FUELS FOR ADVANCED CIDI

ENGINES AND FUEL CELLS

2001

ANNUAL

PROGRESS

REPORT

U.S. Department of Energy

Energy Efficiency and Renewable Energy

Office of Transportation Technologies
ACKNOWLEDGEMENT

We would like to express our sincere appreciation to Argonne

National Laboratory and QSS Group, Inc., for their artistic,

editorial and technical contributions in preparing and 

publishing this report.

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

for their contributions to the programs and all the authors who

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

Office of Transportation Technologies

1000 Independence Avenue, S.W.

Washington, DC 20585-0121

FY 2001

Progress Report for Fuels for Advanced CIDI 

Engines and Fuel Cells

Energy Efficiency and Renewable Energy

Office of Transportation Technologies

Approved by Steven Chalk

November 2001
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

CONTENTS

 Page

iii

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

II. FUEL & LUBRICANT EFFECTS TESTING ON ENGINE PERFORMANCE . . . . . . . .15

A. Oil Consumption Contribution to CIDI Engine PM Emissions During Transient Operation . . . . . . . . . . . . . . . 15

B. Effects of Blending Ethanol with Diesel Fuel on Exhaust Emissions from a Heavy-Duty Diesel Engine . . . . . 18

III. FUEL & LUBRICANT EFFECTS ON EMISSION CONTROL PERFORMANCE . . . . .23

A. Durability of NOx Adsorbers Using Ultra-Low Sulfur Diesel Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

B. Lubricant Property Impact on CIDI Emission Control System Durability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

C. Demonstration of Potential for Selective Catalytic Reduction and Diesel Particulate Filters. . . . . . . . . . . . . . . 31

IV. VEHICLE TEST AND EVALUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

A. The Emissions Impacts of Various Fuels on a CIDI Vehicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

B. EC-Diesel Technology Validation Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

V. SUPPORTING RESEARCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

A. Effects of Oxygenated Diesel Fuels on In-Cylinder Combustion and Soot-Formation Processes . . . . . . . . . . . 42

B. Environmental Performance of Oxygenated Fuel Compounds Used in Advanced Petroleum-Based Fuels. . . . 49

C. Chemical Characterization of Toxicologically Relevant Compounds From Diesel Emissions: A Project of the 

Fuels/Particulate Matter Initiative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

D. DECSE Complementary Study of Fuel Sulfur Effects on Unregulated Emissions from Diesel Particulate Filters 60

E. Cooperative Research in C1 Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

VI. MODELING/DATA ANALYSIS/ASSESSMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

A. The Impact of Oxygenated Blending Compounds on PM and NOx Formation of Diesel Fuel Blends . . . . . . . 70

B. A Multi-Property Vector Approach to Assessment of Diesel Fuels and Emissions Impacts . . . . . . . . . . . . . . . 75

C. System Emissions Reduction (SER) Analysis for Automobiles, Light Trucks, and Heavy-Duty Engines . . . . 78

D. Fuel Property Database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

E. Isotopic Tracing of Fuel Components in Particulate Emissions from Diesel Engines Using Accelerator Mass 

Spectrometry (AMS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

VII. FUELS FOR FUEL CELL VEHICLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90

A. Demonstration of Fuel Cell Vehicles and Refueling Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

B. Well-to-Wheel Analysis of Energy and Emission Impacts of Fuel-Cell Vehicle Fuels . . . . . . . . . . . . . . . . . . . 94

C. Guidance for Transportation Technologies: Fuel Choice for Fuel Cell Vehicles . . . . . . . . . . . . . . . . . . . . . . . . 98

D. Effects of Fuel Constituents on Fuel Processor Catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

E. Testing of Fuels in Fuel Cell Reformers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

F. Standard Hydrocarbon Fuel for Fuel Cell Vehicles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

G. Sulfur Removal from Reformate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

CONTENTS

 Page

iv

VIII. DME FUEL SYSTEM TESTING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122

A. Exhaust Emissions and Performance of a CIDI Engine Fueled with DME - Phase 3 . . . . . . . . . . . . . . . . . . . . 122

APPENDIX A - Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127

APPENDIX B - APBF Technical Targets for CIDI Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . .129

APPENDIX C - Fuels for Fuel Cells Technical Targets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .130
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

1

I. INTRODUCTION

Enabling Advanced Vehicle Technologies through Development and Utilization of Advanced 

Petroleum-Based Fuels

On behalf of the Department of Energy’s Office of 

Transportation Technologies (OTT), we are pleased to 

introduce the Fiscal Year (FY) 2001 Annual Progress 

Report for the Fuels for Advanced CIDI Engines and 

Fuel Cells Activity which is part of the Fuels 

Utilization Program. Together with DOE National 

Laboratories and in partnership with private industry 

and universities across the United States, OTT 

engages in high risk R&D that provides enabling 

technology for fuel efficient and environment-friendly 

vehicles. This Activity is currently focused on: 1) 

advanced fuels for the compression-ignition, direct 

injection (CIDI) engine, an advanced version of the 

commonly known diesel engine, which is used in both 

light- and heavy-duty vehicles, and 2) on ways of 

supplying hydrogen for fuel cell vehicles. Because 

OTT conducts fuels R&D for CIDI engines in both the 

Office of Advanced Automotive Technologies 

(OAAT) and the Office of Heavy Vehicle 

Technologies (OHVT), they have developed a joint 

multiyear program plan1

, called the Advanced 

Petroleum-Based Fuels (APBF) RD&T for CIDI 

Engines and Emission Control Systems. This year’s 

progress report includes all the projects conducted in 

support of the APBF Activity. Fuels R&D is also 

coordinated with the Combustion and Emission 

Control R&D for Advanced CIDI Engines Program 

and Transportation Fuel Cell R&D Activities (which 

have their own separate reports), which rely on this 

Activity for fuels that will enable them to meet their 

out-year objectives.

Since its inception, the Fuels for Advanced CIDI 

Engines and Fuel Cells Activity has supported the 

government/industry Partnership for a New 

Generation of Vehicles (PNGV) through its 

technology research projects. The partnership goals 

are being re-evaluated to identify changes that will 

maximize the potential national petroleum-savings benefit of the emerging technologies. When these goal 

changes have been defined, OTT will adjust the focus of its technology research programs accordingly. The 

1. Multiyear Program Plan, Advanced Petroleum-Based Fuels (APBF) RD&T for Compression-Ignition, Direct 

Injection Engines and Emission Control Systems, DOE Office of Advanced Automotive Technologies and Office of 

Heavy Vehicle Technologies, November 1, 2000.

John Garbak, Program 

Manager, Fuels for 

Automotive Advanced 

CIDI Engines 

Peter Devlin, Program 

Manager, Fuels for Fuel 

Cells and Automotive 

Advanced CIDI Engines

Steve Goguen, Team 

Leader, Fuels and 

Lubricants for HeavyDuty Applications

Kevin Stork, Program 

Manager, Heavy Duty 

Alternative Fuels
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

2

work in advanced petroleum-based fuels is conducted through joint 

programs with the energy and automotive industries. Advanced 

petroleum-based fuels will also be necessary for the 21st Century 

Truck Initiative that proposes to triple medium-duty truck fuel 

economy and double heavy-duty truck fuel economy on a ton-mile per 

gallon basis to meet its goals. In FY 2001, the APBF Activity was 

focused on developing and testing selected advanced fuels in 

combination with near-term emission control technologies in CIDI 

engines and transportation fuel cell power systems.

In his second week in office, President Bush established the 

National Energy Policy Development (NEPD) Group. The NEPD 

Group released the National Energy Policy (NEP) report in May 2001 

which includes key recommendations for a National Energy Policy. 

The NEP took a critical look at our current energy supplies and 

demands, and made several recommendations for moving forward to 

correct imbalances. One of the major imbalances is supply and 

demand for petroleum fuels. Our highway transportation system is 

entirely dependent on petroleum fuels (with the exception of about 3 

percent oxygenates added to gasoline). While vehicles today are more efficient than 25 years ago, the average 

fuel economy of new vehicles has not changed over the past 10 years, in part due to the growth of low fuel 

economy light trucks (pickups, vans, and sport utility vehicles). The NEP recommended that consideration be 

given to increasing the fuel economy of new vehicles without negatively impacting the U.S. automotive 

industry. Advanced Petroleum-Based Fuels R&D activities go to the heart of increasing the fuel economy of 

light trucks and cars in the U.S., in a cooperative manner with the U.S. automotive industry to assure that the 

necessary technology is ready and available for them to implement.

This report highlights progress achieved during FY 2001 and comprises 25 summaries of industry and 

National Laboratory projects that were conducted. It provides an overview of the exciting work being 

conducted to tackle the tough technical challenges associated with developing clean-burning fuels that will 

enable meeting the performance goals of the Emission Control R&D for Advanced CIDI Engines and 

Transportation Fuel Cell R&D Activities. The summaries cover the effects of fuels on CIDI engine emissions 

and fuel cell power system performance; the effects of lubricants on engine emissions; the effects of fuels and 

consumed lubricants on exhaust emission control devices; the effects of hydrocarbon fuel characteristics on 

fuel cell reformers; and the health and safety, materials compatibility, and economics of advanced petroleumbased fuels. A brief snapshot of FY 2001 accomplishments and new directions for FY 2002 is captured on the 

following pages. We are encouraged by the technical progress realized in FY 2001 and look forward to 

making further advancements in FY 2002. 

Advanced petroleum-based fuels are a critical enabler to allow the high fuel economy of dieselpowered vehicles to be maintained while meeting future emission standards. 

The APBF Activity is determining the effects of fuel composition on the efficiency and emissions 

performance of emerging, advanced compression ignition, direct injection (CIDI) engines. Through this 

research, the APBF Activity will identify the most suitable fuels for these engines. Sulfur content is a very 

important issue for the APBF Activity. The most desirable emission control devices for nitrogen oxides (NOx) 

are deactivated by sulfur in currently available fuels. Results from the APBF Activity were a primary source of 

information used by the U.S. Environmental Protection Agency (EPA) to establish new diesel fuel sulfur 

content standards (i.e., 15 ppm maximum) beginning in 2006. Testing to date indicates that current generation 

NOx emission control devices are not durable enough to withstand the combined sulfur from consumed 

lubricating oil plus 15 ppm sulfur content fuel. Future work will focus on quantifying the effect of fuel sulfur 

The National Energy Policy Report 

is available from 

www.whitehouse.gov/energy
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

3

content on the durability of NOx emission control devices, the need 

for sulfur traps, the development of desulfurization strategies using 

engine controls, and reductant technologies such as late cycle 

injection. 

During the past year, the EPA finalized new emission 

regulations for heavy-duty diesel engines (0.2 g/bhp-hr NOx and 

0.01 g/bhp-hr PM). This virtually ensures that heavy-duty CIDI 

engines will need similar emission control devices as needed by 

light-duty CIDI vehicles to meet the Tier 2 standards. Advanced 

petroleum-based fuels will ensure that the high fuel economy 

benefits of advanced CIDI engines are realized while enabling the 

effectiveness and durability of emission control devices over their 

full useful lives. 

A major component of the APBF 

Activity is the Advanced PetroleumBased Fuels - Diesel Emission Control 

project (APBF-DEC). The APBF-DEC 

is an industry/government project to 

identify and evaluate: (1) the optimal 

combinations of low-sulfur diesel fuels, 

lubricants, diesel engines, and emission 

control systems to achieve ultra-low 

NOx and PM emissions for the 2001 to 

2010 time period; and (2), properties of 

fuels and vehicle systems that could 

lead to even lower emissions beyond 

2010. The activities being conducted 

under the APBF-DEC include both 

light-duty and heavy-duty CIDI 

engines. A systems approach is being used, i.e., 

simultaneously investigating fuels, lubricants, engines, and 

emissions control systems. A government/industry steering 

committee and working groups are guiding the APBF-DEC 

project. 

Another important component of the APBF Activity is the 

co-operative projects being conducted with the Ad-Hoc Auto/

Energy Working Group1

. Phase I of the Ad-Hoc program 

looked at engine-out emissions of a diesel fuel with 

dimethoxy methane, an oxygenated diesel fuel additive. The 

results from this study showed that this oxygenated fuel 

additive significantly lowered PM and PAH emissions 

compared to the base diesel fuel, and its emissions were 

essentially equivalent to a Fisher-Tropsch fuel. In Phase II, a 

1. The Auto/Energy Ad-Hoc Working Group consists of the three U.S. automakers, several energy providers 

(BP, ExxonMobil, Shell, Marathon Ashland, Phillips, and Citgo/PDVSA), and DOE. Their primary purpose 

is to explore the effects of fuel formulation on emissions.

Participants in the APBF-DEC Project

Hydrogen Fueling Facility at the California 

Fuel Cell Partnership
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

4

new set of fuels will be evaluated, including different oxygenates blended in refinery produced low-sulfur 

fuels. The goal of Phase II is to determine the impact these fuels have on the physical and chemical 

characterization of PM after an oxidation catalyst and a diesel particulate filter.

Clean hydrocarbon fuels and competitively-priced hydrogen are needed to make fuel cell vehicles a practical reality

While CIDI engines are viewed as a nearer-term opportunity to create fuel efficient cars and light trucks, 

fuel cells are seen as a promising longer-term technology that will be capable of achieving unprecedented fuel 

economy with zero or near-zero emissions. One of the key challenges of producing a fuel cell vehicle is 

developing an appropriate fuel for vehicular applications. Fuel cells can potentially use a wide range of fuels 

such as hydrogen stored directly onboard, or produced onboard from methanol, ethanol, natural gas, or 

gasoline. The fuels effort to support the Transportation Fuel Cell R&D Activity is currently focused on 

determining the effects of petroleum fuels on the fuel cell system performance and identifying advanced 

petroleum-based fuel constituents that will not compromise the fuel cell’s inherently high efficiency. 

Hydrogen stored directly onboard is acknowledged to be the best in terms of energy efficiency and durability 

though its energy storage density is currently too low to achieve acceptable vehicle operating range. 

Additional challenges to direct hydrogen for fuel cell vehicles include developing a production and distribution 

infrastructure and being able to deliver hydrogen safely at a competitive price, all of which are being evaluated 

as part of the Activity.

SIGNIFICANT FY 2001 ACCOMPLISHMENTS

In FY 2001, much effort continued on the 

determination of the effects of fuel sulfur content on 

CIDI NOx and PM emission control devices. From 

this work, preliminary findings indicate that NOx

emission control devices currently do not have 

sufficient durability to last the full useful life of the 

vehicle due to sulfur contamination from the 

combined contributions of 15 ppm sulfur fuel and 

consumed lubricating oil. Future work will focus 

on quantifying the effect of sulfur (from the fuel 

and lubricating oil) on emission control device 

durability, and the need for sulfur traps and 

development of desulfurization strategies to attain 

full useful life operation.

Last year, it was shown that oxygenated diesel 

fuels have the potential to lower engine-out NOx

and PM emissions and to complement the operation 

of exhaust emission control devices. An initial set 

of 71 oxygenates was reduced to two, based on 

physical and chemical properties, compatibility 

with diesel fuel and diesel vehicles, and economic 

viability. This year, Lawrence Livermore National 

Laboratory completed an extensive environmental 

assessment of the two best oxygenates and initiated 

analysis of their combustion kinetics to identify 

why they reduce PM emissions, and Sandia 

Notable FY2001 Accomplishments

• Showed that oxygenates can improve EGR 

tolerance of CIDI engines resulting in significant 

NOx and PM emission reductions with potential to 

meet "fuel reformulation" targets, see Appendix B).

• Developed new measurement technique to 

determine the origin of PM from CIDI engines, 

from both the fuel and lubricating oil.

• Completed environmental assessments of dibutyl 

maleate and tripropylene glycol monomethyl ether.

• Demonstrated that ultra-low sulfur diesel fuel and 

catalyzed PM traps can reduce HC, CO, and PM by 

91 to 99% (preliminary results from an on-going 

heavy-duty vehicle demonstration).

• Developed a model to compare costs of fuel cell 

vehicle fuels.

• Completed a technical and economic analysis of 

the barriers to fuels for fuel cell vehicles.

• Identified the components of gasoline best suited 

for on-board reforming in fuel cells vehicles.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

5

National Laboratories included them in their combustion 

studies using laser imaging techniques. 

In the fuel cell area, work continues on identifying the 

effects of fuel composition on fuel processor performance, 

and on means of removing sulfur from the fuel which would 

otherwise poison the fuel cell. In FY 2001, DOE continued its 

work with the California Fuel Cell Partnership and 

contributed analyses and information about the energy, 

emissions, and greenhouse gases generated by various fuels 

from "well-to-pump." The overall objective of the 

Partnership is to demonstrate the practicality of fuel cell 

vehicles, initially operating with hydrogen as fuel. Over the 

past year, they have held numerous promotional events that 

educate the public about the benefits of fuel cell vehicles. 

The following brief summaries list the highlights of research and testing conducted in the APBF Activity 

during FY 2001. 

APBF-DEC Initiates Six New Projects

Six new APBF-DEC projects commenced in FY 2001 studying the following: (1) effects of lubricant 

composition on emissions, (2) effects of fuel composition on selective catalytic reduction (SCR)/diesel particle 

filter (DPF) systems, (3) assessment of infrastructure issues for SCR, and (4) three projects on the effects of 

fuel composition on NOx adsorber/DPF systems (passenger car, pickup truck, heavy-duty engine). These 

projects build on the earlier APBF-DEC results which showed that low sulfur fuels are needed to make NOx

adsorber catalysts viable and to limit sulfate PM from oxidation catalysts and catalyzed particulate filters. 

Reports from the earlier completed APBF-DEC projects are available from http://www.ott.doe.gov/decse/. 

The following are highlights from the new APBF-DEC projects initiated this year which are focused on longer 

term impacts of fuels and lubricants on diesel emission control devices.

Effects of Lubricant Composition on Emissions

As engine-out emissions are decreased and durability requirements are increased (in 2004, heavy-duty 

engine emission control system durability requirements will be increased to 435,000 miles), the effect of 

consumed lubricating oil becomes more important. Consumed lubricating oil can contribute sulfur and ash to 

the exhaust gases, speeding degradation of emission control devices. This project is underway using a 1999 

International T444E-HT engine with EGR. The engine has been setup in the laboratory, engine speed/load 

operating points have been chosen, EGR rates have been established, and the emissions measurement system 

has been verified to work properly. After the oil consumption rate of the engine and test repeatability have 

been determined, the main test protocol will be initiated.

Effects of Fuel Composition on SCR/DPF Systems

Selective Catalytic Reduction (SCR) using urea as a reductant is gaining support as a NOx reduction 

technology for CIDI engines. This project (with technical support provided by Oak Ridge National Laboratory 

and with Southwest Research Institute as a subcontractor) will evaluate the urea-SCR and its sensitivity to fuel 

variables. The objectives of the project are to: 

• Demonstrate the low-emissions performance of advanced diesel engines plus urea-SCR and diesel 

particulate filters (DPF)
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

6

• Determine the regulated and unregulated emissions 

with and without emissions controls

• Examine the durability of emission control systems

• Determine toxic and unregulated emission levels

• Evaluate the sensitivities of the emission control 

devices to fuel variables

In-kind contributions of important elements of the 

experimental setup have been received from the following 

organizations:

• Caterpillar - two C12 engines

• STT (Sweden) - Low-pressure loop EGR system

• Robert Bosch - Urea injection system

• Manufacturers of Emissions Control Association 

(MECA) - SCR catalysts and DPF systems

Two different SCR systems, combined with DPF systems, will be provided by MECA in order to gain 

experience with different technologies. A fuel matrix of three fuels (minimum) will be evaluated, emphasizing 

the influence of fuel sulfur level on the performance of the systems. 

Assessment of Infrastructure Issues for SCR

Urea is a very effective reductant for SCR systems and a 

leading contender for use in commercial systems. Urea is 

widely used as fertilizer and in industrial products, but use in 

vehicles with CIDI engines would represent an entirely new 

market. A.D. Little is conducting an assessment to determine 

what barriers producing and distributing urea might present to 

using SCR systems. They found that no new or specialized 

technology needs to be developed to distribute urea to the 

transportation market, but additional storage would be 

required at dispensing stations, and specialized dispensing 

technology may be needed. They also determined that 

sufficient urea production capacity exists worldwide to meet 

the demand, even assuming all CIDI vehicles use urea-SCR, 

and the retail price is likely to be in the range of $0.70 to 

$1.00 per gallon depending on whether the urea is 

domestically produced or imported.

Effects of Fuel Composition on NOx Adsorber/DPF Systems (Three Separate Projects)

NOx adsorber catalysts and DPFs offer the potential for drastic emission reduction in a broad class of diesel 

engines, spanning a range of displacement and market segments. As such, three projects have been initiated to 

research and develop systems that cover the potential range of applications. In FY2001, subcontracts were 

placed with the following test laboratories to support this research effort:

• Passenger Car Engine/Vehicle: FEV Engine Technologies (Auburn Hills, MI)

• Light Truck Engine/Vehicle: Southwest Research Institute (San Antonio, TX)

Potential Urea Demand from New On-Road 

CIDI Vehicles

Schematic Layout of Engine and Emission 

Control System
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

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• Heavy-Duty Line Haul Engine: Ricardo, Inc. (Burr Ridge, IL)

The passenger car and light truck projects will employ both 

engine testing and vehicle testing, while the heavy-duty line haul 

project will focus only on engine testing. 

The Passenger Car Engine/Vehicle project has been initiated and 

the following accomplishments have been reported so far:

• Preparation of baseline engine data for use in the development 

of the two test emissions control systems 

• Initial operating strategy development

The test vehicle chosen is an Audi A4 Avant with a 1.9 liter turbocharged CIDI engine (currently not 

offered for sale in the U.S. though Volkswagon uses this engine in their U.S. diesel models). 

The Light Truck Engine/Vehicle project has been initiated, the first task has been completed, and the 

accomplishments thus far include:

• Initiated work with the designated catalyst supplier in the design and development of the emissions control 

systems 

• Initial development of operation strategies

The test vehicle chosen for this project is a GMC 2500 pickup with the Duramax 6.6 liter CIDI engine. 

The Heavy-Duty Line Haul Engine project is just getting off the ground, but substantial progress has been 

achieved. An assessment of single and dual "leg" emission control systems has resulted in selection of the 

single leg system for reasons of system cost and size constraints for installation on the vehicle. The engine and 

emission control system is being installed in a test cell for emissions testing.

SwRI Demonstrates the Advantages of Oxygenated Fuels for NOx and PM Reductions

Southwest Research Institute (SwRI) has shown that oxygenated fuels, with no other changes, can reduce 

PM emissions by up to 50%, with NOx emissions reductions of about 10%. During FY01, SwRI demonstrated 

that oxygenated fuels allow larger usable EGR levels than non-oxygenated fuels, which can result in engineout NOx emissions reductions of up to 45%. This shows the value fuels can have in allowing engine 

manufacturers the flexibility to trade off NOx and PM emissions depending on the exhaust gas emission control 

The GM 6600 Duramax V8 

Test Engine

The Single Leg System Chosen Consisting of a DPF and NOx

Adsorber

Audi A4 Avant Test Vehicle with 1.9 

Liter Turbocharged CIDI Engine
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

8

devices chosen to be used. As a follow-up to these findings, SwRI will test four oxygenated fuel blends and 

one water emulsion to evaluate their potential for reducing NOx and PM (see Future Initiatives Section). 

LLNL Develops New Technique to Determine the Origin of PM Emissions from CIDI Engines

Lawrence Livermore National Laboratory has developed 

a technique to accurately determine the origin of PM 

emissions from CIDI engines using accelerator mass 

spectrometry (AMS). AMS is an isotope-ratio measurement 

technique developed in the late 1970s for tracing long-lived 

radioisotopes (e.g., carbon-14 half life = 5760 yr). The 

technique counts individual nuclei rather than waiting for 

their radioactive decay, allowing measurement of more than 

100 low-level carbon-14 samples per day. This represents a 

significant improvement over the more commonly used Direct 

Filter Ignition/Gas Chromatography (DFI-GC) technique. 

The combustion paradigm assumes that large molecules 

break down into small components and then build up again 

during soot formation. AMS allows specific fuel components 

to be labeled, including oxygenates, trace the carbon atoms, 

and test this combustion modeling paradigm. It can also be applied to the lubricating oil to measure the 

contribution of consumed lubricating oil to PM emissions. The technique works with both the volatile and 

non-volatile portions of the PM. It can even be used to monitor the effectiveness of emission control devices to 

remove specific fuel components. In the coming year, AMS will be used to study the effect of oxygenates on 

PM formation in CIDI engines.

LLNL Completes Environmental Analysis of Promising Diesel Fuel Oxygenates

Research has shown that the addition of oxygen-bearing compounds (oxygenates) to diesel fuel reduces 

particulate emissions significantly. However, candidate oxygenates also need to be evaluated based on their 

overall environmental impact and not only their effect on vehicle emissions. Lawrence Livermore National 

Laboratory has developed a suite of diagnostic models and experimental tests to address this need. This 

methodology has been applied to two candidate oxygenates: dibutyl maleate (DBM) and tripropylene glycol 

monomethyl ether (TGME). Preliminary 

biodegradation tests confirm that DBM is readily 

degraded. TGME also seems to biodegrade, but more 

slowly than DBM or benzene. The biodegradation tests 

were performed using activated sludge, which is a fairly 

aggressive media. In other natural environments, the 

rate of biodegradation could be much slower. This fact 

combined with its high water solubility are indications 

that TGME would be more mobile in the subsurface 

than DBM. Additional studies are needed to determine 

whether TGME would constitute a threat to 

groundwater when stored in subsurface fuel tanks. In 

previous work on dimethoxymethane (DMM), 

indications were that it was likely to be recalcitrant and 

mobile in ground water, behaving similarly to MTBE in 

the environment. The results of the biodegradation 

experiment confirmed the model prediction. These 

Conceptual Diagram of the Intermedia Transfer 

Processes Used to Assess the Environmental 

Impact of Diesel Fuel Oxygenates

The Accelerator Mass Spectrometer at 

Lawrence Livermore National Laboratory
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

9

results suggest that DBM would be a better choice than TGME as a diesel fuel oxygenate from an 

environmental standpoint, but further analysis is needed.

Fleet Tests of EC-Diesel Continue to Show Large Emission Reductions

ARCO, a BP Company, has developed a new diesel 

fuel called Emission Control Diesel (ECD). ECD is a 

heavily hydrocracked fuel produced from typical crude 

oil. ECD has a maximum sulfur content of 15 ppm, about 

10% aromatics by volume, and a nominal cetane number 

of 60. More recently, BP has introduced ECD-1 into the 

southern California market. ECD-1 also has 15 ppm 

maximum sulfur content, but has 22% aromatics and a 

nominal cetane number of 50. ECD-1 contains both 

hydrocracked and hydrotreated stocks. A one-year 

technology validation project was conducted using ECD. 

Vehicles retrofitted with catalyzed particle filters and 

fueled with ECD emitted 91% to 99% less particulate 

matter compared to the California diesel-fueled vehicles 

having no exhaust filter equipment and fueled with 

CARB-specification diesel fuel. Hydrocarbon and carbon 

monoxide emissions were also significantly reduced. The 

same grocery trucks were retested after twelve months of operation and more than 100,000 miles accumulation 

per truck. The particle filters were not serviced prior to the second round emissions tests and average 

particulate matter emissions from the retrofitted trucks were again found to be 89% to 99% less than the 

California diesel-fueled vehicles having no exhaust filter equipment fueled with CARB-specification diesel 

fuel. Through the first five months of operation, there was no detectable difference in fuel economy between 

trucks with and without particle filters, based on an analysis using fleet operation records. In the coming year, 

ECD-1 will be used and emissions tests will be conducted to measure the difference.

The CaFCP Releases Report on the Challenges of Implementing Fuel Cell Vehicles

The California Fuel Cell Partnership (CaFCP) is a path-breaking 

collaboration of auto companies, energy providers, fuel cell 

companies, and government agencies that will demonstrate fuel cell 

electric vehicles on the road in California. The Partnership is taking 

steps to broaden public awareness of fuel cell vehicles by displaying 

vehicles at various public venues, hosting classroom visits to its 

headquarters facility, and speaking about fuel cells to organized 

community groups and industry conferences. Through participation 

in public events, the CaFCP over the past year has reached 

thousands of people. The vehicles have served as the pace cars for 

two marathons - the California International Marathon in 

Sacramento and the Los Angeles marathon; multiple vehicles and 

displays were featured at the Orange County Fair; and as part of 

their ongoing test-drives, vehicles are parked in prominent public 

gathering places around Sacramento, engendering public attention 

and excitement. The Partnership’s Internet website 

(www.fuelcellpartnership.org) provides more educational 

information. The CaFCP also commissioned a report that examines 

the challenges to using various fuels in fuel cell vehicles and 

Average Grocery Truck Emissions over the 

City-Suburban Heavy Vehicle Route, 

February-March 2001
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

10

identifies initiatives that can promote success. The study will 

help start the CaFCP members to begin addressing the 

challenges associated with developing fuels and infrastructure 

for fuel cell vehicles. The report is available at 

www.fuelcellpartnership.org/event_roundtable.html. The 

CaFCP is testing and demonstrating fuel cell electric vehicles in 

California through 2003 under day-to-day driving conditions; 

demonstrating alternative fuel infrastructure technology; 

exploring the path to commercializing fuel cell electric vehicles 

by examining such issues as fuel infrastructure requirements, 

vehicle and fuel safety, market incentives, and consumer 

acceptance; and working to increase public awareness of fuel 

cell vehicle technology and the benefits it can offer.

In FY 2001 DOE led a study of hydrogen vehicle facilities, 

using the CaFCP West Sacramento Facility as a model, to 

determine the impact of hydrogen infrastructure codes and standards on facility costs. Following that initial 

study, the CaFCP Steering Team has authorized a more in-depth study to be conducted by an external 

contractor examining the costs for accommodating hydrogen-fueled vehicles in residential garages, 

commercial parking garages, and service/maintenance facilities, including the cost of retrofitting existing 

facilities designed for conventional gasoline-fueled vehicles.

ANL Identifies Favorable Gasoline Hydrocarbons for Fuel Cell Vehicles

On-board reforming of petroleum-based fuels, 

such as gasoline, may help ease the introduction of 

fuel cell vehicles to the marketplace. Although 

gasoline can be reformed, some constituents and 

impurities may have detrimental effects on the fuel 

processing catalysts, which may lead to compromised 

performance and decreased fuel conversion 

efficiency. In order to identify which constituents are 

beneficial and which are detrimental to the reformer, 

Argonne National Laboratory (ANL) has begun a 

project to test various components of gasoline and 

blends of gasoline streams under autothermal 

reforming conditions. The current work has focused 

on the effects of blends of components and on the effects of sulfur impurities. Blends are being investigated to 

determine if the presence of some components can affect the reforming of others. Sulfur is of particular 

concern due to its propensity to poison catalysts. In the coming year, ANL will continue investigating effects 

of additives (detergents, antioxidants) and impurities, continue investigating reforming of blended fuels, 

determine composition/performance relationships from results, investigate differences in fuel reforming with 

different catalysts, and make recommendations for fuel cell fuels. 

LANL Explores the Effects of Fuels and Impurities on Reformers

Los Alamos National Laboratory is exploring the effects of fuels, fuel constituents and fuel impurities on 

the performance of on-board hydrogen generation devices (reformers) and consequently on the overall 

performance of a PEM fuel cell system using a reformed hydrocarbon fuel. Different fuels were tested to 

observe their relative reforming characteristics under various operating conditions. Both catalytic and 

homogeneous fuel processor partial oxidation stages were used in the tests of pure fuel components and 

Hydrogen Yield from Several Different Fuels

Fuel Cell Vehicles and the Hydrogen 

Refueling Facility
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

11

mixtures such as iso-octane and iso-octane/xylene, and real 

fuels such as a hydro-treated naphtha and reformulated 

gasoline. Carbon formation was monitored during operation 

by in-situ laser measurements of the effluent reformate and 

visual observations of the reactor.

Homogeneous oxidation was found to occur easier with 

‘real’ fuels than with the pure components of iso-octane and 

iso-octane/xylene. The addition of aromatics slows the 

overall reaction rate for catalytic oxidation. Diesel fuel 

components (such as dodecane) require higher residence 

times for similar conversions. The fuel composition 

(especially sulfur and aromatic content) affects the relative 

amount of noble metal required for the fuel reformer. 

Modeling has shown that fuel characteristics can cause 

variation in the temperature for equilibrium onset of carbon 

formation by up to 150°C with varying O/C ratios. 

FUTURE INITIATIVES

Our new Activity initiatives for FY 2002 build upon the progress made in FY 2001 and will focus on those 

areas that industry agrees are major technical barriers. 

Advanced Petroleum-Based Fuels for CIDI Engines

• In a new project just recently awarded, Honeywell will develop and demonstrate an "on-vehicle" 

desulfurization fuel filter suitable for both light- and heavy-duty CIDI vehicles. The project consists of 

four phases: concept design development; prototype filter design; life cycle and regeneration options for 

spent filters; and life testing and component integration. 

• In the coming year, the six recently initiated Advanced Petroleum-Based Fuels - Diesel Emissions Control 

projects (described earlier) are anticipated to complete the activities described in the following:

Effects of Lubricant Composition on Emissions: A more thorough evaluation of emissions utilizing all 

three PM sampling trains will be conducted with two oils of widely different composition. Following this 

initial evaluation, the main test effort to characterize the impact of lubricant-derived species on the 

performance and durability of advanced diesel emission control systems will commence.

Effects of Fuel Composition on SCR/DPF Systems: Durability testing of the two SCR/DPF systems will 

be in progress. Durability testing of 6,000 hours will be initiated.

Assessment of Infrastructure Issues for SCR: An environmental impact assessment of urea spills along the 

distribution pathway will be conducted, and life-cycle greenhouse gas emissions will be estimated for urea 

production and distribution. A final report will be issued.

Effects of Fuel Composition on NOx Adsorber/DPF Systems

> Passenger Car Engine/Vehicle Project: Hardware procurement and operational strategy development 

will be completed. All baseline emissions testing and calibration and optimization strategies will be 

completed or near completion. 

Homogeneous Partial Oxidation Outlet 

Temperature for Several Fuels and Varying 

Oxygen to Carbon Ratios
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

12

> Light Truck Engine/Vehicle Project: The emission control system architecture and design, including 

performance characteristics and requirements for operation of the catalyst/trap (e.g., operating 

temperature, intended feed gas composition, size, and location), will be completed.

> Heavy-Duty Line Haul Engine Project: The test setup will be completed and the optimum control 

strategy will be determined. Fuel sulfur content effects studies will be completed.

• Field testing of ECD-1, a low-sulfur diesel fuel, will be conducted in California in heavy-duty trucks. 

Exhaust speciation data and particle size distribution data are being analyzed and will be reported.

• Southwest Research Institute will measure the contribution of synthetic and mineral-based lubricating oil 

to PM emissions in combination with advanced fuels. A vehicle with a state-of-the-art CIDI engine will be 

used along with a base fuel representative of those expected in 2007.

• Sandia National Laboratories will continue their testing of oxygenated fuels to determine the effect of fuelbound oxygen on PM and NOx emissions. In the coming year, they will test 26 weight-percent di-ethyl 

adipate because it contains no carbon-to-carbon bonds.

• Southwest Research Institute will evaluate different oxygenates blended in refinery produced low-sulfur 

fuels to determine their impact on the physical and chemical characterization of PM after an oxidation 

catalyst and a diesel particulate filter.

• Oak Ridge National Laboratory will demonstrate the potential of urea SCR and diesel particulate filters to 

reduce NOx and PM emissions. The engine they will use for their testing is a 4.0 liter DDC DELTA CIDI 

prototype. The engine is installed for testing and baseline emissions have been measured.

• Southwest Research Institute will test six advanced fuels (oxygenated and water emulsion fuels) in a 

vehicle with a state-of-the-art CIDI engine and using a baseline fuel representative of diesel fuel properties 

expected in 2007. 

Advanced Fuels for Fuel Cells

• The California Fuel Cell Partnership will continue to demonstrate fuel cell vehicles in California, identify 

additional sites for refueling facilities, explore additional fuels to use in demonstrations, and assess 

commercialization activities.

• Arthur D. Little, Inc. will focus their efforts on an integrated analysis of energy, emissions, and economics 

of various fuel chains and fuel cell platforms.

• Argonne National Laboratory will continue their efforts to identify the practical obstacles to fuel cell 

vehicles using hydrocarbon fuels. The projects will include:

> Investigation of the effects of gasoline detergents, anti-oxidants, and impurities on reformer catalysts.

> Finalization of the specifications of a standard fuel cell gasoline that can be used to quantify the 

performance of different fuel processors.

> Improvement of the stability of structured forms of ZnO to remove H2S from reformate streams. 

Conduct feasibility studies of non-adsorption technologies to remove H2S, and evaluate the sulfur 

tolerance of new water-gas shift and PrOx catalysts.

• Los Alamos National Laboratory will continue their efforts to identify the adverse effects of hydrocarbon 

fuels on fuel cell reformers. They will:

> Measure carbon formation of different fuel constituents.

> Measure the effect of bound nitrogen and sulfur on carbon formation.

• During FY 2001, a major solicitation was jointly issued by the Offices of Transportation Technologies and 

Power Technologies calling for proposals for new research and development projects for fuels for fuel 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

13

cells. The following projects selected for negotiation and cooperative agreements will be initiated early in 

FY2002:

> Development of a Turnkey Commercial Hydrogen Fueling Station with Air Products and Chemicals, 

Inc. as the prime contractor.

> Autothermal Cyclic Reformer Based Fueling System to be conducted by GE Energy and 

Environmental Research Corporation.

> Development of High-Efficiency Reformer-Based Hydrogen Fueling Station to be managed by the Gas 

Technology Institute.

> Evaluation of Candidate Fuels for Vehicle Fuel Cell Power Systems to be conducted by Arthur D. 

Little, Inc.

SUMMARY

Advanced petroleum-based fuels enable the use of high efficiency prime movers such as CIDI engines and 

fuel cells to create clean and fuel efficient light-duty and heavy-duty vehicles with the attributes that 

consumers demand. Fuel efficient vehicles with very low emissions are essential to meet the challenges of 

climate change, energy security, and improved air quality. The work being conducted on advanced petroleumbased fuels complements the efforts to build advanced engines and fuel cells while recognizing that the engine, 

fuel, and emission control system must work together to achieve the maximum benefits possible. As the new 

fiscal year begins, we look forward to on-going and new cooperative efforts with the auto and energy 

industries to develop new and innovative technologies that will be used to make advanced transportation 

vehicles that are fuel-efficient, clean, and safe.

