high-temperature MEA's (both 100°C vehicle mechanism and 140°C Grotthuss mechanism) is required for a detailed 50-kW system stack design.

• Development of a high-temperature stack is needed for Phase II for either fuel cell mechanism.

• Once high-temperature stack data are available, the system analysis presented in this report needs to be confirmed (Phase II effort)

• Once a high-temperature stack design is defined based on appropriate testing data, a cost analyses should be done on the stack

• System requirements should be defined in more detail including duty cycles

• An advanced BCHP control system (to include fuel cell, cogeneration and real-time building loads) should be developed. This effort will enable a better understanding of load profiles (electric, heat and cooling) that will allow a determination to be made as to the most appropriate BCHP system design for a Phase III field test.


APPENDIX A

FUEL PROCESSOR SOLICITED DATA

FUEL PROCESSOR SOLICITED DATA

Honeywell contacted fuel processor developers as listed in Table A-1. If the developer expressed an interest in the program, a Request-for-lnformation (RFI) was sent via e-mail, including the following:

Description of the program A spreadsheet including a

• Worksheet with a generic system diagram • Worksheet with a typical natural gas composition

• Worksheets requesting yields at 1, 3, and 6 ATM

The following developers responded with data to the RFI:

• EPYX • Harvest Energy Technology • Hydrogen Burner Technology (HBT) • McDermott • Argonne • Johnson-Mathey • Wellman CJB • UOP

GE-EERC

The initial data collected was reviewed and analyzed. For the most promising developers, visits were arranged, all on a non-proprietary basis. Of the above developers, Honeywell visited EPYX, GE-EERC, Harvest, HBT, Johnson-Mathey, McDermott and UOR EPYX, UOP and Johnson-Mathey chose not to participate in the program after further review.

Table A-2 is a summary of the relative technical maturity of the fuel processor developers.

Argonne, Wellman CJB, GE-EERC were judged at this time to be not ready or appropriate for the Phase II program. Hence, the two developers left for possible inclusion in the Phase II were Harvest and HBT.

Yield data for autothermal reforming (ATR) were given by HBT and for steam reforming (SR) were given by Harvest and are represented in Table A-3.

Honeywell 2K-70886-4 Page A-1

Table A-1 Fuel Processor Developer Contacts Company Argonne ASPEN Systems EERC EPYX Gastec NV Haldor-Topsoe Harvest Technology Hydrogen Burner Technology Johnson-Matthey McDermott Northwest Power Pacific Northwest Lab Shell Texaco UOP Wellman CJB

Initial Contact Name Romesh Kumar Hamed Borhanian Jerald A. Cole Bill Mitchell, James Cross Jacques Smolenaars Richard Newland, Niels Undeergard Dave Warren Root Woods Jessica Reinkingh Rob Privette Dave Edlund Timothy Armstrong, Dean Matson Phillip Baxley Neil Richter David Cepla, Anil Oroskar Robert Dams

Table A-2 Fuel Processor Developer Maturity

Developer

Argonne GE EERC Epyx

Gastec NV

Haldor-Topsoe

Harvest HBT

Johnson-Matthey

McDermott Northwest Power

Pacific Northwest

Shell Texaco UOP

Wellman CJB

Fuel Processor Type

ATR Steam+Adsorption Steam, ATR'

Steam, ATR

Steam

Steam ATR

ATR

Steam Steam/membrane

ATR+Membrane

ATR ATR ATR

Steam

Visited by Honeywell

No Yes Yes

No

No

Yes Yes

Yes

Yes No

No

No No Yes

No

Units Developed

No complete unit No complete unit Several

Unknown; supplier to Plug No complete units for fuel cells 2 development Several

Several developmental w/out controls No complete unit Methanol, etha-nol or propane based units MicroChannel reactors, no complete unit Unknown Unknown 1 developmental unit Methanol development

Size

NA NA Multiple sizes <10kW

NA

<10kW 1 50kW& sub 30 kW <10kW

NA <10kW

NA

Unknown Unknown <10kW

NA

Phase II Availability

Estimated not ready Development needed Not interested

Not available

Not interested

Yes Yes

Not interested

Estimated not ready Not interested

Estimated not ready

Not responsive Not responsive Not interested

Estimated not ready


Table A-3 HBT (ATR) and Harvest (SR) Projected Yield Data REFORMER TYPE SYSTEM PRESSURE, psig Reformate Mole Fraction

H2 H20 N2 AR CH4 CO C02

Total Total Flow, gr/sec Temperature, C H2 Higher Heating Value(HHV) in Reformate, kW Feeds, gr/sec

Natural gas to Reformer reactor Fuel from Natural Gas Air to FP Condensate to FP Fuel from Anode Gas

Feeds, HHV kW Natural gas to Reformer reactor Fuel from Natural Gas Total Natural Gas Feed [Note 1]

Total Natural Gas Feed, HHV Fuel from Anode Gas, HHV Fuel Processor Efficiency, HHV

-H2 Efficiency [Note 2] -Net Efficiency [Note 3]

ATR 3

0.326 0.263 0.288 Trace Trace 1 e-4 0.122 1.0 27.34 223.2 135.6

2.864 2.864 15.25 9.23 0.159

143.2 -143.2 143.2 22.59

94 79

ATR 30

0.34 0.276 0.25 Trace 0.013 1e-4 0.12 1.0 24.25 251 129.6

2.864 2.864 12.16 9.23 0.15

143.2 -143.2 143.2 21.6

90.5 75

ATR 60

0.389 0.18 0.277 Trace 0.019 1e-4 0.137 1.0 20.71 264.5 127.4

2.864 2.864 11.58 8.0 0.149

143.2 -143.2 143.2 21.2

88.9 74

SR 3

0.7 0.05 0.03 -0.03 1e-4 0.18 1.0 8.0 225 135

2.5 0.3 -

4.8 0.16

125 15 140 140 22.5

96.5 80.5

SR 30

0.68 0.12 0.02 -0.04 1e-4 0.17 1.0 7.7 247 129.3

2.54 0.26 -5.0 0.15

127 13 140 140 21.5

92.3 80

SR 60

0.65 0.17 0.03 -

0.04 1e-4 0.13 1.0 7.7 253 127.4

2.58 0.22 -

5.3 0.149

129 11 140 140 21.1

91 79.5

Note 1: Natural gas feed set to create 50 kWe @ 35% HHV efficiency; composition: 95.4% CH4, 0 7% C02, 2.6% C2H6, 0 7%C3, 0 7%C4 Note 2 H2 efficiency = Total H2 in reformate/total natural gas feed * 100% Note 3: H2 in reformate used by the fuel cell/(total natural gas feed) * 100%


APPENDIX B

HIGH-TEMPERATURE FUEL CELL SOLICITED DATA

System Design of a Natural Gas Fired PEM Fuel Cell Cogeneration Power Plant For Building Application

Technical Progress Report # 9 High Temperature Membrane and Stack Technologies (Task 2.6 )

Submitted to:

Honeywell International

Contract No. DE-FC02-99EE27566 Purchase Order No. S00001118

Submitted by: Vesna Stanic

Energy Partners, L.C. 1501 Northpoint Parkway, Suite 102

West Palm Beach, FL 33407

September 27, 2000

1. INTRODUCTION

This report provides an assessment of the high temperature membrane and MEA technologies under development. It identifies critical issues that need to be addressed and resolved in membrane development that potentially could limit the use of high temperature PEM fuel cells in stationary power system applications.

Information on high temperature membrane availability and developmental status was generated by collecting published and solicited data as well as by approaching developers directly. As a part of the effort to assess the current membrane technology objectively, membrane samples that fulfilled some of the specifications set by the DOE (temperature, size) were formally requested from developers. Attempts were made to procure membrane samples from developers but were unsuccessful because of several reasons: they were not willing to provide samples, the technology was still too premature, the samples were too small to integrate and test in a stack, or it required a long delivery time.

In addition, four high temperature membrane developers were chosen for an on site technology assessment. They were: Foster Miller, Inc, The University of Connecticut, Polymer Research Institute and Princeton University. The University of Connecticut was only visited, since Foster Miller, Inc withdrew later due to project funding issues. The other two developers had not respond to our request.

Based on the gathered knowledge of the state-of-the-art of high temperature membranes, recommendations for the Phase II of this project are delivered.

2. STATUS OF HIGH TEMPERATURE MEA TECHNOLOGY DEVELOPMENT

2.1. Developers

Extensive research and developmental efforts in preparation and syntheses of new materials for the high temperature membranes are currently being carried out mostly in US, Canada, Italy, France, Germany and Japan. Major contributors are universities in the USA. All developers identified and contacted during Phase I are listed in Tables land 2 along with the type of high temperature membranes they are developing, contact names, telephone numbers and e-mail addresses.

From all thirty five identified or contacted high temperature membrane developers, twenty two of them disclosed some information about their membranes. The remaining either had no R&D on Hi-T membranes when they were contacted (N/A) or did not reveal any data about the membranes they prepared (UK).

Page B-2

Table 1: Identified but not contacted developers of the high temperature membranes.

