This document summarizes a 12-month evaluation of 15 transit buses operated by St. Louis Metro that compared the performance of 8 buses running on B20 biodiesel fuel to 7 control buses running on ultra-low sulfur diesel (ULSD). Key findings include: - The B20 buses exhibited a 1.7% lower fuel economy than the ULSD buses. - Reliability as measured by miles between road calls was comparable between the two fuel types. - Total maintenance costs were not significantly different, but engine and fuel system maintenance costs were 35% higher for the B20 buses, though this difference was not statistically significant. - The B20 buses had more frequent replacement of fuel filters and fuel inject

1. A national laboratory of the U.S. Department of Energy
Office of Energy Efficiency & Renewable Energy
National Renewable Energy Laboratory
Innovation for Our Energy Future
Technical Report
St. Louis Metro Biodiesel (B20) NREL/TP-540-43486
Transit Bus Evaluation July 2008
12-Month Final Report
R. Barnitt, R.L. McCormick, and M. Lammert
NREL is operated by Midwest Research Institute ● Battelle Contract No. DE-AC36-99-GO10337

2. Technical Report
St. Louis Metro Biodiesel (B20) NREL/TP-540-43486
Transit Bus Evaluation July 2008
12-Month Final Report
R. Barnitt, R.L. McCormick, and M. Lammert
Prepared under Task No. FC08.9460
National Renewable Energy Laboratory
1617 Cole Boulevard, Golden, Colorado 80401-3393
303-275-3000 • www.nrel.gov
Operated for the U.S. Department of Energy
Office of Energy Efficiency and Renewable Energy
by Midwest Research Institute • Battelle
Contract No. DE-AC36-99-GO10337

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4. List of Acronyms
APTA American Public Transit Association
ASTM American Society of Testing and Materials
AVTA Advanced Vehicle Testing Activity
bhp brake horsepower
DOE U.S. Department of Energy
DPF diesel particulate filter
EGR exhaust gas recirculation
g/bhp-hr grams per brake horsepower-hour
GVWR gross vehicle weight rating
MBRC miles between road calls
NREL National Renewable Energy Laboratory
PM preventative maintenance
RC road call
TBN total base number
ULSD ultra-low sulfur diesel
UST underground storage tank
um micrometer
iii

5. Executive Summary
The St. Louis Metro Biodiesel Transit Bus Evaluation project is being conducted under a
Cooperative Research and Development Agreement (CRADA) between the National
Renewable Energy Laboratory (NREL) and the National Biodiesel Board (NBB) to
evaluate the extended in-use performance of buses operating on B20 (20% biodiesel;
80% conventional diesel) fuel. It is one component of a larger effort with respect to
biodiesel testing and evaluation.
The objective of this research project is to compare B20 and ultra-low sulfur diesel
(ULSD) buses in terms of fuel economy, vehicle maintenance, engine performance,
component wear, and lube oil performance.
The evaluations we present in this report examine fifteen 40-foot model year (MY) 2002
transit buses manufactured by Gillig equipped with MY 2002 (2004 emissions
certification) Cummins ISM engines. For a period of 12 months, eight of these buses
operated exclusively on B20 and the other seven operated exclusively on petroleum
ULSD. The B20 and ULSD study groups operated from different depots at St. Louis
Metro, but bus routes were matched for duty cycle parity.
Based on the in-use evaluation results:
• The B20 buses exhibited 1.7% lower fuel economy than the ULSD study group.
• Reliability, as measured by miles between road calls (MBRC), was comparable
between the two study groups.
• There was no significant difference in total maintenance costs between the two
groups.
• Engine and fuel system maintenance costs were 35% higher for the B20 study group,
but because of bus-to-bus variability in maintenance costs, a statistical analysis shows
that this difference is not significant with a high level of confidence (P=0.21).
• The B20 study group had a higher incidence of fuel filter and fuel injector
replacements. Analysis of B100 and B20 samples did not indicate poor fuel quality.
No fuel injectors were retained for tear-down analysis to determine failure mode and
cause.
• Lube oil samples were collected over a wide range of mileage within the drain
interval, and analysis indicates no harm and some potential benefits with B20 use;
notably, soot and wear metals were lower. Viscosity, total base number, and corrosive
metals were generally less degraded by ULSD use, but these qualities were still “in-
grade” for the B20 buses throughout the oil drain interval.
This evaluation is being continued for a second year in order to provide more definitive
answers to questions about how B20 impacts engine and fuel system maintenance, as
well as other factors.
iv