John A. Garbak, Program Manager

Advanced Petroleum-Based Fuels

Office of Advanced Automotive Technologies

Office of Transportation Technologies

Peter R. Devlin, Program Manager

Advanced Petroleum-Based Fuels

Office of Advanced Automotive Technologies

Office of Transportation Technologies

Stephen J. Goguen, Team Leader

Heavy-Duty Fuels and Lubricants

Office of Heavy Vehicle Technologies

Office of Transportation Technologies

Kevin C. Stork, Program Manager

Heavy-Duty Alternative Fuels

Office of Heavy Vehicle Technologies

Office of Transportation Technologies
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

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Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

15

II. FUEL & LUBRICANT EFFECTS TESTING ON ENGINE 

PERFORMANCE

A. Oil Consumption Contribution to CIDI Engine PM Emissions During 

Transient Operation

Edwin A. Frame (primary contact) 

Southwest Research Institute

6220 Culebra Road

San Antonio, TX 78238-5166

(210) 522-2515, fax: (210) 522-3270, e-mail: eframe@swri.edu

DOE Program Manager: John Garbak 

(202) 586-1723, fax: (202) 586-9811, e-mail: john.garbak@hq.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

A. Fuel Property Effects on Engine Emissions and Efficiency

Tasks

2. Fuel & Lubricant Properties - Engine-Out Emissions

Objective

• Quantify the effect of crankcase lubricant type on exhaust emissions measured during transient tests of 

a vehicle powered by a state-of-the-art CIDI engine.

Approach

• A European Mercedes C 220 D vehicle with a CIDI engine will be tested for transient exhaust 

emissions over the light-duty Federal Test Procedure (FTP) and US06 test cycles. 

• Synthetic and mineral-based crankcase lubricants will be tested in combination with advanced fuels to 

determine the effect of lubricant composition on particulate matter (PM) and other exhaust emissions. 

Accomplishments

• Testing has been delayed pending the availability of a specially-produced base fuel that is 

representative of projected 2007 U.S. diesel fuel. 

• The test lubricants have all been obtained and conditioned to reduce volatile light ends.

Introduction

The Phase 1 project "Impact of Consumed Lube 

Oil on Advanced CIDI Engine Emissions" revealed a 

significant oil impact on PM for low-power steadystate conditions and a rather insignificant oil impact 

over the high-power, heavy-duty engine FTP 

transient test cycle. However, the oil impact was not 

investigated for any light-duty transient test cycle. 

In the previous project, it was determined by the 

Direct Filter Ignition/Gas Chromatography (DFIGC) technique (Figure 1) that the oil volatile organic 

fraction (VOF) can be reduced from 27% of PM for a 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

16

petroleum-based SAE 5W30 oil to 8% of PM for a 

synthetic-based SAE 15W50. This illustrated that a 

PM reduction of approximately 19% is obtainable by 

changing the lubricant. This reduction was observed 

under steady-state, light-duty conditions when using 

CARB diesel fuel. The fundamental question is 

whether the oil impact on PM for the light-duty 

transient cycle will be similar to the oil impact on 

PM for the low-power steady-state conditions 

investigated as part of the Phase 1 study. 

Approach

A European Mercedes C 220 D vehicle will be 

tested for transient exhaust emissions following the 

light-duty FTP and US06 test cycles. Synthetic and 

mineral-based lubricants will be tested in 

combination with advanced fuels to determine the 

effect of lubricant composition on PM emissions. 

The European Mercedes-Benz C220 D is 

equipped with the DaimlerChrysler OM611 CIDI 

engine. This advanced four-valve-per-cylinder 

engine is turbocharged and intercooled, and it 

includes a high-pressure common rail fuel injection 

system with pilot injection, exhaust gas recirculation, and intake port cut-off. The vehicle is 

equipped with both a close-coupled oxidation 

catalyst and "lean NOx" catalyst. 

All evaluations will be conducted in triplicate 

over the chassis dynamometer portion of the FTP 

cycle and the US06 aggressive driving cycles.

A low-sulfur baseline fuel that is representative 

of expected U.S. diesel fuel in 2007 will be used for 

the initial evaluation of lubricant contribution to PM 

emission. The following lubricants will be included 

in the test matrix: synthetic SAE 5W30, mineral SAE 

5W30, synthetic SAE 15W50, and synthetic SAE 

0W30. In addition, FTP and US06 tests will be 

conducted using the lubricants and a blend of 2007 

fuel with an oxygenate (tripropylene glycol 

monomethyl ether). 

Exhaust constituents will be analyzed as 

specified in Table 1.

Figure 2 shows a gas chromatogram of the VOF 

of PM. The VOF is fractionated into unburned oil 

and other volatile material.

Figure 1. Direct Filter Injection Gas Chromatograph

Constituent Analysis Method

Total Hydrocarbon Heated Flame Ionization 

Detector

Carbon Monoxide Non-Dispersive Infrared 

Analysis

Carbon dioxide Non-Dispersive Infrared 

Analysis

Oxides of Nitrogen Chemiluminescent Analysis

Particulate Matter Gravimetric

Volatile Organic Fraction of 

PM

Direct Filter Injection Gas 

Chromatography

Oil Fraction of VOF Direct Filter Injection Gas 

Chromatography

Table 1. Methods for Analyzing Exhaust Constituents

Figure 2. Chromatogram of Volatile Organic Fraction of 

PM
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

17

Appropriate statistical techniques will be used to 

determine differences between the PM and other 

exhaust emissions for each lubricant and each 

lubricant/fuel combination.

Results

Testing has been delayed pending the availability 

of the 2007 base fuel. This is a specially produced 

diesel fuel that is projected to be representative of 

2007 U.S. diesel fuel.

FY2001 Publications/Presentations

1. SAE Paper 2001-01-1901 "Impact of 

Lubricating Oil on Regulated Emissions of a 

Light-Duty Mercedes-Benz OM611 CIDIEngine," presented at the SAE International 

Spring Fuels and Lubricants Meeting, Orlando, 

FL. 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

18

B. Effects of Blending Ethanol with Diesel Fuel on Exhaust Emissions from a 

Heavy-Duty Diesel Engine

Michael D. Kass (primary contact), John F. Thomas, John M. Storey, and Norberto Domingo 

Oak Ridge National Laboratory

2360 Cherahala Boulevard

Knoxville, TN 37932

(865) 576-8323, fax: (865) 574-2102, e-mail: kassmd@ornl.gov

DOE Program Manager: Stephen Goguen

(202) 586-8044, fax: (202) 586-1600, e-mail: stephen.goguen@hq.doe.gov

Emissions characterizations of ethanol-diesel fuel blends have been conducted at ORNL for two years at 

the encouragement of the DOE-OHVT Fuels Team Leader, Steve Goguen. This particular effort was 

sponsored by ORNL’s Energy Efficiency and Renewable Energy (EERE) Program Office, State Partnership 

Program (SPP). Projects under the SPP are endorsed by one or more state energy agencies and involve 

significant matching resources from project partners (e.g., private industry, universities, state and local 

government agencies, and nonprofit organizations). Partners targeted by this program are State Energy Offices 

and the Association of State Energy Research and Technology Transfer Institutions. The ORNL SPP Manager 

is Marilyn Brown.

The work was heavily leveraged by the DOE-OHVT Engine/Emission Control Team, which bore the costs 

of engine cell set-up in preparation for other research projects. 

Contractor: UT-Battelle, LLC (Oak Ridge National Laboratory), Oak Ridge, TN

Prime DOE Contract No: DE-AC05-00OR22725

Period of Performance: Feb. 1, 2000 - March 31, 2005

Industrial Partner: David Loos, Illinois Department of Commerce and Community Affairs

(217) 785-3969, e-mail: DLOOS@commerce.state.il.us

Industrial Partner: Glenn Kenreck, Betz-Dearborn Inc.

(281) 681-5235, e-mail: glenn.v.kenreck@betzdearborn.com

Industrial Partner: Mike Lockart, Gromark Industries

(309) 557-6384, e-mail: mlockart@growmark.com 

Industrial Partner: Vinod Duggal, Cummins Engine Company, Inc.

(812) 377-7338, e-mail: vinod.k.duggal@cummins.com

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

A. Fuel Property Effects on Engine Emissions and Efficiency

Tasks

2. Fuel & Lubricant Properties - Engine-Out Emissions
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

19

Objective

• To investigate potential emissions reduction benefits from blending ethanol (as a microemulsion) with 

diesel fuel for heavy-duty diesel engines.

• Evaluate viability of ethanol to displace diesel fuel consumption while rendering air quality benefits 

by lowering particulate matter (PM) and NOx emissions.

Approach

• Blends of 10% and 15% by volume ethanol in diesel fuel were tested in a Cummins ISB 5.9 L diesel 

engine subjected to AVL 8-mode test cycles.

• The AVL 8-mode (steady-state) test was employed to compare emissions from the different fuels. This 

test provides a reasonable estimate of emission results of the Heavy-Duty Transient Federal Test 

Procedure, and also provides comparisons for a variety of engine conditions.

• Comparisons of emission levels and trends were made against a reference diesel fuel as well as prior 

efforts.

Accomplishments

• Addition of ethanol was observed to have no noticeable effect upon NOx emissions and produced 

undesirable but expected increases in CO and total HC.

• Addition of ethanol (10 and 15 vol% blends) was observed to decrease PM by 20-30% respectively.

• Engine performance was derated by about 8% due to the lower energy content of the ethanol.

Future Directions

• Investigate blend performance and emissions impacts (specifically PM) in older engines more 

characteristic of the on-road population. Such blends can mitigate emissions from diesels lacking 

emission control systems.

• Investigate use of such blends to exploit higher CO and HC emissions in enhancing advanced emission 

control systems (e.g. NOx adsorbers) that need reducing agents for regeneration.

• Optimize a diesel engine for ethanol blends and evaluate performance and emissions.

• Characterize PM chemistry, size distribution, and microstructure.

• Evaluate influence of different blending agents separately from the effects of ethanol.

Introduction

Over the past 20 years, ethanol has been 

evaluated as an additive for diesel fuel to both lessen 

the demand for imported petroleum and to promote 

the use of a domestic renewable energy resource to 

power diesel engines. Recent studies have shown 

that ethanol added to diesel fuel results in a 

beneficial reduction in particulate matter (PM) 

emissions. The effects upon carbon monoxide (CO), 

total hydrocarbons (HC) and oxides of nitrogen 

(NOx) are less clear and generally weak. Although it 

is generally considered that emission control systems 

will be required to meet future emissions targets, 

older vehicles may not be required to retrofit them. 

Indeed, fuel additives or blending components that 

reduce NOx and/or PM emissions from unmodified 

engines offer a feasible means of improving the 

pollution from this class of heavy vehicles. 

Additionally, such reduction of NOx and PM may 

also improve durability and performance of emission 

control systems. The purpose of the investigation 

was to explore the potential for reducing emissions 

from a heavy-duty diesel engine fueled with these 

ethanol blends. Fuel mixtures of ethanol and diesel 

are frequently referred to as E-diesel.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

20

Approach

 A study was conducted by the Oak Ridge 

National Laboratory (ORNL) to evaluate emissions 

resulting from E-diesel fuels tested in a heavy-duty 

compression-ignition engine. The test fuels 

evaluated in this study included two diesel-ethanol 

blends consisting of 10 and 15 vol% ethanol. A 

Phillips 66 certification diesel fuel containing 500 

ppm sulfur was used as the base fuel for the E-diesel 

blends (plus a 2% blending agent) as well as being 

the baseline fuel for this study. A Cummins 5.9 liter 

ISB turbocharged direct-injection diesel engine, 

coupled to a 300 hp General Electric DC motoring 

dynamometer, was used for the evaluation. The test 

protocol for running the engine followed the AVL 8-

mode test sequence that is meant to estimate and 

forecast the results for the more complex HeavyDuty Transient Federal Test Procedure (HDFTP). 

Gaseous emissions and PM were measured for each 

mode and a weighted average was used to determine 

emission results. No exhaust emission control 

devices were utilized during testing, nor was the 

engine equipped with exhaust gas recirculation; the 

turbocharger was fixed-geometry with a waste gate.

Gaseous emissions were sampled from the raw 

exhaust stream and directed to both an Fourier 

Transform Infrared (FTIR) spectrometer and a 

standard diesel emissions bench for measurement. 

The standard bench provided measurements of NOx, 

total hydrocarbons (THC), CO, CO2, and O2. The 

FTIR spectrometer provided extended information 

about the speciation of the hydrocarbon emissions. 

Fuel consumption was measured using a Max 

Machinery fuel flow measurement system. A stream 

of exhaust was sent to a mini-dilution tunnel for 

measurement of PM and ethanol content. PM mass 

was measured using conventional filters, while 

ethanol was measured using a photoacoustic 

spectrometer. In addition, numerous temperature and 

pressure measurements were made during the 

evaluation.

For each fuel tested, the maximum load was 

measured for each engine speed used for the AVL 8-

mode test cycle. This information was used to define 

the load parameters for the AVL 8-mode simulation 

of the HDFTP. This test consists of 8 steady-state 

data points that are weighted in a specific fashion to 

produce an estimate of the emissions results for the

HDFTP. The AVL 8-mode test was run twice for 

each fuel blend. During the dilution tunnel PM 

sampling, the dilution ratio was varied to maintain a 

dilution temperature between 110o

C and 125oC. 

Results

The maximum brake torque was measured for 

each engine speed used during the AVL 8-mode test. 

The results are shown in Figure 1. The ethanol 

blends, as expected (due to less volumetric energy 

content), produced less torque at a given condition 

than did the base fuel. The reduction in torque was 

roughly 8% for both ethanol blends; this corresponds 

to the 6-8% difference in the amount of energy 

contained in a gallon of E-diesel compared to the 

baseline fuel. It is unclear why the 15% blend 

reached slightly higher loads at higher speeds than 

the 10% blend. The opposite trend would be 

expected.

The AVL 8-mode regulated emissions results for 

the base fuel and the two E-diesel blends are shown 

in Figures 2 through 5. The emissions output for 

each emission species is expressed in g/hp-h.

 As shown in Figure 2, the levels of NOx were not 

affected (in a statistically significant way) by the 

addition of ethanol to the base diesel fuel. Several 

prior studies had shown lower NOx levels for certain 

operating conditions with added ethanol; however, 

the NOx levels were consistent for the overall AVL 8-

mode test as well as each of the 8 individual modes 

tested in this study.

Figure 1. Full Load Results for the Cummins ISB 

Engine for Each Fuel at Speeds Used for the 

AVL 8-Mode Test
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

21

Ethanol blends demonstrated significantly higher 

levels of CO and THC emissions (Figures 3 and 4) 

than the baseline fuel. (Increases of CO and THC 

emissions have been reported for other studies of 

oxygenated fuels and were anticipated in this 

investigation.) The 10% blend increased CO and 

THC emissions by nearly 60% and 100% 

respectively over the baseline, while the 15% blend 

raised the level of these emissions by 40% and 75%, 

respectively. We have no clear explanation why 

these emissions were highest for the 10% ethanol 

blend, but perhaps a maximum for these pollutants 

exists for a specific ethanol/diesel ratio. 

Furthermore, the effect of the blending agent on CO 

and THC is unknown. Although the emission levels 

of these two species increased for the ethanol fuels, 

they are well below current standards and are easily 

mitigated using commercially-available oxidation 

catalysts.

The PM emissions were observed to decrease 

with added ethanol as shown in Figure 5. For the 

10% and 15% ethanol blends, the PM was reduced 

by 20% and 30% from the baseline fuel, respectively. 

Similar trends have been reported in other studies. 

The AVL 8-mode emissions data from an FTIR 

spectrometer and a Photoacoustic Spectrometer show 

that the acetaldehyde and formaldehyde emissions 

remain at less than 10 ppm at all operating modes for 

each fuel tested. The ethanol emissions were also 

found to be less than 35 ppm for the operating modes 

tested.

Figure 2. NOx Emissions from AVL 8-Mode Tests for 

Ethanol/Diesel Fuel Blends

Figure 3. CO Emissions from AVL 8-Mode Tests for 

Ethanol/Diesel Fuel Blends

Figure 4. HC Emissions from AVL 8-Mode Tests for 

Ethanol/Diesel Fuel Blends

Figure 5. PM Emissions from AVL 8-Mode Tests for 

Ethanol/Diesel Fuel Blends
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

22

Although the results do not show reductions for 

NOx, CO, and THC, they do indicate that PM 

emissions might be reduced substantially over the 

HDFTP for ethanol-added diesel fuels. 

Conclusions

The emission results show that ethanol-diesel 

fuel used in a Cummins 5.9 liter ISB diesel engine 

causes:

1. a significant drop in PM,

2. a significant increase in the emissions of CO and 

THC, but still within current emission standards.

3. a negligible effect on NOx emissions, and

4. no apparent increase in oxygenate emissions.

These results suggest that ethanol-diesel fuel 

blends may have some use as a low emission fuel for 

older model vehicles that are not required to meet 

current EPA emission standards. The use of these 

fuel types might offer a means of reducing levels of 

PM currently produced by older diesel engines still 

operating on the roads. Obviously, much more 

extensive testing of such fuels types in a variety of 

diesel engines would be needed to accurately assess 

performance with ethanol blends. Additionally, the 

higher THC and CO levels observed suggest that 

ethanol blends could possibly offer constituents in 

the exhaust favorable to NOx adsorber regeneration.

FY 2001 Publications / Presentations

1. SAE Paper No. 2001-01-2018, Emissions From 

a 5.9 Liter Diesel Engine Fueled With Ethanol 

Diesel Blends, Michael D. Kass, John F. Thomas, 

John M. Storey, Norberto Domingo and James 

Wade, Oak Ridge National Laboratory; and 

Glenn Kenreck, Betz-Dearborn, Inc.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

23

III. FUEL & LUBRICANT EFFECTS ON EMISSION CONTROL 

PERFORMANCE

A. Durability of NOx Adsorbers Using Ultra-Low Sulfur Diesel Fuels

Shawn D. Whitacre and Matthew J. Thornton, Ph.D. (Primary Contacts), Peg Whalen, Wendy Clark

National Renewable Energy Laboratory

Center for Transportation Technologies and Systems

1617 Cole Blvd., MS 1633

Golden, CO 80401

(303) 275-4267, fax: (303) 275-4415, e-mail: shawn_whitacre@nrel.gov

(303) 275-4273, fax: (303) 275-4415, e-mail: matthew_thornton@nrel.gov

DOE Program Manager: John Garbak

(202) 586-1723, fax: (202) 586-9811, e-mail: john.garbak@hq.doe.gov

DOE Program Manager: Steve Goguen 

(202) 586-8044, fax: (202) 586-1600, e-mail: stephen.goguen@hq.doe.gov

DOE Program Manager: Peter Devlin

(202) 586-4905, fax: (202) 586-9811, e-mail: peter.devlin@hq.doe.gov

Subcontractors: FEV Engine Technology, Inc., Auburn Hills, MI; Southwest Research Institute, San 

Antonio, TX; Ricardo, Inc., Burr Ridge, IL

Other Participants: Technical team with representation from Manufacturers of Emission Controls 

Association (MECA), Engine Manufacturers Association (EMA), American Petroleum Institute (API), 

American Chemistry Council, U.S. Environmental Protection Agency (US EPA), Oak Ridge National 

Laboratory (ORNL), California Air Resources Board (CARB), and South Coast Air Quality Management District (SCAQMD).

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

B. Fuel Property Effects on Exhaust Emission Control System Technology

C. Emission Control System Degradation

D. Sulfur Impacts

Tasks

3. Fuel & Lubricant Properties - Exhaust Emission Control and Emissions

Objectives

• To use a systems approach to demonstrate the viability of achieving future emissions requirements 

with emissions control systems that include NOx adsorber catalysts and diesel particulate filters (DPF), 

for both light- and heavy-duty diesel engines while maintaining high fuel economy.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

24

• To determine whether NOx adsorbers will have sufficient conversion efficiency and durability using 

ultra-low sulfur diesel fuel to meet future emission regulations. The fuel sulfur level will be 

representative of those expected after June 2006 when the sulfur content of on-road diesel fuel falls to 

15 ppm or less.

Approach

The test activities include integrating the selected engines and emission control systems and developing 

and optimizing engine management systems for effective operation with low sulfur and other fuels. Three 

projects have been selected, each of which will:

• Complete the system setup, integration and optimization, which includes measuring baseline engineout emissions and developing regeneration and desulfurization strategies for the emission control 

devices.

• Evaluate system performance for regulated and unregulated emissions over appropriate federal test 

procedure (FTP) and off-cycle emissions points using 3-, 8-, 15- and 30-ppm sulfur fuels while 

keeping all other fuel parameters constant. The most detailed evaluations will be completed using 8- 

and 15-ppm fuels. Though diesel fuel will be regulated to 15 ppm sulfur or less after June 2006, 30 

ppm sulfur fuel was chosen for inclusion in testing to simulate periodic misfueling with higher sulfur 

fuel (e.g., off-road diesel or batches of out-of-spec on-road diesel). Testing using 30 ppm sulfur fuel 

will measure the impact of short-term exposure of higher than regulated sulfur contents, and the ability 

of NOx adsorbers to recover their conversion efficiency (high fuel sulfur content quickly degrades 

conversion efficiency).

• Evaluate system performance with selected fuels to enable investigation of the impact of varying other 

fuel properties. The fuels to be investigated will be determined by the Advanced Petroleum-Based 

Fuels — Diesel Emission Control (APBF-DEC) Fuels and Lubricants Provision work group.

Accomplishments

• Issued a request for proposals seeking to conduct up to two projects involving light-duty engines/

vehicles (one addressing passenger car applications and the other SUV applications) and up to two 

projects involving heavy-duty engines.

• The evaluation team, including representatives from the industries participating in the APBF-DEC 

program, selected a light-duty passenger car, a light-duty SUV and a heavy-duty engine project for 

award.

• Awarded subcontracts, and projects were begun with the following companies during the 4th quarter of 

FY01:

- FEV Engine Technology, Inc.: light-duty, 1.9L engine and passenger car

- Southwest Research Institute: light-duty, 6.6L engine and light-duty truck

- Ricardo, Inc.: heavy-duty, 15L engine

Future Directions

• Complete the engine and/or vehicle system integration and baseline systems evaluations.

• Develop regeneration and desulfurization strategies for each system. 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

25

Introduction

This study is part of a multi-year effort to 

demonstrate the potential of NOx adsorber catalysts 

in combination with diesel particulate filters (DPF), 

advanced fuels, engines, and engine controls to 

achieve stringent emission levels while maintaining 

high fuel economy. The project is one of several 

being conducted under the APBF-DEC project. The 

effort is being conducted with the cooperation of the 

engine and vehicle manufacturers, emission control 

device manufacturers, energy and additive 

companies, and federal and state agencies and 

laboratories. The U.S. Department of Energy’s 

Office of Advanced Automotive Technologies and 

Office of Heavy Vehicle Technologies are funding 

the federal government portion of this program.

The Diesel Emission Control-Sulfur Effects 

(DECSE) project, a predecessor to this effort, has 

shown the effects of fuel-borne sulfur on the 

performance of individual emission control devices, 

including NOx adsorbers, diesel particulate filters 

(DPFs), diesel oxidation catalysts, and lean NOx

catalysts [1-6]. Under the current APBF-DEC effort, 

this project has been designed to demonstrate the 

viability of NOx adsorber catalysts and DPFs when 

combined with advanced fuels and engines. Fuel 

properties (including additives) may also affect the 

performance of advanced emission controls. 

This project aims to demonstrate the viability of 

NOx adsorber and DPF technologies in combination 

with advanced fuels, advanced engines, and engine 

controls to achieve stringent emission levels while 

maintaining high fuel economy. To meet stringent 

Tier 2 light-duty emissions standards, tailpipe 

emissions for NOx must be below 0.2 g/mi. while PM 

emission levels must be below 0.02 g/mi. The goals 

of this project are to meet Tier 2 — Bin 5 with limits 

of 0.07 g/mi NOx and 0.01 g/mi PM. The 2007 

heavy-duty NOx standard is 0.2 g/bhp-hr with a PM 

emission standard of 0.01 g/bhp-hr. These emissions 

levels must be achievable not only on the appropriate 

transient test cycles but in other modes of operation 

as well. Additionally, hydrocarbon and carbon 

monoxide emission standards must be met. 

Minimizing fuel economy impacts while meeting 

emission requirements is also an important aspect of 

the project. The base fuel for the system development 

stage of the project will be the 3-ppm sulfur DECSE 

base fuel [1]. Additionally, the 8-, 15- and 30-ppm 

sulfur fuels will be evaluated, as will other fuels or 

fuel additives, which will be included in later phases 

of the project.

Approach

The integrated system will use advanced 

engines, NOx adsorbers, DPFs, and fuel technologies. 

In order to demonstrate the viability of the system, 

the engine and exhaust emission control technologies 

will be combined and optimized over the appropriate 

FTP cycles and other points on the engine map using 

3-, 8-, 15-, and 30-ppm sulfur level fuels. The 

optimization will be used to insure that the 

appropriate engine operating conditions can be met 

for proper NOx adsorber and DPF regeneration as 

well as adsorber desulfurization while achieving the 

light- and heavy-duty engine emission targets. Offcycle and unregulated emissions will also be 

measured. 

Performance testing will determine the 

combination of engine, fuel, lubricant, and emission 

control systems (NOx adsorber and DPF) required to 

meet future light-duty and heavy-duty emission 

standards. The aim of the testing is ultimately to 

establish the properties of advanced fuels that enable 

these systems to meet emission standards without 

adversely affecting engine performance. 

Investigation of system durability is also of interest, 

and will be pursued in a later project. 

Each project is divided into three primary tasks. 

The first task involves two parts. Part one will setup 

the engine and/or vehicle test cell(s) and will 

measure regulated and unregulated engine-out 

baseline emissions and fuel consumption over the 

appropriate cycles with 3-, 8-, 15-, and 30-ppm sulfur 

fuels. Part two will develop the regeneration (both 

DPF and adsorber) and desulfurization strategies to 

be triggered while running over the appropriate FTP 

cycle (these strategies may require engine operation 

outside of the FTP cycles). The regeneration strategy 

must allow the NOx adsorber and DPF to be 

regenerated at steady-state conditions as well as 

during transients over the appropriate FTP cycles. 

The strategies will be refined and tuned for each fuel 

and new (identical) emission control system (ECS), 

as well as for each engine application. Two different 

emission control systems will be evaluated in each 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

26

project. Members of MECA are committed to 

providing state-of-the-art NOx adsorbers, DPFs, 

other catalysts or emission control system elements, 

and technical support to the projects.

The second task is the system performance 

evaluation. This task involves evaluating the 

performance of the integrated, tuned system for 

regulated and unregulated emissions over the 

appropriate FTP and off-cycle emissions points. 

Setup and benchmarking of each new ECS will be 

conducted with 3-ppm fuel. Fresh emission control 

systems will be aged for at least 300 hours in 50-hour 

increments using 8- and 15-ppm fuels. At each 50-

hour increment, a full evaluation of emissions will be 

conducted. The heavy-duty project will include 

operation at modal (steady-state) points and the 

heavy-duty FTP. Light-duty projects include engine 

and vehicle testing to measure emissions on the FTP, 

the US06 cycle, and the highway fuel economy test 

(HFET). If emission control performance has 

degraded below the defined target level, the 

regeneration strategy will be refined, as appropriate, 

to restore performance, followed by another 

performance evaluation. Limited testing is also 

planned using 30-ppm fuel.

The third task is extended emissions control 

system durability performance evaluation testing. 

Based on the results from the 300 hours of testing 

under task two, extended testing of the "best" 

performing emissions control systems and fuel sulfur 

level combination will be placed under additional 

testing of up to 1000 hours. This testing is intended 

to evaluate the long term performance and durability 

of at least one of the emissions control systems.

In the final task, testing as outlined in the first 

two tasks will be conducted to examine the effects of 

other fuel properties besides sulfur content. The 

specific fuels and properties to be used in this portion 

of the project will be determined by APBF-DEC’s 

Fuels and Lubricants Provision work group. The 

testing will investigate the fuel effects on the 

previously developed regeneration (filter and 

adsorber) and the desulfurization strategies. The 

emission control performance and fuel economy 

impact on the system will be investigated, but the 

testing will not include extensive aging cycles.

Results/Conclusions

The three projects that are currently underway 

are analyzing the effects of fuel composition on a 

light-duty passenger car engine and vehicle, a lightduty SUV/light truck engine and vehicle, and a linehaul class heavy-duty engine. The projects, varying 

in length from 24 to 30 months, started in the last 

quarter of FY01. Because testing has not started, data 

and results are not yet available. The three 

subcontractors are assembling engines and 

appropriate subsystems and instrumentation, and 

preparing test cells. The bulk of the next fiscal year 

will be spent in setup, system integration, and 

developing regeneration and desulfurization 

strategies.

References

1. U.S. Department of Energy, Engine 

Manufacturers Association, Manufacturers of 

Emission Controls Association, "Diesel 

Emission Control-Sulfur Effects (DECSE) 

Program — Phase I Interim Data Report No. 1: 

Phase 1 Interim Data," August 1999

2. U.S. Department of Energy, Engine 

Manufacturers Association, Manufacturers of 

Emission Controls Association, "Diesel 

Emission Control-Sulfur Effects (DECSE) 

Program — Phase I Interim Data Report No. 2: 

NOx Adsorber Catalysts," October 1999

3. U.S. Department of Energy, Engine 

Manufacturers Association, Manufacturers of 

Emission Controls Association, "Diesel 

Emission Control-Sulfur Effects (DECSE) 

Program — Phase I Interim Data Report No. 3: 

Diesel Fuel Sulfur Effects on Particulate Matter 

Emissions," November 1999

4. U.S. Department of Energy, Engine 

Manufacturers Association, Manufacturers of 

Emission Controls Association, "Diesel 

Emission Control-Sulfur Effects (DECSE) 

Program — Phase I Interim Data Report No. 4: 

Diesel Particulate Filters Final Report," January 

2000

5. U.S. Department of Energy, Engine 

Manufacturers Association, Manufacturers of 

Emission Controls Association, "Diesel 

Emission Control-Sulfur Effects (DECSE) 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

27

Program — Phase II Summary Report: NOx

Adsorber Catalysts," August 2000

6. http://www.ott.doe.gov/decse/
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

28

B. Lubricant Property Impact on CIDI Emission Control System Durability

Shawn D. Whitacre (Primary Contact)

National Renewable Energy Laboratory

1617 Cole Blvd., MS 1633

Golden, CO 80401

(303) 275-4267, fax: (303) 275-4415, e-mail: shawn_ whitacre@nrel.gov

DOE Program Manager: John Garbak

(202) 586-1723, fax: (202) 586-9811, e-mail: john.garback@hq.doe.gov

DOE Program Manager: Stephen J. Goguen 

(202) 586-8044, fax: (202) 586-1600, e-mail: stephen.goguen@hq.doe.gov

Other Participants: American Chemistry Council, American Petroleum Institute, Manufacturers of 

Emissions Control Association, Engine Manufacturers Association, Oak Ridge National Laboratory

Subcontractor: Automotive Testing Laboratories, Inc., East Liberty, OH (Phase 1)

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

B. Fuel Property Effects on Exhaust Emission Control System Technology

C. Emission Control System Degradation

D. Sulfur Impacts

Tasks

3. Fuel & Lubricant Properties - Exhaust Emission Control and Emissions

Objectives

• Determine the impact of lubricant properties and composition on engine-out emissions

• Determine if lubricant formulation affects the performance and durability of diesel engine emission 

control systems (ECS)

• Develop guidelines specifying lubricant properties that will be required for use in future lowemissions diesel engines

Approach

• Phase 1: Determine the impact of lubricant formulation (additives and basestock) on the emissions of a 

compression ignition direct-injection (CIDI) engine. Conventional and developmental additive 

technologies blended with four different basestocks will be tested in a medium-duty diesel engine.

• Phase 2: Determine the impact of lubricant related emission components on performance and 

durability of diesel emission control devices using laboratory-scale analysis tools.

• Phase 3: Begin confirmatory testing in cooperation with Advanced Petroleum-Based Fuels - Diesel 

Emission Control (APBF-DEC) systems projects to study lubricant effects on NOx adsorber catalysts 

and selective catalytic reduction (SCR) catalysts in combination with diesel particle filters.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

29

Accomplishments

• An International T444E (7.3L, V8) has been installed in an emission test cell at Automotive Testing 

Laboratories, Inc. The MY 1999 engine has been equipped with exhaust gas recirculation (EGR) and 

closed crankcase ventilation (CCV) hardware similar to future base engine designs. 

• Test lubricants ranging in sulfur content from 0 to 6500-ppm and ash between 0% and 1.85% have 

been prepared in a low sulfur API Group II basestock.

Future Directions

• Gaseous and particulate matter (PM) emissions will be measured during a five mode steady-state 

operating cycle. PM components including sulfate, nitrate, soluble organic fraction, metals, and 

polycyclic aromatic hydrocarbons (PAHs) will be fully characterized.

• Test lubricants will be blended using other basestocks, including basestocks containing higher sulfur 

content and synthetics.

• A bench scale apparatus will be developed to test how lubricant related emissions components impact 

the performance of diesel emissions control catalysts.

Introduction

The Diesel Emission Control—Sulfur Effects 

(DECSE) program quantified the impact of diesel 

fuel sulfur on the performance and short-term 

durability of diesel emission control devices. The 

sensitivity of some of these devices highlighted the 

need to study diesel lubricating oil, which is another 

source of sulfur and other potential poisons.

To address this need, a research program to study 

lubricant formulation (basestocks and additives) 

effects on diesel emission control systems is 

underway. The research is being conducted as part of 

DOE’s APBF-DEC project and leverages 

participation from the Engine Manufacturers 

Association (EMA), the Manufacturers of Emissions 

Controls Association (MECA), the American 

Petroleum Institute (API), the National 

Petrochemical & Refiners Association (NPRA), and 

the American Chemistry Council.

It is anticipated that the results of this study will 

be critical in defining the needs of future lubricant 

formulations for both light-duty and heavy-duty 

diesel engines. Should a need for substantial 

lubricant reformulations be identified, industry 

would require significant development time to 

research "catalyst compatible" formulations that are 

cost-competitive and that continue to deliver the 

superior engine protection and long life demanded by 

engine customers. In addition, engine manufacturers 

recognize that the lubricant reformulations may drive 

the need for more robust engine hardware that is 

tolerant of modified oil chemistry, an endeavor 

requiring significant development time as well.

Approach

This project is being conducted in three 

consecutive phases. The first phase will identify and 

characterize lubricant derived emission constituents. 

This testing is utilizing a medium-duty CIDI engine 

that has been equipped with EGR and CCV (Figure 

1). A matrix of conventional and experimental 

lubricant additive packages blended with various 

petroleum-based and synthetic basestocks is being 

tested. Twelve additive packages have been selected 

to provide a range of components including ash 

content, sulfur, zinc, and phosphorus. The four 

basestocks being tested span the available production 

approaches and include products of varying sulfur 

content, volatility, and degree of saturation. All 

finished lubricants are SAE 15W-40 viscosity grade.

All testing will be conducted at the five steadystate operating modes illustrated in Figure 2. These 

modes span the range of operation of the engine from 

idle to maximum torque and maximum horsepower. 

Two intermediate points are included that are 

representative of vehicle operation. Emissions that 

will be sampled during the five-mode, steady-state 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

30

operating cycle include gaseous hydrocarbons, 

carbon monoxide, sulfur dioxide, nitrogen oxides, 

and PM. The PM will be further analyzed for sulfate 

and nitrate fractions, soluble organic fraction, metals, 

and PAH content.

Follow-up work will be conducted to determine 

if, and to what extent, these lubricant-related 

emissions species affect the performance and 

durability of emission control devices designed to 

reduce NOx and particulate matter (PM) emissions 

from diesel engines. Screening tests will be 

performed on a bench scale apparatus and will be 

followed up with full-scale confirmatory testing on 

full engine systems equipped with advanced 

emissions control technologies.

Results

Phase 1 emissions testing began in July 2001, 

and it will be completed during the first quarter of 

CY 2002. 

Figure 1. International T444E Engine Installation

Figure 2. Steady-State Operating Modes for Emission 

Testing
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

31

C. Demonstration of Potential for Selective Catalytic Reduction and Diesel 

Particulate Filters

Ralph McGill

Oak Ridge National Laboratory

National Transportation Research Center

2360 Cherahala Boulevard

Knoxville, TN 37932

(865) 946-1228, fax: (865) 946-1248, e-mail: mcgillrn@ornl.gov

DOE Program Manager: Steve Goguen 

(202) 586-8044, fax: (202) 586-1600, e-mail: stephen.goguen@hq.doe.gov

Subcontractor: Southwest Research Institute (SwRI), San Antonio, TX

Magdi Khair (Primary Contact)

Southwest Research Institute

6220 Culebra Road

San Antonio, TX 78238

(210) 522-5311, e-mail: MKhair@swri.edu

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

B. Fuel Property Effects on Exhaust Emission Control System Technology

Tasks

3. Fuel & Lubricant Properties - Exhaust Emission Control and Emissions

Objectives

• Demonstrate the low-emissions performance of advanced diesel engines plus urea selective catalytic 

reduction (SCR) and diesel particulate filters (DPF)

• Determine the regulated and unregulated emissions with and without emission controls

• Examine the durability of the emission control systems

• Determine toxic and unregulated emission levels

• Evaluate the sensitivities of the emission controls to fuel variables

Approach

• Set up a heavy-duty engine in an emissions test cell to optimize emission reduction performance of 

two different emission control systems utilizing urea SCR.

• Apply a low-pressure-loop EGR system to reduce engine-out NOx to ~ 2.0 - 2.5 g/hp-hr.

• Add emission control system(s) including diesel particulate filters and SCR systems with urea 

injection to reduce engine-out emissions of both NOx and PM. (Two different emission control 

systems - DPF and SCR catalysts - will be evaluated.)

• Integrate controls and optimize performance of systems to reach the lowest possible emissions of NOx

and PM for both systems.