DEVELOPER Technical University of Denmark

Laval University

Ecole Polytechnique de Montreal AIST

Hi-T PEM TYPE Organic/inorganic polymer

Doped polymer



DEVELOPER De Nora S p A University de Perugia University Montpelher II Gesellschaft fur Funftionelle Memb und Analgentech GmbH Lab D'Electrochimieet de Phys Des Matenaux et des Interfaces Montpelher University

University of Stuttgart

Hi-T PEM TYPE Organic/inorganic composites

Ionic polymers

Doped polymer

Ionic polymer

Ionic polymer

Table 2: Identified and contacted developers of high-temperature membranes.

DEVELOPER Virginia Polytechnic University & LANL Virginia Polytechnic University Foster Miller, Inc

Princeton University

Giner, Inc

Fuel Cell Energy, Inc

Case Western Reserve University University of Connecticut Cape Cod Research, Inc

University of Wisconsin Arthur D Little

University of Centarl Florida, Florida Solar Energy Center Degussa AG Axiva NA Axiva GmbH Polymer Research Institute Syracuse University Pennsylvania State University

Dais, Corp

3M

Johnson Matthey

Texas A&M University

E-Tek,Inc

DuPont Central Research & Development Hoechest-Cellanese Corporation Aventis Research & Technology Hoechst

W L Gore & Associates, inc

Hi-T PEM TYPE Ionic polymers

Ionic polymers

Ionic polymer


Iomc polymer

Iomc polymer

Doped polymer

Organic/inorganic composites Ionic polymer

Ceramic membrane UK

Ionic polymers

N/A N/A UK Ionic polymer

Ionic polymers

UK

N/A

N/A

N/A

N/A

Ionic polymer

UK

UK

UK

UK

CONTACT NAME T Zawodzmski

J McGrath

R Kover

S Snravasan

A LaConti

C-Y Yuh

J Wainnght

J Fenton S Moms M Bharmdipati M Anderson J Thijfen

C Linkous

R Burmeister G Calundann H Land I Cabasso

S Lvov

J Serpico

M Debe

J Frost

J Appleby

E De Castro

M Doyle

M Sansone

J Baunneister

G Frank

J Kolde

TELEPHONE /E-MAIL 505 667 0925

540 231 5976

781684 4114

609 258 5217

781 899 7270

203 825 6112

216 368 2728

860486 2490 508 540 7492

608 262 2674 617 498 6084

407 638 1447

49 618159 5462 908 508 1466 Land @ axiva com 315 470 6857 222

814 863 8377

727 375 8484

651736 9363

44 01189242158

979 845 8281

508 881 7504

Marc Doyle@usa dupont com 908 522 7572

baurmeister@ aventis com Frank@crt hoechst com

410 506 7545 UK unknown polymer type, N/A- do not work on Hi-T membranes

Page B-3

Developers supported by DOE are presented in Table 3. Not listed in the Table are Technical University of Denmark supported by Europian Commission for the Non Nuclear Energy Program JOULE III and De Nora S.p. A sponsored by Europian Commission under Brite-EuRAU. Sponsors of other development efforts are not available.

Table 3: High temperature polymer electrolyte membrane developers supported by DOE

DEVELOPER Virginia Polytechnic University & LANL Foster Miller, Inc

Princeton University

Giner, Inc

Fuel Cell Energy, Inc

Case Western Reserve University

DOE Program Transportation

CARAT

CARAT

CARAT

Transportation

ARPA

DEVELOPER Pennsylvania State University University of Connecticut Cape Cod Research, Inc University of Wisconsin University of Centarl Florida, Florida Solar Energy Center Arthur D. Little

DOE Program CARAT

Transportation

CARAT

Transportation

DOE

SBIR

2.2.1 Princeton University

Srinivasan et al.[2] prepared and evaluated different polymer based composites for use as high temperature membrane materials in Phase I of the project which is being supported by the DOE Corporative Automotive Research for Advanced Technology (CARAT) program. The membranes were based on perfluorosulfonic acid polymer and various inorganic compounds. The most stable performance was demonstrated by Nafion 115/Si02 membrane tested at 140°C in a single fuel cell with active area of 5cm2. The membrane required humidification at pressure of 45psig. Current density of 200 mA/ cm2

at 600mV was achieved using E-Tek electrodes (0.4 mg Pt/cm2) and with pure H2 and O2 as feed gases. With Acipex 1004/SiO2 composite membrane current density of 350 mA/cm2 was achieved under the same conditions. Therefore, the candidates for the Phase II program are composite membranes consisting of perfluorosulfonic acid polymer and hydrated metal oxides. Several organizations (H-Power Corporation, GM-Opel, Fuel Cell Energy Inc., W.L.Gore & Associates, International Fuel Cells) have expressed interest in these materials based on preliminary results.

Page B-4

2.2.2. Giner, Inc

Developers at Giner, Inc prepared membranes based on three different partially or fully perfluorinated polymer films with select grafting and cross-linking[3]. Subcontractor Beta Cure Technologies performed grafting and cross-linking in accordance with Giner's specification. The membranes were tested in a 55 W direct methanol fuel cell at 60[3], 90 and 120°C at 15-30psig [see Appendix]. Humidification of the membrane is necessary but less than that required for Nafion. This work is being supported by the DOE CARAT program.

In Phase I of the DOE project "Advanced Direct Methanol Fuel Cells", Giner Inc subcontracted Foster Miller Inc. for high temperature membrane research and development. However, Giner Inc. is not involved in Phase II of this project.

2.2.3. The University of Connecticut

Fenton et al.[4, 5] at the University of Connecticut are currently working on the preparation of high temperature membranes and on syntheses of new catalysts that are more tolerant to CO. The membranes are made of Nafion and proton conductive solids such as phosphotungstic acid (NTPA) or zirconium hydrogen phosphate (NZHP) supported on a porous Teflon matrix. These were tested in a hydrogen/air fuel cell (37cm2 active area) at 120°C and ambient pressure [see Appendix]. The NTPA membrane showed a stable performance of 400mA/cm2 at 300mV when tested at 120°C and ambient pressure for lOh [5]. Dr. Fenton indicated that the performance of the MEA will be evaluated in a 6 cell stack at Fuel Cell Energy, Inc in the near future. In the beginning of the project, researchers at the University of Connecticut had problems in preparing membranes that are larger than 37cm2 and in attaching the catalyzed electrodes to the membrane. Since then they have achieved several milestones.

This fuel cell laboratory led by Professor Fenton at the University of Connecticut-Chemical Engineering Department was visited on August 21. Dr Fenton showed his laboratories and presented the work on high temperature membranes and ME As. They solved the problem of the membrane size. They are able now to fabricate a 15cm x30cm membrane. The membrane consists of perforated Teflon support (Teflon web) impregnated with a mixture of Nafion solution and phosphotungstic acid. Thickness of the membrane is 25 |im. They successfully solved the problem of MEA preparation but are still working on electrocatalytic layer structure improvement. They showed samples of a 5cm x5cm membrane and a 2.5cm x2.5cm MEA. The MEA was tested in a 25cm2

single fuel cell at ambient pressure, 120°C cell temperature, gas humidification at 90°C and hydrogen/air stoichs 3.4/4.0 respectively. The test was run only for several hours.

Maximum performance achieved was 0.4A/cm2 at 0.5V. These results will be presented at 198th Meeting of the Electrochemical Society[6].

Page B-5

This work was funded by the DOE, Office of Transportation. The University of Connecticut was a subcontractor of Fuel Cell Energy. A patent has been filed recently. All intellectual property belongs to the University of Connecticut.

A spin-off company, IONOMEM, was started with the support of the University to further develop and manufacture the membrane and MEAs. Two former employees from International Fuel Cell, Russell Kuntz and Len Bonville, are the leading men in the company. The pilot plant is located within the University at the Environmental Laboratory. It consists of a tank for membrane processing that has 1.2 m2/day capacity, a bench coater with doctor blade and screen-printing head (0.6m wide). It also has 3D profiler for the MEA preparation by spray coating.

2.2.4. Fuel Cell Energy, Inc

Fuel Cell Energy, Inc[see Appendix] uses composite organic/inorganic membranes for the high temperature PEM fuel cells. Their goal is to prepare 300cm2 membrane and to test it at 140°C. They have done a high temperature membrane test in a single cell. Performance data and operating conditions are not available.

This work was supported by DOE, Office of Transportation.

2.2.5. E-Tek,Inc

This company was not involved in research and development of high temperature membranes. However, it will be willing to do research and development on high temperature MEAs once appropriate polymers become available.

2.2.6. 3M

3M was not involved in high temperature membrane or MEA research and development when contacted. Any plans for the future work have not been revealed.

2.2.7. Dais, Corp.

As a producer of a regular temperature polymer electrolyte membrane, Dais, Corp indicated that they had no intention of becoming involved in high temperature membranes for now.

2.2.8. Foster Miller, Inc

During the Phase I of the "Advanced Direct methanol Fuel Cell" project (DOE Cooperative Automotive Research and Advanced Technologies, CARAT program, DE-FC02-98EE50536) Foster Miller, Inc was Giner's, Inc subcontractor. Their membrane prepared from cyclic sulfonated polymers is a vehicle type proton conductor. It was tested by Giner, Inc in a single cell at 120°C and humidified 30 psig. The test lasted for a

Page B-6

few minutes only due to membrane failure. They also provided the membrane samples to Los Alamos National Laboratory for independent performance evaluation.

Developers from this company are capable of making high temperature samples membrane samples with maximum size of 506cm2. When we asked them, they were willing to provide test samples and to reveal the single cell test results and conditions. However, they withdrew later. From the discussion with the company's vice president Mr. T. Kurschnner we learned that they had a funding problem during the project because the government cut off the DOE CARAT program that had supported them. The company then invested its own money in order to finish the project. Since the project was currently on hold due to lack of money, they were not able to demonstrate their membrane technology on site to the Honeywell/EP team.

They expect that as of October 2000 the project will continue as soon as funding from DOE continues. The membrane performance still needs to be improved.

2.2.9. Polymer Research Institute, Syracuse University

Cabasso et al.[7] prepared a high temperature membrane based on polydimethyl-phenyleneoxide phosphonic acid. The membrane was tested in a fuel cell at 250°C at 30psig. Humidification was necessary [see Appendix]. The test duration was as long as 30 days. The performance of the membrane increased with time. Although the mechanical properties of this membrane are poorer than that of Nafion®, its performance in a fuel cell is better. However, the performance data are not available.

2.2.10. The University of Wisconsin

Anderson et al.[see Appendix] prepared membranes from porous metal oxide composites. The pores in the membranes are filled with water. The membranes were characterized at temperatures below 100°C. The maximum diameter of the membrane was 2.5cm. The membranes were tested in a single cell. However, no further results are available. The work is supported by the DOE.

2.2.11. Virginia Polytechnic Institute and State University

McGrath et al.fsee Appendix] have prepared and tested high temperature polymer membranes in a single cell at 120°C with humidification. The tests lasted for few minutes. The test results are not available.

2.2.12. De Nora S. p. A, Universita di Perugia, Universite Montpellier II, Gesellschaft fur Funktionelle Membranen und Anlagentechnologie GmbH

De Nora S. p. A., University di Perugia, University Montpellier II and Gesellschaft fur Funktionelle Membranen und Anlagentechnologie GmbH jointly developed composite membranes using sulfonated polyetherketone as the organic component and inorganic phosphates and oxides[8]. The performance observed in a hydrogen/oxygen fuel cell at

Page B-7

100°C and pressure 45 psig with a PEEK-S-hybrid membrane containing 25%wt inorganic component, was 500mA/cm2 at 700 mV using E-Tek electrodes (lmg Pt/cm2

loading). The electrodes were not attached to the membrane by hot pressing. Results obtained at 130°C in a hydrogen/air fuel cell also look promising. The conductivity of this membrane is less dependent on humidity than the conductivity of Nafion®. Moreover, developers at De Nora S.p.A. [9] prepared a high temperature membrane from perfluorosulfonic acid and silica particles embedded therein in concentration comprising between 0.01 and 50wt.%. The membrane was tested in a single hydrogen/oxygen fuel cell. Performance of Nafion® /10wt% silica composite was 250mA/cm2 at 0.7V, cell temperature 130°C and pressure 42psig.

2.2.13. W.L. Gore & Associates, Inc

W.L. Gore & Associates [see Appendix] also work on the development of high temperature membranes. However, no information on materials and performance is available.

2.2.14. Pennsylvania State University

AUcock, Lvov et al.[10] have developed high temperature proton conductive membranes for direct methanol fuel cell. Channel-type or domain type membranes were prepared from the sulfonated or phosphonated polymers. Phosphated polymer membranes possess better conductivity than Nafion ®117 (e.g. MAH- Phenoxy Phosphate 2 has 1.63xl0"2

S/cm ionic conductivity at unknown testing conditions). The membrane has not yet been tested in a fuel cell. This research is being sponsored by the DOE. Phosphazene Custom Synthesis Inc., State College, PA which is a Penn State spin-off company carries out polymer synthesis at the industrial scale.

2.2.15. Cape Cod Research, Inc.

Morris et al.[l 1, 12] developed a novel proton exchange membrane demonstrating enhanced electrochemical performance and high proton conductivity at temperatures higher than 150°C. The membrane was prepared by combining selected phosphonic acid additives with Nafion®[l 1] or proprietary ionomer, sulfonated aromatic polymer and perfluoro acid. The ionic conductivity of the membranes was measured at 175°C , ambient pressure and 15% relative humidity [see Appendix]. The conductivity of membrane CCR[12] was 2.0xl0"3 (12cm)"1 at 175°C while that of Nafion® was 2.2xl0"4

(Qcm)"1 at the same conditions. The membrane is also characterized by researchers at the University of South Carolina for oxygen solubility and permeability. The results of this work will be published in the Journal of Electrochemistry. The membrane has not yet been tested in a fuel cell. The research is being sponsored by the DOE.

This company has already started Phase II of the project "Novel Proton Exchange Membrane for High Temperature Fuel Cells". Improvement of the high temperature membrane mechanical properties has been carried out. Developers from this company are

Page B-8

open for collaboration. However, due to existing problems with the membrane mechanical strength, they were not able to produce samples bigger than 25cm2.

The research team at Cape Cod Research, Inc., went through some staff changes. The principal high temperature membrane scientist left the company and established a new enterprise called Materials Discovery, Inc. He has not yet produced membrane samples large enough to be tested in a fuel cell due to mechanical strength problem. He expected to have samples available by August but to date has not made any formal announcement. He also indicated that he planed to have a complete MEA by April 2001. The DOE supported the high temperature membrane R&D.

2.2.16. Case Western Reserve University

Savinell et al.[13-16] examined thermal stability[13] and electro-osmotic properties of phosphoric acid doped polybenzimidazole (PBI) membrane at temperatures above 150°C[14]. In addition they tested sorption and transport properties of water in phosphoric acid doped Nafion reg-sign membrane (conformation sites in polymer where H atoms were substituted with PO groups) at temperatures above 100°C[15], The performance of the membrane was tested in a hydrogen/oxygen fuel cell at 150°C and ambient pressure. The gases were humidified by bubbling through distilled water tanks heated at 48°(hydrogen) and 28°C(oxygen). The maximum power observed in these unoptimized cells was 259mW/cm2 at 700mA/cm2.

Phosphoric acid doped polybenzimidazole membrane was prepared only at the laboratory scale. The maximum size that researchers at this University are able to prepare was 15cmxl5cm.

Developers from this University were contacted and asked to provide a PBI doped high temperature membrane sample for evaluation. They were not willing to provide samples prior to licensing the membrane technology.

The high temperature membrane work was performed under Government program ARPA.

2.2.17. Laval University

Kaliaguine et al.[17] synthesized a polyoxydiazole membrane (POD) impregnated with phosphoric acid for the high temperature application. The membrane exhibits a high conductivity of 7.8xl0"2 (Qcm)"1 at 90°C and was stable up to 150°C. However, the membrane has not yet been tested in a fuel cell.

2.2.18. Ecole Polytechnique de Montreal

Savodago et al.[18] prepared composite membranes consisting of Nafion solution and silicotungstic acid with and without thiophene. The membranes were characterized by various methods after heat treatment at 130°C. No other test results are available.

Page B-9

2.2.19. University of Stuttgart, Germany

Kerres et al[19] synthesized acid-base polymer blends. They mixed sulfonated polyetheretherketone or polyethersulfone as acidic compounds with diaminated polyethersulfone, poly(4-vinylpyrydine), polybenzimidazole or polyethyleneimine as the basic compounds. The membranes are stable at temperatures >270°C. They demonstrated good performance in a single hydrogen/oxygen fuel cell. The cell achieved 1.3A/cm at 0.7Vwith membrane made from 90wt.% sulfonated polyethetetherketone and 10wt.% diaminated polyethersulfone. There are no comments in the report on humidification conditions.

2.2.20. University of Montpellier, France

Glipa et al.[20] prepared a proton conductive membrane by grafting of sulfonated polybenzimidazole. The degree of sulfonation was up to 75% of available sites. Sulfonation increased proton conductivity from 0.0001 in non-modified PBI to 0.01 (Hem)"1 at room temperature for highly sulfonated samples. The test in a fuel cell has not been performed.

2.2.21. Laboratoire d'EIectrochimie et de Physic des Materiaux et des Interfaces, France

Bouchet and Siebert [21] prepared membranes from anhydrous mixtures of polybenzimidazole (PBI) and phosphoric, sulfuric or hydrobromic acid. They investigated the materials by infrared and impedance spectroscopes. The study indicates that acid anions are linked to the polymer by hydrogen bonding. In addition, the best conductivity demonstrated sulfuric acid doped PBI. It is 0.0004 (Qcm)"1 at room temperature when a PBI/ sulfuric acid membrane is in anhydrous state. No other test results are available.