• Perform 6,000 hour durability tests simultaneously with the two different systems, checking 

emissions - regulated and unregulated - at 2,000 hour intervals.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

32

Accomplishments

• In-kind contributions of important elements of the experimental setup have been received:

- Caterpillar - C12 engine(s)

- STT Emtec (Sweden) - Low-pressure loop EGR system

- Robert Bosch - Urea injection system

- Manufacturers of Emission Control Association (MECA) - SCR catalysts and DPF systems

• Set up of engine has begun in the emissions lab where the emission control systems will be optimized 

for emission reductions before moving to the durability phase of the project

Future Directions

• The project has begun at SwRI. The work plan calls for 22 months of effort - 10 months of 

performance optimization of two different SCR systems followed by 12 months of durability testing of 

both systems, running 6,000 hours total with emissions re-checks at 2,000-hour intervals.

Introduction

SwRI was chosen to be the contractor for this 

project as a result of a competitive procurement 

issued by ORNL. Working with the Advanced 

Petroleum-Based Fuels — Diesel Emission Control 

(APBF-DEC) teams and industry groups, we have 

arranged for significant in-kind support from the 

Engine Manufacturers Association (EMA), MECA, 

and individual companies. Caterpillar will supply 

the engines; MECA will supply the integrated 

emission control systems (DPF combined with SCR 

catalysts); STT will provide low-pressure-loop EGR 

systems; and Robert Bosch will provide the urea 

injection systems with controls.

Two different SCR systems, combined with DPF 

systems, will be provided by MECA in order to gain 

experience with different technologies. A fuel matrix 

of three fuels (minimum) will be evaluated, 

emphasizing the influence of fuel sulfur level on the 

performance of the systems.

Accomplishments

The subcontract was awarded to SwRI, and the 

contract was officially started in early May, 2001. 

SwRI has dedicated a heavy-duty emissions test cell 

to the project for its duration. Two durability test 

cells will be utilized during the second phase of the 

project with two identical engines running with the 

two different emission control packages. The engine 

and associated systems are being set up in the 

emissions lab at SwRI. Fuel has been received for 

the start of the project, and a urea supplier has been 

identified. Other elements - the EGR system, the 

urea injection system, and the emission control 

systems from MECA - are in the process of being 

provided.

Technical Approach in SwRI Subcontract

SwRI will spend the first 10 months integrating 

the systems on the engine and optimizing 

performance for lowest emissions. This will occur in 

series for the two different emission control systems. 

The general approach is to start with characterizing 

the engine-out emissions, which for NOx is expected 

to be about 4 g/hp-hr. Adding the EGR system and 

optimizing its performance is expected to reduce the 

engine-out NOx to about 2 g/hp-hr. Then, the 

addition of the SCR and DPF emission control 

system and optimization of its performance at 90% 

conversion efficiency should reduce the NOx to the 

future standard of 0.2 g/hp-hr. 

Two engines will be set up in separate durability 

test cells for the 12-month durability test. This will 

be a 6,000-hour test running the OICA cycle 

continuously during the period. At 2,000-hour 

intervals, the emission control systems will be 

removed from the durability engines, returned to the 

emissions test cell, mated with the original engine 

and retested for emissions performance.

 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

33

Concern for preventing excessive back pressure 

and other practical considerations dictated that the 

exhaust emission control system be divided into two 

identical legs. So, for a given SCR/DPF 

combination, the exhaust will be split into two 

pathways, each comprised of first the DPF, followed 

by urea injection, the SCR catalyst, a final oxidation 

catalyst (for oxidizing any ammonia slip), and finally 

a flow balancing valve. This is illustrated in Figure 

1. This complicates the control systems because it 

will require two urea injection systems plus the 

controls for balancing the exhaust flow. However, 

this was considered a better option than either 

accepting a higher back pressure or trying to acquire 

catalysts of a size that would not impose higher back 

pressures.

Currently, efforts are under way to set up the 

experiments at SwRI.

Figure 1. Diesel Engine and Emission Control System 

Configuration
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

34

IV. VEHICLE TEST AND EVALUATION

A. The Emissions Impacts of Various Fuels on a CIDI Vehicle

Edwin A. Frame (primary contact) 

Southwest Research Institute

6220 Culebra Road

San Antonio, TX 78238-5166

(210) 522-2515, fax: (210) 522-3270, e-mail: eframe@swri.edu

DOE Program Manager: John Garbak 

(202) 586-1723, fax: (202) 586-9811, e-mail: john.garbak@hq.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

B. Fuel Property Effects on Exhaust Emission Control System Technology

E. Toxic Emissions

Tasks

3. Fuel & Lubricant Properties - Exhaust Emission Control and Emissions

Objective

• Quantify the exhaust emission effects of advanced petroleum fuel oxygenate blends in a vehicle 

powered by a state-of-the-art CIDI engine (DaimlerChrysler OM611).

Approach

• Six fuels will be evaluated for tailpipe exhaust emissions from a European Mercedes Benz "C" (220) 

series vehicle with the OM611 CIDI engine following the chassis dynamometer portion of the Federal 

Test Procedure (FTP) and the US06 aggressive driving cycle. 

Accomplishments

• The matrix of test fuels includes advanced oxygenate blends, an advanced ethanol-containing fuel, and 

a fuel blend containing water.

• Testing has been delayed pending the availability of a specially produced base fuel that is 

representative of projected 2007 U.S. diesel fuel.

Future Directions

• Evaluate the effects of fuel blends containing oxygenated materials in an advanced CIDI powered 

vehicle that has advanced emission control devices such as NOx adsorption and diesel particulate filter 

technologies.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

35

Introduction

Potential exhaust emission reductions have been 

demonstrated in many previous studies for advanced 

and reformulated diesel fuels. In previous 

investigations, exhaust emissions were determined in 

a Mercedes Benz "C" Series European vehicle for a 

series of advanced petroleum-based fuels (see Table 

1). The vehicle is powered by the OM611 engine, 

which has a displacement of 2.2 L, and has the 

following properties: direct-injection, four valves per 

cylinder, turbocharged and intercooled, highpressure common rail fuel injection system with pilot 

injection, exhaust gas recirculation, and intake port 

cut-off. According to the vehicle manufacturer, the 

emission control system of this vehicle includes one 

catalytic converter close to the engine with a volume 

of 2.1 L and an additional underbody catalytic 

converter with a volume of 1.8 L. Both converters 

have a platinum coating on a zeolith substrate and 

provide oxidation of HC and CO with a slight 

reduction in NOx. The converter closest to the 

engine has an internal by-pass so that the underbody 

converter is supplied with hydrocarbons to assist in 

an additional slight reduction in NOx. Figure 1 is a 

photograph of the Mercedes Benz C 220 test vehicle.

In the previous investigations, all fuels tested in 

the C 220 vehicle had exhaust emissions exceeding 

the EPA Tier 2 standards. (Note that this vehicle was 

built to meet European emission regulations, which 

are less stringent than the upcoming Tier 2 

standards.) With respect to test cycle severity, the 

US06 aggressive driving cycle was the most severe, 

followed by the Federal Test Procedure (FTP) and 

then the European cycles. Overall, the results 

showed a benefit in PM reduction for the oxygenated 

fuel in the FTP and European cycles. While a benefit 

was also observed for the oxygenated fuel over the 

US06 aggressive driving cycle, the reduction was not 

significant compared to the baseline diesel fuel PM 

emissions. The fuel blend containing 15% 

dimethoxymethane (DMM) consistently produced 

the lowest PM emissions; however, a slight increase 

in NOx was observed. DMM15 fuel consistently had 

the lowest levels of volatile organic fraction (VOF). 

Fuel economy for the DMM15 fuel ranged from 8% 

to 11% less than the baseline fuel (2D).

Approach

This project will include exhaust emission 

evaluations of a Mercedes-Benz C 220 diesel vehicle 

equipped with the CIDI OM611 engine. This vehicle 

is equipped with "lean NOx" catalyst technology 

(described previously), which relies on low-sulfur 

fuel to be effective. The vehicle will be tested using 

the following six fuels:

• 2007 Fuel (projected 2007 U.S. diesel fuel)

• 2007 Fuel + tripropylene glycol monomethyl 

ether (TPGME) @ 7% oxygen content

• 2007 Fuel + TPGME @ 3.5% oxygen 

content

• 2007 Fuel + di-butyl maleate @ 7% oxygen 

content

• Pure Energy blend (ethanol plus additives) 

in 2007 Fuel

• Puri-NOx blend (water emulsion) using 2007 

Fuel

Fuel Code Fuel Description

2D 2-D EPA Certification Diesel

CA California Reference Diesel

LS Low Sulfur Diesel

FT100 Neat Fischer-Tropsch Diesel

DMM15 15% DMM with 85% LS Diesel

FT20 20% Fischer-Tropsch with 80% LS Diesel

B20 20% Biodiesel with 80% LS Diesel

Table 1. Test Fuels Used in Previous Studies

Figure 1. Mercedes Benz C 220 CIDI Diesel Test Vehicle
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

36

All six fuels will be evaluated over the chassis 

dynamometer portion of the FTP and the US06 

aggressive driving cycle. All test cycles will be 

conducted in triplicate.

Testing will utilize a Horiba 48-inch single-roll 

chassis dynamometer. This dynamometer 

electrically simulates inertia weights up to 12,000 

pounds over the FTP (up to 7,000 pounds for 

vehicles capable of following the US06 driving 

trace) and provides programmable road load 

simulation of up to 125 hp continuously at 65 mph 

(300-hp momentary duty at 65 mph). SwRI will use 

a Mears Model to calculate a road load curve for the 

vehicle. This model requires coastdown data from 

drive and non-drive axles. A total of three 

coastdowns will be conducted on each axle, and the 

average results will be used as input for the Mears 

Model. The resulting calculated road load curve 

coefficients will be entered as the target "a", "b", and 

"c" values for use during the Horiba Road Load 

Derivation routine. With this routine, coastdowns 

are conducted with the vehicle on the chassis 

dynamometer to determine appropriate chassis 

dynamometer load coefficient settings. Vehicle 

equivalent test weight will be the measured curb 

weight of the vehicle with a 40 percent fuel fill in the 

main tank plus 300 pounds to account for a driver 

and luggage.

Dilute exhaust emission sampling will utilize a 

positive displacement-type constant volume sampler 

(CVS). An 18-inch diameter by 16-ft. long stainless 

steel dilution tunnel will be used in conjunction with 

the CVS to maintain an average tunnel sampling 

zone temperature of 110o

F, with the maximum 

temperature not to exceed 125o

F during the standard 

Federal Test Procedure. Nominal CVS flow rate will 

be 600 cfm. A constant-speed cooling fan of 5,000 

cfm capacity will be used in front of the vehicle 

during operation.

Regulated exhaust emissions (total 

hydrocarbons, carbon monoxide, oxides of nitrogen, 

and particulate matter) and carbon dioxide will be 

sampled and measured in a manner consistent with 

EPA protocols for light-duty emission testing as 

given in the Code of Federal Regulations. 

Proportional dilute exhaust gas samples will be 

collected in Tedlar bags for analysis of carbon 

monoxide and carbon dioxide. Total hydrocarbons 

and oxides of nitrogen will be measured 

continuously from the dilution tunnel. Concurrently, 

a proportional sample of the dilute exhaust will be 

drawn through Pallflex T60A20 fluorocarbon-coated 

glass fiber filters for determination of particulate 

matter. Filter samples will be analyzed by direct 

filter injection gas chromatography (DFI/GC) to 

determine the particulate VOF and lubricating oil 

contribution to VOF. Exhaust constituents will be 

analyzed as specified below:

Appropriate statistical techniques will be used to 

determine differences between the six fuels. Analysis 

of variance (ANOVA) will determine whether the 

average response of the six fuels is statistically 

different. All comparison tests will be made at the 

5% level of significance.

Results

Testing has been delayed pending the availability 

of the 2007 base fuel. This is a specially produced 

diesel fuel that is projected to be representative of 

2007 U.S. diesel fuel.

Constituent Analysis Method

Total Hydrocarbon Heated Flame Ionization Detector

Carbon Monoxide Non-Dispersive Infrared Analysis

Carbon Dioxide Non-Dispersive Infrared Analysis

Oxides of Nitrogen Chemiluminescent Analysis

Particulate Matter Gravimetric

Volatile Organic 

Fraction of PM

Direct Filter Injection Gas 

Chromatography

Oil Fraction of VOF Direct Filter Injection Gas 

Chromatography
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

37

B. EC-Diesel Technology Validation Program

Keith Vertin

National Renewable Energy Laboratory

1617 Cole Blvd.

Golden, CO 80401

(303) 275-4422, fax: (303) 275-4415, e-mail: keith_vertin@nrel.gov

DOE Program Manager: Stephen Goguen

(202) 586-8044, fax: (202) 586-4166, e-mail: stephen.goguen@hq.doe.gov

Subcontractors: West Virginia University, Morgantown, WV; Battelle Memorial Institute, Columbus, 

OH

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

B. Fuel Property Effects on Exhaust Emission Control System Technology

C. Emission Control System Degradation

E. Toxic Emissions

F. Ultra-fine Particles

Tasks

3. Fuel & Lubricant Properties - Exhaust Emission Control and Emissions

Objectives

• Compare exhaust emissions from vehicles fueled with EC-Diesel and California diesel fuels. ECDiesel, also known as ECD, is an ultra-low sulfur diesel fuel with 15 ppm maximum sulfur content. 

• Evaluate the performance, emissions, and durability of the vehicles retrofitted with catalyzed particle 

filters and fueled with ECD over twelve or more months of service.

• Collect fuel consumption, maintenance, reliability, and operating cost data for the participating vehicle 

fleets and compare to control vehicles fueled with California diesel fuel.

Approach

• Establish a government and industry working group to guide the program.

• Select vehicle fleets in Southern California to participate.

• Retrofit a select number of vehicles with catalyzed particle filters and assist with start-up of the test 

fleets.

• Conduct a first round of vehicle emissions tests in the winter of 2000.

• Conduct a second round of vehicle emissions tests in the winter of 2001 and compare with first round 

results.

• Objectively analyze vehicle performance and emissions data for both fuels, and draw conclusions.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

38

Accomplishments

• A government-industry working group has been established. Industry participants include ARCO (a 

BP Company), DDC (Detroit Diesel Corporation), International Truck and Engine Corporation, 

Cummins Engine Company, Ford Motor Company, Engelhard Corporation, Johnson-Matthey, 

Corning, NGK-Locke, and Fleetguard Nelson. Participating government agencies include the U.S. 

Department of Energy, the National Renewable Energy Laboratory, the California Air Resources 

Board, the California Energy Commission, and the South Coast Air Quality Management District. 

• The following fleets have been retrofitted with catalyzed particle filters and are participating in the 

program: San Diego School District School Buses, ARCO Tanker Trucks, Ralphs Grocery Trucks, LA 

City Refuse Haulers, Los Angeles County MTA Transit Buses, Hertz Equipment Rental Trucks, and 

shuttle vehicles.

• First round vehicle test results were published in three SAE technical papers. Second round emissions 

tests have been completed and will be published at the 2002 SAE World Congress. The start-up 

experience for the Ralphs Grocery truck fleet was published to document retrofit considerations and 

report on operating cost, maintenance and fuel economy through the first five months of vehicle 

operation.

Future Directions

• The program has been expanded to test ECD-1, a new fuel that BP is introducing into the California 

market.

• Three vehicles were selected to chemically characterize the exhaust emission species. These vehicles 

were fueled with California diesel, EC-Diesel and ECD-1. The vehicles were tested with and without 

the particle filters. Exhaust speciation data and particle size distribution data are being analyzed and 

will be published in 2002. 

• Further testing is needed to examine the capabilities and limitations of passive particle filters in colder 

climates and in older vehicles.

Introduction

ARCO, a BP Company, has developed a new 

diesel fuel called Emission Control Diesel (ECD). 

ECD is a heavily hydrocracked fuel produced from 

typical crude oil. ECD has a maximum sulfur 

content of 15 ppm, about 10% aromatics by volume, 

and a nominal cetane number of 60. More recently, 

BP has introduced ECD-1 into the southern 

California market. ECD-1 also has 15 ppm maximum 

sulfur content, but has 22% aromatics and a nominal 

cetane number of 50. ECD-1 contains both 

hydrocracked and hydrotreated stocks.

Previous studies in the engine laboratory have 

shown that catalyzed particle filters operate more 

efficiently as diesel fuel sulfur content decreases 

[1,2,3]. Ultra-low sulfur fuels lower the exhaust gas 

temperature required to burn particulate matter 

collected on the filter element. Ultra-low sulfur fuels 

expand the exhaust gas temperature window needed 

for filter regeneration, thereby improving particulate 

matter conversion efficiency over a wider range of 

engine operating conditions.

A one-year technology validation program is 

being conducted to evaluate ECD and catalyzed 

particulate filters using diesel vehicles operating in 

southern California. The fuel’s performance, impact 

on engine durability and vehicle performance, and 

emission characteristics are being evaluated in truck 

and bus fleets.

Approach

Seven vehicle fleets are being evaluated in 

southern California. All vehicles are equipped with 

modern electronically-controlled diesel engines. 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

39

Each fleet contains unmodified vehicles fueled with 

a typical California (CARB) diesel fuel, hereafter 

referred to as control vehicles. For each fleet, a 

select number of vehicles were retrofitted with either 

the Engelhard catalytic soot filter (hereafter 

designated DPXTM), or the Johnson-Matthey 

continuously regenerating technology (hereafter 

designated CRTTM). Both DPX and CRT units are 

passive devices that were installed in place of the 

existing muffler system, without any modification to 

the engines. The retrofitted vehicles are fueled 

exclusively with ECD fuel using segregated fuel 

storage tanks. 

Each fleet participating in the program contains a 

number of vehicles that are nominally identical 

(same model year, engine, chassis configuration, and 

equipment) except for the exhaust system which may 

have been retrofitted with DPX or CRT filter. 

A subset of vehicles from each fleet was selected 

for emissions testing. The vehicles were tested 

using the West Virginia University transportable 

emissions laboratory. The transportable laboratory 

consists of a heavy-duty chassis dynamometer and an 

emissions measurement laboratory (Figure 1). 

Emissions of carbon monoxide (CO), nitrogen oxides 

(NOx), total hydrocarbons (HC) and particulate 

matter (PM) were measured over the City-Suburban 

Heavy Vehicle Route (CSHVR) and a number of 

other driving schedules.

Results

Vehicles retrofitted with catalyzed particle filters 

and fueled with ECD emitted 91% to 99% less 

particulate matter compared to the California dieselfueled vehicles having no exhaust filter equipment. 

Hydrocarbon and carbon monoxide emissions were 

also significantly reduced. Average exhaust 

emissions results for the grocery trucks are compared 

in Figure 2.

The same grocery trucks were retested after 

twelve months of operation and more than 100,000 

miles accumulation per truck. The particle filters 

were not serviced prior to the second round 

emissions tests (Figure 3). Average particulate 

matter emissions from the retrofitted trucks were 

again found to be 89% to 99% less than the 

Figure 1. Grocery Truck Testing on the West Virginia 

University Transportable Chassis 

Dynamometer and Emissions Laboratory

Figure 2. Average Grocery Truck Emissions over the 

City-Suburban Heavy Vehicle Route, 

February-March 2000

Figure 3. Average Grocery Truck Emissions over the 

City-Suburban Heavy Vehicle Route, 

February-March 2001
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

40

California diesel-fueled vehicles having no exhaust 

filter equipment. 

Through the first five months of operation, there 

was no detectable difference in fuel economy 

between grocery trucks with and without particle 

filters, based on an analysis using fleet operation 

records (Figure 4).

Conclusions

Several types of heavy vehicles have been 

successfully retrofitted with catalyzed particle filters. 

Second round emissions tests indicate that the 

particle filters have operated reliably over a twelve 

month period and continue to dramatically reduce 

particulate matter, hydrocarbon, and carbon 

monoxide emissions without adversely affecting fuel 

economy. 

References

1. U.S. Department of Energy, Engine 

Manufacturers Association, and Manufacturers 

of Emission Controls Association, "Diesel 

Emission Control- Sulfur Effects (DECSE) 

Program, Phase I Interim Data Report No. 4: 

Diesel Particulate Filters Final Report", http://

www.ott.doe.gov/decse, Jan. 2000.

2. Warren, J., Allansson, R., Hawer, P., Wilkins, A., 

"Effects of After-Treatment on Particulate Matter 

when Using the Continuously Regenerative Trap 

(CRTTM)", IMechE Technical Paper S491/006/

98, 1998.

3. Cooper, B., Thoss, J., "Role of NO in Diesel 

Particulate Control", SAE Technical Paper 

890404, 1989.

Publications

1. Vertin, K., Chandler, K., LeTavec, C., Goguen, 

S., Keski-Hynnila, D., Chatterjee, S., Smith, G. 

& Hallstrom, K., "Class 8 Trucks Operating on 

Ultra-Low Sulfur Diesel with Particulate Filter 

Systems: A Fleet Start-Up Experience," SAE 

Paper 2000-01-2821.

2. Clark, N.N., Boyce, J.E., Xie, W., Gautam, M., 

Lyons, D.W., Vertin, K., LeTavec, C.A. & 

Coburn, T.C., "Class 8 Trucks Operating on 

Ultra-Low Sulfur Diesel with Particulate Filter 

Systems: Regulated Emissions," SAE Paper 

2000-01-2815.

3. Chatterjee, S., McDonald, C., Conway, R., 

Windawi, H., Vertin, K., LeTavec, C.A., Clark, 

N.N. & Gautam, M., "Emission Reductions and 

Operational Experiences with Heavy Duty 

Diesel Fleet Vehicles Retrofitted with 

Continuously Regenerated Diesel Particulate 

Filters in Southern California," SAE Paper 2001-

01-0512, 2000.

Presentations

1. Vertin, K., "Class 8 Trucks Operating on UltraLow Sulfur Diesel with Particulate Filter 

Systems: A Fleet Start-Up Experience," 

presented at the SAE International Fall Fuels and 

Lubricants Meeting, October 16-19, 2001.

2. Clark, N.N., "Class 8 Trucks Operating on UltraLow Sulfur Diesel with Particulate Filter 

Systems: Regulated Emissions," presented at the 

SAE International Fall Fuels and Lubricants 

Meeting, October 16-19, 2001.

3. LeTavec, C., "EC-Diesel Technology Validation 

Program," presented at the 2000 SAE Truck and 

Bus Conference, December, 2000.

4. Chatterjee, S., "Emission Reductions and 

Operational Experiences with Heavy Duty 

Diesel Fleet Vehicles Retrofitted with 

Continuously Regenerated Diesel Particulate 

Filters in Southern California," presented at the 

2001 SAE World Congress, March 5-8, 2001.

Figure 4. Monthly Average Fuel Economy for Grocery 

Trucks with and without Diesel Particle Filters
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

41

5. Vertin, K., "Emissions from Grocery Trucks and 

Refuse Haulers Retrofitted with Diesel Particle 

Filters," presented at the 2001 SAE Government/

Industry Meeting, May 15, 2001.

6. LeTavec, C., "EC-Diesel Technology Validation 

Program: Round 2 Emissions," presented at the 

2001 DOE Diesel Engine Emissions Reduction 

(DEER) Workshop, August 5-9, 2001.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

42

V. SUPPORTING RESEARCH

A. Effects of Oxygenated Diesel Fuels on In-Cylinder Combustion and SootFormation Processes

Chuck Mueller (Primary Contact), Mark Musculus, and Glen Martin

Sandia National Laboratories

7011 East Ave., MS 9053

Livermore, CA 94550-9517

(925) 294-2223, fax: (925) 294-1004, e-mail: cjmuell@sandia.gov

DOE Program Manager: Stephen Goguen

(202) 586-8044, fax: (202) 586-1600, e-mail: Stephen.Goguen@hq.doe.gov

DOE Program Manager: Gurpreet Singh

(202) 586-2333, fax: (202) 586-4166, e-mail: Gurpreet.Singh@hq.doe.gov

DOE Program Manager: Kevin Stork

(202) 586-8306, fax: (202) 586-4166, e-mail: Kevin.Stork@ee.doe.gov

DOE Program Manager: John Garbak

(202) 586-1723, fax: (202) 586-9811, e-mail: John.Garbak@hq.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

A. Fuel Property Effects on Engine Emissions and Efficiency

F. Ultra-fine Particles

Tasks

2. Fuel & Lubricant Properties - Engine-Out Emissions

Objectives

• Enhance understanding of how diesel oxygenates affect in-cylinder combustion and emissionsformation processes. Specifically:

- Determine whether oxygen content alone governs the soot-reduction potential of an oxygenated 

fuel blend, as has been suggested in several recent studies.

- If it is found that oxygen content is not the only important factor, identify and quantify the extent 

to which other parameters (e.g., oxygenate molecular structure, fuel thermophysical properties, 

flame lift-off length, etc.) influence the sooting tendencies of a fuel.

• Collaborate with research groups in academia, industry, and national laboratories to maximize the 

value of research capabilities unique to Sandia.

• Feed back new knowledge to engine manufacturers, fuel suppliers, and other stakeholders so that 

engine design and fuel formulation can be used together in an optimal manner to meet future emissions 

and efficiency goals.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

43

Approach

• Phase 1: Implement and verify proper operation of a production Caterpillar hydraulically-actuated, 

electronically controlled unit injector (HEUI) fuel-injection system in the optical 4-stroke DI diesel 

engine.

• Phase 2: Prepare a suite of laser/imaging and traditional diagnostics to study the in-cylinder 

combustion processes of oxygenated fuels in the optical engine.

• Phase 3: Identify four fuel formulations that represent limiting cases that can be used to help 

determine mechanisms by which fuel property variations can lower emissions and enhance efficiency. 

• Phase 4: Conduct experiments that apply the suite of diagnostics developed in Phase 2 to each of the 

fuels selected in Phase 3.

• Phase 5: Analyze results and report findings to collaborators in industry, academia, and the national 

laboratories. Publish in the open literature to broadly disseminate results and conclusions.

Accomplishments

• Completed Phase 1. Injector and laboratory infrastructure modifications were made to enable the use 

of a production Caterpillar HEUI fuel-injection system. Performance of the new system was verified 

to be representative of production hardware.

• Completed Phase 2. The diagnostics selected are:

- Imaging of direct luminosity (DL) for general characterization of ignition locations and evolution 

of regions of high soot concentration and temperature

- Imaging of Mie-scattered light to visualize spray development and to verify proper injector 

performance with each experimental fuel

- Measurement of injected fuel quantity to determine engine efficiency

- Measurement and thermodynamic analysis of cylinder pressure data to determine heat release rate 

profiles and combustion phasing

• Completed Phase 3. The fuels selected are:

- A non-oxygenated, 45-cetane hydrocarbon fuel used as a baseline for comparison with oxygenated 

fuel results

- A 50 wt%-oxygen, low-cetane fuel that requires use of a glow plug (GP) for repeatable ignition

- A 26 wt%-oxygen, typical-cetane fuel containing an ether oxygenate

- A 26 wt%-oxygen, typical-cetane fuel whose ignition delay has been matched to that of the ethercontaining fuel but that contains a di-ester oxygenate1

• Completed Phase 4. Baseline engine characterization using the non-oxygenated hydrocarbon fuel was 

completed. Experiments investigating the GP-assisted ignition and combustion of the highlyoxygenated, low-cetane fuel were completed. Experiments with the two 26 wt%-oxygen fuels also 

were completed. 

• Phase 5 is near completion. Results from Phase 1 have been published in a Sandia Report [2]. Results 

from Phase 4, using the first two fuels from Phase 3 and the diagnostics from Phase 2, have been 

1. Both the ether oxygenate and the di-ester oxygenate selected for these tests were identified during the CIDI

Oxygenates Screening Project [1].
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

44

published in a Society of Automotive Engineers paper [3]. Analysis of results from Phase 4 using the 

two 26 wt%-oxygen fuels from Phase 3 is in progress. Some key results:

- GP-assisted combustion of the 50 wt%-oxygen, low-cetane fuel reduces in-cylinder soot by at 

least two orders of magnitude relative to standard diesel fuel while maintaining engine efficiency 

and reducing engine noise.

- GP-assisted ignition and combustion is strikingly different from standard diesel combustion and 

may have a pronounced effect on emissions.

- Overall oxygen content is not the only important parameter governing the soot-reduction potential 

of an oxygenated fuel blend. Differences in oxygenate molecular structure and/or in-cylinder 

processes can change in-cylinder soot by a factor of two or more even when all other engine 

parameters are held constant.

Future Research Directions

• Add a blend containing a third oxygenate, di-ethyl adipate, to the 26 wt%-oxygen fuels selected in 

Phase 3, and conduct experiments using diagnostics from Phase 2. This oxygenate is of interest 

because it is a di-ester similar to the di-ester tested above, but different in that it contains no carboncarbon double bonds. Study of such a molecule will further aid in the assessment of the role of 

molecular structure in soot production.

• Conduct experiments to measure flame lift-off lengths for the three 26 wt%-oxygen fuels. These 

results will help determine whether differences in in-cylinder soot are due primarily to differences in 

fuel-air premixing.

• Conduct Laser Induced Incandescence (LII) experiments to study the spatial development of incylinder soot for the three 26 wt%-oxygen fuels. These results will provide additional insight into the 

mechanisms by which different oxygenates affect the production and oxidation of soot.

Introduction

Blending oxygen-containing compounds 

("oxygenates") with diesel fuel can lead to reduced 

soot and NOx emissions, as well as reduced fuel 

consumption. The detailed mechanisms that cause 

such reductions are not well understood. For 

instance, the literature contains conflicting results as 

to whether overall oxygen content is the only 

important parameter in determining the sootreduction potential of a given fuel, or if oxygenate 

molecular structure or other variables also play 

significant roles. The goal of this research is to 

enhance the understanding of how diesel oxygenates 

affect in-cylinder combustion and emissionsformation processes. Such an improved 

understanding will help engine designers, fuel 

suppliers, and policy makers use diesel fuel 

formulation to greatest advantage to reduce 

emissions and cost while enhancing efficiency and 

energy security.

Engine and Fuels

The Sandia alternative fuels optical engine 

laboratory shown in Figure 1 features a singlecylinder version of a modern, Caterpillar 4-stroke DI 

diesel engine that has been modified by Sandia to 

provide extensive optical access into the combustion 

chamber. The optical engine is based on the 

Caterpillar 3176/C-10 platform used in heavy-duty 

trucking. A schematic of the optical engine is shown 

in Figure 2. The large window in the piston enables 

combustion processes to be imaged, and a glow plug 

(GP) enables the study of certain low-cetane 

alternative fuels. Specifications of the optical engine 

are provided in Table 1. Fuel compositional 

information is provided in Table 2. A 1200-rpm, 

moderate-load operating condition was studied, and 

injection timing was optimized independently for 

each fuel such that the engine always operated at 

peak efficiency.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

45

Figure 1. Sandia Alternative Fuels Optical Engine 

Laboratory in Operation

Figure 2. Schematic diagram of the Sandia/Caterpillar 

optical engine. Inset: View of combustion 

chamber showing orientation of fuel sprays 

with respect to glow plug during experiments 

with M100 fuel.

Production engine type 6-cyl. Caterpillar 3176/C-10

Research engine type 1-cyl. version of 3176/C-10

Cycle 4-stroke CIDI

Valves per cylinder 4

Ignition assist In-cylinder glow plug

Bore 125 mm

Stroke 140 mm

Peak cylinder pressure 14.0 MPa

Intake valve open 318o ATDC compression

Intake valve close 146o BTDC compression

Exhaust valve open 107o ATDC compression

Exhaust valve close 343o

 BTDC compression

Connecting rod length225 mm

Connecting rod offset None

Bowl diameter 90 mm

Bowl depth16.4 mm

Swirl ratio 0.59

Displacement per cyl. 1.72 liters

Compression ratio 11.3:1

Simulated compr. ratio* 16.0:1

* TDC conditions in the production engine are matched 

in the optical engine by preheating and boosting the pressure of the intake air.

Table 1. Specifications of the Sandia/Caterpillar Optical 

Engine

Fuel Composition 

(by volume)

Oxygen Content 

(by weight)

CN45 64.7% C16H34 as HMNa

35.3% C16H34 as NHDb

0%

M100 100.0% methanol

95 ppm DCI-11c

50%

GE80 80.0% TPGMEd

20.0% C16H34 as HMNa

26%

BM88 88.0% DBMe

7.0% C16H34 as NHDb

5.0% EHNf

26%

a

2,2,4,4,6,8,8-heptamethylnonane

b

n-hexadecane

c

corrosion-inhibiting additive from Octel-Starreon Co.

d

tri(propylene glycol) methyl ether

e

di-butyl maleate

f

2-ethylhexyl nitrate

Table 2. Compositions of Test Fuels
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

46

Diagnostics

In-cylinder images of direct luminosity (DL) and 

spray development were acquired and coupled with 

measurements of cylinder pressure and injected fuel 

quantity. The DL image sequences show the 

evolution of regions of high soot concentration and 

temperature throughout the combustion event. The 

spray-development images provide verification that 

the experimental fuels do not degrade fuel-injection 

system performance over time. The cylinder 

pressure and injected quantity measurements provide 

information about heat-release rates and engine 

efficiency, respectively.

Results

The goal of the first set of experiments was to 

study the GP-assisted ignition and combustion of a 

low-cetane, highly-oxygenated fuel [3]. The fuel 

selected for these experiments, M100, had an oxygen 

content of 50 wt% and a cetane number < 5 such that 

GP-assisted ignition was essential for stable engine 

operation. The M100 data show significant 

departures from the traditional diesel combustion 

features exhibited by the CN45 hydrocarbon 

reference fuel. Whereas CN45 readily autoignites at 

the engine operating conditions studied, M100 does 

not. The GP-assisted ignition of M100 was found to 

be strongly dependent on GP temperature and 

proximity to a fuel jet. The DL images show that 

M100 ignition occurs at the GP, followed by 

combustion propagation first to the two jets 

straddling the GP, then to the adjacent two jets, and 

finally to the last two jets emanating from the 6-hole, 

centrally-located injector nozzle. Figure 3 shows this 

process and indicates how the three spikes in the 

M100 apparent heat release rate (AHRR) profile are 

observed to correspond to these pair-wise jet ignition 

events. Spatially integrating the DL signal within a 

given image yields a measure of the amount of hot, 

in-cylinder soot at that crank angle. Calculation of 

this parameter in each image of the sequence yields a 

curve showing the variation with crank angle for 

each fuel. Such data for CN45 and M100, shown in 

Figure 4, suggest that in-cylinder soot concentrations 

during M100 combustion are at least 2 orders of 

magnitude lower than those during CN45 

combustion. Peak heat release rates during M100 

combustion are only half of those achieved during 

the premixed burn phase of CN45 combustion, 

resulting in noticeably quieter engine operation. This 

observation highlights one advantage of using a GP 

to assist ignition of a low-cetane fuel, because cetane 

number decreases typically result in increased, rather 

than reduced, combustion noise.

Figure 3. Pair-wise Jet Ignition Events Observed in 

Direct Luminosity Images of M100 

Combustion Correspond to Peaks in Apparent 

Heat Release Rate

Figure 4. Variation of spatially-integrated direct 

luminosity for the four test fuels. Peak signal 

is used as a measure of peak in-cylinder soot.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

47

The goal of the second set of experiments was to 

study two oxygenated fuel blends whose only 

difference is the type of oxygenate used, in order to 

determine if the type of oxygenate affects the sootreduction performance of the fuel. Nominal oxygen 

content was matched at 26 wt% for the two blends 

selected, GE80 and BM88 (see Table 2). The 

ignition improvers 2-ethylhexyl nitrate (EHN) and 

cetane were used to offset the poor ignition quality of 

DBM (whose cetane number is only approximately 

30), shortening the ignition delay of BM88 so that it 

matches that of GE80. Since injection timing was 

not changed, this ensured that combustion phasing 

was matched for the two oxygenated fuels. All 

engine operating conditions (e.g., TDC temperature 

and density, speed, load, etc.) were held constant 

across the experiments as well. The DL images 

presented in Figure 5 show no dramatic evidence of 

differences in ignition or combustion processes 

between the two fuels. Whereas general combustion 

features are similar, differences between the two 

blends become apparent when the peak spatiallyintegrated DL signals are compared. Figure 4 shows 

that the peak spatially-integrated DL signal for 

BM88 is more than twice as large as that for GE80. 

This result suggests that overall oxygen content may 

not be the only important factor governing the sootreduction potential of these oxygenated fuels. The 

difference in peak spatially-integrated DL between 

the two fuels may be due to molecular structure 

effects, differences in the degree of fuel-air 

premixing (lift-off length), and/or limitations of the 

diagnostic technique. These issues will be addressed 

in a series of follow-on experiments. 

References

1. Naegeli, D., "Oxygenate Analysis Project," Proc. 

of CIDI Engine Combustion, Emission Control, 

and Fuels Program Review, Argonne National 

Laboratory, Argonne, IL (2000). 

2. Musculus, M.P. and Mueller, C.J., "Initial 

Alternative Fuels Research Results Obtained 

Using the Sandia/Caterpillar Optical Engine," 

Sandia Report SAND 2001-8035, Sandia 

National Laboratories, Livermore, CA (2001).

 3. Mueller, C.J. and Musculus, M.P., "Glow Plug 

Assisted Ignition and Combustion of Methanol 

in an Optical DI Diesel Engine," SAE Paper 

2001-01-2004, Society of Automotive Engineers, 

Warrendale, PA (2001).

FY 2001 Publications and Presentations

1. Mueller, C.J. and Musculus, M.P., "Glow Plug 

Assisted Ignition and Combustion of Methanol 

in an Optical DI Diesel Engine," SAE Paper 

Figure 5. Direct luminosity image sequences for GE80 

and BM88 fuels. Significant differences in 

ignition and combustion processes are not 

evident. Comparison of apparent brightness 

between images cannot be used to estimate 

differences in spatially-integrated direct 

luminosity because camera gain was adjusted 

for each image to ensure proper exposure.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

48

2001-01-2004, Society of Automotive Engineers, 

Warrendale, PA (2001). 

2. Musculus, M.P. and Mueller, C.J., "Initial 

Alternative Fuels Research Results Obtained 

Using the Sandia/Caterpillar Optical Engine," 

Sandia Report SAND 2001-8035, Sandia 

National Laboratories, Livermore, CA (2001). 

3. Mueller, C.J., "Recent Research Results on InCylinder Combustion Processes of Alternative 

Fuels for Diesel-Cycle Engines," Proc. of CIDI 

Engine Combustion, Emission Control, and 

Fuels Program Review, Argonne National 

Laboratory, Argonne, IL (2000).

4. Mueller, C.J., "Alternative Fuel Combustion in 

Diesels," Annual Report for CRADA SC99/

01561, U.S. Dept. of Energy Online Digest

(2000).