2.2.22. DuPont Central Research and Development, USA

Developers at DuPont [22] prepared a high temperature membrane from Nafion® swollen with the ionic liquid 1-butyl, 3-methyl imidazolium trifluoromethane sulfonate. The membrane has an ionic conductivity 0.1 (^cm)"1 at 180°C when measured in a glove box in a dry nitrogen atmosphere. This material is water sensitive. It has not been tested in a fuel cell. Results of conductivity dependence on temperature published in this paper[4] were used for generating polarization curves used as a base for cogeneration system modeling and analysis in this project.

Developers at DuPont were contacted. They were not willing to discuss any other information about their research except the one published earlier.

Page B-10

2.2.23. AIST, Japan

Honma et al.[23] prepared organic/inorganic nanocomposite membranes consisting of silica particles and polyethylene oxide. This material was synthesized by sol-gel processing and then doped with solid acids such as monododecylphosphate or phosphotungstic acid. Materials show good conductivity at temperatures above 100°C The membranes also have good thermal stability. The material has not been tested in a fuel cell.

2.2.24. Arthur D. Little, Inc

They tested two different Hi-T membranes, one at slightly over 100°C and the other at 150-160°C. The company who is ADL's long-term supplier of MEAs for the standard temperature PEM fuel cells also supplied the samples of Hi-T MEAs. The membrane technology was developed as a result of a DOE SBIR Phase I award. ADL did not reveal the name of the supplier and indicated that they only do fuel cell testing for that company. The size of the MEAs that are available is 10cm2, however ADL claims that they can be manufactured to any size required. Tests were performed in a single fuel cell at pressures lower than those necessary to maintain water as liquid since this type of Hi-T membrane does not require liquid water for humidification. They got encouraging MEA performance results. Endurance of the MEAs was measured only for several hours because of the limited availability of the testing facility

2.2.25. Texas A&M University

There is no high temperature membrane research and development going on at Texas A&M University. Moreover, this institution has not ever been involved in the evaluation and testing of Hi-T membranes for PEM fuel cells.

2.2.26. University of Central Florida, Florida Solar Energy Center

Linkous et al. have synthesized a number of proton exchange high temperature polymers for water electrolysis [24, 25]. They also tested hydrolytic stability of polymers for 24h at 200-400°C under steam/hydrogen or steam/oxygen atmosphere [26]. Moreover, they studied previously synthesized polymer's water uptake and proton conductivity at a temperature range of 110-180°C[27], They compared the results obtained with Nafion 117 at similar conditions and concluded that the Nafion membrane is still a superior material in comparison to the synthesized polymers. Their work was sponsored by DOE.

2.2.27. Axiva GmbH

One of the potential high temperature membrane developers, Axiva GmbH, Frankfurt Germany, was contacted before it merged with Plug Power. No answer has been received yet.

Page B-ll

2.2.28. Axiva NA

This is a consulting company acting as an Axiva GmbH representative in the US and North America. Dr Gordon Calundann from Axiva NA stated that Axiva's membranes are made from PBI doped with phosphoric acid. They can be produced in any size. Their business plan is to make only MEAs. They tested the Hi-T membrane in a single cell with an active area of 250cm2. Endurance test was done for lOOOh. They had no problems with carbon corrosion or phosphate build up on the cathode catalyst. The membranes were tested at 140-200°C. All the tests were performed in a Frankfurt lab, Germany. The performance results obtained in the Axiva GmbH have not been published. However, Dr. Calundann said that the results are similar to those already published by other groups. He pointed out that the mechanical properties of the membrane they make are not relevant, since the membrane is sandwiched between electrodes.

We officially asked for a sample of their membrane or MEA. There is no response yet. We have no information on the sponsor of the research and development at Axiva GmbH.

2.2.29. Hoechest-Cellanese Corporation

This corporation, one of the world largest chemical companies and a manufacturer of polybenzimidazole, was contacted. Information on high temperature R&D is not available since they have not yet responded to our questionnaire.

2.2.30. Aventis Research &Technologies

This is a Hoechst spin-off company that manufactures polymer membranes. We contacted them, but they have never responded to us. Therefore, there is no information available on high temperature membrane R&D.

2.2.31. Hoechst

The Hoechst Corporate Research & Technology group located in Frankfurt, Germany was contacted. We have not yet received the answers from them. Information on high temperature R&D was not available.

2.2.32. Degussa AG (DMC2)

This company has no internal research and development on high temperature membranes for PEM fuel cells. Nevertheless, the developers at this company are willing to make the high temperature MEAs when the membrane becomes available.

2.2.33. Technical University of Denmark

Qingfeng et. al [28] prepared PBI doped with phosphoric acid high temperature membrane. The membrane was solution casted from PBI (Celasole® PBI, Cellanese). The thickness of the membrane samples prepared was 90-140 |im. They prepared appropriate electrocatalyst layers using the tape casting technique. The catalyst was

Page B-12

deposited on the gas diffusion layer. The proton conductor used was phosphoric acid and it was incorporated into the electrodes by doping. The electrodes were attached to the membrane by hot pressing.

The MEA was tested in a 5cm single fuel cell at the following testing conditions: operating temperature range 55-190°C, operating pressure of one atmosphere for both hydrogen and pure oxygen and without humidification. Polarization curves generated under these conditions are shown in Fig. 1. As presented in Fig. 1, the performance of the fuel cell increased with temperature. The maximum power output was 0.55 W/cm2

achieved at 1.2A/cm2 and 190°C. However, at 0.7V the power was 0.245mW/cm2 at the same operating conditions, still lower than the DOE target of 0.350mW/ cm2.

The same temperature effect on a fuel cell performance is observed from polarization curves presented in Fig. 2, generated in this project as a base for cogeneration system modeling using data from ref.[22]. At the pressure of 1.21atm (~ 3psig) and potential of 0.7V, power outputs were 0.245mW/cm2 at 100°C and 0.392mW/ cm2 at 120°C, demonstrating that with the appropriate high temperature membrane the same or even higher cell performance can be achieved at much lower temperature. Qingfeng et. al showed that the cell performance was unchanged at 190°C even with 3% CO. The duration of the test was not reported.

This work was supported by European Commission for the Non Nuclear Energy Program JOULE III.

>

0.8

0.6

= 0.4 ■

0.2 ■

500 1000 Current density, mA/cm:

1500

Figure 1: Performance curves of the PBI fuel cell at different temperatures. The cell operates with hydrogen-oxygen at atmospheric pressure and flow rate of 0.160L/min without humidification. Platinum catalyst loading was 0.45 mg/cm2 for both electrodes[2].

Page B-13

Goal Polarization Cuves (Hgji T Pa/PC) Linear Cuves Used for SystemModeling

Q6 as

QjrertCfensity.Afcnf

Figure 2: Polarization curves generated in this project from Nernst equation and resistivity data published by DuPont [22] in order to examine the effect of temperature and pressure.

1.4

2.2.34. Los Alamos National Laboratory

The PEM fuel cell group at Los Alamos National Laboratory (LANL), Materials Science and Technology Division led by T. Zawodzinski use to be an independent arbitrator for evaluation of many developmental high temperature membranes. LANL has recently become actively involved in research and development of high temperature polymer electrolyte membranes and MEAs in collaboration with J.McGrath from Virginia Polytechnic University. The project is supported by the DOE Transportation program. Polymers are synthesized at the University and electrochemically characterized at LANL. They synthesize ionic type of polymer membranes. They are still at the early stage of the research and have not yet tested the membranes in a fuel cell. They perform polymer screening by various materials characterization methods. Only those membranes that have good proton conductivity, mechanical strength and thermal stability will be chosen for further development, MEA preparations and fuel cell tests.

In addition, the research funds will enable them to do specific studies such as mass and water transport in the membranes, oxygen reduction kinetics, and work on the problem of developing the electrode structure and MEA preparation.

Page B-14

During our visit to LANL, we discussed with T. Zawodzinski about the maturity of high temperature membrane technology and asked him to assess it. In his group at LANL many of developmental high temperature membranes were tested. He did not release any performance data since all of the membrane tests were performed under confidentiality agreements. Nonetheless, he believes that there is no adequate high temperature membrane technology that can achieve DOE requirements. He believes that a completely new approach is necessary in membrane technology and that most of the DOE goals are achievable, although he is concerned about pressure requirement. T. Zawodzinski indicated that it will be hard to reach this requirement due to water management. He also believes that due to lack of appropriate high temperature membrane it is not yet time for high temperature stack development.

3. PROTON CONDUCTIVITY AND CLASSIFICATION OF HIGH TEMPERATURE POLYMER ELECTROLYTE MEMBRANES

3.1. Chemistry of solid proton conductors

Proton conductivity in ionic conductors, such as polymers, ceramics and composites is governed by hydrogen bond formation. Proton conducting materials have special chemical structures or entities that cause proton conductivity [1] such as the following:

• Protonated anions in anhydrous materials: OH", HPO42", H(S04)23".

Compounds such as metal hydroxides, phosphoric, sulfuric and other acids, protonated metal oxides, acidic phosphates and sulfates fall under this category.

• Cationic proton hydrates [H(H20)n]+: H30+, H502+, H703

+, etc. Some examples of this type of proton conductors are heteropolyacids such as phosphotungstic acid H3PW12O40»nH2O, zirconium phosphate hydrate Zr(HP04)2»nH20, hydrous oxides, Nation®.