5. "Glow Plug Assisted Ignition and Combustion of 

Methanol Studied in a Direct-Injection Diesel 

Engine," Combustion Research Facility News, 

23: 3, Sandia National Laboratories, Livermore, 

CA (2001).

6. "Glow Plug Assisted Ignition and Combustion of 

Neat Methanol," Joint Heavy-Duty/Alternative 

Fuels Diesel Combustion CRADA Meeting, 

October 10, 2000, US Council for Automotive 

Research, Detroit, MI.

7. "Effects of Oxygenated Fuels on Diesel Engine 

Emissions: Review of Recent Studies and Plan 

for Optical Engine Experiments," Joint HeavyDuty/Alternative Fuels Diesel Combustion 

CRADA Meeting, January 25, 2001, Sandia 

National Laboratories, Livermore, CA.

8. "Effects of Oxygenated Diesel Fuels on InCylinder Combustion and Soot-Formation 

Processes," DOE Office of Transportation 

Technologies Mid-Year Program Review, March 

29, 2001, Sandia National Laboratories, 

Livermore, CA (via videoconference).

9. "Progress in the Search for Better Diesel Fuels," 

Combustion Research Facility Omnium 

Gatherum Invited Lecture Series, May 1, 2001, 

Sandia National Laboratories, Livermore, CA.

10. "Glow Plug Assisted Ignition and Combustion of 

Methanol in an Optical DI Diesel Engine," SAE 

Spring 2001 Fuels and Lubricants Meeting, May 

9, 2001, Sheraton World Resort, Orlando, FL.

11. "Effects of Oxygenated Diesel Fuels on InCylinder Combustion and Soot-Formation 

Processes," CIDI Engine Combustion, Emission 

Control, and Fuels Program Review, June 12, 

2001, National Transportation Research Center, 

Knoxville, TN.

12. "Effects of Oxygenated Compounds on 

Combustion and Soot Evolution in a DI Diesel 

Engine: Direct-Luminosity Imaging," Joint 

Heavy-Duty/Alternative Fuels Diesel 

Combustion CRADA Meeting, June 27, 2001, 

University of Wisconsin, Madison, WI.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

49

B. Environmental Performance of Oxygenated Fuel Compounds Used in 

Advanced Petroleum-Based Fuels

David Layton (Primary Contact), Alfredo A. Marchetti, Mark Knize

Health and Ecological Assessment Division

Lawrence Livermore National Laboratory

PO Box 808

Livermore, CA 94551

(925) 422 0918, fax: (925) 423 6785, e-mail: layton1@llnl.gov

DOE Program Manager: John Garbak 

(202) 586-1723, fax: (202) 586-9811, e-mail: John.Garbak@ee.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

H. Health, Safety, and Regulatory

Tasks

8. Safety, Health, and Consumer Acceptance Aspects of Liquid Fuels

Objectives

• Use a suite of diagnostic models to assess the environmental performance of oxygenated compounds 

that are candidates for use in advanced petroleum-based fuels to reduce particulate emissions from 

CIDI engines.

• Design and implement experiments to evaluate the biodegradation potential of selected fuel 

oxygenates. Compare experimental results against predictions to help establish the level of accuracy 

and the limitations of biodegradation models.

• Evaluate the nature and magnitude of potential human exposures to oxygenates released to the 

environment.

Approach

• Review data on the physicochemical properties of two new oxygenate candidates, dibutyl maleate 

(DBM) and tripropylene glycol monomethyl ether (TGME), and determine their potential for 

degradation in the environment.

• Determine relevant environmental transport properties.

• Implement and run diagnostic models to determine the fate of DBM, TGME, dimethoxymethane 

(DMM), and reference fuel compounds for various environmental release scenarios.

• Perform biodegradation experiments, and include benzene and methyl tert-butyl ether (MTBE) as 

benchmark compounds for data interpretation. 

Accomplishments

• Selected, implemented, and improved environmental models suitable for conducting screening-level 

analyses of fuel oxygenates.

• Simulated the transport and fate of DMM, DBM, TGME, and other fuel compounds in environmental 

media. 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

50

• Conducted biodegradation experiments on DMM, DBM, TGME, and other fuel compounds to serve as 

a reference (i.e., benzene and MTBE).

• Evaluated potential human exposures to water contaminated with DBM, TGME, MTBE, and benzene. 

Future Directions

• Continue to build and improve our library of diagnostic models to assess the environmental impact of 

oxygenated and other fuel components.

• Develop modeling and experimental methods for studying the fate of fuel compounds and additives in 

complex mixtures.

• Carry out selected experiments to verify predictions and fill key data gaps for oxygenates and other 

fuel compounds of interest. 

Introduction

Research has shown that the addition of 

oxygenated compounds to diesel fuels reduces 

particulate emissions. There are potentially many 

oxygenates that could be used, but some may have 

undesirable environmental effects. This project aims 

to establish a methodology to study the potential 

environmental impacts of oxygenated fuel 

compounds. Data developed by the project will 

assist DOE/OTT and industrial partners in evaluating 

the potential environmental performance of proposed 

fuel additives such as TGME and DBM. These 

compounds were chosen through a selection process 

based on a series of tests performed by the Southwest 

Research Institute on 71 oxygenates. 

Results

Our analysis of the physicochemical properties 

indicates that TGME and DBM will not partition 

significantly into air because of their low vapor 

pressures, about 5 orders of magnitude less than 

those of DMM, MTBE and benzene. In addition, 

DBM has a very low solubility and a high octanolwater partition coefficient (Kow), and therefore will 

tend to adsorb to the organic phase of soils. On the 

other hand, TGME is very soluble and will tend to 

migrate with water. A biodegradation model based 

on chemical-structure relationships predicts that 

DBM will biodegrade readily, but TGME will not.

We used an equilibrium model to determine the 

partitioning of DBM and TGME between the air, 

water, and solid phases of a reference soil (see Figure 

1, MTBE and benzene also included). Neither DBM 

nor TGME distributes in any significant amount to 

the air phase. DBM partitions primarily to the solid 

phase because of its high affinity for organic matter, 

and TGME partitions preferentially to the water 

phase because of its high solubility.

Transport in unsaturated soil was simulated 

using an analytical advection-dispersion model. The 

initial contamination source was assumed to be 

uniformly distributed between 1.00 and 1.30 meters 

beneath the surface of a reference sandy soil. Figure 

2 shows the concentration profiles after a year for 

Figure 1. Distribution of Fuel Compounds in the Phases 

of a Reference Sandy Soil (bulk density = 1.59 

g/cm3

; porosity = 0.4 (total), 0.18 (water), 0.22 

(gas); organic fraction = 0.0075)
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

51

DBM, TGME, and MTBE. Diffusion of MTBE in 

the gas phase redistributes it through the soil column. 

TGME moves with infiltrating water, but DBM has 

barely moved due to its affinity for the solid phase.

Initial results of the biodegradation experiment 

given as CO2 concentration in the headspace of 

sealed microcosm flasks as a function of time are 

presented in Figure 3. There is no significant 

difference in the CO2 concentration between the 

control, DMM, and MTBE, in a 28-day incubation 

period. On the other hand, benzene shows a very 

steep rise in the CO2 concentration within the first 5 

days. DBM shows a clear increase above the 

background level by day 8 and from then on the CO2

concentration rises a little and remains more or less 

constant. TGME shows rising values above 

background from day 15 on. 

We estimated water-based exposures to humans 

using a nominal concentration of 1 ppm for DBM, 

TGME, MTBE, and benzene (see Figure 4). Among 

these compounds, DBM would have the largest skin 

uptake due to its relatively high Kow, although most 

of its net uptake would occur via ingestion. TGME 

exposure would occur exclusively through ingestion. 

Conversely, the dominant pathway for benzene and 

MTBE is inhalation. DBM and TGME have very low 

Henry’s Law constants and thus the inhalation 

pathway is insignificant.

Conclusions

Preliminary biodegradation tests confirm that 

DBM is readily degraded. TGME also seems to 

biodegrade, but more slowly than DBM or benzene. 

The biodegradation tests were performed using 

activated sludge, which is a fairly aggressive media. 

In other natural environments, the rate of 

Figure 2. Concentration Profiles of DBM, TGME, and 

MTBE in Soil after 1 Year of Transport from a 

Buried Source Uniformly Distributed between 

1.00 and 1.30 m at Time = 0

Figure 3. CO2 Concentration in the Headspace of 

Microcosm Flasks Containing: DMM, TGME, 

DBM, MTBE, and Benzene, as a Function of 

Time

Figure 4. Comparison of Water-based Exposures to 

DBM, TGME, MTBE, and Benzene in 

Drinking Water via Inhalation, Dermal Uptake, 

and Ingestion
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

52

biodegradation could be much slower. TGME’s 

slower biodegradation combined with its high 

solubility are indications that TGME would be more 

mobile in the subsurface than DBM. Additional 

studies are needed to determine whether TGME 

would constitute a threat to groundwater when stored 

in subsurface fuel tanks. In our previous work on 

DMM, we indicated that it was likely to be 

recalcitrant and mobile in ground water, behaving 

similarly to MTBE in the environment. The results 

of the biodegradation experiment confirmed our 

model prediction. 

Presentations and Publications

1. D. Layton, A.A. Marchetti, and M. Knize, 

"Environmental Performance of Fuels for 

Advanced Engines: Oxygenate Assessment", 

presented at the annual review of the Office of 

Advanced Automotive Technologies, US DOE, 

June 11-13, 2001. 

2. A.A. Marchetti, and D. Layton, "Environmental 

Performance of Dimethoxymethane (DMM)", 

(for submission to Chemosphere).
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

53

C. Chemical Characterization of Toxicologically Relevant Compounds From 

Diesel Emissions: A Project of the Fuels/Particulate Matter Initiative

Douglas M. Yost (Primary Contact), Edwin A. Frame, Ed C. Owens

Southwest Research Institute

6220 Culebra Road

San Antonio, TX 78238-5166

(210) 522-3126, fax: (210) 522-3270, e-mail: dyost@swri.org

DOE Program Manager: John Garbak

(202) 586-1723, fax: (202) 586-9811, e-mail: john.garbak@hq.doe.gov

Industry Partners: Ford Motor Company and Marathon Ashland Petroleum LLC

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

E. Toxic Emissions

Tasks

2. Fuel & Lubricant Properties - Engine-Out Emissions

Objectives

Phase I (Completed)

• Investigate the role of fuels on the engine-out exhaust emissions of potentially toxicologically relevant 

compounds.

• Determine polycyclic aromatic hydrocarbon (PAH) content of organic solvent extracts of exhaust 

particulate matter, gaseous exhaust PAH, and other gaseous exhaust "toxics" collected from a diesel 

engine using various fuel compositions.

Phase II (In Progress)

• Investigate the role of fuels on tailpipe exhaust emissions of potentially toxicologically relevant 

compounds, utilizing a diesel oxidation catalyst and a catalyzed particulate filter.

• Investigate the role of high moleculer weight oxygenate on diesel exhaust toxicity.

• Determine the PAH content of organic solvent extracts of exhaust particulate matter; gaseous exhaust 

PAH; other gaseous exhaust "toxics" collected from a diesel engine using various fuel compositions.

Approach

• A Daimler-Benz OM611 diesel engine was used to determine the effect of diesel fuel type on 

toxicologically relevant compounds from engine-out exhaust emissions.

• The engine was controlled by a SwRI Rapid Prototyping Electronic Control System (RPECS).

• Four gaseous EPA Clean Air Act "toxic" exhaust emissions were measured.

• Eleven gaseous PAH compounds were measured.

• Seventeen PAH compounds were determined for the soluble organic fraction of the exhaust particulate 

matter.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

54

Phase I

• The matrix included 5 fuels (including one oxygenate blend) operated over 5 speed/load points.

• Each speed/load point operated to hold the Location of Peak Pressure (LPP) of combustion at 7° after 

top dead center (ATDC), while maintaining cylinder balance within 5% of the Indicated Mean 

Effective Pressure (IMEP), with pilot fuel injection disabled.

• Two of the speed/load points were operated at two different pilot fuel injection strategies. One pilot 

strategy was the stock controller; the other was to include pilot fuel injection while maintaining the 

Location of Peak Pressure at 7°ATDC.

Phase II

• The matrix will include 6 fuels, including two oxygenate blends with tripropylene glycol monomethyl 

ether (TPGME), operated over 4 speed/load points.

• The engine will be operated utilizing pilot fuel injection at a low-NOx engine-out calibration specific 

for each fuel and speed/load point.

• Measurements are to be taken at engine-out, downstream of the diesel oxidation catalyst, and 

downstream of the catalyzed particulate filter. 

Accomplishments

Phase I

• The project plan was finalized with coordinated input from DOE and industry representatives. The 

industry representatives specified the cylinder balance approach and EGR levels for each speed/load 

condition.

• All fuels were tested in triplicate for five modes, pilot injection off, LPP operation. Pilot fuel injection 

evaluation for all fuels completed in triplicate for two modes and two pilot fuel injection strategies.

• Statistically significant fuel effects on exhaust emissions were identified.

• Oxygenate containing fuel and Fischer-Tropsch fuel produced the lowest overall toxic gas and PAH 

exhaust emissions.

Phase II

• The project plan has been finalized with coordinated input from DOE and industry representatives. 

The industry representatives defined the NOx emission index targets.

• Consulted with industry representatives to define the methodology to achieve the low engine-out NOx

emission index target.

• An engine-out NOx emission index reduction of 30% is achievable using stock engine modal 

calibrations.

Future Directions

• Determine fuel effects on emission characterization utilizing a NOx trap.

• Determine fuel effects on emission characterization for NOx and particulate trap regeneration. 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

55

Introduction - Phase 1

This project is part of an overall study that 

examines the effects of alternative diesel fuels, 

including one oxygenated compound 

(dimethoxymethane) in diesel fuel, on the emissions 

of particulate matter, oxides of nitrogen, and fuel 

economy. It also addresses the chemical 

characterization of emission compounds with known 

or suspected toxicological properties (e.g. 

carcinogens).

Phase 1 Objective

The goal of this project is to better understand 

the role of fuels on the emissions of a subset of 

potentially toxicologically relevant compounds. 

Objectives of this project are: 1) to measure the 

polycyclic aromatic hydrocarbon (PAH) content of 

organic solvent extracts of particles collected from 

diesel engines under a matrix of engine and fuel 

conditions; 2) to measure the gas-phase polycyclic 

aromatic hydrocarbons from this engine; and 3) to 

measure formaldehyde, acetaldehyde, benzene, and 

1,3-butadiene using the same conditions that are used 

to collect particles. These measurements are being 

made on engine-out emissions. 

Phase 1 Approach

A standard set of polycyclic aromatic 

hydrocarbons (PAH) in organic solvent extracts of 

diesel particles and from the gas phase of diesel 

emissions were measured. In addition, four toxic air 

pollutants were quantified. The DaimlerChrysler 

OM611 diesel engine was run at five different engine 

speeds and loads and controlled to hold location of 

peak pressure of combustion at 7°ATDC. Individual 

cylinder balance was maintained within 5% of the 

Indicated Mean Effective Pressure (IMEP), with 

pilot fuel injection disabled. The engine was also 

controlled at two speed and load combinations using 

two different pilot injection control strategies. 

Particulate filter samples were collected at each load 

and control condition. The engine operating 

conditions are shown in Table 1.

The four mobile source toxic air pollutants cited 

in the Clean Air Act (formaldehyde, acetaldehyde, 

benzene, and 1,3-butadiene) were measured in 

triplicate at each of the points discussed above. The

five test fuels, along with selected fuel properties, are 

shown in Table 2. They are California Reference 

Diesel Fuel (CA), Low Sulfur Diesel Fuel (ALS), 

Fischer-Tropsch Diesel (FT-100), Oxygenate Blend 

of 15% Dimethoxymethane in ALS (ADMM15), and 

EPA 2D Certification Fuel (DF-2).

The particulate matter was sampled from a 203 

mm dilution tunnel using carbon dioxide tracer for 

determining dilution ratio. A polyurethane foam and 

XAD-2 resin trap were utilized for sampling gas 

phase PAH compounds. Soluble phase PAH 

compounds were extracted from 90mm filters. 

Benzene and 1,3-butadiene were collected in a 

sample bag from the dilution tunnel sample zone. 

Formaldehyde and acetaldehyde were trapped on a 

dinitrophenylhydrazine (DNPH) adsorbent cartridge 

from the dilution tunnel sample zone.

Phase 1 Discussion

Fuel comparisons utilizing the Auto/Energy 

Panel Mode Weighting Factors shown in Table 3 

were made for brake-specific exhaust emissions with 

the engine operated under LPP control. 

Several statistically significant trends were 

apparent from an analysis of variation (ANOVA) of 

the weighted average brake specific emissions data. 

For HC, CO, PM, and soluble organic fraction 

(SOF), the lowest emitting fuels were ADMM15 and 

Mode RPM BMEP, bar %EGR

M 12 900 0.10 40

M 11 1500 2.62 30

M 10 2000 2.00 30

M 6 2300 4.2 15

M 5 2600 8.8 5

Table 1. OM611 Engine Operating Conditions

CA ALS FT-100 ADMM15 DF-2

H, wt% 13.4 14.4 15.1 13.7 13.0

C, wt% 86.4 85.6 84.8 81.6 86.7

O, wt% 0.2 0.0 0.1 4.7 0.3

Cetane 

Number

45 63 84 59 44

Sulfur, ppm 176 1 0 <2 337

Aromatics, 

wt%

18.9 9.0 0.2 8.2 30.3

Table 2. Toxicity Test Fuels for OM611 Engine
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

56

FT-100, with the higher emitting fuels being DF-2, 

then CA. The highest NOx emitter was DF-2, 

followed jointly by ADMM15, FT-100, and CA, with 

ALS being the lowest NOx emitting fuel. 

While the mass emissions of PM and SOF reflect 

the same relative order of fuels, the relative order of 

the percent of extractable mass from particles 

generated from the different fuels is not the same. 

The percent of extractable mass from particles 

emitted using the different fuels shows a different 

rank order (Table 4). In this case, ADMM-15 is the 

fuel that generates PM with the highest percentage of 

organic soluble material while Fischer-Tropsch fuels 

have the lowest percentage emissions of organic 

soluble compounds. This may be important for a 

complete vehicle system that is equipped with an 

oxidation catalyst emission control device. A vehicle 

equipped with an oxidation catalyst, using an 

ADMM-15 fuel, could conceivably emit very low 

PM because the catalyst would oxidize most of the 

organic material bound to the particle, thereby 

reducing the mass of particles emitted from the 

vehicle.

The emissions of the four toxic air pollutants 

specifically cited in the Clean Air Act (benzene, 1,3-

butadiene, formaldehyde, acetaldehyde; Table 5) 

show very similar trends. The use of either the 

Fisher-Tropsch fuel or the ADMM-15 fuel resulted in 

the lowest emissions for benzene and 1,3-butadiene. 

The worst fuels for emitting benzene and 1,3-

butadiene were consistently the CA or the DF-2 fuel. 

All of the fuels were statistically indistinguishable 

from each other for the emissions of formaldehyde 

and acetaldehyde. For the four EPA air toxic 

compounds, ADMM15 and FT-100 were statistically 

similar emitting fuels.

For both the gas phase and soluble phase PAH 

compounds, the fuels ranked in the general order 

from highest emitter DF-2, CA, ALS, with ADMM15 

and FT-100 being in the same statistically equivalent 

lowest grouping. The PAH response appears to be a 

function of fuel aromatic content. Table 5 

summarizes the general rank order for the weighted 

average mass emissions during LPP engine 

operation.

The effect of pilot fuel injection on exhaust 

emissions, compared to the LPP operation can be 

characterized as follows:

• PM emissions increase with pilot fuel 

injection

• NOx emissions decrease with pilot fuel 

injection 

• Gaseous air toxic levels increase with pilot 

fuel injection

• Both soluble and gas phase PAH increase 

with pilot fuel injection

The fuel rank order for exhaust emissions with 

pilot fuel injection operation can be summarized as 

follows:

Mode Mode Weights, seconds

Mode 11 600

Mode 10 375

Mode 6 200

Mode 5 25

Total 1200

Table 3. Auto/Energy Weighting Factors for Engine-Out 

Emissions

Fuel Percent of 

Extractable 

Mass (%)

Mass of PM 

(g/kW-h)

Mass of SOF 

(g/kW-h)

ADMM-15 86 0.1431 0.1237

CA 84 0.2627 0.2207

DF-2 79 0.2888 0.2279

ALS 71 0.2249 0.1608

FT-100 54 0.1337 0.0723

Table 4. Percent of PM Extracted by Organic Solvents

Rank Highest Lowest

PM DF-2 CA ALS ADMM15 FT-100

SOF DF-2 CA ALS ADMM15 FT-100

NOx DF-2 ADMM15 FT-100 CA ALS

Benzene CA DF-2 ALS FT-100 ADMM15

1,3 - 

Butadiene

CA DF-2 ALS ADMM15 FT-100

FormaldehydeDF-2 ALS CA ADMM15 FT-100

AcetaldehydeDF-2 ALS CA ADMM15 FT-100

Gas Phase 

PAH

DF-2 CA ALS ADMM15 FT-100

Soluble 

Phase PAH

DF-2 CA ALS ADMM15 FT-100

Table 5. Fuel Rank Order from ANOVA for Weighted 

Average Emissions for LPP Operation 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

57

• PM rank for ADMM15 and FT-100 lowest, 

with DF-2 highest

• NOx rank is FT100 lowest, ADMM15 

middle, and DF-2 highest

• Gaseous air toxic rank is FT-100 and 

ADMM15 lowest, with DF-2 highest

• Both soluble and gas phase PAH rank is 

FT100 and ADMM15 statistically similar as 

lowest, with DF-2 the highest emitting fuel

Phase I Conclusions

Statistically significant (95% confidence) fuel 

effects on weighted average exhaust emissions were 

identified for both regulated and unregulated species.

The oxygenated low sulfur diesel fuel was 

statistically the same as Fischer-Tropsch fuel for 

toxic air pollutants, gaseous and soluble PAH, and 

PM emissions.

The ADMM15 fuel has a larger fraction of SOF 

than the FT-100 fuel, which has the statistically 

smallest SOF of all test fuels.

The effect of pilot fuel injection on exhaust 

emissions, compared to the LPP operation with pilot 

off can be summarized as follows:

• PM emissions increase, NOx emissions 

decrease with pilot fuel injection

• The ratio of SOF/PM changed with pilot fuel 

injection condition

• Toxic air pollutant levels and both soluble 

and gas phase PAH increase with pilot fuel 

injection.

• Toxic air pollutants and soluble and gas 

phase PAH rank FT100 and ADMM15 

statistically lowest.

• The magnitude of the emission response 

changes but does not significantly alter the 

fuel rank order.

Phase I Recommendations

The demonstrated effect of the oxygenate 

compound blended into low sulfur diesel fuel on 

lowering both regulated and unregulated emissions 

warrants further investigation. Although the 

oxygenate utilized in this study, dimethoxy methane, 

has shown positive emissions benefits, it is a poor 

choice for commercialization due to volatility 

characteristics. A parallel oxygenates program has 

identified two suitable oxygen-bearing compounds 

which warrant investigation as to oxygenate 

composition effects on toxic or PAH emissions. 

There is evidence which suggests oxygenbearing diesel fuels would tolerate further EGR 

before a smoke limit is reached, and thus would be 

beneficial for lowering engine-out NOx. The impact 

on toxic emissions with increased EGR with oxygenbearing fuels warrants investigation.

Another effect of oxygen is the tendency to 

increase the SOF content of the total particulate 

matter, which may be beneficial for PM control with 

an oxidation catalyst. The oxidation of SOF in a 

catalyst may crack higher molecular weight PAH 

compounds into smaller ringed components and 

increase levels of gaseous PAH or toxic emissions. It 

is recommended to evaluate the effect of an 

oxidation catalyst on toxic and PAH emissions.

To meet Tier 2 emission levels, engine-out NOx

emissions will need to be reduced, which will result 

in an increase in PM emissions. Thus the use of a 

Diesel Particulate Filter (DPF) to meet Tier 2 PM 

emission levels may be required. However, the DPF 

will act as a trap that will periodically need 

regeneration to lower engine backpressure. The DPF 

may act as a PAH sponge, trapping toxic compounds. 

The potential change in gaseous PAH levels due to 

the accumulation of PM on a DPF warrants 

investigation.

Phase II Objective & Background

The PM Analysis Phase II project is part of an 

overall study that examines the effect of oxygenated 

compounds in diesel fuel on the emission of 

particulate matter, emission of oxides of nitrogen, 

and fuel economy when emission control devices are 

used. The project will focus on the chemical 

characterization of emission compounds with known 

or suspected toxicological properties. Exhaust 

emissions of these compounds will be measured 

before and after emission control devices to better 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

58

understand the effects of emission control devices 

and alternative fuels. 

The control of NOx emissions is probably the 

greatest technical challenge in meeting future 

emission regulations for diesel engines. In this 

project, lowering engine-out emissions of NOx by 

increasing EGR and retarding timing will likely 

cause an increase in PM emissions. In Phase I of this 

program, it was shown that the use of an oxygenated 

diesel fuel additive will lower PM emissions. Use of 

an oxygenated diesel fuel additive thereby can 

minimize the increase in PM emissions that 

accompany the techniques used to decrease NOx

emissions. 

The overall objective of this project is to better 

understand the role of fuels and emission control 

devices on the exhaust emissions of a subset of 

potentially toxicologically relevant compounds with 

an engine operated to minimize NOx emissions. The 

three objectives of this program are to measure the 

following pollutants collected from diesel engines 

under a matrix of engine and fuel conditions:

1. polycyclic aromatic hydrocarbon (PAH) content 

of organic solvent extracts of particulate matter

2. gas phase polycyclic aromatic hydrocarbons

3. gaseous toxic compounds (formaldehyde, acetaldehyde, benzene and 1,3-butadiene)

These measurements will be made on engine-out 

exhaust emissions and, downstream of an oxidation 

catalyst, and downstream of a diesel particulate filter. 

Phase II Discussion

PM Analysis II Emission Control System Selection

A document was prepared for submittal to 

Manufacturers of Emissions Control Association 

(MECA) that will serve as the basis for obtaining the 

required oxidation catalyst and catalyzed diesel 

particulate filter (CDPF). The document was 

thoroughly reviewed by the Ad-Hoc CIDI group 

before release. MECA has surveyed its membership 

and has received interest in participation. Upon 

completion of survey responses, MECA will select a 

supplier. 

Low-NOx Operating Point Definition

The overall program goal is to define reasonable 

(not fully optimized) low-NOx operating conditions. 

Substantial reductions in the NOx Emissions Index 

(NOxEI, g/lb fuel) are achieved by moving from the 

conditions of the Phase I project to the stock OEM 

calibrations for the engine. Additional NOxEI 

reductions are obtained by varying the EGR rate and 

injection timing. The objective of this effort is to 

determine the operating points (e.g., injection timing 

and percent EGR) to be used for each of the four 

modes in the PM Analysis Project-Phase II. These 

points may vary by fuel. For each mode, an attempt 

to determine the limit between stable and unstable 

engine operation for low-NOx operating conditions 

will be made. New fuel injectors and a fuel injection 

pump were installed in the OM611 test engine. 

An initial methodology for determining the 

operating condition parameters was conducted with 

ECD-1 (BP-ARCO ultra-low sulfur diesel fuel) fuel 

at the Mode 11 (1500-rpm/2.62-bar bmep) operating 

condition. The approach was to start at the Engine 

Control Module (ECM) point and add EGR and 

retard timing, and evaluate NOx reduction versus 

change in fuel consumption. Initial data suggest 

EGR is more cost effective for NOx reduction in 

terms of fuel consumption, but leads to high smoke 

levels. Subsequently, data sets have been generated 

for Mode 10 (2000-rpm/2.0-bar bmep), Mode 6 

(2300-rpm/4.2 bar-bmep), and Mode 12 (900-rpm/

1.0bar bmep). Preliminary data were generated for 

Mode 5. Auto company participants were asked to 

obtain review/input from their driveability/

calibration staff on the EGR and timing sweeps.

The following summary gives the type of vehicle 

operation each engine mode represents:

Mode 12: Idle with accessory load

Mode 11: Low speed cruise

Mode 10: Low speed cruise with slight acceleration

Mode 6: Moderate acceleration

Mode 5: Hard acceleration

The general rules for selecting operating 

conditions were revised and are shown in Table 6. 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

59

The operating condition which gave the largest NOx

decrease while meeting the tabulated rules was 

selected as the specific operating condition.

Based on the selection criteria shown in Table 6, 

the Ad-Hoc CIDI group selected the following 

operating conditions for the ECD-1 fuel. NOx index 

reductions are on the order of 30% for each operating 

condition selected:

Mode 6

The crank angle for 50% burn was used to indicate 

engine retard.

Stock conditions are 15.8% EGR/ 15.9 Location of 

CA50, dATDC

The group selected the following operating point:

EGR=22.5 ± 2% 

Location of CA50=16.4 ±1, dATDC

Mode 10

Stock conditions are 32.9% EGR/ 16.1 dATDC 

location of peak pressure-main combustion (LPPm).

The group selected the following operating point:

EGR=38.9 ± 2%

LPPm=18.4 ±1, dATDC

Mode 11

Stock conditions are 35.3% EGR/ 12.5 dATDC for 

LPPm

The group selected the following operating point:

EGR=40 ± 2%

LPPm=16 ± 1, dATDC

Mode 12

Stock conditions are 58.4% EGR/ 11.7 dATDC for 

LPPm

The group selected the following operating point:

EGR=60 ± 2%

LPPm=13.3 ± 1, dATDC

Project Status

1. Final agreement pending on selection of emission 

control devices.

2. Process to define changes in operating conditions 

for each mode with respect to each of the other 

test fuels is in progress.

Publications/Presentations

1. D.M. Yost and E.A. Frame, "Particulate Matter 

Analysis from an Advanced Diesel Engine; 

Phase I & II", CIDI Engine Combustion, 

Emission Control, and Fuels R&D, Merit 

Review and Peer Evaluation, Oak Ridge 

National Laboratory, 6-8 June 2001.

2. Ball, et. al., "Dimethoxy Methane in Diesel 

Fuel: Part 1. The Effect of Fuels and Engine 

Operating Modes on Emissions of Toxic Air 

Pollutants and Gas/Solid Phase PAH," SAE 

2001-01-3627.

3. Ball, et. al., "Dimethoxy Methane in Diesel 

Fuel: Part 2. The Effect of Fuels on Emissions of 

Toxic Air Pollutants and Gas/Solid Phase PAH 

Using a Composite Of Engine Operating 

Modes," SAE 2001-01-3628.

4. Ball, et. al., "Dimethoxy Methane in Diesel 

Fuel: Part 3. The Effect of Pilot Injection, Fuels 

and Engine Operating Modes on Emissions of 

Toxic Air Pollutants and Gas/Solid Phase PAH,"

SAE 2001-01-3630.

MODE 6 10 11 12

EGR >OEM 

(15.8%)

>OEM 

(32.9%)

>OEM 

(35.3%)

>OEM 

(58.4%)

BSFC 3% max. 

increase

3% max. 

increase

3% max. 

increase

3% max. 

increase

BOOST 50% max. 

decrease

50% max. 

decrease

>0 N/A

SMOKE 100% max. 

increase

100% max. 

increase

100% max. 

increase

100% max. 

increase

HC No rule No rule No rule 100% max. 

increase

Table 6. Rules for Defining Low-NOx Operating 

Conditions
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

60

D. DECSE Complementary Study of Fuel Sulfur Effects on Unregulated 

Emissions from Diesel Particulate Filters

John Storey

Oak Ridge National Laboratory

NTRC

2360 Cherahala Blvd.

Knoxville, TN 37932

(865) 946-1231, fax: (865) 946-1348, e-mail: storeyjm@ornl.gov

DOE Program Manager: Steve Goguen 

(202) 586- 4166, fax: (202) 586-4166, e-mail: stephen.goguen@hq.doe.gov

Industry Participants: Detroit Diesel Corp., Manufacturers of Emissions Control Association

(MECA)

Contractor: UT-Battelle, LLC (Oak Ridge National Laboratory), Oak Ridge, TN

Contract Number DE-AC05-000R22725 from February 1, 2000 - March 31, 2005

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

E. Toxic Emissions

F. Ultra-fine Particles

Tasks

2. Fuel & Lubricant Properties - Engine-Out Emissions

3. Fuel & Lubricant Properties - Exhaust Emission Control and Emissions

Objectives

• Investigate the effect of fuel sulfur on the ability of diesel particulate filters (DPFs) to eliminate air 

toxics.

• Investigate the effect of fuel sulfur on the formation of nanoparticles by DPFs.

Approach

• Use the same fuel and DPF devices used in the Diesel Emissions Control - Sulfur Effects (DECSE) 

project.

• Measure volatile and semivolatile organics, aldehydes and ketones, and PM soluble organic fraction 

(SOF) and sulfate (SO4). 

• Use different levels of exhaust dilution and a scanning mobility particle sizer (SMPS) to determine the 

particle size distribution of the PM from the DPFs.

• Establish the effect, if any, of fuel sulfur on the destruction or formation of air toxics and the formation 

of nanoparticles by DPFs.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

61

Accomplishments

• Applied a full range of hydrocarbons (HCs) to the exhaust entering DPFs to investigate their 

destruction efficiency and found that:

- Aldehydes in and out of the device were variable at low engine speeds and loads.

- Light HC were oxidized burned even at low temperatures .

- Fuel sulfur at 40 ppm concentration had only a small effect on HC conversion.

• Conducted particle sizing measurements.

Future Direction

• This project is complete.

Introduction

The recently completed Diesel Emissions 

Control - Sulfur Effects (DECSE) joint IndustryDOE project provided a comprehensive examination 

of fuel sulfur effects on the performance of four 

types of emission control devices for diesel engines 

[1]. Missing from the DECSE program were the 

complementary evaluations of the effect of fuel 

sulfur on the devices testing particle size distribution 

and on the emissions of volatile organic compounds 

(VOCs), semi-volatile organic compounds (SVOCS) 

and air toxics. The Advanced Propulsion 

Technology Center (APTC) at the Oak Ridge 

National Laboratory (ORNL) recognized the 

opportunity to leverage some important additional 

research with that of the existing DECSE program, 

and thus provide valuable supplemental information 

on fuel sulfur effects. 

The DPFs are likely to have a very positive effect 

on non-regulated emissions, such as air toxics, 

benzene, and formaldehyde - an effect which may 

well be tempered by the presence of sulfur in the 

fuel. A very recent study showed that a catalyzed 

diesel particulate filter (CDPF) has a positive effect 

on poly-aromatic hydrocarbron (PAH) destruction 

[2]. Furthermore, the ability of the device to remove/

affect the soluble organic fraction (SOF) of the PM 

may be dependent upon sulfur level. 

Previous research has demonstrated an influence 

of emission controls and, perhaps more importantly, 

test dilution conditions on PM size. For instance, it 

was found that under EPA-approved dilution 

conditions, production of ultrafine PM (size<100 

nm) can increase with use of particulate traps and 

oxidation catalysts [3]. Comparing 3000 ppm sulfur 

fuel with 500 ppm sulfur fuel, Johnson demonstrated 

that the sulfur contribution to the ultrafine PM was 

very important [4], thus providing further argument 

to reducing the level of sulfur in fuel. ORNL 

evaluated a CDPF with No. 2 diesel reference fuel 

and also found that the ultrafine fraction of the PM 

was increased 100-fold [5]. In addition, it was found 

that this distribution was sensitive to dilution ratio - 

increasing dilution ratio resulted in smaller and 

smaller particles.

Experimental Approach

A 1998 heavy-duty (HD) engine with transit bus 

emission calibration (0.05 g PM/hp-hr) was used for 

this study. DPFs identical to the ones used in the 

DECSE project were procured and included a 

continuously regenerable diesel particulate filter 

(CR-DPF) and a catalyzed diesel particulate filter 

(CDPF). DECSE 3 ppm sulfur fuel was used 

throughout and splash-blended with DECSE 150 

ppm sulfur fuel to make 40 ppm sulfur fuel. Dilution 

for the bag and filter samples was done using a mini 

dilution tunnel. Dilution for the particle-sizing 

experiments was accomplished with an ejector pump 

micro-dilutor, based on a design by Kittelson et al 

[3]. All transfer lines were heat traced, and the 

dilution ratio was maintained above 20:1 using 

filtered air. A TSI Scanning Mobility Particle Sizer 

(SMPS) was used to obtain PM size distributions.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

62

Bag HCs were analyzed by gas chromatography 

with flame ionization detection (GC-FID). Dinitrophenylhydrazine (DNPH) cartridges were used to 

collect aldehydes from the dilute exhaust and were 

analyzed by high-pressure liquid chromatography 

(HPLC).

Results

The results in general showed excellent removal 

of all HCs, including aldehydes, by the DPFs. Even 

at temperatures well below the balance point (the 

temperature at which the DPF is burning PM as fast 

as it accumulates), there was excellent HC 

conversion. At idle, however, there was evidence of 

partial oxidation processes, wherein the DPF actually 

emitted more of certain aldehydes than went into the 

device. Particle sizing results showed excellent 

removal of PM by the DPFs, to near background 

levels. Fuel sulfur, however, contributed to a 1000-

fold increase in the number concentration of particles 

under 10 nm under certain conditions.

HC Results

Light and heavy HCs as well as aldehdyes were 

measured. As an example, Figure 1 shows aldehyde 

conversion results for a CR-DPF at a moderate 

exhaust temperature (225°C), which is well below 

the balance point of this device. Note the excellent 

conversion of all species, including formaldehyde, 

which is somewhat resistant to oxidation at low 

temperatures. The conversion of aldehydes at higher 

temperatures was 100%. Fuel sulfur had little or no 

effect on the device’s ability to destroy these 

compounds. Figure 2 shows the same chart at idle 

conditons. In this case, there is poor conversion of 

formaldehyde, and, in the case of benzaldehyde and 

butanal, actual aldehyde formation, which results in 

"negative" formation. Note also that fuel sulfur has a 

positive effect on the removal of formaldehyde. This 

may be due to the reaction of the formaldehyde with 

SOx to form methanesulfonic acid, which was not 

measured. The low temperatures at idle, the 

relatively higher engine-out HCs, and the reactive 

surfaces of the catalyzed DPFs represent ideal 

conditions for doing partial oxidation reactions and 

other chemistry. This result points out the need to 

consider the impact of extended idling periods on 

emissions when implementing emission control 

device alternatives.