• Combination of hydrogen with nitrogen: ammonium NHV", hydrazinium N2H5

+, hydrazonium N2H5 + . Polymers such as polybenzimidazole (PBI) and

polyoxydiazole (POD) belong to this group of proton conductors.

3.2. Mechanisms of proton conductivity

The conduction of protons in the materials occurs via two different mechanisms:

• Proton-carrying mechanism (the vehicle mechanism) • Lone proton migration (Grotthuss mechanism or translocation.).

Page B-15

The type of proton conducting mechanism in a particular material depends on its protonic species it has and the crystalline structures formed by the latter. The occurrence of different types of defects in the crystalline structure can also influence the proton conducting mechanism. These defects can be [H(H20)n]+ and H+ ions that occur either as thermally activated (Frenkel) excess sites or voids. The mechanism can change in the same material if the temperature and water vapor partial pressure change. For instance, in phosphotungstic acid conduction occurs by Grotuss mechanism at low temperatures, while it changes into the vehicle mechanism at high temperatures.

3.2.1. Grotthuss mechanism

In this mechanism the H+ ion is displaced along a hydrogen bond from one bond to the next. The activation energy necessary for the H+ ion transport by this mechanism is high(0.5 eV)[l] and is related to the presence of the defects. This mechanism is typical for anhydrous proton conductors which contain protonated anions. Moreover, polymers containing N-H protonic sites, conduct protons by this mechanism. In addition, anhydrous polymers blended with strong acids conduct protons by this mechanism. Their proton conductivity is not limited by the presence of water since pure acids such as sulfuric and phosphoric acids conduct protons by extensive self-ionization and self-dehydration.

3.2.2. Vehicle Mechanism

This mechanism requires the presence of vehicle molecules such as H20 or NH3, in the material. Mobile species H30+ and NH4+ conduct protons by this mechanism. The conduction occurs via either (a) the available empty sites (defects) in a crystal or (b) counter-flow of protons and vehicles, where voids are created by thermal activation. Activation energy of this process is highly affected by temperature. If temperature increases, the activation energy enormously decreases. The typical value for the activation energy at room temperature is 0.25 eV[l]. This mechanism is typical for heteropolyacid hydrates such as phosphotungstic acids at high temperatures (a) and for polymers modified with inorganic acid such as Nafion® (b).

3.3. Classification of the high temperature membranes

Polymer electrolyte high temperature membranes that are being presently developed for application in high temperature PEM fuel cells can be classified in three major groups in accordance to their chemical structure:

ionic polymers

doped polymers

organic/inorganic composites.

Page B-16

In Table 4 developers of the high temperature membranes are listed along with the type of the membrane they synthesized.

Proton conductors prepared from porous hydrate metal oxides are not considered since their operating temperatures are below 100°C.

Table 4: Different types of the high temperature membranes synthesized by various developers.

DEVELOPER

Cape Cod Research

Virginia Polytechnic Inst Foster Miller University of Wisconsin Princeton University Giner Inc Polymer Res Ins Syracuse Univ Case Western Reserve University University of Connecticut Pennsylvania State University

De Nora S p A Universita di Perugia Universite Montpellier II Gesellschaft fur FunftionelleMemb und Anlagentech GmbH DeNora S p A Laval University

Ecole Polytechnique De Montreal University of Stuttgart

Montpellier University Lab D'Electrochimie et de Phys Des Matenaux et des Interfaces DuPont Central R&D AIST

POLYMER COMPONENT

Sulfonated and Phosphonated aromatic polymers Polymer

Cyclic sulfonated polymers N/A

Nafion Perfluonnated polymer Phosphonated

Polvdimethylphenyleneoxide Polybenzimidazole (PBI)

Nafion

Sulfonated or phosphonated polyphosphazenes

Sulfonated polyetherketone (PEK)

Sulfonated polyetheretherketone (PEEK)

Nafion Polyoxidiazole

Nafion

Sulfonated polyetherether ketone (PEEK), polyethersulfone, Polyvinylpyndine, polybenzimidazole, polyethyleneimine Sulfonated polybenzimidazole (PBI) Polybenzimidazole (PBI)

Nafion Polyethylene oxide

INORGANIC COMPONENT

Sulfonic acid Phosphonic acid N/A

Sulfonic acid Porous metal oxides

Silica (Si02) N/A Phosphonic acid

Phosphoric acid

Phosphotungstic acid

Sulfonic or Phosphomc acid

Sulfonic acid

Sulfonic acid

Silica Phosphoric acid

Silicotungstic acid

Sulfonic acid

Sulfonic acid Phosphonc acid Sulfunc acid Hydrobromic acid Sulfonic acid Silica, Phosphonic acid Phosphotungstic acid

TYPE OF THE MEMBRANE

Ionic polymer

N/A

Ionic polymer Inorganic

Organic/inorganic composite N/A Ionic polymer

Doped polymer

Orgamc/morganic composites

Ionic polymer

Ionic polymer

Ionic polymer

Organic/inorganic composite Doped polymer

Organic/inorganic composites

Ionic polymer

Ionic polymer Doped polymer

Organic/inorganic composite Org an lc/in organic composite

NA- not available

Page B 17

3.3.1. Ionic polymers

Sulfonated and phosphonated polymers belong to the group of ionic polymers. They are compounds where ionic groups such as -SO3H or -PO4H2 are attached to the organic macromolecule. Sulfonic or phosphonic acid used as a precursor in the polymer synthesis is an ionic organic compound, where hydrogen atoms in an acid (phosphoric, sulfuric) are substituted with an organic group[29]. They are usually very unstable compounds, extremely sensitive to water.

Nafion® is the best known and the most studied ionic polymer. The chemical synthesis of Nafion® is a process that consists of several steps[l]. During the copolymerization step, sulfonylfluoride vinylether and tetrafluorethylene react forming resin. Nafion® is formed by hydrolysis of this resin in sodium hydroxide.

This procedure illustrates a general idea of preparation of ionic polymers that contain either sulfonic or phosphonic acidic sites. Similar to Nafion® it is expected that the ionic sites attached to the polymeric molecules are responsible for proton conductivity of the polymers. Moreover, it can be anticipated that proton conductivity may occur by vehicle mechanism, the same as in Nafion®. In order to keep water liquid, high pressure is necessary at high operating temperatures. For instance, for a temperature range from 100 to 140°C, the corresponding pressure range is 0-64psig.

3.3.2. Doped polymers

Doped polymer is a solid solution of a polymer and a pure acid such as phosphoric or sulfuric. Polymers used usually contain highly basic nitrogen sites in any of the following forms: azole, imidazole, azen, pyridine, and imine. The strong acids are connected to these basic sites with either hydrogen bonding or protonation. Preparation of doped polymers that can potentially be used as high temperature membranes, is demonstrated with phosphoric acid doped polybenzimidazole [30].

The polybenzimidazole (PBI) film is casted from a polymer solution and then boiled in water to remove residuals and impurities. The film is then immersed in phosphoric acid. Thermal gravimetric analysis in air shows that PBI is stable up to 500°C [31]. PBI is a poor proton conductor [20]. Therefore, its role in this type of high temperature membrane is to be a matrix for phosphoric acid and to increase the temperature resistance of a membrane.

Proton conductivity in phosphoric acid occurs by Grotthuss mechanism through self-ionization and self-dehydration[l]:

5H3P04 <-> 2H4PO/ + H30+ + H2PO4" + H2P2072'

An increased acid dissociation occurs due to hydrogen bonding of the acid to the basic sites in PBI. The conductivity of doped PBI is 0.01-0.04 (Qcm)"1 for temperatures between 130 and 200°C and relative humidity from 4-40% that corresponds to water

Page B-18

partial pressures between 0.1-lpsig [32]. Limitation in this type of high temperature membrane is caused by thermal instability of the acid. Thus, at the boiling point (213°C [29]) phosphoric acid starts to degrade losing water and forming pyrophosphoric acid H4P2O7. Durability of the PBI/H3PO4 membrane has not been reported yet.

3.3.3. Organic/inorganic composites

This type of membrane is made of a polymer and an inorganic compound that is usually hydrated metal oxide or solid acid. The material is a two phase composite. There have been two approaches in preparation procedures of these composites. The first one consists of the swelling of a polymer membrane such as Nafion® in an appropriate solvent and incorporating a second, inorganic, phase within the polymer by diffusion [9, 22]. The second approach is used more often and it consists of mixing polymer solution (Nation®) with a solid compound (e.g. phosphotungstic acid) and recasting a membrane from the mixture [23, 30].

Composite membranes prepared by described procedures, include phases that are proton conductors, Nafion® and an inorganic compound. The conductivity of Nafion® strongly depends on humidification level as confirmed by intensive study, indicating that protons are conducted by vehicle mechanism.

However, hydrated metal oxides such as hydrated silica, conducts protons by Grotthuss mechanism only when in the hydrated state. Therefore, it is expected that its conductivity still depends on humidity but probably not at the same level as Nation's®.