Work on light HCs is summarized in Figures 3 

and 4. Figure 3 shows the elimination of most light 

HC emissions by both the CDPF and CR-DPF at 

moderate load conditions and a temperature below 

the balance point. Of course, at higher temperatures 

there is complete conversion of HC emissions. 

Figure 4 shows engine idle data for the CR-DPF. At 

Figure 1. CR-DPF Aldehyde Conversion at Low-Load, 

225°C

Figure 2. The CR-DPF Forms Some Aldehydes at Idle

Figure 3. Conversion of Light HCs
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

63

idle conditions, there was moderate conversion of 

the light HCs. The main difference between the 3 

ppm sulfur fuel results and the 40 ppm sulfur fuel 

results is the apparent formation of 1-pentene during 

idle conditions. The extra sulfur in the exhaust may 

provide the acidic condition on the catalyst necessary 

for cracking of fuel HCs to occur. The aldehyde 

formation (Figure 2) was enhanced when 40 ppm 

sulfur fuel was used.

Particle Sizing Results

As many others have shown, the DPFs are very 

effective at removing PM mass. This is evident in 

the particle sizing results, where the large soot 

fraction that is present in engine-out exhaust 

disappears in the catalyst-out exhaust . The larger 

fraction contains most of the mass of the PM. In 

contrast, the particle emissions from the DPFs 

compare favorably to ambient particle concentrations 

in the Smoky Mountain National Park. Figure 5 

compares the PM size distribution from a CDPF 

exhaust with 3 ppm and 40 ppm sulfur fuels to the 

PM size distribution of ambient air in a National 

Park. Particle sizing on the exhaust showed the 

biggest effect of fuel sulfur level. Even at dilution 

ratios of approximately 20, which is higher than 

standard full flow dilution tunnels, the higher sulfur 

content fuel led to the formation of nucleation mode 

particles on the order of 3-10 nm at concentrations 

100-1000X what was present in the low sulfur fuel 

sample.

Conclusions

Fuel sulfur appeared to have little effect on the 

ability of the CR-DPF and CDPF to remove HCs at 

moderate load, and no effect on HC conversion at 

high load. With the CR-DPF, under idle conditions, 

the formation of some aldehydes and a fuel cracking 

product, 1-pentene, was enhanced by the presence of 

fuel sulfur. Fuel sulfur, however, has a large impact 

on ultrafine particle formation by the DPFs. A 2 to 3 

order-of-magnitude rise in number concentration was 

observed for the CDPF operating at high exhaust 

flow and temperature with 40 ppm sulfur fuel.

References

1. Liang, C. Y., Baumgard, K. J., Gorse, R., Orban, 

J., Storey, J. M., Tan, J. C., Thoss, J. E., and 

Clark, W. (2000). "Effects of Diesel Fuel Sulfur 

Level on Performance of a Regenerating Diesel 

Particulate Filter and a Catalyzed Particulate 

Filter." SAE 2000-01-1876. Society of 

Automotive Engineers (2000).

2. Johnson, J. H., , Suresh, A., , Bagley, S. T., , and 

Leddy, D. G. (2001). "A Study of the Effect of a 

Catalyzed Particulate Filter on the Emissions 

from a Heavy-Duty Diesel Engine with EGR." 

SAE 2001-01-0910. Society of Automotive 

Engineers (2001).

3. Abdul-Khalek, I. S., Kittelson, D. B., Graskow, 

B. R., Wei, Q., and Brear, F. (1998). "Diesel 

Figure 4. The CR-DPF removes most light HCs at idle, 

but forms 1-pentene with the higher sulfur 

fuel.

Figure 5. Comparison of number-based particle size 

distributions from the diluted exhaust of a 

CDPF using 3 ppm and 40 ppm sulfur fuel. 

(Engine at full load, rated speed, dilution ratio 

of 20)
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

64

Exhaust Particle Size: Measurement Issues and 

Trends." SAE 980525. Society of Automotive 

Engineers (1998).

4. Gratz, L. D., Bagley, S. T., King, K. S., 

Baumgard, K. J., Leddy, D. G., and Johnson, J. 

H. (1991). "The Effect of a Ceramic Particulate 

Trap on the Particulate and Vapor Phase 

Emissions of a Heavy-Duty Diesel Engine." 

SAE 910609. Society of Automotive Engineers 

(1991).

5. Storey, J. "Exhaust Emission Control Effects on 

Diesel Particulate Matter Characteristics." 

Proceedings of Diesel Engine Emissions 

Reduction Workshop, Castine, ME, 1999. 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

65

E. Cooperative Research in C1 Chemistry

Gerald P. Huffman, Director

Consortium for Fossil Fuel Liquefaction Science 

533 S. Limestone Street

111 Whalen Building

University of Kentucky

Lexington, KY 40506-0043

(859) 257-4027, fax: (859) 257-7215, e-mail: cffls@pop.uky.edu

DOE Program Manager: Peter Devlin

(202) 586-4905, fax: (202) 586-9811, e-mail: peter.devlin@ee.doe.gov

DOE Program Manager: Richard Noceti

(412) 378-5955, e-mail: noceti@netl.doe.gov

Contractor: University of Kentucky, Lexington, KY

Subcontractors: Auburn University, Auburn, AL; University of Pittsburgh, Pittsburgh, PA; University 

of Utah, Salt Lake City, UT; West Virginia University, Morgantown, WV

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

G. Advanced Fuel Production and Cost

Tasks

5. Refinery and Fuel Processing Economics

Objectives

• Develop technology for conversion of C1 source materials (natural gas, synthesis gas, carbon dioxide 

and monoxide, and methanol) into clean, high efficiency transportation fuel. 

• Develop novel processes for producing hydrogen from natural gas and other hydrocarbons.

Approach

• Faculty and students from five universities (Kentucky, West Virginia, Utah, Pittsburgh and Auburn) are 

collaborating on a basic research program to develop novel C1 chemistry processes for the production 

of clean, high quality transportation fuel. An Industrial Advisory Board (IAB) with members from 

Chevron, Eastman Chemical, Energy International, Teir Associates, and the Department of Defense 

has been formed to provide practical guidance to the program.

Accomplishments

• The addition of acetylenic compounds in Fischer-Tropsch (FT) synthesis is found to produce 

significant amounts of oxygenated products in FT diesel fuels. Such oxygenated products should 

decrease particulate matter (PM) emissions. 

• Nanoscale, binary, Fe-based catalysts supported on alumina have been shown to have significant 

activity for the decomposition of methane into pure hydrogen and potentially valuable multi-walled 

carbon nanotubes.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

66

• Catalytic synthesis processes have been developed for synthesis of diethyl carbonate, higher ethers, 

and higher alcohols from C1 source materials. Testing of the effect of adding these oxygenates to 

diesel fuel on PM emissions has begun using a well-equipped small diesel engine test facility. 

• Supercritical fluid (SCF) FT synthesis has been conducted under SCF hexane using both Fe and Co 

catalysts. There is a marked effect on the hydrocarbon product distribution, with a shift to higher 

carbon number products.

Future Directions

• Future research projects will emphasize improvements in FT synthesis, hydrogen production from 

various hydrocarbons, evaluation of carbon nanotube byproducts, and C1 synthesis of fuel additives 

and high value chemicals. 

Introduction

Since 1986, the Consortium for Fossil Fuel 

Liquefaction Science (CFFLS) has been engaged in 

research on the development of alternative sources 

for transportation fuel. For the past two years, the 

CFFLS research program has focused on C1 

chemistry, which refers to the conversion of feed 

stocks that have one carbon atom per molecule 

(natural gas, synthesis gas, carbon dioxide and 

monoxide, and methanol) into clean, high efficiency 

transportation fuel. Synthesis gas, or syngas, is a 

mixture of CO and H2 that can be produced by 

reforming of natural gas or gasification of coal, 

biomass, petroleum coke, and waste materials. 

Because of the abundance of remote natural gas, the 

advent of integrated gasification combined cycle 

(IGCC) power generation, and environmental 

advantages, syngas availability and industrial interest 

in C1 chemistry as a source of transportation fuel are 

growing rapidly. The CFFLS is therefore performing 

a valuable national service not only by generating 

novel C1 technology for the synthesis of premium 

transportation fuels, but also by providing science 

and engineering graduates trained in this important 

area. 

The current report briefly summarizes some of 

the research highlights of the second year of the 

program. 

Effect of Probe Molecules on Oxygenated 

Products in Fischer-Tropsch Synthesis

It is reported that particulate matter (PM) emission 

reductions of 4-10% can be achieved forevery 1% of 

oxygen blended into diesel fuel. In this project, the 

production of oxygenated diesel fuels by modifying 

Fischer-Tropsch (FT) catalysts and reaction 

conditions is being investigated. The addition of 

acetylenic molecules, specifically 1- and 2-hexyne, 

into the FT synthesis with iron and cobalt catalysts to 

produce oxygenated products is reported here.

1-Hexyne is readily incorporated into the FT 

reaction to produce heptanol, heptanal and C8+ 

straight chain alcohols. In the case of 2-hexyne 

addition, a large amount of branched C7+ oxygenates 

is produced. At lower temperatures, these hexynes 

initiate chain-growth in the FT reaction and produce 

mainly C7+ products. Typical gas chromatography/

mass spectroscopy (GC/MS) analyses of the FT 

products of such reactions are shown in Figure 1. 

The mode of incorporation of acetylenic molecules 

into FT reactions is under investigation.

Figure 1. GC/MS Analysis of FT Products with 2-

Hexyne Addition
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

67

Hydrogen Production by Catalytic Decomposition of Methane 

Traditionally, hydrogen has been produced by 

reforming or partial oxidation of methane to produce 

synthesis gas, followed by the water-gas shift 

reaction to convert CO to CO2 and produce more 

hydrogen, followed in turn by a purification or 

separation procedure. This research is investigating 

the direct catalytic decomposition of undiluted

methane into pure hydrogen and carbon using 

nanoscale, binary, Fe-M catalysts (M = Pd, Mo, and 

Ni) supported on alumina [(4.5% Fe — 0.5%M)/

Al2O3]. All of the supported Fe-M catalysts reduced 

methane decomposition temperature by 400-500°C 

relative to non-catalytic thermal decomposition and 

exhibited significantly higher activity than Fe or any 

of the secondary metals (Pd, Mo, and Ni) supported 

on alumina alone. At reaction temperatures of 

approximately 700-800°C and space velocities of 0.1 

per hour, the product stream was comprised of over 

85 volume % of hydrogen, with the balance being 

unconverted methane. No C2 or higher 

hydrocarbons were observed in the product gas. 

High resolution scanning electron microscopy 

(SEM) and transmission electron microscopy (TEM) 

characterization established that almost all carbon 

produced at 700-800°C is in the form of potentially 

useful multi-walled nanotubes (Figure 2). At 

somewhat higher temperatures (> 850°C), hydrogen 

production is decreased and carbon is deposited on 

the catalysts in the form of amorphous carbon, 

carbon flakes, and carbon fibers. 

Supercritical Fluids as a Reaction Medium 

for Fischer-Tropsch Synthesis 

Supercritical fluids offer several advantages over 

traditional solvents as reaction media for catalytic 

reactions. Advantages of SCF-phase FischerTropsch synthesis (SCF-FT) include high diffusivity 

and improved heat transfer (relative to a liquid) and 

high solubility (relative to a gas). In this 

investigation, FT synthesis has been conducted under 

SCF hexane conditions in a continuous, highpressure reactor employing traditional Fe and Co 

catalysts (e.g., 15%Co-0.5%Pd/Al2O3). Steady-state 

operation was quickly achieved under SCF 

conditions and the product distributions obtained 

were constant over extended periods of operation 

(over 40 hours). The SCF-FT process has a marked 

effect on the hydrocarbon product distribution with a 

shift to higher carbon number products due to 

enhanced heat and mass transfer from the catalyst 

surface. Relatively flat product distributions with 

similar mass percentages of the C11-C17 products 

were obtained (Figure 3). In addition, an obvious 

difference is observed for the 1-olefin content 

obtained in the SCF-FT synthesis, which is always 

higher than that from gas or liquid phase FT 

synthesis. This phenomenon suggests that the SCFFT reaction rate is not diffusion controlled, whereas 

the secondary olefin hydrogenation and 

isomerization reactions are diffusion limited. The 

SCF-FT process results in higher diffusivity and 

Figure 2. Carbon Nanotubes Produced by 

Decomposition of Methane over a (4.5%Fe0.5%Mo)/Al2O3 Catalyst

Figure 3. Product Distribution from Fischer-Tropsch 

Synthesis under SCF Hexane Conditions
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

68

more rapid removal of high molecular weight 1-

olefins from the catalyst surface thereby suppressing 

secondary hydrogenation and isomerization 

reactions.

Catalytic Synthesis and Testing of Oxygenated Compounds for Use as Fuel Additives

Effective catalysts have been developed for the 

synthesis of several oxygenated compounds that may 

be useful as fuel additives. These include higher 

alcohols, higher ethers, and organic carbonates. 

• Carbon-supported molybdenum-based 

catalysts, promoted with Ni and K, were 

found to be good catalysts for synthesis of 

higher alcohols from syngas. Reactivity 

studies were carried out at 250-350°C. The 

liquid product contained appreciable 

quantities of C1-5 alcohols in an aqueous 

phase with no hydrocarbon phase. 

• A C7 ether, 2,3 dimethyl-2-methoxybutane 

(DM2MB), was synthesized from dimethyl 

butene and methanol. Several other higher 

ethers were synthesized from this olefin and 

butanol, propanol and ethanol, as well as 

binary mixtures of these alcohols. Reactions 

were performed using the commercial 

catalyst, Amberlyst-15, and several 

laboratory-prepared catalysts (Zr(SO4)2 on 

sulfuric acid-treated SiO2 ). 

• Synthesis of diethyl carbonate (DEC) from 

ethanol, CO, and O2, was accomplished 

using a Cu/Pd/activated carbon catalyst 

pretreated with potassium hydroxide, KOH. 

X-ray diffraction characterization of the 

catalysts has established that the most active 

state of the catalyst is paratacamite, 

Cu2Cl(OH)3.

Diesel Engine Test Facility

A small diesel engine test facility utilizing a twocylinder Kubota model Z482B has been established. 

The facility includes a TSI Scanning Mobility 

Particle Sizer (SMPS) that measures particle size 

distributions from 7 nm to 300 nm, and a Lasair 310 

optical particle counter (OPC) that measures particle 

counts in seven size ranges from 0.3 μm to 10 μm. 

The laboratory also has a high volume particulate 

matter (PM) sampler for collecting large quantities of 

PM with diameter less than 10 μm. For gas-phase 

emissions, the laboratory has the capabilities to 

measure CO, CO2, NOx, and total hydrocarbons. In 

addition, the laboratory can measure real-time PAH 

and elemental carbon on particles. Initial tests 

conducted using the DEC additive in a conventional 

diesel fuel exhibited a significant reduction in PM 

emissions. 

Hydrocracking and Isomerization of Alkane 

Chains Representative of FT Products

Laboratory work was carried out successfully in 

a small continuous trickle-bed reactor using a Pt/

ZrO2/WO3 catalyst. A 90 wt% iso-C16 selectivity and 

a 71wt% iso-C16 yield were achieved at 79 wt% 

conversion of hexadecane. The objective in the last 

half-year has been to extend research to the 

conversion of paraffins longer than hexadecane, such 

as those produced in the FT process, to a variety of 

clean transportation fuels. This was carried out using 

the stable and selective Pt/ZrO2/WO3 catalyst to 

hydroisomerize and hydrocrack pure compounds, 

namely n-C16, n-C20, n-C24 n-C28 and their mixtures, 

representative of alkane chains found in FT products.

Figure 4 shows yield-product distribution graphs 

at two different conversions for octacosane (C28) at 

Figure 4. Effect of Conversion on Product Distribution 

for Reacted C28 at 220°C and 500 psig
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

69

220°C. The lube-base oil yield is highest at 79% 

conversion (Figure 4, top) and consists of only 

branched isomers, mostly iso-C28. The yield of lubebase oil decreases gradually with increasing 

conversion as the yield of diesel fuel and gasoline 

increases. The major product is diesel fuel at 99% 

conversion (Figure 4, bottom), only a 20% change in 

conversion. If the reaction is carried to 100% 

conversion, the major product becomes highly 

branched gasoline. Switching between these three 

fuels occurs at high conversion values. It appears 

possible to obtain the desired fuel range by adjusting 

the conversion at a selected temperature but 

maintaining relatively high conversion.

Conclusions

Collaborating faculty and students at the five 

CFFLS universities (Kentucky, West Virginia, 

Pittsburgh, Utah, and Auburn) have continued to 

make excellent progress on research to develop 

innovative C1 chemistry processes to produce clean, 

high efficiency transportation fuel. In the second 

year of the program, emphasis was placed on various 

aspects of Fischer-Tropsch synthesis and on 

hydrogen. 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

70

VI. MODELING/DATA ANALYSIS/ASSESSMENTS

A. The Impact of Oxygenated Blending Compounds on PM and NOx Formation 

of Diesel Fuel Blends

Charles K. Westbrook (Primary Contact), William J. Pitz

Lawrence Livermore National Laboratory

P. O. Box 808, L-091

Livermore, CA 94551

(925) 422-4108, fax: (925) 422-2644, e-mail: westbrook1@llnl.gov

DOE Program Manager: John Garbak 

(202) 586-1723, fax: (202) 586-9811, e-mail: John.Garbak@ee.doe.gov

DOE Program Manager: Gurpreet Singh 

(202) 586-2333, fax: (202) 586-4166, e-mail: Gurpreet.Singh@ee.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

A. Fuel Property Effects on Engine Emissions and Efficiency

E. Toxic Emissions

F. Ultra-fine Particles

Tasks

2. Fuel & Lubricant Properties - Engine-Out Emissions

Objectives

• Develop detailed chemical kinetics reaction models for hydrocarbon species existing in diesel fuel

• Develop detailed chemical kinetics reaction models for oxygenated hydrocarbon fuel additives

• Use kinetic models to study the fundamental chemistry of PM production and NOx production in diesel 

combustion

• Characterize the role of oxygenated additives in reduction of PM emissions from diesel engines

• Collaborate with other contractors to simulate chemistry of diesel combustion

Approach

• Identify components of diesel fuels and potential diesel additives and their molecular structures

• Develop kinetic reaction mechanisms for diesel fuels and additives

• Compute ignition temperature of fuel mixture or model flame structure for fuel/air and fuel/air/

additive mixtures

• Compare predicted levels of PM and NOx with and without additive and use a detailed chemical model 

to determine the mechanisms for the emissions changes
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

71

Accomplishments

• Studied ignition under diesel conditions and identified key chemical reactions responsible for ignition

• Used ignition insights to explain role of diesel ignition enhancers

• Predicted reductions in PM emissions for mixtures of diesel fuel with addition of methanol, ethanol, 

dimethyl ether and dimethoxy methane

• Developed model for simulated biodiesel fuel and predicted reduction in PM emissions for biodiesel 

additives

• Based on kinetic model predictions, developed correlation between amount of oxygen in diesel/

additive fuel mixture and PM reduction that agrees with experimental results in diesel engines

• Determined fundamental limits to possible NOx reductions from diesel engines, based on combustion 

lean flammability limit at minimum diesel engine compression pressure levels

Future Directions

• Extend model capabilities to additional fuel constituent compounds, especially aromatics

• Extend model capabilities to additional oxygenated blending compounds

• Increase collaborations with programs outside LLNL dealing with diesel fuel issues

Introduction

The application of a combination of laser 

diagnostics and computational chemistry modeling 

has profoundly changed our current understanding of 

the details of diesel combustion [1]. This 

understanding offers new opportunities to reduce 

diesel emissions of oxides of nitrogen (NOx) and soot 

or particulate mass (PM) to comply with federal 

Clean Air Act regulations. However, diesel 

combustion remains extremely complex. For 

example, diesel fuel is a mixture of many classes of 

hydrocarbon molecules, each of which can affect PM 

and NOx production in different ways, so it is 

essential to have the capability to model the 

combustion of each class of fuel components. While 

past kinetic modeling studies have provided a great 

deal of valuable information on these processes, the 

kinetic models being used have not included two 

important classes of hydrocarbons, cycloalkane and 

aromatic compounds. The present work includes 

extension of the modeling to include these additional 

classes of fuel components. In addition, we have 

used the kinetic model to examine the fundamental 

chemical kinetics of ignition, determining the key 

chemical reactions and showing how ignition leads 

directly to PM production under conditions typical of 

diesel engine combustion.

Recent experimental studies have indicated that 

the use of selected oxygenated diesel fuel additives 

can reduce these emissions, especially PM emissions 

[2]. However, these have been purely experimental 

correlations, without any fundamental understanding 

of why such additives are so effective. In particular, 

the experiments alone do not provide any basis for 

prediction of other possible oxygenated additives 

which might be even more effective in reducing PM 

emissions. The present project is intended to provide 

a fundamental explanation for the experimental 

observations and guidance for screening other 

potential oxygenated compounds as diesel fuel 

additives. Further kinetic modeling is used in a 

similar manner to address NOx production in diesel 

combustion and possible methods of NOx reduction.

Approach

The analysis employs chemical kinetic modeling 

of diesel combustion processes, including ignition, 

formation of PM precursors, kinetic interactions 

between the fuel and any additive molecules, and 

eventual production of NOx. The inclusion of the 

very detailed chemical kinetic reaction pathways 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

72

makes the computed results very general, and the 

technical conclusions derived can be extended 

conveniently to other related problems.

Kinetic reaction models have been developed at 

LLNL for many realistic hydrocarbon fuels and fuel 

mixtures, most recently for n-heptane [3], a singlecomponent fuel that represents many of the 

combustion characteristics of diesel fuel. The diesel 

modeling work has computed diesel ignition and 

combustion using the heptane model and additional 

models for many oxygenated additives of interest to 

industry and DOE, including methanol, ethanol, 

dimethyl ether, dimethoxy methane, and, in the past 

year, biodiesel fuels. 

Similar kinetic model calculations, using a 

variety of fuels, were carried out at operating 

conditions characteristic of diesel combustion, 

particularly at elevated pressures, to try to understand 

the fundamentals of NOx production in diesel 

engines. Model results have provided considerable 

insights into this problem.

Results

Using operational insights derived from recent 

diesel engine experiments by Dec [4], it is assumed 

that PM production in diesel combustion occurs from 

reactions of chemical species created during fuel-rich 

ignition near the fuel injection location. Because 

there is insufficient oxygen in this region to burn the 

fuel completely, the hydrocarbon species remaining 

there react instead to produce PM. Our kinetics 

calculations show that when the fuel itself contains 

some oxygen, that oxygen helps convert more of the 

ignition products into chemical species that do not 

contribute to PM production. 

The reduction in the levels of PM produced 

during diesel combustion can be dramatic. Figure 1 

shows the computed reductions in concentrations of 

diesel soot precursors as the amounts of oxygen in 

the fuel/additive mixture is steadily increased. 

Somewhat surprisingly, sooting tendency is reduced 

at approximately the same rate by all of the 

oxygenated blending agents. In each case, it appears 

that the soot production is completely suppressed 

when the oxygen level in the mixed fuel reaches 

about 35% by mass. The rate of soot reduction, the 

prediction that soot production disappears at 30-35% 

oxygen, and the relative independence of this 

behavior on the specific oxygenate being added, all 

agree very well with experimental results from diesel 

engine experiments [5,6].

It is important to realize, however, that 35% 

oxygen in the fuel mixture corresponds to a fuel 

which is dominated by the oxygenated additive, so 

most practical operations in real diesel engines 

would take place at oxygen levels of less than 10%. 

Still, the computed results not only provide the 

chemical understanding of the mechanism of soot 

reduction, but also suggests strongly that the critical 

parameter for soot reduction is the total amount of 

oxygen and not the particular type of molecule which 

contains the oxygen. This type of result can guide 

studies looking for better, more efficient and perhaps 

more engine-friendly additives that will still be 

effective at providing soot reduction.

The model also shows that much of the kinetic 

activity in toluene combustion occurs on the methyl 

side chain, which is converted to -CH2 (benzyl 

radical) and then to -CH2O, as seen in the Figure 2. 

The same work [7] showed that when toluene is 

present as 30% of the total diesel fuel, its main 

contribution to soot precursor production is a 

significant increase in benzene concentrations in the 

products of the fuel-rich ignition event. 

Figure 1. Reduction of PM precursors with fraction of 

oxygen in fuel. Oxygenated additives include 

methyl butanoate (MB, a biodiesel fuel), 

dimethoxy methane (DMM), ethanol, 

methanol and dimethyl ether (DME).
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

73

The inclusion of a typical aromatic species will 

also make other diesel combustion modeling projects 

more useful and more likely to reflect the true 

character of diesel fuel. We are currently working to 

add a similar submodel for methyl cyclohexane as a 

typical cycloalkane fuel component.

In other work carried out this year, kinetic 

modeling was used to simulate flame propagation 

near the lean limit of combustion at pressures in the 

ranges found in diesel combustion, which are 

commonly as high as 100 bar. This work [8] showed 

that these high pressures modify the rates of specific 

elementary chemical reactions that are important for 

flame propagation, especially reactions between 

atomic hydrogen and molecular oxygen:

H + O2 = O + OH (1) and

H + O2 = HO2 (2)

This competition, which favors the less reactive 

path (2) at elevated pressures, gradually suppresses 

flame propagation to the extent that the lean limit for 

flame propagation at 100 bar pressure is reached at 

an equivalence ratio of about 0.65, compared to the 

lean limit at atmospheric pressure of about 0.5. More 

importantly, the adiabatic flame temperature (or the 

product flame temperature) at the lean limit at 100 

bar is about 1950K, compared to the flame 

temperature at atmospheric pressure of about 1400K.

Production of NOx is extremely sensitive to 

flame temperature and begins to become rapid at 

temperatures of about 1900K and above. The 

computed kinetic modeling results therefore indicate 

that the high pressures characteristic of diesel engine 

combustion makes it inevitable that NOx will be 

produced in significant amounts in diesel engines, 

regardless of strategies employed to limit that 

production. The same is true of spark-ignition 

engines and shows that some degree of exhaust gas 

catalytic treatment will always be required for diesel 

and spark-ignition engines to reduce NOx levels to 

those required by regulations. This is not true in 

engines using Homogeneous Charge Compression 

Ignition (HCCI) due to the very low equivalence 

ratio of such engines and the lack of any requirement 

to propagate a flame.

Finally, we have used kinetic modeling [9] of 

diesel ignition to demonstrate that the elementary 

reaction step that is responsible for the actual ignition 

is the unimolecular decomposition of hydrogen 

peroxide,

H2O2 = OH + OH(3)

which floods the reactive fuel/air mixture with highly 

reactive OH radicals, each of which consumes a fuel 

molecule and permits the reaction to proceed very 

rapidly. This decomposition occurs when the 

temperature provides enough thermal energy to break 

the O - O bond, which takes place at about 1000K, 

consistent with experimental observations in the 

engine. The insights provided by this analysis 

explain the effectiveness of such diesel ignition 

enhancing additives as ethyl hexyl nitrate, which 

provide early heat release and make the reactive 

mixture reach this ignition temperature earlier in the 

engine cycle.

Conclusions

Kinetic modeling has been used to extract a 

considerable amount of valuable insight into the 

controlling features of diesel engines and the 

processes leading to PM and NOx production. This 

information has contributed to experimental 

advances in engine technology. In addition, this 

modeling approach has discovered areas, especially 

those dealing with NOx production, where it is very 

unlikely that any combustion modification will 

Figure 2. Reaction pathways for toluene consumption. 

Toluene is shown in the top center of the 

figure, showing reactions with OH to produce 

either phenol or the benzyl radical. The benzyl 

radical then reacts via other paths to produce 

benzylaldehyde. A key feature of this process 

is that most of the reaction occurs on the side 

chain rather than through reactions of the ring 

structure itself.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

74

entirely eliminate emissions and where exhaust gas 

catalytic treatment will always be required.

References

1. Flynn, P.F., Durrett, R.P., Hunter, G.L., zur Loye, 

A.O., Akinyemi, O.C., Dec, J.E., and Westbrook, 

C.K., "Diesel Combustion: An Integrated View 

Combining Laser Diagnostics, Chemical 

Kinetics, and Empirical Validation," Society of 

Automotive Engineers (SAE) paper SAE-1999-

01-0509 (1999).

2. Miyamoto, N., Ogawa, H., Nurun, N.M., Obata, 

K., Arima, T., "Smokeless, Low NOx, High 

Thermal Efficiency, and Low Noise Diesel 

Combustion with Oxygenated Agents as Main 

Fuel," SAE publication SAE-980506 (1998).

3. Curran, H. J., Gaffuri, P., Pitz, W. J., and 

Westbrook, C. K., "A Comprehensive Modeling 

Study of n-Heptane Oxidation," Combustion and 

Flame 114, 149-177 (1998).

4. Dec, J.E., "A Conceptual Model of DI Diesel 

Combustion Based on Laser-Sheet Imaging," 

SAE publication SAE-970873 (1997).

5. Fisher, E. M., Pitz, W. J., Curran, H. J., and 

Westbrook, C. K., "Detailed Chemical Kinetic 

Mechanisms for Combustion of Oxygenated 

Fuels," Proc. Combust. Inst. 28: 1579-1586 

(2000). 

6. Curran, H. J., Fisher, E. M., Glaude, P.-A., 

Marinov, N. M., Pitz, W. J., Westbrook, C. K., 

Layton, D. W., Flynn, P. F., Durrett, R. P., zur 

Loye, A. O., Akinyemi, O. C., and Dryer, F. L., 

"Detailed Chemical Kinetic Modeling of Diesel 

Combustion with Oxygenated Fuels," Society of 

Automotive Engineers paper SAE-2001-01-0653 

(2001).

7. Pitz, W. J., Seiser, R., Bozzelli, J. W., Da Costa, 

I., Fournet, R., Billaud, F., Battin-Leclerc, F., 

Seshadri, K., and Westbrook, C. K. "Chemical 

Kinetic Description of Combustion of Toluene," 

5th International Conference on Chemical 

Kinetics,16 - 20 July 2001.

8. Flynn, P. F., Hunter, G. L., Farrell, L. A., Durrett, 

R. P., Akinyemi, O. C., zur Loye, A. O., 

Westbrook, C. K., and Pitz, W. J., "The 

Inevitability of Engine-Out NOx Emissions from 

Spark-Ignition and Diesel Engines," Proc. 

Combust. Inst. 28: 1211-1218 (2000).

9. Westbrook, C. K., "Chemical Kinetics of 

Hydrocarbon Ignition in Practical Combustion 

Systems," Proc. Combust. Inst. 28: 1563-1577 

(2000).
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

75

B. A Multi-Property Vector Approach to Assessment of Diesel Fuels and 

Emissions Impacts

Gerald Hadder (Primary Contact), David Greene

Oak Ridge National Laboratory

2360 Cherahala Blvd.

Knoxville, TN 37932-6472

(865) 946-1311, fax: (865) 946-1314, e-mail: haddergr@ornl.gov

DOE Program Manager: John Garbak 

(202) 586-1723, e-mail: John.Garbak@hq.doe.gov 

Contractor: UT-Battelle, LLC

Contract No. DE-AC05-00OR22725 

Subcontractors: R.W. Crawford, R.W. Crawford Energy Systems, Tucson, AZ; H.T. McAdams, AccaMath Services, Carrollton, IL; Energy and Environmental Analysis, Inc., Arlington, VA; EnSys 

Energy and Systems, Flemington, NJ

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

A. Fuel Property Effects on Engine Emissions and Efficiency

Tasks

2. Fuel & Lubricant Properties - Engine-Out Emissions

4. Develop Empirical Relationships

Objectives

• Characterize relationships between fuel properties and emissions for diesel technologies to meet nearterm (for example, Texas Low Emission Diesel Fuel) and Tier 2 emissions standards.

• Use advanced statistical methods and refinery modeling to study reformulated diesel fuel production 

impacts on the transportation fuel supply system.

Approach

• Analyze role of diesel fuel composition changes on emissions from advanced diesel engines. 

• Provide guidance on diesel engine emissions test designs. 

• Provide insights on cost-effective refinery production of reformulated diesel fuels.

Accomplishments

• Reports on statistical analysis of diesel fuel quality and emissions (McAdams, Crawford, and Hadder, 

2000a and 2000b).

• Report on engine test program design concepts and recommendations (McAdams, 2001). 

Future Directions

• Develop emissions models for optimizing refinery production of reformulated diesel fuels.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

76

Introduction

Multiple regression analysis is widely used for 

expressing the dependence of a response variable on 

several predictor variables. In spite of its evident 

success in many applications, multiple regression 

analysis can face serious difficulties when the 

predictor variables are to any appreciable extent 

covariant. Efforts to evaluate the separate effects of 

fuel variables on the emissions from heavy-duty 

diesel engines are often frustrated by the close 

association of fuel properties. 

Most heavy-duty diesel engine research has been 

conducted with test fuels "concocted" in the 

laboratory to vary selected fuel properties in 

isolation. While it might eliminate the confounding 

effect caused by naturally covarying fuel properties, 

this approach departs markedly from the real world, 

where reformulation of fuels to reduce emissions will 

naturally and inevitably lead to changes in a series of 

interrelated properties. To address these concerns, 

we have implemented an alternative approach to 

modeling the effects of fuel characteristics on 

emissions.

Approach

The alternative approach is based on the use of 

Principal Components Analysis to describe fuels in 

terms of vector quantities called eigenfuels. Each 

eigenfuel represents a unique and mathematically 

independent characteristic of diesel fuel, and the 

most important eigenfuels can be related to refinery 

processing and blending. When applied as predictors 

for emissions in regression analysis, eigenfuels have 

many advantages, including:

• Simplification of the analysis, because the 

mathematical independence of eigenfuels 

eliminates correlations among the variables 

and the complications introduced by multicollinearity.

• Economy of representation, because a 

smaller number of such vector variables may 

effectively replace a larger number of 

original variables.

• Greater understanding of the patterns of 

variation that are important to emissions,

and how these patterns relate to refinery 

processing and blending.

• New insight into the optimal economic 

formulation of fuels to reduce emissions, and 

improved experiment design for the 

estimation of fuels effects. 

Knowing the extent of interdependence among 

fuel variables, we should not be surprised by the 

difficulty of selecting an "optimal" set of variables 

for a regression model. We may believe that natural 

cetane or density has an important influence on 

emissions, but either may be nearly replaced by a 

combination of other variables. Stepwise regression, 

a commonly used multiple regression analysis 

technique, searches through a sequence of differing 

model formulations to find one that is "optimum." 

With diesel fuel test data, there can be many different 

sets of variables that perform nearly as well as the 

one set ultimately chosen. 

Figure 1 brings this point into focus. There are 

4,095 different regressions models that can be 

formed from twelve fuel properties, and these models 

form the universe among which stepwise regression 

searches.

It will take all twelve properties to place a model 

at the very end of the curve. Forty-five different 

models populate the last 0.02 in R2

, and these models 

typically involve 7-9 fuel property variables. The 

coefficients of the fuel property variables can be 

significantly different among these models, leading 

to uncertainty about their relative importance in 

testing and in the cost-effective blending of refinery 

stocks. However, models based on a small number 

of eigenfuels perform well, with five eigenfuels 

explaining nearly 97 percent of the fuels-related 

variance in NOx. The eigenfuel coefficients are 

unambiguous and theoretically correct for test 

designs and for cost-effective blending of refinery 

stocks.

Conclusions

A database of heavy-duty diesel engine testing 

was compiled from the literature and used to 

demonstrate the eigenfuel methodology, recognizing 

that the existing data are inadequate to answer fully 

the many questions related to the effect of fuels on 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

77

emissions. Within this limitation, we find that the 

eigenfuel approach leads to new perspectives on 

diesel fuel-emissions relationships:

• Fuel properties are only surrogate variables 

for underlying causal factors. Much of the 

emissions reduction seen in past testing 

comes from reducing highly aromatic 

cracked stocks in diesel fuel. Because these 

stocks are low in cetane number and high in 

density, researchers have tended to attribute 

the emissions reductions to the increase in 

cetane number or reduction in density 

associated with their removal, rather than to 

the compositional change itself.

• How one varies a fuel property can be the 

most important factor in determining the 

emissions response. A given fuel property 

can be changed in many ways, and a unit 

change in that property can produce 

markedly different effects on emissions 

depending on how that change is introduced.

• Past studies may understate the impacts of 

fuels on emissions. If density is varied in 

several ways - one of which has a strong 

effect on emissions and the others not all - a 

study will tend to see only the average, 

diluted effect. 

The eigenfuel approach provides new ways to 

design test fuels that are far more likely to be 

representative of future fuels that will be produced in 

refineries, compared to fuels blended in an effort to 

vary selected properties independently. These test 

fuels will express the natural correlations among 

fuels properties. While these correlations would be 

confounding factors in conventional analysis, they 

can be exploited in eigenfuel analysis. 

References/Publications

1. H.T. McAdams. 2001. "Experiment Design and 

Data Analysis; A Phenomenological Dual," 

Working Paper No. ACCA-00-4, under contract 

with Oak Ridge National Laboratory, Carrollton, 

IL, February 8.

2. H.T. McAdams, R.W. Crawford, G.R. Hadder. 

2000a. "A Vector Approach to Regression 

Analysis and Its Application to Heavy-Duty 

Diesel Emissions," SAE 2000-01-1961, Society 

of Automotive Engineers International Spring 

Fuels & Lubricants Meeting & Exposition, Paris, 

France, June 19-22.

3. H.T. McAdams, R.W. Crawford, G.R. Hadder. 

2000b. "A Vector Approach to Regression 

Analysis and Its Application to Heavy-Duty 

Diesel Emissions," ORNL/TM-2000/5, Oak 

Ridge National Laboratory, Oak Ridge, TN 

37831, November.

Figure 1. NOx Variation Explained by All Possible 

Regressions
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

78

C. System Emissions Reduction (SER) Analysis for Automobiles, Light Trucks, 

and Heavy-Duty Engines

Matthew Thornton (Primary Contact) and Robert McCormick

National Renewable Energy Laboratory

1617 Cole Blvd.

Golden, CO 80401

(303) 275-4273, fax: (303) 275-4415, e-mail: matthew_thornton@nrel.gov

(303) 275-4432, fax: (303) 275-4415, e-mail: robert_mccormick@nrel.gov

DOE Program Manager: John Garbak 

(202) 586-1723, fax: (202) 586-9811, e-mail: john.garbak@ee.doe.gov

DOE Program Manager: Bob Kost

(202) 586-2334, fax: (202) 586-6109, e-mail: robert.kost@ee.doe.gov

DOE Program Manager: Steve Goguen

(202) 586-8044, fax: (202) 586-4166, e-mail: stephen.goguen@ee.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

A. Fuel Property Effects on Engine Emissions and Efficiency

B. Fuel Property Effects on Exhaust Emission Control System Technology

D. Sulfur Impacts

E. Toxic Emissions

F. Ultra-fine Particles

Tasks

2. Fuel & Lubricant Properties - Engine-Out Emissions

3. Fuel & Lubricant Properties - Exhaust Emission Control and Emissions

4. Develop Empirical Relationships

Objectives

• Establish system emissions reduction (SER) analysis framework.

• Develop and use systems level analysis tools that incorporate empirical emission relationships and 

first principle models to identify the best pathways for achieving the technical targets for compression 

ignition direct injection (CIDI) engines, identified in the Advanced Petroleum-Based Fuels (APBF) 

Multiyear Program Plan (MYPP).

Approach

• Define the SER framework to augment the Advanced Vehicle Simulator (ADVISOR) with new 

component modules (e.g., emission control devices) and laboratory data.

• Develop empirical data relationships on sulfur effects for pathway analysis, initially making use of 

data and analysis from the Diesel Emissions Control — Sulfur Effects (DECSE) project.

• Provide a sample pathway analysis for one type of vehicle and configuration from each of the three 

platforms.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

79

• Recommend future analyses and continue to expand input databases, identify gaps in the data required 

for valid predictions and use this information as a guide to develop future R&D programs.

Accomplishments

• Developed and refined SER analysis framework and data collection protocols.

• Performed vehicle sample pathway analysis for two platforms results from light truck platform 

provided in Figure 1.

• Developed engine modeling enhancements within the analysis framework using 1-D engine modeling 

software (25% complete).

• Integrated diesel oxidation catalyst model with ADVISOR as an initial test of emission control system 

submodel integration.

Future Directions

• Expand understanding of fuel formulation effects on emissions.

• Identify and collect relevant data already existing from research partners.

• Refine SER analysis approach by continuing to analyze data and develop maps and modules for 

ADVISOR.

• Analyze pathways for reducing emissions from enhanced samples for three platforms and investigate 

specific applications of analysis tools such as the effect of compression ratio, EGR, and emission 

control devices on efficiency.

• Develop a process to validate the model at a systems level.

Introduction

The APBF program seeks to identify and 

establish the ability of advanced petroleum fuels and 

non-petroleum fuel blending components to enable 

light-duty CIDI vehicles and heavy-duty CIDI 

engines to meet future emission standards, while 

continuing to improve engine efficiency and 

durability. 

A component of the APBF program is 

establishing a SER analysis framework for 

automotive, light truck, and heavy-duty engine 

applications. This framework focuses on applying a 

systems approach to analyzing emission reduction 

pathways and fuel options. Establishing the SER 

analysis approach requires analyzing available data 

and developing maps and submodels to add to the 

existing ADVISOR vehicle system model. 

Approach

NREL is using fuel property and emission data 

from APBF-DEC and associated empirical data 

relationships, in conjunction with first-principle 

models to evaluate the most promising pathways for 

reducing emissions using the SER approach. The 

system concept consists of an analysis tool that 

accounts for the interaction of fuel, combustion 

strategy, and emission control devices. This 

approach is being built around NREL’s ADVISOR 

(advanced vehicle simulator) model. ADVISOR 

requires a detailed map of gaseous emissions, PM 

emissions (real-time), fuel consumption, exhaust 

temperature and EGR temperatures, at many engine 

speeds and loads. Such maps can be acquired as 

actual datasets from engine testing or generated 

using one-dimensional engine models with a more 

limited (i.e. 8-mode) dataset and various engine 

parameters as input. This work will involve 

continually developing these engine performance 

maps using data acquired from other APBF projects, 

as well as incorporating conversion efficiency data 

(as a function of exhaust temperature and flow 

parameters) for various emission control devices. 

Empirical relationships of emissions and specific, 

targeted fuel properties such as sulfur content, cetane 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

80

number, and aromatic content will be used to 

estimate the impacts of fuel properties. These 

components will be used to evaluate the best 

pathways for achieving the technical targets of the 

overall APBF-DEC Program. 

The SER approach is designed around the 

following:

• Use ADVISOR as an analysis platform to 

link system components (i.e. empirical 

emission relationships, first principle 

models, and parameterized models). Identify 

the best pathways for achieving the technical 

targets on a vehicle level as defined by the 

APBF Program.

• Collect data sets from engine laboratories 

and develop empirical relationships linking 

emissions to fuel properties.

• Develop 1-D engine models for vehicle 

platforms for which complete datasets are 

not available. Expand the CIDI engine map 

library in ADVISOR and provide enhanced 

exhaust gas characteristics to be used as 

inputs to emission control device submodels.

• Expand the emissions control and emission 

control device modeling capabilities in 

ADVISOR in order to enhance emissions 

predictions.

Results

Information is needed to investigate SER 

pathways. Table 1 identifies the three systems of 

interest and the types of information that will enable 

pathway analysis to be completed. Technical targets 

for NOx and particulate matter (PM) are identified, 

and projects representing sources for emissions data 

are included.

Two primary activities contributed to the results 

in FY01. The first is the development of the SER 

analysis framework and testing of analysis pathways. 

The second is the development of emission control 

device submodels and the initiation of 1-D engine 

modeling development. Sample pathway analyses 

for two platforms have been completed. Figure 1 

shows the results of an emissions reduction pathway 

for the light-duty truck platform using low sulfur fuel 

in conjunction with exhaust gas recirculation (EGR), 

a diesel particulate filter, and a NOx adsorber 

catalyst. This figure illustrates how the progressive 

addition of emissions control approaches can reduce 

PM and NOx emissions. The figure also shows the 

estimated fuel consumption impacts that will parallel 

these emissions reductions. 

Conclusions

Progress has been made on developing 

components necessary to enable a system level 

analysis of the emissions pathways for advanced 

engines and vehicles. Relationships between fuel 

and emissions data obtained from testing engines, 

vehicles, and advanced emission control devices are 

NOx Reduction PM Reduction

Advanced 

Automobile - 

1.7 to 2.2 liter 

HSDI with 

Common Rail 

Injection

Target: 0.07 g/mile

Research: NOx

adsorber, engine 

optimization, and 

EGR strategies

Target: 0.01 g/mile

Research: Engine 

optimization, fuel 

formulation, and 

DPF

Light-Duty 

Truck - 

Navistar 7.3 

liter T44/

Powerstroke

Target: 0.07 g/mile

Research: NOx

adsorber, engine 

optimization, and 

EGR strategies

Target: 0.01 g/mile

Research: Engine 

optimization, fuel 

formulation, oxidation catalyst and 

DPF

Heavy-Duty 

Truck 

Engine - 11 

to 12 liter 

CIDI

Target: 0.2 g/bhp-hr

Research: leanNOx catalyst, NOx

adsorber, and 

EGR strategies

Target: 0.01 g/bhp-hr

Research: Engine 

optimization, fuel 

formulation, oxidation catalyst and 

DPF

Table 1. Targets and Representative Research Areas for 

Data

Figure 1. Sample Pathway Analysis Results for LightDuty Truck Platform
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

81

being developed in submodels that form the building 

blocks of the SER framework. This framework will 

provide the capability to predict potential emissions 

and efficiency improvements for automobiles, lighttrucks, and heavy-duty engines. 

Future efforts will focus on: 1) expanding the 

number of parameterized emission control device 

submodels, 2) enhancing the empirical data 

relationships previously developed, and 3) applying 

the analysis tool. Significant effort will be focused 

on continuing to develop an array of engine 

performance/emissions maps and 1-D engine models 

to enhance the SER analysis capabilities. Additional 

effort will be devoted to developing fuel property 

versus emissions correlations using NREL’s existing 

database, enhancing NREL’s database, and 

incorporating other fuel property emissions 

databases such as the one being developed by EPA. 

The project will continue to focus on evaluating three 

technology platforms (automobile, light-duty truck, 

and heavy-duty engine) and will emphasize the 

inclusion of a heavy-duty engine model into 

ADVISOR. The project will also evaluate 

applications related to these platforms as required by 

DOE and the needs of the APBF-DEC program. The 

SER analysis will provide DOE with analysis of the 

potential effectiveness of different combinations of 

fuel, CIDI engine control strategies, and emission 

control devices on achieving emission reduction 

targets and engine and vehicle performance goals.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

82

D. Fuel Property Database

Robert McCormick (Primary Contact), Matthew Thornton, Teresa Alleman, Keith Vertin

National Renewable Energy Laboratory

1617 Cole Boulevard

Golden, CO 80401

(303) 275-4432, fax: (303) 275-4415, e-mail: robert_mccormick@nrel.gov

DOE Program Manager: John Garbak

(202) 586-1723, fax: (202) 586-9811, e-mail: john.garbak@ee.doe.gov

DOE Program Manager: Steve Goguen

(202) 586-8044, fax: (202) 586-1600, e-mail: stephen.goguen@hq.doe.gov

NREL Computer Support: Paul Bergeron, Mark Winter, and Karen Guilbeault

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

A. Fuel Property Effects on Engine Emissions and Efficiency

B. Fuel Property Effects on Exhaust Emission Control System Technology

D. Sulfur Impacts

E. Toxic Emissions

F. Ultra-fine Particles

Tasks

2. Fuel & Lubricant Properties - Engine-Out Emissions

3. Fuel & Lubricant Properties - Exhaust Emission Control and Emissions

Objectives

• Establish and populate a web-based, searchable fuel property database for the Advanced PetroleumBased Fuels (APBF) program, which links to available emissions data.

• Utilize the database to develop empirical relationships between emissions and fuel properties.

Approach

• Define the fuel properties, engine and vehicle characteristics, and emissions to be included in the 

database. 

• Build the database, web pages and appropriate web interfaces for the searchable database. 

• Utilize regression analysis to reveal empirical relationships between targeted fuel properties (such as 

sulfur content) and emissions from advanced emission control systems.

Accomplishments

• Completed a searchable fuel property database and made it available on the World Wide Web at http://

www.ott.doe.gov/fuelprops/.

• Linked the fuel property database to the existing heavy vehicle emissions database.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

83

• Implemented an improved user interface to facilitate connection of fuel property and emissions 

databases.

• Initiated implementation of a similar database, also linked to the fuel property database, for engine 

emissions results from the APBF program.

• Developed regression equations allowing the prediction of particulate matter (PM) emissions from 

engines equipped with diesel particulate filters (DPF) and NOx adsorber/catalyst systems.

Future Directions

• Continue to populate fuels and emissions databases as data become available.

• Complete expansion of the emissions database to include light-duty emissions data and engine 

emissions data, particularly from the APBF program.

• Examine other empirical correlations including impact of fuel properties on exhaust treatment systems 

and engine-out emissions.

Introduction

Numerous studies have investigated the impact 

of fuel properties such as density, aromatic content, 

sulfur content and cetane number on emissions from 

various diesel engines. There is also a great deal of 

data on diesel vehicle emissions using various 

advanced and alternative fuels (such as ultra-low 

sulfur diesel, CARB diesel, biodiesel, and FT-diesel). 

Fuel properties directly affect combustion chemistry, 

diesel spray properties, and performance of 

mechanical systems such as fuel injectors. Fuel 

properties can also impact aftertreatment systems, 

with sulfur content as the most obvious example. As 

engine systems advance and in many cases become 

more complex, it becomes critical to understand how 

engine technology and fuel properties interact to 

influence performance and emissions. 

The Advanced Petroleum-Based Fuels program 

includes a System Emissions Reduction Analysis 

effort that will develop predictive tools for 

estimating the effects that fuel property variations 

can have on the emission response of engines and 

exhaust emission control systems. A detailed fuel 

property database is a key information component 

and resource for the development of these predictive 

empirical models.

Approach

Over the past several years the Alternative Fuels 

Data Center website at NREL has accumulated a 

large database of heavy-duty vehicle chassis testing 

emissions data. This database has proven useful for 

examination of trends in diesel emissions [1], as well 

as comparison of diesel and alternative fuel 

emissions. Many of these studies also included a 

detailed analysis of the test fuel, and this is currently 

a requirement for all ongoing and future studies. 

Under this project a database for this fuel property 

information has been created and populated, and 

linked to the vehicle emissions database. 

Additionally a user-friendly interface for database 

queries has been developed that requires no 

particular programming skill. Search results can be 

displayed or exported to text files for examination 

with other software tools. 

Results

The fuel property database was developed to 

include physical, chemical, and operability property 

data, as well as environmental health and safety 

information. The database is accessible via the World 

Wide Web at http://www.ott.doe.gov/fuelprops/ (see 

Figure 1).

The database was set up to allow the user to 

select individual fuels or properties, or to select all 

fuel and all property data. The initial page includes 

lists of fuels and properties that can be selected (see 

Figure 2). Output can be displayed in either SI or 

English units. The users can also access information 

on the test method used to obtain the property data, 

the reference source for the data, and a brief 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

84

description of the fuel. Figure 3 provides a sample of 

the results a user would get back from a query, with 

all selected (or available) data displayed in a table 

format. The database is also linked to the heavy 

vehicle chassis emissions data available from various 

DOE projects managed by NREL. The user can 

select the fuel in which he or she is interested (see 

Figure 4) and display vehicle characteristics and 

emissions data for all vehicles tested with that fuel.

Ongoing developments will allow creation of 

data files containing selected fuel properties for 

many fuels and related, selected vehicle and 

emissions data. For example, one could examine the 

impact of several diesel fuel properties on emissions 

for vehicles powered by conventional diesel, 

biodiesel, and Fischer-Tropsch diesel. A similar 

capability has been created for engine testing data. 

Engine data on how fuel sulfur content impacts 

performance of DPF and NOx adsorber/catalyst 

systems were obtained as a part of the APBF 

Program. These results were used to develop 

empirical correlations of emissions with fuel sulfur 

content. As an example, results for the DPF are 

described here. The DPF study generated engine-out 

and post-filter PM emissions data from a Caterpillar 

3126 engine using fuel containing sulfur at four 

levels (3, 30, 150, and 350 ppm) under three test 

conditions: (1) OICA 13-mode (one integrated 

sample), (2) "Road-Load" OICA mode 4 (733 Nm @ 

1,783 rpm), and (3) "Peak-Torque" OICA mode 2 

(1,047 Nm @ 1,440 rpm). Two types of DPF systems 

were tested: Catalyzed diesel particulate filter 

(CDPF) and continuously regenerated diesel 

particulate filter (CR-DPF). The best fit, based on 

linear correlation coefficients and other goodness-offit criteria, was achieved with the following model:

log(PM) = α + β *log(S) + e, (3.1)

where:

• log(PM) = log (base 10) of total PM 

emissions (g/bhp-hr)

• α and β are constants

• log(S) = log (base 10) of fuel sulfur level 

(ppm)

• e is a random error associated with 

measurement and testing. 

This model was applied separately to engine-out, 

post-CDPF, and post-CR-DPF total PM emissions. 

A comparison of data and empirical model 

predictions for engine-out and post-CDPF PM 

Figure 1. Fuel Property Database Homepage

Figure 2. Fuel Property Database Selection Page

Figure 3. Sample Results from Fuel Property Query

Figure 4. Heavy Vehicle Chassis Emissions Data 

Selection Page
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

85

emissions as a function of fuel sulfur content are 

shown in Figure 5. The models developed quite 

accurately fit engine-out emissions. For the postCDPF results there appears to be certain lack of fit at 

the 350-ppm sulfur fuel; this is likely due to 

increased variability that is typically found at higher 

emissions values. Log-linear models, commonly 

used in emissions analysis, assume that the 

magnitude of experimental error is proportional to 

the average value. Thus, the uncertainty in the 

predicted emissions tends to be proportional to the 

prediction. On a log scale the deviations from the 

regression line appear to be random, and variability 

is constant across fuel sulfur levels.

Conclusions

The fuel property database has been designed 

and developed, and it is being populated with fuel 

property data from various sources and programs. 

The database is accessible to DOE research partners 

via the Internet. This database is a warehouse of fuel 

properties, and as the database grows it will be 

utilized to develop predictive tools for estimating the 

effects that fuel properties have on emissions and 

emission control system performance. 

References

1. Yanowitz, J., McCormick, R.L., Graboski, M.S. 

"Critical Review: In-Use Emissions from HeavyDuty Diesel Vehicles" Environmental Science & 

Technology 34 729 (2000).

Figure 5. Predicted and average measured engine-out 

PM emissions (Cat 3126 engine) versus fuel 

sulfur level (top). Predicted and average 

measured post-CDPF PM emissions versus 

fuel sulfur level (bottom).
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

86

E. Isotopic Tracing of Fuel Components in Particulate Emissions from Diesel 

Engines Using Accelerator Mass Spectrometry (AMS)

Bruce A. Buchholz (Primary Contact)

Center for Accelerator Mass Spectrometry, L397

Lawrence Livermore National Laboratory

P.O. Box 808

Livermore, CA 94551

(925) 422-1739, fax: (925) 423-7884, e-mail: buchholz2@llnl.gov 

Charles J. Mueller

Sandia National Laboratories

7011 East Ave., MS 9053

Livermore, CA 94550-9517

(925) 294-2223, fax: (925) 294-1004, e-mail: cjmuell@sandia.gov

DOE Program Manager: John Garbak 

(202) 586-1723, fax: (202) 586-9811, e-mail: john.garbak@ee.doe.gov

DOE contract number W-7405-Eng-48

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

A. Fuel Property Effects on Engine Emissions and Efficiency

Tasks

2. Fuel & Lubricant Properties - Engine-Out Emissions

Objectives

• Determine contribution of diesel fuel components and oxygenates to soot formation.

• Separate volatile and non-volatile fractions of soot.

• Test combustion paradigm that all carbon and oxygen in fuel is equal.

• Produce data to validate combustion modeling.

Approach

• Construct filter assembly to collect exhaust soot.

• Analyze carbon isotope content of all fuel components and lubrication oil.

• Collect soot from skip fired 1.7L optical engine. Complete isotopic analyses of soot and determine 

contributions from available carbon sources.

Accomplishments

• Filter assembly constructed and in use.

• Preliminary tests completed to determine engine operating conditions for loading filters with sufficient 

soot for isotopic analyses. 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

87

• Determined lubrication oil leakage into the cylinder to be a major contributor of carbon emissions 

from the test engine.

Future Directions

• Determine contributions of major fuel components to soot production and test selected oxygenates.

• Collect gaseous emissions and separate major components.

• Obtain carbon-14 (14C) labeled lube oil and run it in conventional diesel engine. Determine 

contribution of lube oil to soot and CO2 emissions.

• Apply tracing techniques to HCCI engines.

Introduction

Accelerator mass spectrometry (AMS) is an 

isotope-ratio measurement technique developed in 

the late 1970s for tracing long-lived radioisotopes 

(e.g., 14C half life = 5760 yr). The technique counts 

individual nuclei rather than waiting for their 

radioactive decay, allowing measurement of more 

than 100 low-level 14C samples per day (Vogel et al, 

1995) (see Figure 1).

The contemporary quantity of 14C in living things 

(1.2 parts in 1012 or 110 fmol 14C/ g C) is highly 

elevated compared to the quantity of 14C in 

petroleum-derived products. This isotopic elevation 

is sufficient to trace the fate of bio-derived fuel 

components in the emissions of an engine without 

the use of radioactive materials. If synthesis of a fuel 

component from biologically-derived source 

material is not feasible, another approach is to 

purchase 14C-labeled material (e.g., dibutyl maleate 

(DBM)) and dilute it with petroleum-derived 

material to yield a contemporary level of 14C. In each 

case, the virtual absence of 14C in petroleum-based 

fuels gives a very low 14C background that makes 

this approach to tracing fuel components practical.

Regulatory pressure to significantly reduce the 

particulate emissions from diesel engines is driving 

research into understanding mechanisms of soot 

formation. If mechanisms are understood, then 

combustion modeling can be used to evaluate 

possible changes in fuel formulation and suggest 

possible fuel components that can improve 

combustion and reduce PM emissions. The 

combustion paradigm assumes that large molecules 

break down into small components and then build up 

again during soot formation. AMS allows us to label 

specific fuel components, including oxygenates, 

trace the carbon atoms, and test this combustion 

modeling paradigm.

Volatile and non-volatile organic fractions (VOF, 

NVOF) in the PM can be further separated. The VOF 

of the PM can be oxidized with catalysts in the 

exhaust stream to further decrease PM. The 

effectiveness of exhaust stream catalysts to oxidize 

products from tracer fuel components can be 

monitored through AMS measurement of carbon in 

PM.

Approach

The 14C concentration of all fuel components and 

the lubrication oil were checked by AMS and 

confirmed to be of petroleum origin (14C/C ratios 

~10-15). A test fuel containing 88% DBM, 7% nFigure 1. View of LLNL AMS system from above the 

high energy magnets. The shared facility 

annually measures 10,000 14C samples at 

precisions up to 0.8% and 14C/C ratios as low 

as 1 part in 1015.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

88

hexadecane (NHD) and 5% ethylhexyl nitrate (EHN) 

was spiked with [maleate-1,4-14C]- DBM to obtain 

fuel containing 78 fmol 14C/ g C, approximately 70% 

of the 14C found in living things.

Pre-combusted quartz filters were loaded with 

PM drawn from the exhaust manifold of a moderntechnology, 4-stroke, heavy-duty DI diesel engine 

that has been modified to provide extensive optical 

access into the combustion chamber. Injection timing 

was optimized such that the engine produced 

maximum gross indicated torque. The engine 

operated at 1200-rpm and moderate load (8.00 bar 

gross indicated mean effective pressure (gIMEP)). 

The optical engine was run in skip fire mode (firing 

every 12th cycle) and required 48 fires to deposit 

sufficient soot for isotopic analysis (see Figure 2). 

Filters were handled with stainless steel forceps and 

placed on aluminum foil after loading to avoid 

contamination with other carbon sources.

Some filters were baked at 340°C for 2 hr to 

remove the VOF fraction of the soot. The remaining 

carbon on the filters was assumed to be the NVOF. A 

procedure was developed using NIST SRM 2975 

diesel soot to obtain consistent isotope ratios and 

mass fraction of the NVOF. SRM 2975 has a 7% 

VOF by this procedure. A similar VOF is expected 

from the optical engine since the soot is collected 

close to the exhaust manifold without using a 

dilution tunnel. 

Results

All filters were loaded with a significant amount 

of carbon. Lubrication oil deposition on the filters 

was found to be a major component of the carbon 

inventory. The lube oil deposition decreased over 

the course of a day, but the total carbon remained 

significant on filters collected with motored cycles 

only (see Figure 3). The mass of carbon on filters 

collected with skip fires was no higher than those 

with motored cycles only. Furthermore, the 14C 

content of the motored and skip fired samples is 

almost identical. Although the 14C concentration in 

the fuel is ~1000x that of the lube oil, the carbon 

mass on the filters is almost entirely due to lube oil or 

its combustion products. The thermal treatment to 

isolate the NVOF removed all the carbon on control 

filters loaded with 2-7 mg of lube oil. Removing the 

VOF from the skip fired filters produced a consistent 

carbon mass (0.05 mg), but the isotope content 

varied by a factor of six. Only one NVOF sample 

had elevated 14C content so it is not clear if the 

labeled DBM in the NVOF or contemporary 

contamination introduced during processing is 

responsible for the signal. With the limited data 

available, it appears as though the 14C atoms in the 

DBM do not participate in soot formation.

Figure 2. Quartz filters loaded with emissions from 

optical engine. The filters were loaded with 

the following engine operating conditions: (A) 

motored only without firing, 12x48 cycles, 0.2 

mg C from lube oil; (B) motored with 48 skip 

fires, 12x48 cycles, 0.28 mg C from lube oil 

and soot; (C) motored with 96 skip fires, 

2x12x48cycles, 0.61 mg C from lube oil and 

soot. Figure 3. Carbon mass deposited on motored (M) and 

skip fired (F) filters during a day of operation. 

The filters are listed on the x-axis in the order 

in which they were collected. The mass of 

carbon was normalized to12x48 cycles for 

samples with different collection times. The 

NVOF carbon mass appeared to be consistent, 

suggesting the lube oil departed in the VOF.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

89

Conclusions

The large contribution of lubricating oil to the 

exhaust emissions, both as oil from non-fired cycles 

and as combusted soot, complicates quantitation of 

fuel components in PM. Results indicate that 14C 

atoms in the DBM contribute virtually no carbon to 

soot formation in this engine. It is impossible to 

separate the contributions of the other fuel 

components, NHD and EHN, from the lube oil due to 

their similar isotopic signatures. The lube oil signal 

needs to be reduced either by limiting leakage down 

the valves and into the cylinder or by removing noncombusted oil as part of sample pretreatment. The 

logical next step is to obtain labeled lubrication oil 

for use in this and a conventional engine and 

determine its contribution to PM emissions. 

Determining the contribution of lube oil to 

emissions is important for assessing viability of 

exhaust catalyst technology. 

Reference

1. Vogel, J. S.; Turtletaub, K. W.; Finkel, R.; 

Nelson, D. E. (1995) Accelerator Mass 

Spectrometry - Isotope Quantification at 

Attomole Sensitivity. Anal. Chem. 67, 353-9A

FY 2001 Presentation

1. Bruce Buchholz, Chuck Mueller, and Glen 

Martin. "Isotopic Tracing of Fuel Components 

in Particulate Emissions from Diesel Engines 

Using Accelerator Mass Spectrometry." DOE 

2001 Review of OTT CIDI Engine Combustion, 

Emission Control, & Fuels R&D National 

Laboratory Program, Oak Ridge, TN, June 11-

13, 2001.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

90

VII. FUELS FOR FUEL CELL VEHICLES

A. Demonstration of Fuel Cell Vehicles and Refueling Technology

Joseph J. Irvin

California Fuel Cell Partnership

3300 Industrial Boulevard, Suite 1000

West Sacramento, CA 95691

(916) 371-2870, fax: (916) 375-2008, e-mail: jirvin@cafcp.org

Website: www.fuelcellpartnership.org

DOE Program Manager: Pete Devlin

(202) 586-4905, fax: (202) 586-9811, e-mail: Peter.Devlin@ee.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

E. Health, Safety, and Regulatory Issues

F. Fueling Infrastructure For Non-Petroleum Based Fuels

H. Hydrogen Storage and Dispensing

J. Codes and Safety Standards

K. Full Fuel Cycle Emissions Analysis

Tasks

6. Demonstrate Off-board Hydrogen Fueling Infrastructure Technologies

Objectives

• Demonstrate fuel cell technology by operating and testing vehicles on California’s roads.

• Demonstrate alternative fuel refueling infrastructure technology.

• Explore the path to commercializationof fuel cell vehicles.

• Increase public awareness of fuel cell vehicles through a coordinated outreach plan.

Approach

• Adopt an organizational structure consisting of an Executive Committee, a Working Group, and a 

Communications Team to provide a decision-making structure for developing a workplan, budget, 

headquarters facility, and outreach strategy under the following timetable:

- Phase I through 1999, project development and planning, adding new partners, and preparing 

vehicle and refueling facilities;

- Phase II 2000-2001, demonstrate cars and buses using hydrogen fuel;

- Phase III 2002-2003, demonstrate more cars and buses using hydrogen, methanol, gasoline or 

other fuels as determined by the Partnership.

Accomplishments

• Headquarters facility built and occupied.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

91

• Additional partners added.

• Vehicle demonstration plans underway.

• Fuel Scenarios study completed.

Future Directions

• Identify additional fueling sites and fuel choices; assess commercialization issues; and determine 

potential post-partnership activities.

Introduction

The California Fuel Cell Partnership (CaFCP) is 

a path-breaking collaboration of auto companies, 

energy providers, fuel cell companies and 

government agencies that will place fuel cell electric 

vehicles on the road in California. The partners 

include companies and organizations from around 

the world: DaimlerChrysler, Ford, General Motors, 

Honda, Hyundai, Nissan, Toyota and Volkswagen; 

Ballard Power Systems, International Fuel Cells, and 

XCELLSiS; BP, ExxonMobil, Shell, and Texaco; and 

the California Air Resources Board, the California 

Energy Commission, the United States Department 

of Energy, the United States Department of 

Transportation and the South Coast Air Quality 

Management District. 

Additionally, there are ten Associate Partners 

who assist with specific areas of expertise to help 

meet the CaFCP’s goals: hydrogen gas suppliers (Air 

Products and Chemicals, Inc. and Praxair); hydrogen 

fueling stations (Hydrogen Burner Technology, 

Pacific Gas & Electric, Proton Energy Systems, Inc., 

and Stuart Energy Systems); a methanol fuel supplier 

(Methanex); and transit bus agencies (AC Transit and 

Santa Clara Valley Transportation Authority which 

operate in the Greater San Francisco Bay area, and 

SunLine Transit Agency in the Palm Springs area). 

Together, these members are working to 

investigate and evaluate the commercialization of 

fuel cell vehicle technology for the 21st century. 

The CaFCP is testing and demonstrating fuel cell 

electric vehicles in California through 2003 under 

day-to-day driving conditions; demonstrating 

alternative fuel infrastructure technology; exploring 

the path to commercializing fuel cell electric vehicles 

by examining such issues as fuel infrastructure 

requirements, vehicle and fuel safety, market 

incentives, and consumer acceptance; and working to 

increase public awareness of fuel cell vehicle 

technology and the benefits it can offer.

Approach 

Highlighting progress for the past year is 

completion of a headquarters facility in West 

Sacramento, California, which opened in November 

2000 to serve as an operations base for vehicle 

demonstrations and fueling operations (see Figure 1). 

The facility houses vehicle maintenance bays and a 

hydrogen fueling station (see Figure 2). It also serves 

as an educational center for fuel cell technology, with 

a public gallery and scheduled facility tours. 

To demonstrate fuel cell technology, ten 

passenger cars and one bus are currently operating on 

the city streets and highways of California. Over 70 

are expected to be in operation by the end of 2003. 

This activity not only provides vital technical 

information, but also serves to raise the profile of 

fuel cell vehicles by operating in public view and 

through participation in special public events.

Figure 1. The CaFCP Headquarters Facility in West 

Sacramento, CA
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

92

To support the driving demonstration, a fueling 

infrastructure for fuel cell vehicles is underway, 

beginning with hydrogen fuel. Methanol is expected 

to be in use by the end of 2001. The partners are also 

working together to promote the development of 

standards and specifications for fuels and the 

vehicle-fueling interface. This is a key benefit of 

bringing together vehicle manufacturers and fuel 

providers early in the process.

The members also commissioned a consultantdeveloped report that examines the challenges of 

using various fuels and infrastructure and identifies 

initiatives that can promote success. (Known as the 

Fuel Scenarios Study, the report was released to 

CaFCP members and the public in Fall 2001—see 

Figure 3.) Although the report has a California 

focus, similar challenges will exist in markets across 

the United States and around the world. The study 

will help the CaFCP members as well as others to 

become more fully engaged in addressing the 

challenges associated with the different possible fuel 

scenarios. 

The Partnership is taking steps to broaden public 

awareness of fuel cell vehicles by displaying vehicles 

at various public venues (see Figures 4 and 5), 

hosting classroom visits to its headquarters facility, 

and speaking about fuel cells to organized 

community groups and industry conferences. 

Through participation in public events, the CaFCP 

over the past year has reached thousands of people. 

The vehicles have served as the pace cars for two 

marathons — the California International Marathon in 

Figure 2. The Hydrogen Fueling Station - West 

Sacramento, CA

Figure 3. The fuels scenarios study, completed in 

October 2001, is available at 

www.fuelcellpartnership.org/

event_roundtable.html.

Figure 4. Vehicles on Display at the Headquarters 

Facility

Figure 5. Ford Focus on Display at Earth Day 2001 

Event, Los Angeles, CA
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

93

Sacramento and the Los Angeles marathon; multiple 

vehicles and displays were featured at the Orange 

County Fair; and as part of their ongoing test-drives, 

vehicles are parked in prominent public gathering 

places around Sacramento, engendering public 

attention and excitement. The Partnership’s Internet 

website (www.fuelcellpartnership.org) provides 

more educational information. 

Conclusion

The second year of the project featured several 

milestones marking the cooperative progress of this 

diverse, competitive, yet cooperative effort. The 

construction of a headquarters facility has boosted 

the effort to provide hands-on, visible evidence of the 

fuel cell in operation — a necessary step on the road 

to commercialization.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

94

B. Well-to-Wheel Analysis of Energy and Emission Impacts of Fuel-Cell Vehicle 

Fuels

Michael Wang

Argonne National Laboratory

ESD362/B215

9700 S. Cass Avenue

Argonne, IL 60439

(630) 252-2819, fax: (630) 252-3443, e-mail: mqwang@anl.gov

DOE Program Manager: Peter Devlin 

(202) 586-4905, fax: (202) 586-9811, e-mail: peter.devlin@ee.doe.gov

DOE Program Manager: Philip Patterson 

(202) 586-9121, fax: (202) 586-1637, e-mail: philip.patterson@ee.doe.gov

DOE Program Manager: David Rodgers 

(202) 586-7182, fax: (202) 586-9815, e-mail: david.rodgers@ee.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

K. Full Fuel Cycle Emissions Analysis

Tasks

2. Conduct Technical, Economic, and Environmental Assessments

Objectives

• Develop a comprehensive model to evaluate "well-to-wheel" (WTW) energy and emissions associated 

with fuel-cell vehicles powered by different fuels. 

• Characterize production pathways of various fuel-cell fuels, such as gaseous hydrogen, liquid 

hydrogen, methanol, gasoline, ethanol, and Fischer-Tropsch (FT) naphtha.

• Analyze key issues in production and distribution of fuel-cell fuels and evaluate their impacts on 

WTW energy and emissions.

Approach

• Revise Argonne’s GREET (Greenhouse gases, Regulated Emissions, and Energy use in 

Transportation) model to accommodate fuel-cell fuel options.

• Estimate emissions of greenhouse gases (CO2, CH4, and N2O) and criteria pollutants (VOCs, CO, NOx, 

PM10, and SOx) and energy use for all energy sources, fossil fuels (petroleum, natural gas, and coal), 

and petroleum used to make fuel-cell fuels.

• Specify production and distribution pathways for individual fuel-cell fuels.

• Search for literature and contact experts to obtain data on new technologies, energy efficiencies, and 

emissions associated with key WTW activities (e.g., fuel production and fuel-cell vehicle operations).

• Evaluate and process the data obtained for application to the GREET model.

• Conduct GREET simulations to generate WTW energy and emission results for various fuel-cell fuels.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

95

Accomplishments

• Included the following fuel-cell fuels in the GREET model: gaseous hydrogen (G.H2), liquid hydrogen 

(L.H2), methanol, gasoline, ethanol, naphtha, compressed natural gas (CNG), diesel, liquefied natural 

gas (LNG), and liquefied petroleum gas (LPG).

• Specified production and distribution pathways for each of the above fuels.

• Completed a new version of the GREET model — GREET 1.6. The beta version was sent to a group of 

selected GREET users for testing and evaluation.

• Applied GREET 1.6 to a study with General Motors Corporation comparing different vehicle 

technologies and fuels (see www.transportation.anl.gov). 

• Generated WTW energy and emission results for various fuel-cell fuels for the California Fuel-Cell 

Partnership.

Future Directions

• Revise key assumptions in GREET l.6 to reflect future technologies related to hydrogen production, 

distribution, and storage.

• Coordinate with managers of other ongoing DOE projects to better predict fuel economy of fuel-cell 

vehicles powered by different fuels.

• Seek feedback from GREET users to further improve the functionality of the GREET model.

• Continue to evaluate WTW energy and emissions impacts of fuel-cell fuels.

Introduction

Fuel-cell vehicles are being promoted for their 

energy efficiency and zero or near-zero emissions. 

Although experts agree that, in the long term, 

hydrogen will be selected as the best fuel-cell fuel, it 

may not be available on a large scale in the 

foreseeable future, mainly because of production and 

distribution infrastructure constraints. Intensive 

R&D efforts are being focused on other potential 

fuel-cell fuels. Because production and distribution 

of various fuel-cell fuels are subject to different 

energy efficiencies and emissions, WTW analysis is 

necessary to obtain impartial evaluations of fuel-cell 

vehicle/fuel systems.

Since 1995, with funds from DOE’s Office of 

Transportation Technologies (OTT), Argonne has 

been developing the GREET model to estimate fuelcycle energy use and emissions associated with new 

transportation fuels and advanced vehicle technologies. We have released a series of GREET versions 

with revisions, updates, and upgrades. The newest 

version — GREET 1.6 — is discussed in Wang (2001). 

Approach

For a given vehicle technology/transportation 

fuel combination, the GREET model separately 

calculates:

1. Fuel-cycle energy consumption for three energy 

categories (total energy, fossil fuels, and petroleum)

2. Fuel-cycle emissions of three greenhouse gases 

(CO2, CH4, N2O)

3. Fuel-cycle emissions of five criteria pollutants 

(total and urban emissions — VOCs, CO, NOx, 

PM10, and SOx)

Figure 1 shows the stages covered in GREET 

simulations of fuel cycles. A fuel-cycle analysis 

(also called a WTW analysis) includes the feedstock, 

fuel, and vehicle operation stages. The feedstock and 

fuel stages together are called well-to-pump (WTP) 

stages, and the vehicle operation stage is called the 

pump-to-wheel (PTW) stage. In GREET, fuel-cycle 

energy and emission results are presented separately 

for each of the two stages.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

96

GREET includes a variety of vehicle propulsion 

technologies and transportation fuels, of which fuelcell technologies and fuels are a sub-set. Table 1 lists 

the fuel-cell fuels included in the GREET model. 

GREET can simulate multiple options for a given 

pathway. For example, GREET 1.6 includes 48 

options for G.H2 and L.H2 pathways.

Results and Conclusions

Argonne applied GREET 1.6 to estimate WTW 

energy and emission impacts of various fuel-cell 

fuels. We cannot include all the results here, but 

Figures 2-4 provide a snapshot of WTW total energy 

use, fossil energy use, and CO2-equivalent 

greenhouse gas (GHG) emission impacts of fuel-cell 

fuels (see Figure Notes at end of section). 

For total energy use (including both 

nonrenewable and renewable energy sources), use of 

electrolysis hydrogen and cellulosic ethanol may 

increase total energy use, relative to baseline 

gasoline vehicles. However, when one considers 

fossil energy use (petroleum, natural gas, and coal), 

cellulosic ethanol is much more superior to any other 

fuel-cell fuels in reducing fossil fuel use.