In Nafion®/phosphotungstic acid composite, Nafion® still conducts protons by vehicle mechanism while phosphoric acid conducts by Grotthuss mechanism only if in a solid crystalline form. At ~90°C phosphotungstic melts losing a crystalline form and hence changes the conduction mechanism from Grotthuss to vehicle. In this case, the major limitation of the application of this type of membrane is the instability of the inorganic phase and drying and possible breaking of Nafion®. These changes influence both the conduction mechanism and durability of the membrane.

4. HIGH TEMPERATURE MEMBRANE/MEA PERFORMANCE, MATURITY AND COST

4.1. Criteria used for the assessment of high temperature membrane/MEA technology

The overall technical performance of a 50kW natural gas PEM fuel cell cogeneration power plant is highly dependent on the performance of the high temperature PEM fuel stack. The most important technical challenge in developing high temperature PEM fuel cells is the availability of an appropriate high temperature membrane. The maturity of

Page B-19

high temperature membrane technology is assessed on the basis of how closely membrane properties and performance match the requirements set by DOE (Table 5). The difference between required and achieved values determines the technology maturity. It also assists in understanding of major gaps in the high temperature PEM fuel cell technology.

Table 5: DOE requirements for High-temperature Membranes for PEM Fuel Cells.

• • • • • • • •

Thickness: Area specific resistance: Gas permeability: Operating temperature: Operating pressure: Size: Durability: Power density in a fuel cell stack:

<75u. <20 n-cm2

<0.1% 100-140°C <1.5atm >200cm2

20,000h 350 mW/cm2 at 0.7V.

Properties of high temperature membranes are determined by chemistry of the membranes. Therefore, it is of crucial importance to understand the fundamental physicochemical properties of membrane in order to improve its thermal and mechanical properties as well as fuel cell performance and thus to overcome existing technology gap.

4.2. High temperature membrane performance

Based on information presented in Tables 1 and 2, twelve of the Hi-T membranes are ionic polymers, six are organic/inorganic polymers and three are doped polymers. The polymer types of other high temperature membranes are unknown (Table 2, UK). The chemistry of the membrane determines the proton conductivity mechanism which further defines the operating conditions such as pressure as a function of fuel cell temperature. The predicted disadvantages of a particular type of membrane chemistry are as follows:

• Ionic polymer: since protons are conducted via vehicle mechanism in these membranes, high pressure is necessary for operation at high temperatures and replenishment of the vehicle lost during the proton transport.

• Doped polymer : the potential problems are similar to those in phosphoric acid fuel cells that include acid leaching and poisoning of the cathode catalyst.

• Organic/inorganic composite: if the composites are prepared from Nafion solution and any type of particles, high operating temperature and low humidification will cause Nafion drying and breaking of the composite structure over some period of

Page B-20

time. In order to keep the consistency of the composite structure, high pressure is necessary at high temperatures.

None of the current chemical approaches to the Hi-T membrane synthesis and preparation have demonstrated ability to meet DOE performance targets. Results published on membrane performances lack information such as humidification pressure, power achieved, membrane durability and CO tolerance level. Developers listed in Table 4 have presented the most complete test results of the membranes tested in single fuel cells. In addition, no membrane tested in a single fuel cell fulfills the DOE performance requirements [33], presented in Table 6.

Table 6: Performance of high temperature membranes tested in single fuel cells.

DEVELOPER

University of Connecticut Princeton University

Case Western Reserve University Technical University of Denmark *De Nora S.p.a University di Perugia University Montpellier II Gesellschaft fur FunfttionelleMemb und Anlagentech GmbH

Hi-T PEM TYPE

Organic/inorgani c composite Organic/inorgani c composite Doper polymer

Doped polymer

Organic/inorgani c composite

OPERATING TEMPERATURE

(°C) 120

140

150

190

130

PRESSURE (atm)

0

3

0

0

3

MAX POWER DENSITY <W/cm*) 0.200

0.120

0.250

0.550

0.350

ENDURANCE TEST

GO 2

N/A

N/A

N/A

N/A

CO TOLLERANCE

N/A

N/A

N/A

3

N/A

4.3. High temperature membrane maturity

The following parameters were used to assess the membrane maturity:

• performance under fuel cell operation • endurance test • large scale manufacturing

Performance results indicate that high temperature PEM fuel cells have not reached the performance of the regular PEM fuel cells with hydrogen/air reactant gases yet. They neither meet DOE performance targets, nor requirements such as operating pressure and endurance. Since performance of a membrane is determined by both membrane proton

Page B-21

conductivity and MEA activity, factors such as membrane chemistry, electrode structure and MEA processing must be improved in order to achieve the requested performance.

Large scale manufacturing of high temperature membrane is determined by its mechanical properties. From data published and solicited, only four developers are capable of manufacturing membranes larger than 200 cm and can thus meet DOE requirement for the minimum membrane size. They are presented in Table 7. Even though the membranes presented in Table 7 achieved this goal, they do not meet the other two important maturity criteria, durability and performance. From Table 7, information on endurance testing is rarely available and the maximum test length is not more than lOh. This raises a question about the high temperature membrane thermal stability and whether it was a detrimental factor of the endurance test length.

Table 7: List of developers capable of manufacturing Hi-T membranes that meet DOE minimum membrane size requirement.

DEVELPOER Foster Miller, Inc

Polymer Research Institute, Syracuse University

Case Western Reserve University

University of Connecticut

POWER (W/cm2) N/A

N/A

0.250

0.200

ENDURANCE (h) < 1

N/A

N/A

2

MAX. SIZE 500 cm'

>200 cm'

* 225 cm2

1.2 m2/day

*Case Western Reserve University is no longer being supplied with the PBI membrane and therefore might not be able to supply the MEA.

4.4. High temperature membrane cost

Production cost of high temperature polymer electrolyte membrane includes material cost, labor, equipment and energy. There is no data published about membrane cost analysis since most of the membranes are still produced in laboratories. However, in order to predict roughly what would be the cost of some of the high temperature membranes, we calculated costs of an organic/inorganic composite membrane and a PBI based membrane.

If we assume that a composite membrane is prepared from Nafion® solution, inorganic particles and Teflon web support and that only 1/3 of the membrane weight is made of

Page B-22

Nafion, then the cost of the 25 urn thick membrane will be $ 0.106/ cm2. The calculation was based on the Nafion membrane area density 0.006g/cm2 and on the price of lOOmL 5% Nafion® solution, $260. In Table 8 the calculated price of this membrane is compared with commercially available membranes Nafion® 117 and 1135 that are used in regular PEM fuel cells.

The price of PBI membrane usually used for doped polymer type high temperature membrane preparation is also presented in Table 8. The assumption made is that doped high temperature membrane -100% of polymer, so that the membrane price is determined only by the price of PBI.

Table 8: Calculated polymer costs of Nafion® based organic/inorganic composite membrane and doped PBI membrane are compared to the cost of commercially available Nafion® membranes.

Membrane

Nafion® 117 Nafion® 1135 PBI Nafion® based organic/ inorganic membrane

Thickness (|xm)

178 90 76 25

Price ($/cm2)

0.090 0.075 0.020 0.106

All the costs presented in Table 8 are the current market prices. High volume membrane production might decrease cost to $0.0055/cm2 as predicted in Arthur. D. Little's report [34]. However, the thickness of a membrane used in a high temperature PEM stack will be also a price-determining factor in addition to the membrane surface area.

4.5. High temperature membrane technology status

Based on the results of the data collected on the state-of-the-art high temperature membrane research and development, the following observations can be made:

• Developers who claim they have high temperature membrane technology that fulfills DOE requirements have no performance data published (Arthur D. Little, Axiva NA, Foster Miller, Inc).

• Developers with extensive published performance results usually have prepared membranes that do not fulfill yet the DOE requirements and need more government funding for further research and development.

• Large corporations, such as DuPont, do not release any information on in-house high temperature membrane development.

Page B-23

• All the high temperature membranes were tested in single cells with active areas <150cm2.

• A crucial parameter for high temperature membrane evaluation, endurance test, is either not available or is much lower than requested by DOE.

• Only two developers, the University of Connecticut and the Technical University of Denmark, have started to solve the MEA issue.

• Generally, the issue of high temperature stack technology has not been addressed yet. Lack of an appropriate high temperature membrane might be the major reason for this situation.

4.6. High temperature membrane development risk

Information collected on high temperature membranes for PEM fuel cells indicate that many unresolved problems in this technology still exist which may limit the application of these materials in a fuel cell power plant application. The risks that have been identified are listed below.

High temperature membrane endurance

There is lack of data for some of the basic membrane characteristics, such as chemical and thermal stabilities, mechanical strength and creep. In addition, fuel cell endurance test results published for high temperature membrane show that the tests were performed for a maximum of several hours. One of the major risks with this lack of information is that it is not practical to build a fuel cell stack for a membrane that has not undergone extensive endurance testing.

Membrane electrode assembly technology

This technology is immature. Published information on high temperature membrane performance tests show that majority of developers are using commercially available catalyzed gas diffusion layers (E-Tek's ELAT), traditionally used in standard temperature PEM stacks.

Cost

One of the major limitations for regular temperature PEM fuel cells to be commercialized is the cost of proton exchange membranes. At the current level of high temperature membrane development this parameter can not be even predicted since it is not available on the market.