Except for hydrogen via electrolysis, all the fuel-cell 

fuels achieve GHG emission reduction benefits 

(although if clean electricity such as hydroelectricity 

is to be used for hydrogen production, electrolysis 

hydrogen pathways will certainly achieve large GHG 

emission reduction benefits). Not surprisingly, 

renewable ethanol achieves the largest GHG 

emission benefits. 

Figure 1. Stages Covered in GREET Fuel-Cycle 

Analysis

FuelCell Fuel Production Pathways

G.H2 and 

L.H2

Central plant production from NA and NNA NG

Central plant production from NNA flared gas (FG)

Refueling station production from NA & NNA NG

Refueling station production from NNA FG

Solar photovoltaic

Electrolysis of water with conventional electricity

Methanol Production from NA and NNA NG

Production from NNA FG

Gasoline Federal Reformulated Gasoline (RFG)

California RFG

Diesel Low-sulfur diesel

Ethanol Production from corn

Production from woody biomass

Production from herbaceous biomass

CNG and 

LNG

Production from NA and NNA NG

Production from NNA FG

LPG Production from crude oil

Production from NG

Naphtha Production from NA and NNA NG via FT process

Production from NNA FG via FT process

Production from crude oil

Table 1. Fuel-Cell Fuels and Production Pathways

Figure 2. WTW Total Energy Use of Fuel-Cell Vehicles 

(Btu/mile)
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

97

The results depend heavily on assumptions 

regarding fuel production efficiencies and fuel-cell 

vehicle fuel economy. The GREET model can 

readily test alternative assumptions and provide 

WTW energy and emission results.

Figure and Table Notes

NA North American

NNA Non-North American

NG natural gas

FG flared gas

Central G.H2 gaseous hydrogen produced in 

centralized plants 

Central L.H2 liquid hydrogen produced in 

centralized plants 

Station G.H2 gaseous hydrogen produced in 

refueling stations with NA NG

Station L.H2 liquid hydrogen produced in 

refueling stations with NA NG

Electro. G.H2 gaseous hydrogen produced in 

refueling stations via electrolysis 

with U.S. average electricity

Electro. L.H2 liquid hydrogen produced in 

refueling stations via electrolysis 

with U.S. average electricity

MeOH methanol produced from NA NG

CNG compressed NG produced from NA 

NG

FT naphtha naphtha produced from NNA NG 

via the Fischer-Tropsch (FT) process

Crude naphtha naphtha produced from crude oil in 

petroleum refineries

WTP well-to-pump stages

PTW pump-to-wheel stages

Reference

1. Wang, M., 2001, Development and Use of 

GREET 1.6 Fuel-Cycle Model for 

Transportation Fuels and Vehicle Technologies,

ANL/ESD/TM-163, Center for Transportation 

Research, Argonne National Laboratory, 

Argonne, Ill., June.

Figure 3. WTW Fossil Energy Use of Fuel-Cell Vehicles 

(Btu/mile)

Figure 4. WTW Greenhouse Gas Emissions of Fuel-Cell 

Vehicles (grams/mile)
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

98

C. Guidance for Transportation Technologies: Fuel Choice for Fuel Cell Vehicles

Stephen Lasher (Primary Contact), Johannes Thijssen, Stefan Unnasch

Arthur D. Little, Inc.

Acorn Park

Cambridge MA, 02140

(617) 498-6108, fax: (617) 498-7054, e-mail: lasher.stephen@adlittle.com

DOE Program Manager: Peter Devlin 

(202) 586-4905, fax: (202) 586-9811, e-mail: Peter.Devlin@ee.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

C. Emission and Environmental Impacts

D. Advanced Fuel Production, Specifications, and Costs

E. Health, Safety, and Regulatory Issues

F. Fueling Infrastructure For Non-Petroleum Based Fuels

G. Distributed Hydrogen Production

H. Hydrogen Storage and Dispensing

I. Economic Feasibility

J. Codes and Safety Standards

K. Full Fuel Cycle Emissions Analysis

Tasks

2. Conduct Technical, Economic, and Environmental Assessments

7. Conduct Technical, Economic, and Environmental Assessments for Hydrogen Fueling Infrastructure

Objectives

The goal of this project is to help establish refined research and development (R&D) targets for directhydrogen fuel cell vehicles (FCVs) based on a comprehensive analysis of direct-hydrogen FCVs and 

competing vehicle technologies.

• Establish R&D targets for direct-hydrogen FCVs based on well-to-wheel comparison to reformerbased FCVs and other vehicles.

- Provide an independent analysis that leverages, and can be easily related to, previous DOE and 

Arthur D. Little analyses.

• Characterize various fuel chain and vehicle options based on well-to-wheel efficiency, greenhouse gas 

emissions, cost, and safety.

- Include methanol, ethanol, diesel, and gasoline, but focus on hydrogen fuel chains.

- Include internal combustion engine and hybrid vehicles, but focus on direct-hydrogen and 

reformer-based FCVs.

Approach

• Task 1: Develop a well-to-tank fuel chain model.

• Task 2: Determine fuel costs for each fuel chain.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

99

• Task 3: Develop a tank-to-wheel vehicle model.

• Task 4: Determine vehicle costs.

• Task 5: Perform a fuels safety analysis.

Accomplishments

All tasks have been completed, and final results are under review. 

This paper reports on the final results for Tasks 1 and 3 (efficiency and emissions analyses), as well as 

preliminary results for Tasks 2 and 4 (cost analyses). All data shared are still under final review and should 

therefore be considered preliminary.

Future Directions

As a part of the remainder of Phase II of this project, we will:

• Review preliminary fuel chain and vehicle results internally and with industry experts.

• Develop targets for on-site hydrogen production options and direct-hydrogen fuel cell vehicle systems.

In Phase III of the program, to commence in FY 2002, we will further expand the list of fuels considered, 

evaluate the impact on the current fuels infrastructure in more detail, and evaluate the risk of the fuel chain 

options to each of the stakeholders, in particular with respect to the financial exposure and risk for each of 

the stakeholders in the fuel chain.

Background

The DOE Office of Transportation Technologies 

has been supporting the development of polymer 

electrolyte membrane fuel cells (PEMFCs) for 

transportation applications. It has focused on 

gasoline-fueled fuel cell vehicles (FCVs), where the 

fuel (e.g. gasoline) is processed onboard the vehicle 

to generate hydrogen. An alternative strategy is to 

generate hydrogen at a fueling station and carry the 

molecular hydrogen onboard the vehicle for use in 

the PEMFC. DOE has commissioned this study to 

assess the opportunities and costs for generating 

hydrogen at fueling stations and storing it onboard 

vehicles, comparing the feasibility, efficiency, 

economy, and safety of this option with on-board 

reforming of gasoline. This information will develop 

a firm basis from which to set targets for a directhydrogen fuel cell vehicle program.

Approach

Arthur D. Little is developing detailed well-towheel performance and cost calculations taking into 

account technology options, system integration and 

efficiencies, hybridization, vehicle weight, and drive 

cycle. To the extent possible, we have taken 

advantage of Argonne National Lab’s Greenhouse 

gases, Regulated Emissions, and Energy use in 

Transportation (GREET) model, which provides a 

relatively well-referenced backbone for the model. 

This approach ensures efficient utilization of DOE’s 

resources and provides results that are as consistent 

with previous Argonne results as possible. However, 

we made several important improvements and 

extensions to the capabilities of GREET:

• We separated the well-to-tank analysis from the 

tank-to-wheel analysis to allow for sensible and 

transparent comparisons with existing fuel 

chains; 

• we updated the assumptions (especially for the 

fuel chain) with in-house Arthur D. Little 

information and original analysis where 

necessary; and

• we incorporated a more detailed and thorough 

analysis of fuel cell power unit performance over 

the drivecycle, based on a careful assessment of 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

100

fuel cell system turn-down characteristics. The 

basis for the analysis was the fuel cell 

performance model developed as a part of the 

automotive fuel cell costing program.

Additionally, we are determining fuel and 

vehicle ownership costs based on detailed local 

hydrogen fueling station cost analysis and bottom-up 

fuel cell component cost analysis. The vehicle cost 

estimates are based on, and consistent with, our 

automotive fuel cell costing study also carried out for 

DOE OTT. Also, we are identifying major potential 

safety issues for each of the fuel chains and 

comparing them to each other. Finally, we are using 

the analysis results to help formulate well-founded 

targets for the DOE’s direct-hydrogen FCV program.

Each of the options analyzed and shown in this 

report represents a future established market for fuels 

and vehicles, not early market penetration of the 

technologies. This means that for the purpose of the 

analyses, we assumed that for each fuel chain:

• Assumptions are consistent with established 

markets:

• The necessary fuel infrastructure has been 

established for each option and the 

infrastructure is operating at normal 

capacity.

• Vehicles are produced in high volumes (i.e. 

500,000 units per powertrain configuration).

• Assumptions are consistent with the situation in 

2010:

• Scenarios for 2010 technology performance 

and cost are used.

• EIA commodity energy price estimates for 

2010 were used as the baseline for energy 

price calculations.

Following is a brief description of the tasks 

carried out in this study.

Task 1: Develop well-to-tank fuel chain model

Arthur D. Little has adopted Argonne National 

Lab’s GREET framework to obtain efficiency and 

emissions results (on a g/GJ basis) independent of 

vehicle choice. The GREET model already includes 

a number of petroleum-based fuels, ethanol, 

methanol, and hydrogen, with inputs expressed as 

lower heating value efficiencies. We reviewed model 

inputs and compared those with existing internal 

models and data. Technology selection and other fuel 

chain assumptions were checked and additional 

hydrogen fuel chains were analyzed. For each 

hydrogen fuel chain, we evaluated the efficiency and 

emissions based on in-house information, literature 

review, and detailed system modeling. Centralized 

and local on-site hydrogen production options and 

high- and low-pressure hydrogen storage options 

were evaluated.

Task 2: Determine fuel costs for each fuel chain

The sources and methodology used to arrive at 

the fuel costs varied from fuel chain to fuel chain. 

For some of the conventional fuel chains, commodity 

price forecasts could be used, while for other options 

(including all the distributed hydrogen production 

options) costs were established based on detailed 

vendor quotes. All of the information was 

augmented with in-house ADL information and 

system modeling when appropriate. The capital cost 

estimates were based on an assumption of significant 

market penetration of each of the fuel chains (i.e. not 

addressing the "first hydrogen station" issue). Fuel 

prices are being determined based on the capital, 

operation and maintenance (O&M), and energy costs 

and appropriate economic assumptions.

Task 3: Develop tank-to-wheel vehicle model

Arthur D. Little is developing detailed tank-towheel performance calculations for fuel cell vehicles 

(FCV) incorporating vehicle weights, specifications 

(acceleration, top speed, hill climb), degree of 

hybridization, drivetrain efficiencies, and drive 

cycle. Technology selection and performance 

assumptions of the FCV options are being checked 

with in-house information, literature review, and 

system modeling, when appropriate. We are basing 

our FCV powerplant efficiency and power density 

estimates on our detailed 50 kW automotive fuel cell 

system model, which we developed for DOE/OTT 

under a separate program. Vehicle power plant size 

is scaled to vehicle weight for different drivetrain 

options. Drivetrain efficiencies at partial load (i.e. 

performance curves) have been generated based on 

available data and additional analysis.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

101

Task 4: Determine vehicle costs

Vehicle costs are being estimated based on 

component capital and O&M costs. A detailed cost 

assessment is being conducted on the fuel cell 

vehicle components, including the fuel cell stack, 

fuel processor or hydrogen storage, motor/

transmission, hybrid batteries (if necessary), and 

balance of plant. Vehicle capital costs are being 

combined with fuel costs to determine the total 

consumer cost for fuel cell, electric, hybrids, and 

conventional vehicle options. We are basing our FCV 

powerplant cost estimates on our detailed 50 kW 

automotive fuel cell system model, which we 

developed for DOE/OTT under a separate program.

Task 5: Perform fuels safety analysis

Arthur D. Little is reviewing the latest 

information on codes and standards and is 

identifying the key safety barriers for each fuel chain 

and end use option. As all of the fuels are already 

produced for industrial applications, the safety 

analysis is focusing on local storage, transportation, 

and vehicle end use. The results of this task include a 

presentation style report that documents references 

of fuel safety issues and properties of each fuel that 

affect safety. In addition to reviewing how fuel 

properties affect safety, the information is being 

categorized in terms of safety barriers for fuel 

dispensing, vehicle operation, and vehicle garage/

maintenance.

Preliminary Results

The drivetrain efficiency assumptions (i.e. 

performance curves) for FCVs are presented in 

Figure 1 with a comparison to a conventional internal 

combustion engine (ICE). Power electronics and 

motor efficiencies are not presented, but each varies 

between 85-95%. The performance curves are 

constructed from the sum of the fuel cell, parasitic 

power, and reformer (when present) efficiencies at 

full to partial load. The fuel cell efficiencies are 

constructed from our kinetic analysis of reformate 

and direct-hydrogen fuel cells based on current data 

and projected future performance. The analysis 

includes the effect of low pressure at partial load and 

high temperature membrane operation. The singlecell voltage at full power is selected to be 0.8 V for 

consistency with the cost analysis and previous DOE 

analyses. The single-cell voltage operating point is 

higher at partial load. The parasitic power 

calculations are based on the DOE goals for 

compressor/expander module performance and our 

own thermodynamic analysis for direct-hydrogen 

and reformer-based systems. The reformer 

efficiencies are based on in-house thermodynamic 

and kinetic analyses. We assumed future 

improvements in reformer turn-down and/or 

operating strategies that will allow a turn-down of 

20:1.

Preliminary well-to-wheel energy use (MJ/mi) 

results for conventional Internal Combustion Engine 

Vehicles (ICEV), Hybrid Electric Vehicles (HEV), 

and Fuel Cell Vehicles (FCV) can be found in Figure 

2. Additional results for direct-hydrogen FCV 

Figure 1: Drive-train Efficiency Assumptions Figure 2: Well-to-Wheel Energy Use for Various 

Vehicles
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

102

options and a Battery-Electric Vehicle (BEV) are 

presented in Figure 3. FCV results are based on 

aggressive technology improvements compared with 

the current technology status. These improvements 

would occur if existing multi-year R&D programs 

were successful in achieving their technical targets 

within reasonable bounds, and if the system 

integration were optimized to take advantage of the 

improvements in basic stack and fuel processor 

technology. The most significant improvement in 

fundamental technology assumed here was the 

availability of high temperature membranes.

The gasoline (RFG) and ethanol (E100) FCVs 

are assumed to be PEMFCs with autothermal 

reformers (ATR) for hydrogen generation. The 

methanol FCV uses a low temperature steam 

reformer (SR) to generate hydrogen, while the 

hydrogen for the compressed hydrogen (cH2) FCVs 

is produced off-board. Energy inputs for corn stover 

and corn-based E100 production are partially 

allocated to other coproducts. The corn stover option 

reflects collecting corn residue or other agricultural 

residues from existing agricultural operations.

The central production cH2 options include 

central steam reformer production from natural gas 

(NG) with tube trailer, liquid, and pipeline delivery 

to a hydrogen fueling station. The on-site cH2

production options include local on-site SR 

production from NG and on-site electrolyzer 

production from the U.S. average power plant mix. 

The energy station option assumes on-site SR 

production from NG with cogen heat from the 

reformer exhaust. All cH2 FCV options assume high 

pressure on-site storage (3600 psia on-site storage to 

5000 psia on-board the vehicle) except the metal 

hydride (MH) FCV option, which assumes low 

pressure on-site storage (100 psia on-site and onboard storage). Energy inputs for EV operation are 

based on the U.S. average power plant mix.

Preliminary fuel cost estimates ($/GJ) for 

gasoline (RFG), diesel, methanol, ethanol, electricity, 

and cH2 can be found in Figure 4. "Central Plant 

Cost" includes the central production costs and "Fuel 

Station Cost" includes transportation from the central 

plant (when applicable), capital, operation and 

maintenance, and energy costs of the local fueling 

station. The gasoline and diesel central plant costs 

are based on the EIA 2010 projection of crude oil 

price and historical wholesale gasoline to wholesale 

crude price ratios. The ethanol central plant cost is 

based on a USDA benchmark survey of wet and dry 

mill corn ethanol plants and our internal estimates for 

new dry mill capital costs. The methanol central 

plant cost is based on internal estimates and previous 

analysis. All central plant options assume 50 miles 

transportation distance to the local fueling station. 

Figure 3: Well-to-Wheel Energy Use for EVs and 

Direct-Hydrogen FCVs

Figure 4: Fuel Cost for Various Fuels

Figure 5: Fuel Cost Hydrogen
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

103

Costs include margins but exclude taxes. Fuel prices 

for a variety of hydrogen options are shown in Figure 

5. Hydrogen fueling station capital costs are based 

on detailed vendor quotes for equipment, which we 

have adjusted for higher production volumes. 

Assumed capital recovery factors for fueling stations 

and central plants are 11% and 17%, respectively. 

The EIA Annual Energy Outlook projected 2010 

electricity and natural gas prices are used to calculate 

fuel and power cost inputs to the central plant and 

local fueling station. The natural gas and electricity 

costs for the local fueling stations are assumed to be 

$5/MMBtu and $0.07/kWh, respectively, based on 

the EIA projection for commercial rates. All fueling 

stations assume 275,000 scfd hydrogen capacity 

(~300 vehicles/day) integrated into existing gasoline 

fueling stations.

Preliminary vehicle factory cost estimates are 

presented in Figure 6. FCV costs are based on 

stretch goals for fuel cell system performance and 

assume high automotive production volume (500,000 

units/year) manufacturing. The results presented 

separate the cost of the precious metals in the fuel 

cell and reformer (when applicable). These precious 

metals will likely have 80-90% salvage value at the 

end of the vehicle life. ICEV costs are based on 

conventional vehicles. All vehicles assume the same 

mid-sized vehicle platform with 350 mile range 

except for the EV, which has only a 120 mile range. 

Figure 7 shows vehicle ownership costs on a $/year 

basis. The analysis assumes 14,000 miles/yr of 

driving, 4% APR interest rate, 5 years finance period, 

and 39% residual vehicle value at the end of the 5 

year finance period for all vehicles. The precious 

metal content is assumed to have an 85% salvage 

value. Fuel costs are estimated based on calculated 

vehicle fuel economies and fuel prices before taxes. 

The fuel price for hydrogen vehicles assumes $20/

GJ. Operation and maintenance (O&M) costs 

assume 5,000 hour fuel cell stack life. O&M costs 

have not been analyzed in detail and are assumed to 

be essentially the same for all vehicles.

Well-to-wheel emissions data is not presented 

but will be included in the final report. The safety 

issues analysis is currently under review and results 

are not presented here.

Conclusions

Although some of the analyses are still under 

review, some key conclusions can already be drawn:

Drivetrain Efficiency Assumptions (Figure 1):

• Partial load efficiency is a major contributor to 

overall well-to-tank energy use because the 

vehicle spends most of its time at partial load.

• Reformer-based drivetrains have much lower 

efficiency at partial load due to heat losses and 

other inefficiencies in the reformer.

• High turn-down or other operating strategies that 

improve the minimum load efficiency are 

essential to the performance of reformer-based 

vehicles.

Well-to-Wheel Energy Use Results (Figures 2 and 3):

• Fuel cell powertrains are expected to be able to 

achieve the lowest well-to-wheels energy 

Figure 6: Vehicle Capital Costs for Various Vehicles

Figure 7: Vehicle Ownership Costs for Various Vehicles
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

104

consumption, provided efficient fuel chains are 

used. 

• Direct-hydrogen FCVs carrying compressed 

hydrogen produced from natural gas can 

offer well-to-wheels energy consumption of 

approximately half of conventional gasolinefueled vehicles: an unparalleled well-towheels efficiency.

• This high efficiency for direct-hydrogen 

FCVs is due to high continuous power 

efficiency and excellent turn-down 

performance. 

• Achieving this high efficiency is possible 

with hydrogen production from natural gas, 

provided that:

- hydrogen production facilities are 

thermally well-integrated,

- high vehicle fuel economy can be 

attained, and

- transportation distances are modest (50 

miles or less) for centralized production.

• If hydrogen for FCVs is produced via 

electrolysis, or hydrogen is liquefied in the 

fuel chain, well-to-wheels energy use of 

those FCVs is expected to be worse than that 

of vehicles based on other advanced 

powertrains. The electrolysis option would 

almost double primary energy use compared 

with conventional vehicles.

• Gasoline-fueled FCVs (with on-board 

reformer) are expected to achieve a 40% 

lower well-to-wheels energy consumption 

than conventional vehicles.

• The use of methanol in fuel cell vehicles 

leads to a considerably higher well-towheels energy consumption, despite the high 

vehicle efficiency, due to the significant 

losses incurred in fuel production. However, 

the use of methanol simplifies on-board fuel 

processing.

• The inefficiency of ethanol production leads 

to well-to-wheels primary energy 

consumption for ethanol FCVs slightly 

above that of conventional vehicles. Primary 

fossil fuel consumption is, of course, 

strongly reduced.

• Diesel HEVs can also approach a 40% reduction 

in well-to-wheels energy consumption over 

conventional vehicles.

• EV "fuel" chains have high energy consumption 

due to the relative inefficiency of power 

generation, resulting in a well-to-wheels energy 

consumption roughly the same as that of 

conventional vehicles.

Fuel Cost Results (Figures 4 and 5):

• The most economical hydrogen fuel chains are 

expected to be two to three times more expensive 

than gasoline, on a $/GJ basis.

• Hydrogen capital costs are four to seven 

times more expensive than gasoline capital 

costs (including local fueling station and 

central plant capital).

• Transportation and distribution costs 

(including on-site compression and storage 

for distributed production) are far higher 

than those for gasoline.

• Ethanol production and distribution in high 

volume is slightly less expensive than hydrogen 

from natural gas with the assumptions used in 

this study; however, these results depend 

strongly on natural gas prices and ethanol 

production costs.

• Future methanol price projections are close to 

gasoline prices on a $/GJ basis, assuming largescale fuel-methanol plants will be built in regions 

with remote or stranded natural gas.

• Electrolyzer-based production is costly with EIA 

energy price projections. Scenarios for load 

shifting and power price reductions were not 

analyzed here.

• Some alternative fuels, especially hydrogen, will 

require a significant upfront investment, 

representing a risk to both vehicle manufacturer 

and fuel provider stakeholders. Dealing with this 

risk represents a formidable barrier to the use of 

hydrogen for FCVs.

Vehicle Cost Results (Figures 6 and 7):

• Even including the technology improvements 

over current FCV technology, FCVs are 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

105

expected to add several thousand dollars to 

conventional ICE powertrain cost.

• Powertrain costs for direct-hydrogen FCVs are 

lower than those of systems with on-board 

reformers:

• Fuel processors add cost directly.

• Weight of fuel processors increases power 

requirements to achieve desired 

performance, thus increasing powerunit 

capacity.

• Reformer-based system fuel cell stack cost is 

higher due to reformate quality effects.

• Direct-hydrogen FCV cost could be further 

reduced if cost were optimized such that 

efficiency dropped to provide equal well-towheels primary energy consumption to gasoline 

FCVs.

• Higher vehicle costs for gasoline reformer based 

FCVs make them more expensive despite fuel 

cost savings. However, fuel costs have a 

significant impact on consumer opinion.

• Substantial additional technology breakthroughs 

will be required to achieve FCV cost 

competitiveness with ICEVs. 

• Fuel economy results and cost results are based 

on aggressive technology goals for hydrogen 

storage, fuel cell, and reformer power density, 

cost, and performance.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

106

D. Effects of Fuel Constituents on Fuel Processor Catalysts

John P. Kopasz (Primary Contact), Dan Applegate, Xiaoping Wang, Laura Miller, Shabbir Ahmed

Argonne National Laboratory

9700 S. Cass Ave

Argonne, IL 60439

(630) 252-7531, fax: (630) 972-4405, e-mail: Kopasz@cmt.anl.gov

DOE Program Manager: Peter Devlin 

(202) 586-4905, fax: (202) 586-9811, e-mail: peter.devlin@ee.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

B. Impact of Specific Fuel Constituents and Impurities on Fuel Processor/Fuel Cell Systems

Tasks

3. Evaluate Effects of Candidate Fuels on Fuel Processor

Objectives

• Identify the effects of major constituents, additives, and impurities of petroleum-based fuels on 

reformer performance.

• Evaluate the effects of fuel constituents and impurities on catalyst stability.

• Collaborate with major oil companies for development of future fuels for fuel cells.

Approach

• Investigate autothermal reforming of fuels and fuel constituents in microreactor. Rate performance 

based on byproduct formation, catalyst deactivation, and dependence of hydrogen yield and 

conversion efficiency on temperature and residence time.

• Begin tests with major constituents of gasoline, then test selected minor constituents, additives, and 

impurities by mixing with iso-octane.

• Test blends of fuel components to establish a composition/performance relationship matrix.

• Use long-term tests (>1000 h) to determine effects of fuel components on catalyst stability, poisoning 

and long-term degradation.

Accomplishments

• Completed short-term testing of major gasoline components

• Made recommendations to DOE on benchmark fuel compositions

• Completed long-term tests on iso-octane and two benchmark fuels, one without sulfur, one with sulfur

• Completed long-term testing of four reforming catalysts with benchmark fuels

• Determined that fuels with high aromatic content can be reformed for long periods (1000 h) with no 

adverse effects.

• Determined effects of sulfur on reforming catalyst performance are dependent on the catalyst

• Determined that Pt/Ceria catalysts are sulfur tolerant
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

107

• Determined that sulfur promotes coking on Co/Ceria catalysts

Future Directions

• Continue investigating effects of additives (detergents, antioxidants) and impurities

• Continue investigating reforming of blended fuels, determine composition/performance relationships 

from results

• Investigate differences in fuel reforming with different catalysts

• Make recommendations for fuel cell fuels

Introduction

On-board reforming of petroleum-based fuels, 

such as gasoline, may help ease the introduction of 

fuel cell vehicles to the marketplace. Although 

gasoline can be reformed, some constituents and 

impurities may have detrimental effects on the fuel 

processing catalysts, which may lead to 

compromised performance and decreased fuel 

conversion efficiency. In order to identify which 

constituents are beneficial and which are detrimental 

to the reformer, we have begun a program to test 

various components of gasoline and blends of 

gasoline streams under autothermal reforming 

conditions. 

Prior work focused on the autothermal reforming 

of some of the major constituents of gasoline. We 

investigated the autothermal reforming of iso-octane, 

n-octane, octane, trimethylbenzene, toluene, 

methylcyclohexane, and methylcyclopentane. These 

chemicals represent the branched paraffins, straight 

chain paraffins, olefins, aromatics, and cyclic 

paraffins present in gasoline. We observed that 

trimethylbenzene required more severe reforming 

conditions than the other components [1]. The 

current work has focused on the effects of blends of 

components and on the effects of sulfur impurities. 

Blends are being investigated to determine if the 

presence of some components can affect the 

reforming of others. Sulfur is of concern due to its 

propensity to poison catalysts. 

Approach

Reforming of the fuel blends is performed under 

constant O2:C and H2O:C ratios ( 0.42 and 1.4 ) on 

identical catalysts to allow for comparisons between 

the different fuels. Short term (<20h) tests are 

performed in a reactor containing ~2g of catalyst. 

The fuel and water are vaporized, then mixed and 

sent to the reactor where oxygen is added. Four 

sampling ports allow for testing at various positions 

(and space velocities) in the catalyst bed. A small 

portion (< 1%) of the gas stream is diverted through 

one of these ports to the residual gas analyzer for 

analysis. The remainder of the gas stream continues 

through the reactor bed to the exit stream. Batch 

sampling can be performed at the reactor exit.

Long-term tests (> 1000 h) are performed in a 

separate reactor equipped with a solid state on-line 

hydrogen sensor and infrared carbon monoxide and 

carbon dioxide detectors. Batch sampling can be 

performed at the exit stream. This system allows us 

to determine the durability of the autothermal 

reforming catalyst and to determine if there are any 

long-term problems (poisoning, coking) caused by 

the fuel components. 

Results

Testing blended fuels/mixtures

We have investigated the effects of reforming 

several fuel blends and refinery streams as well as 

mixtures of iso-octane and xylene to try to determine 

if there are synergistic or inhibitory effects from 

mixing the different components. As expected, 

aromatic fuel streams with high (>90%) aromatic 

content reformed poorly at low temperatures. In 

addition, blended streams that contained aromatics at 

about the 20% level provided lower hydrogen yields 

than paraffinic fuels at 750°C. Results from some of 

these tests are shown in Figure 1. We also observed 

that when aromatics were present the kinetics of C4 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

108

decay was decreased (C4 species are the main 

thermolysis product from isooctane). This is 

illustrated in Figure 2, which plots the butane decay 

constants determined for a paraffinic fuel and a 

paraffinic fuel with 20 wt% aromatics. This is similar 

to the inhibiting effects observed in combustion 

studies [2,3].

Effect of Sulfur

The effect of sulfur impurities on iso-octane 

reforming was determined by reforming iso-octane 

doped with benzothiophene to provide solutions with 

50 wppm sulfur. The effect on hydrogen yield at a 

gas hourly space velocity (GHSV) of 15,000 and a 

temperature of 800°C is shown in Figure 3. 

Hydrogen yields dropped for Ni, Co and Ru doped 

ceria catalysts, but increased for the Pt doped ceria 

catalyst. This suggests that sulfur is detrimental to 

reforming over Ni, Co and Ru catalysts, but that the 

Pt catalyst appears to benefit slightly from S. To 

investigate this effect further, isooctane solutions 

doped with benzothiophene to provide S levels of 0, 

10, 100, and 1000 wppm were investigated. The 

product gas composition for reforming these 

solutions at 800°C and a GHSV of 15,000 is shown 

in Figure 4. The hydrogen and CO yields increase 

when going from pure iso-octane to iso-octane + 10 

wppm S, but then decrease as the sulfur content is 

increased to 100 and 1300 wppm. Conversely, the 

methane and CO2 levels decrease when the sulfur 

level is increased from 0 to 10 wppm, then increase 

as the sulfur level is increased to 100 and 1300 

wppm. These tests indicate that the effect of sulfur 

impurities on reforming depends on the catalyst, and 

Figure 1. Hydrogen Yield from Different Fuels at 750°C 

and GHSV of 15000 Showing Lower 

Hydrogen Yields for Fuels with High 

Aromatic Content

Figure 2. C4 Decay Constants as a Function of 

Temperature for a Paraffinic Fuel and a 

Paraffinic Fuel with 20 wt% Aromatics Added

Figure 3. Comparison of Hydrogen Yield from 

Reforming Iso-octane and Iso-octane + 50 

wppm S over Several Different Catalysts 

(T=800°C, GHSV 15,000 h-1)

Figure 4. Effect of Sulfur Concentration on Reforming 

of Iso-octane over Pt-Ceria Catalysts 

(T=800°C, GHSV 15,000 h-1)
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

109

can vary from a negative effect for Ni, Co, and Ru 

catalysts to a positive effect for the Pt catalyst. With 

the Pt catalyst, the effect of sulfur impurities is also 

dependent on the sulfur content of the fuel. 

Long-term tests were also performed to 

determine the long-term effect of sulfur on 

reforming. The fuel for these tests was the 

benchmark fuel (74 wt% iso-octane, 20 wt% xylenes, 

5 wt% methylcyclohexane, 1 wt% pentene) doped 

with benzothiophene to provide 50 wppm S. Results 

for reforming over Pt-doped ceria and Co-doped 

ceria are shown in Figure 5. The Co catalyst activity 

decreased rapidly. The catalyst was regenerated and 

the test resumed, however activity again died off. 

After several regeneration-reaction cycles the 

original activity could no longer be achieved and the 

test was stopped. In contrast, the Pt catalyst activity 

remained high throughout the test, and degradation 

over the length of the test was similar to that for 

sulfur-free fuel.

Post-test examination of the Co catalyst revealed 

extensive coke formation, with carbon levels of 10-

14 wt% on the catalyst. A microscopic examination 

revealed the formation of carbon throughout the 

catalyst and the formation of carbon fibers extending 

into the void regions. However, very little sulfur was 

found on the catalyst (< 50 wppm S). These tests 

suggest that sulfur promotes coking on the Co-doped 

ceria catalysts. 

Conclusions

Fuel composition can have a large effect on 

reforming behavior. Fuels with high aromatic 

content were more difficult to reform. Aromatics 

were also found to have an impact on the kinetics for 

reforming of paraffins. The effects of sulfur 

impurities were dependent on the catalyst. Sulfur 

was detrimental for Ni, Co and Ru catalysts. Sulfur 

was beneficial for reforming with Pt catalysts; 

however, the effect was dependent on the sulfur 

concentration.

References

1. J. P. Kopasz, S. Ahmed, M. Krumpelt, and P. 

Devlin, SAE Technical Paper Series 20001-01-

1915, 2001.

2. J. J. Spivey, Ind. Eng. Chem. Res. 1987, 

26,2165-2180.

3. A. Barresi and G. Baldi, Ind. Eng. Chem. Res. 

1994,33,2964-2974.

Publications/Presentations

1. Effects of Gasoline Components on Fuel 

Processing and Implications for Fuel Cell Fuels, 

J. P. Kopasz, D. Applegate, L. Ruscic, S. Ahmed 

and M. Krumpelt, 2000 Fuel Cell Seminar, 

Portland, OR, Oct 30-Nov 2, 2000.

2. Gasoline- How Its Composition Affects 

Reforming and the Implication for Developing 

New Catalysts for On-board Reforming for Fuel 

Cell Vehicles, T. R. Krause, J. P. Kopasz, S. 

Ahmed and M. Krumpelt, AIChE Fall 2000 

Meeting, Los Angeles, CA, Nov. 12-17, 2000.

3. Challenges in Reforming Gasoline: All 

Components Are Not Created Equal, J. P. 

Kopasz, S. Ahmed, M. Krumpelt, and P. Devlin, 

SAE Technical Paper Series 20001-01-1915, 

Presented at SAE International Spring Fuels & 

Lubricants Meeting, Orlando FL, May 7-9, 2001.

Figure 5. Long-term Effects of Reforming Fuel with 50 

wppm S over Pt-Ceria and Co-Ceria Catalysts 

(GHSV 5,200 h-1)
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

110

E. Testing of Fuels in Fuel Cell Reformers

Rod Borup (Primary Contact), Michael Inbody, Lee Brown, Byron Morton, Troy Semelsberger, Lee 

Perry and Jerry Parkinson

ESA-EPE, MS J580

P.O. Box 1663

Los Alamos National Laboratory

Los Alamos, NM 87545

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

DOE Program Manager: Peter Devlin

(202) 586-4905, fax: (202) 586-9811, e-mail: Peter.Devlin@ee.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

A. Impact of Fuel Properties on Fuel Processor Performance

Tasks

4. Test Fuels in Fuel Processors and Fuel Cell Stack Systems

Objectives

• Explore effects of fuels, fuel components and fuel impurities on the performance of hydrogen 

generation technologies

- Quantify fuel effects on fuel processor performance

- Quantify fuel and fuel impurity effects on catalyst durability

- Understand the parameters that affect fuel processor lifetime and durability

Approach

• Examine fuel effects on fuel processing

- Examine individual fuel components

- Examine fuel component blends

- Examine ‘real’ fuels

• FY 2001: Concentrate on the fuel effects on:

- Carbon formation

- Gas phase vs. catalytic oxidation

- Catalyst performance and degradation

• Model fuel reforming chemistry

- Model carbon formation 

- Model equilibrium gas composition 

- Model thermodynamic properties
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

111

Accomplishments

• Tested iso-octane, iso-octane/xylene, naphtha, reformulated gasoline, diesel fuel components

• Examined fuels effects with:

- Homogeneous partial oxidation

- Catalytic oxidation

- Measurement of fuel oxidation kinetics and conversion 

- Diesel fuel components (dodecane, hexadecane)

• Observed carbon formation during experiments

- Used in situ laser diagnostics to monitor carbon formation

- Visually monitored carbon formation

• Modeled fuel and fuel component chemistry 

- Carbon formation conditions

- Equilibrium gas compositions

- Thermodynamic properties of fuel mixtures

Future Directions

• Evaluate effects of fuel constituents on fuel processor operation:

- Monitor carbon formation

• Measure carbon formation in situ with an adiabatic reactor and laser scattering

• Map carbon formation onset for component/component blends as a function of operating 

conditions

• Delineate carbon formation mechanisms

• Measure carbon effect on reforming and oxidation kinetics

• Measure carbon formation during start-up and reactor transients

• Measure carbon formation kinetics

• Define catalyst requirements for durability

- Measure fuel impurity effects

• Measure effects of bound nitrogen compounds

• Define partial oxidation/steam reforming nitrogen conversion products

• Measure sulfur effect on carbon formation

- Determine fuel additive effects on fuel processing

• Anti-oxidants

• Fuel detergents

• Oxygenated hydrocarbons

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

fuels
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

112

Introduction

This report describes our FY01 technical 

progress in examining the effects of fuel on hydrogen 

generation technology. The technology under study 

is designed to produce hydrogen for polymer 

electrolyte membrane (PEM) fuel cells for 

transportation. The goal of this research is to explore 

the effects of fuels, fuel constituents and fuel 

impurities on the performance of on-board hydrogen 

generation devices and consequently on the overall 

performance of a PEM fuel cell system using a 

reformed hydrocarbon fuel.

Different fuels have been tested to observe their 

relative reforming characteristics with various 

operating conditions. Both catalytic and 

homogeneous fuel processor partial oxidation stages 

were used in the tests of pure fuel components and 

mixtures such as iso-octane and iso-octane/xylene, 

and real fuels such as a hydro-treated naphtha and 

reformulated gasoline. Carbon formation was 

monitored during operation by in situ laser 

measurements of the effluent reformate and visual 

observations of the reactor.

Approach

To examine the fuels’ effects on hydrogen 

production devices, various fuel components and real 

fuels have been tested in fuel reformers. These fuels 

have been tested in catalytic partial oxidation and 

steam reforming reactors, and in non-catalytic 

(homogeneous) partial oxidation/steam reformers. 

Homogeneous partial oxidation has a potential 

advantage for meeting DOE start-up targets, as 

homogeneous partial oxidation does not require 

preheating before light-off of the reactor. This 

reactor was added to existing test facilities in 

FY2001, and is shown in Figure 1. 