4.7. Estimates of time and cost to overcome the technology gaps

During the past 5 years several government, university and industry sponsored research projects have attempted to understand and improve high temperature membrane technology. This technology has witnessed increased attention over the last 2 years in recognition that it may solve or mitigate several issues associated with conventional

Page B-24

membrane technology. These include, CO tolerance, waste heat extraction for cogeneration, and humidification requirements. Although several technical advances have been made, the data collected for this project indicates that there are currently no commercially available high temperature membranes. Furthermore, none of the experimental and prototype membranes that were identified met all of the DOE requirements. Significant improvements as a result of further research and development will be required to overcome the existing technology gaps. A parallel effort to develop the catalyst deposition technology consistent with the membrane's operational envelope will also be required to construct suitable MEAs. The R&D activities of high temperature membranes/MEAs must include molecular modeling, polymer synthesis, membrane processing, electrode preparation, membrane-electrode assembling, membrane and MEA materials characterizations, and both single cell and stack testing as the final steps.

Based on the knowledge and experience gained in the past five years, the technology may still need 2-4 years of developmental effort to be ready for commercialization. The cost can only be estimated but it may well be in the tens of millions of dollars.

5. RECOMMENDATIONS

Based on the data gathered in this project, it is estimated that the development of high temperature membranes/MEAs for a PEM fuel cell stack will require several more years of development. Even though the technology is not mature enough to presently build a fully operational fuel cell stack, there were no technology obstacles identified that would impede the technology from developing. Below are the recommendations that will impact the next phases of development of this effort:

• Pressure requirement set by DOE for high temperature membrane/MEA should be reconsidered since the results of Phase I of this project suggest the cogeneration system operation at higher pressure. Based on both the cogeneration system performance and fuel cell stack size, it was concluded that the system operation at 3atm is more favorable for any type of high temperature membrane.

DOE pressure requirement of <1.5 atm excludes membranes with vehicle type mechanism for application in the cogeneration system. However, our system analysis results show that a system with a membrane having vehicle type proton conductivity mechanism can be operated up to 110°C and 3atm and still meet the DOE requirement for 35% efficiency. Therefore, increased pressure will provide higher system efficiency and will keep more flexibility for R&D that can faster overcome the high temperature membrane technology gaps.

Page B-25

• R&D programs sponsored in the future should concurrently consider both membrane and MEA development since it will demonstrate applicability of polymers in MEAs immediately and shorten time for development of MEAs. MEA processing is a complex technological problem that involves two major steps: electrode preparation and membrane-electrode assembly. Incorporation of a proton conductor into electrodes can be a potential problem due to catalyst poisoning or polymer solubility. It is expected that new high temperature polymers will have higher glass transition temperature and that hot pressing technique applied for regular temperature MEAs will not be an appropriate method for high temperature MEA processing.

• R&D teams that work on high temperature membranes/MEAs should involve molecular modeling, polymer synthesis, materials and fuel cell engineering experts. Their joint knowledge and experience will accelerate the development of high temperature MEAs.

This strategy may require increased funding per R&D group and involve a smaller number of R&D institutions. However it can be expected that overall the funding will be more efficient.

• The results obtained by the system analysis in Phase I of this effort can be used as a basis for molecular modeling of polymers that are going to be used for high temperature membranes.

For a membrane with water as a proton "vehicle" maximum operating temperature is 110°C for 35% stack efficiency. Therefore, based on this result, if water is substituted with a substance that has lower partial vapor pressure at higher temperatures, the operation temperature will be increased as well as the system efficiency. Molecular modeling can use this data to define fundamental parameters necessary for the modeling.

• The important issue of membrane/MEA cost for new developments should be concurrently considered with material development. Economical analysis of membrane/MEA cost at various production levels (pilot-plant to high production) should be carried out in order to predict the cost of a product. This type of analysis can also be applied as criteria for continuation of funding of particular research.

• Phase II of this program, the construction of a 50 kW prototype system, may be impacted by the lack of maturity in high temperature membranes and the level of effort required to evolve the current state of the technology. The expectations of the Phase II effort may need to be reassessed and the program rescoped to address the planned developmental activities in high temperature membranes. The development of membrane and stack cannot be done independently, so it is critical that early on a developer of high temperature membranes be identified and selected to work as part of the team. It is recommended that Phase II of the

Page B-26

effort concentrate on stack design and membrane development. The final deliverable would be a 2-3 kW prototype stack along with the support hardware required to functionally operate it.

Page B-27

REFERENCES

1. Proton conductors, solids, membranes and gels - materials and devices, edited by P. Colomban (University Press, Cambridge, GB, 1992).

2. "Novel Membranes for PEMC Operation at 120-200°C", J. Ogden, S. J. Lee, P. Costuming, C. Yang, K. Adjemian, J. Benziger, A. Bocarsly, S. Srinivasan, Presentation at the DOE/OAAT CARAT Forum, Troy, MI, Sept. 23, 1999.

3. "Advanced Methanol Fuel Cells", J. A. Kosek, Presentation at the DOE/OAAT CARAT Forum, Troy, MI, September 23, 1999.

4. "Preparation of High Temperature Membranes for Hydrogen Proton Exchange Membrane Fuel Cells", J.M. Fenton, M.B. Cutlip, K.H. Russell, L. Jung-Chou,

Hazardous and Industrial Wastes, Proceedings of the Mid-Atlantic Industrial Waste Conference (Storss, CT, USA 1999) p 656-662.

5. "Preparation of High Temperature Membranes for Hydrogen Proton Exchange Membrane Fuel Cells", J.M. Fenton, M.B. Cutlip, K.H. Russell, L. Jung-Chou,

Presentation at the Electrochemical Society Conference, Hawaii, November 12, 1999.

6. "Composite Membranes for Fuel Cell Operation at Higher Temperature", J.-C. Lin, J.M. Fenton, H.R. Kunz, and M.B. Cutlip, in Proceedings from 198th Meeting of the Electrochemical Society, Phoenix, October 2000.

7. "Preliminary Study of Phosphate Ion Exchange Membrane for PEM Fuel Cells", I. Cabasso, X. Xu, Poly Mat. Set, 68 (1993) 120.

8. "Hybrid Organic-inorganic Membranes for a Medium Temperature Fuel Cell", B. Bonnet, D.J. Jones, J. Roziere,L. Tchicaya, G. Alberti, M. Casciola, L. Massinelli Bernard Bauer, Antonella Peraio, Enrico Ramunni in New Materials for Electrochemical Systems III- Extended Abstracts of the 3rd International Symposium on New Materials for Electrochemical Systems, edited by O Savadogo (Ecole Polytechnique de Montreal, Monteral, Canada, 1999) p244.

9. "Polymeric membrane electrochemical cell operating at temperatures above 100°C", A. Antonino, M. D'Alunzio, EP Al 00926754, 1999-06-30.

10. "High Temperature Direct Methanol-Fueled Proton Exchange Membrane Fuel cells ", H. R. Allcock, A. Cannon, C. Kellam, R. Morford, M. Hofmann, S. N. Lvov, M. Fedkin, X. Y. Zhou, Presentation at the DOE/OAAT CARAT Forum, Troy, ML September 23, 1999.

11. "Novel Proton Exchange Membrane for High Temperature Fuel Cells", S.R. Morris, M. Bhamidipati, E. Lazaro, F. Lyons,, edited by D.S. Ginley, D.H. Doughty, B. Scrosati, T. Takamura, Z. Zhang in Materials for Electrochemical Energy storage

Page B-28

and Conversion II-Batteries, Capacitors and Fuel Cells (Mater. Res. Soc, Warrendale, PA, USA, 1998) p217-222.

12. "Novel Proton Exchange Membrane for High Temperature Fuel Cells ", S.R. Morris, M. Bhamidipati, M. Perkins, M. Dixon, Presentation.

13. "Thermal Stability of Proton Conducting Acid Doped Polybenzimidazole in Simulated Fuel Cell Environments ", R.F. Savinell, S.R. Samms, S. Wasmus, /.

Electrochem. Soc, 143(1996) 1225-32.

14. "Electro-osmotic Drag Coefficient of Water and Methanol in Polymer Electrolytes at Elevated Temperatures", R.F. Savinell, D. Weng, J.S. Landau, J.S. Wainright, J.Elecrtochem. Soc, 143 (1996) 1260-63.

15."Sorption and Transport Properties of Water in Nafion reg-sign/H sub # P 0 4 polymer Electrolyte at Elevated Temperatures", R.F. Savinell, D. Weng, J.Landau, J.S. Wainright, edited by S.Srinivasan, D.D. Macdonald, A.C. Khandkar in: Electrode materials and processes for energy conversion and storage (Electrochemical Society, Inc, Pennington, NJ, US, 1995).

16. "Acid-Doped Polybenzimidazoles:A New Polymer Electrolyte", R.F. Savinell, D.Weng, J-T Wang, J.S. Wainright, J. Electrochem. Soc. 142 (1995) L121-3.

17. "Proton Conducting Membranes Based on Polyoxadiazoles", S.M.J. Zaidi, S.F.Chen, S.D. Mikhailenko, S. Kaliaguine (Laval Univesity, Canada) in New Materials for Electrochemical Systems III- Extended Abstracts of the 3r

International Symposium on New Materials for Electrochemical Systems, edited by O. Savadogo (Ecole Polytechnique de Montreal, Monteral, Canada, 1999) p225.

18. "Preparation and Characterization of New Membranes Based on Nafion, Silicotungstic Acid and Thiophene", B.Tazi, O. Savadogo in New Materials for Electrochemical Systems III- Extended Abstracts of the 3r International Symposium on New Materials for Electrochemical Systems, edited by O Savadogo (Ecole Polytechnique de Montreal, Monteral, Canada, 1999) p225.

19. "Synthesis and characterization of novel acid-base polymer blends for application in membrane fuel cells", J. Kerres, A. Ullrich, F. Meier, T. Haering, Solid State Ionics 125 (1999) 243-249.

20. "Synthesis and characterization of sulfonated polybenzimidazole: a highly conducting proton exchange polymer", X. Glipa, M. El Haddad, DJ. Jones, J. Roziere, Solid State Ionics 97 (1997) 323-331.

21. "Proton conduction in acid doped polybenzimidazole", R. Bouchet, E. Siebert, Solid State Ion. Dijfus. React. 118 (1999) 287-299.

Page B-29

22. "High-Temperature Proton Conducting membranes based on Perfluorinated Ionomer Membrane -Ionic Liquid Composites", M. Doyle, S.K. Choi, G. Proulx, J. Electrochem. Soc, 147 (2000) 34-37.

23. "Protonic conducting properties of sol-gel derived organic/inorganic nanocomposite mmembranes doped with acidic funvtional molecules", I. Honma, Y. Takeda, J.M. Bae, Solid State Ionics 120 (1999) 255-264.

24. "Development of New Proton Exchange Electrolytes for Water Electrolysis at Higher Temperature", C.A. Linkous, H.R. Anderson, R.W. Kopitzke and G.L. Nelson, Int. J. Hydrogen Energy 23(1998) pp 522-529.

25. "Sulfonation of Poly( phenylquinoxaline) Film", R.W. Kopitzke, C.A. Linkous, G.L. Nelson, J.Polym.Sci. Part A: Polym. Chem. 36(1998)ppl 197-1199.

26. "Thermal Stability of High Temperature Polymers and their Sulfonated Derivatives under Inert and Saturated Vapor Conditions" C.A. Linkous, H.R. Anderson, R.W. Kopitzke and G.L Nelson, Polymer Degradation and Stability 67(2000)pp335-344.

27. "Conductivity and Water Uptake of Aromatic Based Proton Exchanged Membrane Electrolytes" C.A. Linkous, H.R Anderson, R.W. Kopitzke and G.L Nelson, to be published in ACS conference Proceedings, July 2000.

28. "Polymer Electrolyte Membranes for Advanced Fuel cells Using Impure Hydrogen", L. Quinfeng, H. A. Hjuler, N. J. Bjerrum, in Proceedings from 13th

World Hydrogen Energy Conference, Beijing, June 2000.

29. 2 CRC Handbook of Chemistry and Physics, 72nd , edited by D. R. Lide (CRC Press, 1991-1992).

30. "Acid-doped polybenzimidazoles: A new polymer electrolyte", J.S. Waimight, J-T. Wang, R.F. Savinell, M.Litt, J. Electrochem. Soc, 142 (1995) L121- 123.

31. "Thermal stability of proton conducting acid doped polybenzimidazole in simulated fuel cell environments", S.R. Samms, S. Wasmus, R.F. Savinell, J. Electrochem. Soc, 143 (1996) 1225-1232.

32. "Acid doped plybenzimidazole as a polymer electrolyte for methanol fuel cell", J.S. Wainright, R. F. Savinell, M.H. Litt, in New Materials for Electrochemical Systems II-Proceedings of the 2n International Symposium on New Materials for Electrochemical Systems, edited by O.Savadogo and R. Roberge (Ecole Polytechnique de Montreal, Montreal, Canada, 1997) p60.

33. The U.S. Department of Energy Solicitation for "Research and development for fuel cells, direct injection engines, and fuels: energy efficiency and renewable energy technology for transportation and buildings", Appendix A, Topic 1: Fuel

Page B-30

cells for Transportation and Buildings - Building, Specific Fuel Cell Components and Systems, Section (m).

34. "Cost Analysis of Fuel Cell System for Transportation" Arthur D. Little, Inc, Task 1 & 2 Final Report to DOE (DE-SC02-98EE50526).

Page B-31

APPENDIX A

Developers' Response to Energy Partners Questionnaire on High Temperature MEAs

Page B-32

QUESTIONNAIRE MEMBRANES FOR HIGH-T PEM FUEL CELLS

Contact: Dr. Anthony B LaConti, Giner Inc 781.899.7270 Date: November 4, 1999

1. Which type (organic/inorganic) do you prepare?

Polymer. BetaCure Technologies, Inc did R&D.

2. What is the maximum size that you are able to prepare?

Any, tested 100cm2

3. What is the maximum testing temperature?

120°C, most of the tests at 60 and 90.

4. Did you test them in the fuel cells?

Yes, 55kW DMFC.

5. Do they require humidification?

Yes, but less than Nafion. Pressure was 15-30psig.

6. What is the test duration?

At high T (90-120°C) days.

7. Who tested your membranes?

In house and independent laboratories.

8. Can you compare the results (V-I) with Nafion performance?

Yes.

9. Please, list names and addresses of other people doing the same R&D

Foster Miller, Gore.


Contact: James M. Fenton, University of Connecticut, 860.486.2490, [email protected] Date: November 18, 1999


Similar to Gore's: porous teflon matrix impregnated with nafion and solid acids. They are solvent cast by PVDS process.


They made 37 cm2 MEA.


130°C at ambient pressure.


They made a 6 cell stuck for Fuel Cell Energy, which is doing a trial.


Yes, but at 1 atm

6. What is the test duration? Only four days, since they have only 1 lab cell and need it often to try different samples they make.


They in the lab cell and FCE in the stuck who they have the contract with.


They compared with Gore's.


Provided lots of information.

Page B-34

mailto:[email protected]


Contact: Israel Cabasso, Polymer Research Institute, Syracuse University, 315.470.6857.222 Date: November 11, 1999


Polymer


Any


250°C


Yes


Yes, 30psig


1-30 days, performance increase with time


Our lab


Better performance except mechanical properties


Ballard


Contact: Dr. Robert Kover, Foster Miller, Massachusets, 781.684.4114 Date: November 2, 1999


Cyclic sulfonated polymers


10" diameter sheets.


120°C.


Yes.


Yes, p=30psig


Few minutes, believe that creep and humidification caused failure.


Giner Inc, they also provided a sample to Los Alamos Lab.


N/A


N/A


Contact: Scott Morris, Cape Cod Research, 508. 540.7492 Date: November 11, 1999


Polymer based composite.


Laboratory, 1ft2.


175°C at ambient pressure.


No, only characterized.


Yes, but little. It is 15% humidity necessary at 175 and latm.


N/A

7. Who tested your membranes? Characterized by independent institute, University of South Carolina for O solubility and permeability.


Yes, conductivity lOOx better at 80C and lOx better at 175C .


Gore, Dow, Asahi

Page B-37


Contact: Jeff Kolde, Gore & Associates, 410.506.7545 Date: November 29, 1999


Variety of different materials.


Any, however did not tell which particular size was tested.


100-200°C.


Yes, some in the house and some at the partners (did nor release the partner names


Some yes, some not but for all p<30psig.


No info.


In house and partners.


Still early to compare.


It is well known?

Page


Contact: James McGrath, Virginia Polytechnic Institute, 540.231.5976 Date: November 3, 1999


Organic.


No answer.


120°C.


Yes.


Yes.


More than few minutes.


No answer.


Have potential.


Gore, Ballard, Los Alamos


Contact: Marc Anderson, University of Wisconsin, 608.262.2674 Date: November 2, 1999


Inorganic metal oxide composites. They are porous (pore d<10nm) filled with water.


1" pellets.


Bellow 100°C.


No, they did only material characterization.


Yes.


N/A


N/A


N/A


N/A

Page B-40


Contact: C-Y. Yuh, Fuel Cell Energy, 203.825.6112 DATE: November 3, 1999


Composite, still optimizing composition


Goal is 300cm2


Goal is 140°C


Small PEM cell


No info


No info


We


No info


Information sent by e-mail was not readable.


Contact: Serguei Lvov, Pennsylvania State University, 814.863.8377 Date: December 6, 1999


The polyphosphazenes


5 x 5 cm


150°C


Not yet. However, the conductivity and crossover tests have been carried out.


Yes


We have tested the conductivity and crossover of polyphosphazenes over many hours.


Ourselves


Yes we can. The polyphosphazenes membranes have 60 to 80% less than Nafion methanol crossover and similar to Nafion conductance.


None.

Page B-42

Honeywell Engines & Systems Honeywell Inc 2525 West 190th Street Torrance, CA 90504

Form AS0723 (12/99)

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