In situ laser measurement of the effluent 

reformate and visual observation of the reactor 

catalyst during operation have been developed and 

used in this work to monitor carbon formation during 

operation. The relative distribution of the catalytic 

conversion has been observed with various fuel 

components with different catalyst substrates 

(monoliths and reticulated foams). Mapping of the 

onset of carbon formation for different fuel 

components as a function of operating conditions has 

been initiated with these techniques. The reactor 

with catalyst observation windows, laser extinction, 

and scattering facilities is shown in Figure 2.

Expected outlet concentrations of the fuel 

reformer, and the relative fuel component effects on 

the fuel reformer outlet have been modeled. In 

particular, modeling of equilibrium carbon formation 

has been used to predict the operating conditions for 

the onset of carbon formation for various fuel blends. 

The thermodynamic properties of fuel components 

have been calculated and modeled to create blends of 

pure fuel components that simulate gasoline with a 

minimal number of chemical components.

Figure 1. Homogeneous Partial Oxidation/Catalytic 

Steam Reforming System

Figure 2. Catalytic Partial Oxidation with Facilities for 

Laser Extinction and Scattering Measurements 

with Catalyst Observation
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

113

Results

Fuel Effects Comparisons of Homogeneous and 

Catalytic Partial Oxidation

Fuel effects on the relative rates of the catalytic 

partial oxidation reaction for different fuels have 

been measured. Figure 3 shows relative oxygen 

conversion as a function of residence time at an O/C 

= 0.7 for iso-octane, iso-octane/xylene, reformulated 

gasoline, and hydro-treated naphtha. As the reactor 

residence time decreases the relative conversion 

decreases for all of the different fuels tested; 

however, the addition of aromatic compounds to isooctane decreases the relative conversion at all 

residence times. At a higher relative oxygen content, 

O/C = 1.0, the fuel component effect on conversion 

is decreased as evidenced by Figure 4.

The fuel components and impurities help define the 

amount of noble metal that is required for the partial 

oxidation/steam reforming reactor. Sulfur has been 

observed to poison nickel steam reforming catalysts, 

whereas sulfur-free fuels may be reformed over 

nickel.1

 The addition of aromatic compounds 

decreases the relative conversion, thus increasing the 

need for additional noble metal loading. The results 

Figure 3. Catalytic Partial Oxidation Fuel Effects at O/C 

= 0.7 with Varying Residence Times

Figure 4. Catalytic Partial Oxidation Fuel Effects at O/C 

= 1.0 with Varying Residence Times

Figure 5. Homogeneous Partial Oxidation Outlet 

Temperature for Various Fuels with Varying 

O/C

Figure 6. Visual Observation of Partial Oxidation 

Catalyst Showing the Initiation and Hystersis 

of Carbon Formation
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

114

from the catalytic partial oxidation reactor indicate 

that for about a 50 kWe equivalent fuel production, 

about 2 g Pt is required if sulfur-free aliphatic 

hydrocarbons are used. However, with aromatic fuel 

addition, this increases by almost a factor of 2. 

The partial oxidation conversion for different 

fuels in a reactor with non-catalytic partial oxidation 

and catalytic steam reforming sections is shown in 

Figure 5. The results for homogeneous oxidation are 

significantly different than those for catalytic 

oxidation as the homogeneous reactor can operate 

with ‘real’ fuels achieving full conversion at lower 

O/C ratios. With the pure components the 

homogeneous oxidation could not fully convert the 

fuel, and the reactor temperature was drastically 

decreased. For full fuel conversion with the pure 

components, the required O/C ratio was > 1.0.

Carbon Formation

Figure 6 is a series of digital images of the outlet 

of the partial oxidation reactor during operation with 

hydro-treated naphtha fuel. As the O/C carbon ratio 

is decreased, carbon formation initiates at a relatively 

cool portion of the catalyst monolith, at an O/C ratio 

of 0.7. As the O/C ratio is increased, carbon 

formation continues, even though the operating 

conditions are repeated where it was not previously 

observed.

Laser extinction measurements have also been 

conducted to observe carbon formation. An example 

of this is shown in Figure 7. As the O/C carbon ratio 

is decreased, the outlet temperature (T19) decreases, 

and as the outlet temperature reaches approximately 

620°C, an increase in laser absorbance is measured, 

indicating the onset of carbon formation. Laser 

scattering measurements are being initiated to 

provide greater sensitivity in the measurement of 

carbon formation.

Figure 8 shows the results of modeling the onset 

of carbon formation for different fuels and operating 

conditions to compare with the experimental 

measurements. Diesel fuel components show higher 

temperatures are required to prevent carbon 

formation, with relative S/C ratio having a dramatic 

impact on the carbon formation temperature.

 

Conclusions

Various fuel components and fuels have been tested 

with various O/C and S/C ratios in both catalytic and 

homogeneous partial oxidation reactors. Homogeneous oxidation occurs easier with ‘real’ fuels than 

with the pure components of iso-octane and isooctane/xylene. The addition of aromatics slows the 

overall reaction rate for catalytic oxidation. Diesel 

fuel components (such as dodecane) require higher 

residence times for similar conversions. The fuel 

composition, especially sulfur content and aromatic 

content, affects the relative amount of noble metal 

required for the fuel reformer. Modeling has shown 

that fuel effects on the temperature for equilibrium 

onset of carbon formation can vary up to 150°C with 

varying O/C ratios. Carbon formation has been 

observed to occur with hysteresis.

Figure 7. Extinction Laser Signal Showing Carbon 

Formation as Partial Oxidation O/C Ratio is 

Decreased (as observed by decreasing 

temperature)

Figure 8. Equilibrium Modeling of Carbon Formation 

for Various Fuels and Conditions
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

115

References

1. Borup et al. Fuel Composition Effects on Fuel 

Processor Dynamics, Office of Advanced 

Automotive Technologies Transportation Fuel 

Cell Power Systems FY 2000 Accomplishments 

Report.

Presentations/Publications

1. "Devising 3-, 4-, and 6-Component Simulated 

Gasolines for Use in Modeling Studies and 

Laboratory Experiments," Los Alamos National 

Laboratory publication, LAUR-01-2477, May 

2001.

2. "Thermodynamic Aspects of Autothermal 

Processes for Generating Hydrogen-Rich FuelCell Feeds," AIChE Meeting, Spring 2001, 

Houston Texas, Los Alamos National Laboratory 

publication, LAUR-01-2156, April 2001.

3. "Hydrogen Production and Utilization in PEM 

Fuel Cells," (poster), National Hydrogen 

Association Meeting, Washington D.C., Los 

Alamos National Laboratory publication, 

LAUR-01-1074, March 2001.

4. "Hydrogen Production and Utilization in PEM 

Fuel Cells," (abstract), National Hydrogen 

Association Meeting, Washington D.C., Los 

Alamos National Laboratory publication, 

LAUR-01-683, February 2001.

5. "Hydrogen Production for Fuel Cells: Fuel 

Constituent Effect on Fuel Processor 

Performance, Catalyst Durability and Carbon 

Formation," North American Symposium on 

Chemical Reaction Engineering, Houston, TX, 

Los Alamos National Laboratory publication 

LAUR-00-5657, December 2000.

6. "Fuel Constituent Effect on Fuel Processor 

Performance, Catalyst Durability and Carbon 

Formation," American Institute of Chemical 

Engineers, Houston, TX, Los Alamos National 

Laboratory publication LAUR-00-5656, 

December 2000.

7. "Fuel Composition Effects on Fuel Processor 

Dynamics," American Institute of Chemical 

Engineers, Los Angeles, CA, Los Alamos 

National Laboratory publication LAUR-005395, 

November 2000.

8. "Catalysts for Improved Fuel Processing," 

American Institute of Chemical Engineers, Los 

Angeles, CA, Los Alamos National Laboratory 

publication LAUR-005392, November 2000.

9. "Thermodynamic Aspects of Autothermal 

Processes for Generating Hydrogen-Rich FuelCell Feeds from Various Primary Fuels," 

American Institute of Chemical Engineers, 

Houston, TX, Los Alamos National Laboratory 

publication LAUR-00-5236, November 2000.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

116

F. Standard Hydrocarbon Fuel for Fuel Cell Vehicles

John Kopasz (Primary Contact), Shabbir Ahmed, and Michael Krumpelt

Argonne National Laboratory 

9700 South Cass Avenue 

Argonne, IL 60439

(630) 252-7531, fax: (630) 972-4405, e-mail: kopasz@cmt.anl.gov

DOE Program Manager: Peter Devlin 

(202) 586-4905, fax: 202-586-4500, e-mail: peter.devlin@ee.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

D. Advanced Fuel Production, Specifications, and Costs

Tasks

3. Evaluate Effects of Candidate Fuels on Fuel Processor

Objectives

• The objective of this project is to determine the specifications for a fuel cell reference fuel which can 

be used to quantify the performance of different fuel processors. 

Approach

• Specify a mixture (blend) of a small number of individual hydrocarbons and some of the typical 

gasoline additives.

• Test the benchmark fuel in the Argonne National Laboratory (ANL) auto-thermal reformer (ATR) to 

characterize its performance.

Accomplishments

• Specifications for a benchmark fuel (Fuel I) have been developed.

• The composition/formulation of Benchmark Fuel I has been provided to several organizations that are 

developing automotive fuel processors.

Future Directions

• This project has been carried to completion to support the currently planned fuel reformer and fuels 

characterization R&D at ANL. Other fuel constituents can be added to the fuel specification to support 

future work as needed.

Introduction

California reformulated gasoline (C-RFG) has 

been identified as one fuel to be used in fuel cell 

systems to be developed under DOE sponsorship. 

However, there are considerable variations in the 

composition of C-RFG from one batch to the next. 

Another option is to use the certified gasoline 

provided by Phillips Petroleum Company for 

emissions certification of new vehicles in fuel 

reformer development. A third alternative is to 

specify a mixture (blend) of a small number of 

individual hydrocarbons and some of the typical 

gasoline additives. This blend could then be 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

117

prepared by any of the fuel processor or fuel cell 

system developers as and when needed. A 

preliminary selection of a Benchmark Fuel I has been 

developed and is being used in Argonne fuel 

processing R&D. The formulation has also been 

provided to others developing fuel processors for 

transportation applications. Specifications for 

additional benchmark fuels can be developed as 

needed.

Approach 

Our approach involved a literature survey of 

gasoline formulations, detailed analyses of selected 

samples of retail gasoline, consultations with major 

energy suppliers, and modeling and experimental 

work. Experimental studies were conducted in a 

microreactor system to validate the predicted 

operating parameters. 

Results

Based on discussions with suppliers, a survey of 

the literature, and detailed chemical analyses of 

selected samples of retail gasoline, the most 

representative components of current gasoline blends 

were selected in the percentage amounts shown in 

Table 1 to define the Benchmark Fuel I. 

To represent the sulfur anticipated to be present 

in future grades of reformulated gasoline, 

benzothiphene may be added to provide 50 ppm (by 

weight) of sulfur. 

An example of the initial reformate produced by 

the autothermal reforming of Benchmark Fuel I 

using a commercial formulation of the Argonnedeveloped catalyst is shown in Figure 1. The test 

was begun with sulfur-free Benchmark Fuel I. After 

115 h, the fuel was switched to sulfur-containing 

Benchmark Fuel I. The data show the reformability 

(product gas composition) of the sulfur-free and 

sulfur-containing fuels to be comparable. 

Conclusions

Benchmark Fuel I was developed to be 

representative of future reformulated gasoline using 

widely available hydrocarbons. This fuel 

specification can be reproduced in any laboratory, 

and the results for reforming this fuel can be 

compared to determine the difference attributable to 

the process and not the input fuel. Further 

development of a standard fuel can be undertaken as 

needed in the future to accommodate further 

refinements in fuel cell component development 

objectives.

Component Wt% in Benchmark Fuel I

Iso-octane 74

Xylenes 20

Methylcyclohexane 5

n-pentene 1

Table 1. Benchmark Fuel I Composition

Figure 1. Long-term Test of Commercial Autothermal 

Reforming Catalyst with Benchmark FuelI 

without and with 50 wppm S
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

118

G. Sulfur Removal from Reformate

Theodore Krause (Primary Contact), David Carter, Jennifer Mawdsley, Romesh Kumar, and Michael 

Krumpelt

Argonne National Laboratory 

9700 South Cass Avenue 

Argonne, IL 60439

(630) 252-4356, fax: (630) 972-4463, e-mail: krause@cmt.anl.gov

DOE Program Manger: Peter Devlin 

(202) 586-4905, fax: (202) 586-9811, e-mail: peter.devlin@ee.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

B. Impact of Specific Fuel Constituents and Impurities on Fuel Processor/Fuel Cell Systems

Tasks

3. Evaluate Effects of Candidate Fuels on Fuel Processor

Objectives

• Adapt proven technologies for on-board fuel processing capable of reducing the H2S concentration to 

<1 ppm in reformate.

• Develop new technologies or improve existing technologies to meet the following DOE targets for 

H2S removal: (1) H2S concentration of <0.1 ppm in reformate, (2) a reactor size of <0.06 L/kWe 

(<0.06 kg/kWe), and (3) gas hourly space velocity (GHSV) of 50,000 h-1.

Approach

• Perform thermodynamic calculations to predict the H2S equilibrium partial pressure for candidate 

adsorbents (metal sulfide-H2S equilibrium) and identify candidate materials.

• Complete reaction modeling to estimate the operating parameters for a sulfur removal unit based on 

adsorption.

• Conduct experimental studies in a microreactor system to determine design parameters (e.g., sulfur 

loading capacity, rate of reaction) as a function of operating parameters (e.g., temperature, GHSV, 

water content in reformate).

Accomplishments

• ZnO-coated monoliths were fabricated by Sud-Chemie.

• Evaluated the performance of the ZnO-coated monoliths, demonstrating that the H2S concentration can 

be reduced to ~1 ppm under fuel processing conditions.

• Concluded that a sulfur removal process based solely on ZnO will not meet the DOE targets for onboard sulfur removal.

• Identified new classes of compounds that may be capable of meeting the DOE target for the H2S 

concentration in reformate.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

119

Future Directions

• Improve the mechanical stability of the ZnO microchannel and evaluate its performance. 

• Screen CuO/MnO and CuO/MoO sorbents for use in fuel processing.

• Conduct feasibility studies of non-adsorption technologies such as membrane separations and 

chemical processing for removing sulfur from reformate in the fuel processor.

• Evaluate sulfur tolerance of new water-gas shift and POx catalysts.

Introduction

With the new lower sulfur content of 30 ppm 

average and 80 ppm maximum (by weight) proposed 

for gasolines in FY 2006, reformate produced by 

autothermal reforming of these gasolines will contain 

3-8 ppm of H2S. Even at this low concentration, H2S 

is known to poison many of the catalysts being 

developed for use in the fuel processor for polymer 

electrolyte membrane fuel cell (PEMFC) systems. 

For example, an H2S concentration of <50 ppb is 

recommended for copper-zinc oxide water-gas shift 

catalysts. Further, the Pt-anode catalyst in the 

PEMFC is irreversibly poisoned at an H2S 

concentration as low as 200 ppb.1

In earlier work, we conducted a review of the 

technical and patent literature to identify candidate 

technologies for removing H2S from reformate under 

fuel processing conditions. We identified adsorption 

with chemical reaction as the most promising 

technology. Based on thermodynamic equilibrium 

calculations, we identified candidate metals and 

metal oxides that should be capable of reducing the 

concentration of H2S to <1 ppm and which do not 

promote any undesirable side reactions under fuel 

processing conditions. Zinc oxide was selected as 

the initial candidate sorbent. We concluded that a 

thin ZnO layer (~50-100 μm) supported on a 

structured form, such as a monolith or microchannel, 

would be better suited for transportation applications 

than the commercial pellet form of ZnO, resulting in 

a significant reduction in the weight of the sulfur 

removal unit while providing better mechanical 

stability.

Approach

Our approach involves both modeling and 

experimental work. Thermodynamic equilibrium

calculations and non-catalytic gas-solid reaction 

models, such as the shrinking core model, are used to 

design the sulfur removal unit and to determine the 

optimal operating parameters (e.g., temperature, 

space velocity, bed lifetime) for ZnO. Experimental 

studies are conducted in a microreactor system to 

validate the predicted operating parameters. 

Based on such modeling, a thin ZnO layer (~50-

100 μm) supported on a structured form, such as a 

monolith or a microchannel configuration, is 

predicted to provide a higher reactive surface area 

per unit volume and to be more efficient than a pellet 

form for removing H2S from reformate in a fuel 

processor. To test these conclusions, a cordierite 

monolith was coated with a thin ZnO layer by SudChemie, Inc. The monolith was cored to provide 

smaller diameter samples for testing in our 

microreactor system (see Figure 1). The samples 

were evaluated by exposing them to simulated 

reformates containing 10-100 ppm H2S at various 

temperatures, space velocities, and water vapor 

Figure 1. Core Sample of a ZnO-Coated Cordierite 

Monolith Produced by Sud-Chemie, Inc.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

120

content. The removal efficacy was determined by 

measuring the H2S concentration in the effluent 

stream (using gas chromatography) as a function of 

the H2S and H2O concentration in the inlet stream, 

temperature, and gas hourly space velocity.

Results

Based on thermodynamic calculations, ZnO 

should be able to reduce the H2S concentration to 

≤1 ppm in reformate containing ≤0.35 atm of H2O at 

an operating temperature of ≤400°C (see Figure 2). 

To meet the more stringent DOE FY 2008 target of 

0.1 ppm H2S, the ZnO sorbent would need to operate 

at a temperature of ≤300°C. 

Experimental testing of the core samples from 

the ZnO monolith indicated that high operating 

temperatures are required to overcome the slow 

reaction rate

H2S + ZnO ↔ ZnS + H2O

and that equilibrium concentrations of H2S can not be 

achieved when operating at ≤400°C, even at a GHSV 

as low as 1000 h-1 (see Figure 3). For simulated 

reformate containing 19 ppm H2S and 0.18 atm H2O, 

an H2S concentration of 1-2 ppm was measured in 

the effluent after contacting the ZnO-coated monolith 

at 480°C and a GHSV of ≤2000 h-1. When the 

temperature was decreased to 280°C, the H2S 

concentration increased to 4-5 ppm, in contrast to the 

thermodynamic equilibrium value of ~60 ppb. A 

comparison of the residual H2S concentration for a 

dry and a wet (0.18 atm) reformate, both containing 

19 ppm H2S, shows that the H2S concentration 

increases nearly linearly with increasing GHSV 

above 2000 h-1 at 380°C (see Figure 4). This 

increase in the residual H2S concentration with 

increasing GHSV is most likely due to 

"breakthrough" as a consequence of the laminar flow 

in the flow channels of the monolith.

Conclusions

ZnO offers certain advantages for sulfur removal 

in fuel processing: it is stable under reformate 

conditions, it does not need any activation before 

use, and it does not catalyze any undesirable 

secondary reactions. Because of the extremely slow 

reaction kinetics, however, a ZnO-based sulfur 

Figure 2. Equilibrium Concentration of H2S as a 

Function of the H2O Partial Pressure in 

Reformate at Temperatures between 300°C 

and 500°C

Figure 3. Outlet H2S Concentration as a Function of 

GHSV at Various Temperatures for an Inlet 

H2S Concentration of 19 ppm and a Water 

Partial Pressure of 0.18 atm H2O

Figure 4. Outlet H2S Concentration as a Function of 

GHSV for Two H2O Partial Pressures (0 atm 

and 0.18 atm H2O) at 380°C for an Inlet H2S 

Concentration of 19 ppm
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

121

removal unit will need to operate at temperatures 

well above those that are necessary to achieve the 

target of 0.1 ppm H2S. Even at the higher 

temperatures, this structured form of ZnO must be 

operated at a GHSV considerably lower than the 

long-term target value of 50,000 h-1.

References

1. T. Zawodzinski, F. Uribe, W. Smith, T. Springer, 

J. Valerio, D. Vernon, T. Rockward, 

D. McMurry, G. Bender, M. Hickner, E. Brosha, 

B. Orler, and C. Adams, "R&D on Optimized 

Cell Performance for Operation on Reformate 

and Air," presented at the DOE Fuel Cells for 

Transportation National Laboratory R&D 

Meeting, June 6-8, 2001, Oak Ridge, TN.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

122

VIII. DME FUEL SYSTEM TESTING

A. Exhaust Emissions and Performance of a CIDI Engine Fueled with DME - 

Phase 3

Jim McCandless

AVL Powertrain Technologies, Inc.

47519 Halyard Drive

Plymouth, MI 48170-2438

(734) 414-9588, fax: (734) 414-9690; e-mail: jim.mccandless@avlna.com 

DOE Program Manager: John Garbak 

(202) 586-1723, fax: (202) 586-9811, e-mail: john.garbak@ee.doe.gov

DOE Program Manager: Lucito Cataquiz

(202) 586-0729, fax: (202) 586-9811, e-mail: lucito.cataquiz@ee.doe.gov

This project addresses the following OTT R&D Plan barriers and tasks:

Barriers

A. Fuel Property Effects on Engine Emissions and Efficiency

Tasks

2. Fuel & Lubricant Properties - Engine-Out Emissions

7. Vehicle Materials Compatibility

Objectives

• Develop a dimethyl ether (DME) fuel injection system for a small CIDI engine

• Demonstrate the exhaust emissions potential of a DME fueled CIDI engine under road loads

Approach

• Phase 1— Design a DME common rail fuel injection system suitable for use on a small CIDI engine, 

including a variable displacement, high-pressure supply pump to ensure system efficiency (reported 

previously—not part of this report).

• Phase 2 — Fabricate fuel system; test and develop hardware on a test bench (reported previously—not 

part of this report).

• Phase 3 — Demonstrate exhaust emissions and performance of the Ford DIATA CIDI engine fueled 

with DME (using the fuel system developed in previous phases).

Accomplishments

• NOx emissions were lowered 85-90% (to 0.33 g/kW-hr) compared to the best published diesel results 

by use of much larger percentages of EGR than is possible with compression-ignition direct injection 

(CIDI) engines using diesel fuel.

• Smoke was reduced below the level of detection (0.05 Bosch Smoke Number).

• Fuel consumption (energy equivalent) was similar to the diesel baseline
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

123

• CO emissions were excessive at very low NOx levels; an oxidation catalyst is necessary to provide 

acceptable levels of CO.

Introduction

The potential of dimethyl ether (DME) as an 

automotive fuel was first reported in 19951

. This 

report showed that very low emissions could be 

achieved using DME, but that an all-new fuel system 

would be necessary.

In 1997, AVL Powertrain Technologies began the 

development of a complete DME fuel system for a 

small CIDI engine. Ultimately, this program led to 

the emissions demonstration reported here.

The fuel system that was developed and later 

demonstrated includes a unique fuel storage tank and 

delivery system2

, a novel common rail fuel injection 

system3

, and a highly efficient, variable displacement 

(inlet throttled) high pressure supply pump4

. In 

addition to these hardware developments, significant 

investigations were made regarding the thermochemical properties of DME5

.

Summary of Results

Figure 1 shows the DME fuel injection system 

installed on the Ford DIATA CIDI engine. This 

hardware packages well on the engine and is 

production feasible.

Figure 2 compares diesel and DME NOx

emissions, fuel consumption and smoke at 2000 rpm, 

2-bar brake mean effective pressure (bmep). As 

shown, DME achieves an 85% NOx reduction with 

similar or lower fuel consumption (energy 

equivalent). Smoke emissions are reduced below 

detection limits with the use of DME.

The very low NOx levels with DME were 

achieved by using high rates of EGR (~70%). This is 

not possible using diesel fuel because EGR raises 

smoke emissions significantly and the allowable 

smoke limit is reached at 15 to 40% EGR, depending 

on engine speed and load.

Figure 3 compares NOx-CO-HC emissions of the 

diesel baseline and DME at 2000 rpm, 2-bar bmep. 

CO & HC emissions are similar for both fuels at a 

given NOx emission level. When NOx emissions are 

lowered to <1 g/kW-hr (1/2 the diesel best), CO 

1. SAE 950061 A New Clean Diesel Technology: Demonstration of ULEV Emissions on a Navistar Diesel 

Engine Fueled with DME

2. SAE 2001-01-0652 Development of a Liquid-DME 

Fuel Tank A Two-Fluid Thermodynamic Pump

3. SAE 970220 Development of a Novel Fuel Injection 

System for DME 

4. SAE 2001-01-0687 Development of a Variable Displacement Rail Pressure Supply Pump for DME

5. SAE 2001-01-0154 Thermochemical Characteristics of 

DME an Alternative Fuel for Compression-Ignition 

Engines

Figure 1. DME Fuel System Installed on Ford DIATA 

CIDI Engine

Figure 2. NOx-BSFC-Smoke Relationship (2000 RPM, 2 

Bar BMEP-Optimum Calibration)
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

124

emissions increase rapidly. An oxidation catalyst can 

suppress CO & HC emissions to acceptable levels 

when NOx is lowered to ~0.3 g/kW-hr.

Tables 1-3 summarize and compare emissions and 

performance of diesel to those of DME at 3 speeds 

and loads. DME reduces NOx emissions 85-90%, 

eliminates smoke emissions and achieves similar fuel 

consumption (energy equivalent). Although CO and 

HC emissions are high at very low levels of NOx, an 

efficient oxidation catalyst circumvents this problem.

A fuel pump mechanical failure terminated the 

test program before all of the desired test data could 

be run. A plunger slipper separated from the cam 

face, causing damage to the cam and adjacent 

plungers (see Figure 4).

Failure analysis showed that the plunger spring 

force was not sufficient to assure that slippers remain 

in their proper orientation with the cam under all 

running conditions. Design changes have been made 

to increase plunger spring loads and eliminate future 

similar failures.

Figure 3. NOx-CO-HC Characteristics (2000 RPM, 2-

bar bmep)

Fuel Diesel DME DME

NOx (g/kW-hr) 2.06 0.33 0.33

BSFC (g/kW-hr) 404 385 385

CO (g/kW-hr) 4.97 26 2.6

HC (g/kW-hr) 0.89 2.19 0.219

Smoke (Bosch) 0.76 0 0

EGR (%) 40 65-70 65-70

Remarks Baseline 

diesel @ 

smoke limit

DME 

engine out

Estimated 

DME + 

oxidation 

catalyst

Table 1. 2000 RPM, 2-bar bmep Emissions and 

Performance Summary

Fuel Diesel DME DME

NOx (g/kW-hr) 2.12 0.29 0.29

BSFC (g/kW-hr) 332 326 326

CO (g/kW-hr) 8 29.4 2.94

HC (g/kW-hr) 0.60 2.13 0.213

Smoke (Bosch) 0.70 0 0

EGR (%) 32 65-70 65-70

Remarks Baseline 

diesel @ 

smoke limit

DME 

engine out

Estimated 

DME + 

oxidation 

catalyst

Table 2. 1500 RPM, 2.62-bar bmep Emissions and 

Performance Summary

Fuel Diesel DME DME

NOx (g/kW-hr) 4.3 0.42 0.42

BSFC (g/kW-hr) 290 328 328

CO (g/kW-hr) 2.22 18.34 1.83

HC (g/kW-hr) 0.37 2.94 0.29

Smoke (Bosch) 0.79 0 0

EGR (%) 15 65-70 65-70

Remarks Baseline 

diesel @ 

smoke limit

DME 

engine out

Estimated 

DME + 

oxidation 

catalyst

Table 3. 2300 RPM, 4.2-bar bmep Emissions and 

Performance Summary

Figure 4. Cross-Section of DME Direct Injection Fuel 

Pump Illustrating the Plunger Slipper Failure
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

125

Conclusions

• A production feasible DME fuel system has been 

successfully demonstrated.

• Test results with DME indicate that with 

additional development, Tier 2 NOx and 

particulate emissions might be achieved (though 

probably only the higher bins) without the use of 

emission control devices such as particulate traps 

and NOx adsorbers.

• DME facilitates much lower NOx emissions 

through much higher tolerance of EGR.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

126
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

127

APPENDIX A - Acronyms

1-D One-dimensional

AIChE American Institute of Chemical 

Engineers

Al2O3 Aluminum oxide

ANL Argonne National Laboratory

APR Annual Percentage Rate

atm Atmospheres

bhp-hr Brake horsepower-hour

Bmep Brake mean effective pressure

BSFC Brake Specific Fuel Consumption

C Carbon

o

C Degrees Celsius

CARB California Air Resources Board

CFD Computational Fluid Dynamics

cfm Cubic feet per minute

CH4 Methane

CIDI Compression Ignition Direct Injection

Co Cobalt

CO Carbon monoxide

CO2 Carbon dioxide

CRADA Cooperative Research & Development 

Agreement

Cu Copper

CuO Copper oxide

DECSE Diesel Emissions Control Sulfur 

Effects

DI Direct Injection

DIATA Direct Injection, Aluminum, Throughbolt Assembly

DOE Department of Energy

DPF Diesel Particulate Filter

ECS Emission Control System

EGR Exhaust Gas Recirculation

EIA Energy Information Administration

EPA Environmental Protection Agency

o

F Degrees Fahrenheit

Fe Iron

FT Fischer Tropsch

ft Foot/feet

FTP Federal Test Procedure

FY Fiscal Year

g Grams

g/GJ Grams per gigajoule

g/hp-h Grams per horsepower-hour

GHSV Gas Hourly Space Velocity

hHours

H2 Diatomic hydrogen

H2O Water

HC Hydrocarbon

HCCI Homogeneous Charge Compression 

Ignition

He Helium

HO2 Hydroxyl radical

hp Horsepower

hr Hour

H2S Hydrogen sulfide

ISB Integrated System B (Cummins diesel 

engine)

J/deg Joules per degree

K Potassium

kg Kilogram

kW Kilowatt

kWe Kilowatt-electric

kWh or kW-hr Kilowatt-hours

L Liter

LANL Los Alamos National Laboratory

LHV Lower Heating Value

LLNL Laurence Livermore National 

Laboratory

MECA Manufacturers of Emissions Controls 

Association

mg Milligram

mi Mile

MJ/mi Megajoule per mile

μm Micron

mm Millimeter

MMBtu Million British Thermal Units

MnO Manganese oxide

Mo Molybdenum 

MoO Molybdenum oxide

MPa Megapascals

mphMiles per hour

Ni Nickel

Nm Newton-meters

nm Nanometers

NO Nitric oxide

N2O Nitrous oxide

NOx Oxides of nitrogen

NREL National Renewable Energy Laboratory

NVOF Non-Volatile Organic Fraction

O2 Diatomic oxygen

OAAT Office of Advanced Automotive 

Technologies

O/C Oxygen to carbon ratio

OEM Original Equipment Manufacturer
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

128

OH Hydroxyl radical

OHVT Office of Heavy Vehicle Technologies

ORNL Oak Ridge National Laboratory

OTT Office of Transportation Technology

PAH Polycyclic Aromatic Hydrocarbon

Pd Palladium

PM Particulate Matter

PEM Polymer Electrolyte Membrane

POx Partial oxidation

ppb Parts per billion

ppm Parts per million

psia Pounds per square inch absolute

psig Pounds per square inch gauge

Pt Platinum

R&D Research and Development

RPM Revolutions Per Minute

Ru Ruthenium 

s Seconds

S Sulfur

SAE Society of Automotive Engineers

S/C Steam to carbon ratio

scfd Standard cubic feet per day

SCR Selective Catalytic Reduction

Si Silicon

SNL Sandia National Laboratories

SO4 Sulfate

SOF Soluble Organic Fraction

SOx Oxides of sulfur

SUV Sport Utility Vehicle

SwRI Southwest Research Institute

TDC Top Dead Center

THC Total hydrocarbons

US06 EPA high speed/load transient driving 

cycle

USDA United States Department of Agriculture

V Volts

VOC Volatile organic compound

VOF Volatile organic fraction

vol% Percent by volume

WO3 Tungsten trioxide

wt-% or wt% Percent by weight

yr Year

ZnO Zinc oxide

Zr Zirconium 
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

129

APPENDIX B - APBF Technical Targets for CIDI Engines

Table B-1. 2003 Targeted Emissions-Reduction Contributions for the Major Elements of CIDI Engine Power Systems

[For an 80-mpg PNGV-type passenger car (2000 lb)]

Emissions, g/mile

Emission reductions, 

g/mile

Percentage 

reduction Comments

NOx PM NOx PM NOx PM

Baseline 0.40 0.04

Scaled from emissions 

index from current CIDI 

engines extrapolated to a 

PNGV-type passenger car

Engine development 0.36 0.04 0.04 0 10 0

Advanced combustion, 

improved fuel injection, 

optimum use of EGR

Fuel reformulationa 0.36 0.03 0 0.01 0 25 Estimates supported by 

existing data

Emission control 

devices 0.07 0.01 0.29 0.02 81b 67b Assumes NOx adsorber 

and catalyzed soot filter

Targets 0.07 0.01 Targets met

Table B-2. Technical Targets for Advanced Petroleum-Based Fuels

Characteristic Units

2003 Targets

80-mpg PNGV-type car

Health effects

 Unregulated toxics and ultra-fine PM

 Groundwater contamination potential

 Health and safety of fuel

(by analysis) No significant increase in composite 

risk compared with conventional fuels

Life-cycle greenhouse and criteria emissions (by analysis) No increase

Increase in fuel price % of retail premium 

diesel <5

Cost-effective emission reduction (NOx plus 

nonmethane hydrocarbons; based on incremental emission control system costs)

$/ton less than 5000a

a

These are emission targets obtained by advanced petroleum-based fuels that must also enable all CIDI engine targets (e.g., 

durability, emissions, fuel economy penalty) to be met simultaneously. b

These are the average percentage reductions needed. It is recognized that the actual percentage reductions will need to be higher 

to account for deterioration in use and production variability.

 a

Value based on EPA estimates in the Tier 2 Regulatory Impact Analysis for a Tier 2 light-duty vehicle relative to a national lowemission vehicle.
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

130

APPENDIX C - Fuels for Fuel Cells Technical Targets

1 2004 target taken to be halfway between current status and 2008 targets. The 2004 targets represent a 1.5X vehicle in terms of

fuel efficiency and a 2.1X vehicle in terms of GHGs. The 2008 targets represent a 2.0X vehicle in terms of fuel efficiency and a 2.3X 

vehicle in terms of GHGs. 2

 Cost based on a hydrogen fueling station serving 300 cars per day (~10,000 std m3 per day). Assumes 3 employees at $50,000/

year. Annual capital charge, mark-up (profit, marketing, etc.), and maintenance assumed to be 15%, 25%, and 10% of total capital cost, 

respectively. 3

 Based on ADL bottoms-up cost analysis of a partial oxidation (POX) reformer and BOP at production volumes of 100 units per 

year. Natural gas and electricity demand based on ADL experience. Assumes a natural gas price of $3/GJ and electricity price of $0.05/

kWh.4

 The reformer exhaust goes directly into the purification process, where the GHGs are separated from hydrogen and emitted.

5

 Assuming a steam methane reformer operating at 5-20 atm.

Table C-1. Technical Targets for the Fuels for On-Board Fuel Flexible Fuel Processing

Description Target

• Fuel Retail Price • <5% increase over premium gasoline at retail

• Fuel Processor/Fuel Cell Stack System 

Durability

• Over 5,000 hours thermal cycling simulating realistic driving 

cycles

• Well-to-Wheel Fuel Cycle Energy 

Efficiency

• Factor of 1.5 improvement relative to conventional SI-IC engine

• Emissions • 0.02 g/mile NOx and 0.01 g/mile PM (full useful life FTP 

emissions)

• Greenhouse Gases • One-third reduction compared to conventional SI-IC engines in 

similar type vehicles

• Health and Safety Impacts

 - Toxics

 - Groundwater contamination

• Equal to or improvement relative to conventional gasoline (by 

model analysis)

Table C-2. Preliminary Technical Targets for the Off-Board Hydrogen Infrastructure

Units Current 2004 1 2008

Reforming

Cost 2 $/GJ H2 7.38 3 7.20 7

GHGs 4 g/km 0 0 0

Energy Efficiency % (HHV) 75-80 5 80-82 85

Purification

Cost 2 $/GJ H2 1.50 6 1.20 1

GHGs 4 g/km 108 100 91

Energy Efficiency % (HHV) 75-90 7 82-90 90

Compression

Cost 2 $/GJ H2 2.06 8 1.50 1 9

GHGs 4 g/km 10 8.5 7

Energy Efficiency % (HHV) 80-90 10 82-92 85-93

Storage & 

Dispensing

Cost 2 $/GJ H2 2.40 11 2.20 2

GHGs 4 g/km 0 0 0

Energy Efficiency % (HHV) 100 12 100 100
Fuels for Advanced CIDI Engines and Fuel Cells FY 2001 Progress Report

131

6

 Based on low end of vendor quotes for a small-scale PSA system.

7

 Assuming a small-scale PSA system operating at reformer outlet pressure.

8

 Based on a 4 stage compressor with intercooling and a cooling tower. Maximum outlet pressure assumed to be 400 atm. 

Compressor assumed to be 20% more expensive than comparable CNG compressors. Assumes an electricity price of $0.05/kWh. 9

 Assuming low-pressure (50 atm) hydrogen storage (such as hydrides). Compressor electricity demand would be about half that 

at high pressure (400 atm). Assumes compressor capital costs would also be reduced in half due to simplicity of design (less 

intercooling, no cooling tower, etc.). 10 Based on a 4 stage intercooled compressor with an exit pressure of 400 atm. Assumes a US average power generation efficiency 

of 30%, and compressor adiabatic efficiency of 65-75%. 11 Based on high-pressure (400 atm) gas storage. Estimated from multiple vendors of comparable CNG equipment.

12 Assuming high-pressure gas storage with no leaks during storage or dispensing.
This document highlights work sponsored by agencies of the U.S. Government. Neither the U.S.

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or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately

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expressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof.

Printed on recycled paper
www.cartech.doe.gov

DOE/EERE/OTT/OAAT - 2001/005

Office of Transportation Technologies

Series of 2001 Annual Progress Reports

• Office of Advanced Automotive 

Technologies FY 2001 Program Highlights

• Vehicle Propulsion and Ancillary Subsystems

• Automotive Lightweighting Materials

• Automotive Propulsion Materials

• Fuels for Advanced CIDI Engines and Fuel Cells

• Spark Ignition, Direct Injection Engine R&D 

• Combustion and Emission Control for 

Advanced CIDI Engines

• Fuel Cells for Transportation

• Advanced Technology Development 

(High-Power Battery) 

• Batteries for Advanced Transportation 

Technologies (High-Energy Battery) 

• Vehicle Power Electronics and Electric Machines

• Vehicle High-Power Energy Storage

• Electric Vehicle Batteries R&D