6. Table of Contents
Background ......................................................................................................... 1
Objectives ............................................................................................................ 1
St. Louis Metro Fleet Operations and Facilities ............................................... 1
Operations..........................................................................................................................1
Facilities ............................................................................................................................2
Approach ............................................................................................................. 2
Vehicle Selection ...............................................................................................................2
Route / Duty-Cycle Selection ............................................................................................3
Vehicle Fueling and Data Collection ................................................................................4
Vehicle Reliability .............................................................................................................4
Vehicle Maintenance and Data Collection ........................................................................4
Vehicle Warranty Repairs ...............................................................................................5
Biodiesel Fuel Analysis .....................................................................................................5
Lube Oil Analysis ..............................................................................................................5
Evaluation Results .............................................................................................. 6
Bus Use ..............................................................................................................................6
Fuel Economy and Cost.....................................................................................................7
Vehicle Reliability Analysis ..............................................................................................8
Maintenance Cost Analysis ...............................................................................................9
Total Maintenance Costs ...............................................................................................10
Engine and Fuel System Maintenance Costs ................................................................11
Fuel System Component Replacements ..........................................................................13
Biodiesel Fuel Analysis and Results ...............................................................................16
Lube Oil Analysis and Results ........................................................................................18
Conclusions ...................................................................................................... 22
Appendix ........................................................................................................... 23
Evaluation and Vehicle Specifications ............................................................................23
v

7. Background
This project is being conducted under a Cooperative Research and Development Agreement
(CRADA) between the National Renewable Energy Laboratory (NREL) and the National
Biodiesel Board (NBB). This project is one component of a larger effort with respect to biodiesel
testing and evaluation. Under the CRADA, NREL accomplished a detailed data collection and
analysis on the St. Louis Metro (Metro) transit fleet's experience operating on B20 (20%
biodiesel; 80% conventional diesel) for a period of 12 months. This study is the first B20 in-use
fleet study using exhaust gas recirculation (EGR) equipped buses. This study is also the first
study to compare the use of B20 to ultra-low sulfur diesel (ULSD).
The work is being performed by the Fleet Test and Evaluation (FT&E) team at NREL, which
provides unbiased evaluations on alternative fuel and advanced transportation technologies that
aim to reduce U.S. dependence on foreign oil while improving the nation’s air quality. The
FT&E team’s role is to bridge the gap between research and development (R&D) and the
commercial availability of alternative fuels and advanced vehicle technologies. FT&E supports
DOE’s Vehicle Technologies Program by examining market factors and customer requirements,
evaluating the performance and durability of alternative fuel and advanced technology vehicles,
and assessing the performance of these vehicles in fleet applications.
The FT&E team supports vehicle research activities at NREL by conducting medium- and
heavy-duty vehicle evaluations. The team’s tasks include selecting appropriate technologies to
validate, identifying fleets to evaluate, designing test plans, gathering on-site data, preparing
technical reports, and communicating results on its Web site and in print publications. NREL has
completed numerous light- and heavy-duty vehicle evaluations based on an established data
collection protocol, known as the General Evaluation Plan, 1 developed with and for DOE. This
project supports DOE’s Nonpetroleum Based Fuels (NPBF) activity.
Objectives
The objective of this project is to evaluate the extended in-use performance of B20 fuel. Specific
objectives are to compare fuel economy, vehicle maintenance, engine performance, component
wear, and lube oil performance against ULSD.
St. Louis Metro Fleet Operations and Facilities
Operations
St. Louis Metro (Metro) was created in 1949 through a compact between the states of Missouri
and Illinois and ratified by the United States Congress. Metro's broad powers enable it to cross
local, county, and state boundaries to plan, construct, maintain, own, and operate specific
facilities in its efforts to enhance the quality of life in the region. Its service area encompasses
200 municipalities.
Metro owns and operates the St. Louis Metropolitan region's public transportation system. The
system includes MetroLink, the region's light rail system; MetroBus, the region's bus system; and
Metro Call-A-Ride, a paratransit van system. Metro also oversees the operations of the St. Louis
1
Available on the Web at www.nrel.gov/vehiclesandfuels/fleettest/pdfs/32392.pdf.
1

8. Downtown Airport and surrounding industrial business park, the Gateway Arch Revenue
Collections Center, the Gateway Arch Transportation System, the Gateway Arch Riverboats, and
the Gateway Arch Parking Facility.
In FY 2005, Metro transported over 46.5 million passengers on the MetroLink, MetroBus, and
Metro Call-A-Ride systems. Metro maintains a fleet of 433 buses, 77 light rail vehicles, and 125
paratransit vans.
Facilities
Metro maintains four garage facilities (Main, Brentwood, Debaliveire and Illinois), two of which
are the focus of this evaluation. The Brentwood Garage (BW) dispatches and maintains the B20-
fueled buses and the Debaliveire Garage (DB) is the diesel bus control group.
Buses at each garage are fueled daily, to every other day at two indoor fueling dispensers. As
part of service and cleaning operations, the buses are washed and fueled in the evening hours as
buses return to the garage. Service and cleaning personnel fuel the buses, while hubodometer
readings and fuel volume dispensed are automatically logged electronically.
Maintenance is also performed on the buses at each facility in several bays dedicated for
maintenance operations. Depending on the service required, buses are lifted on hoists or driven
over pits to perform necessary repairs or inspections. Maintenance work is recorded
electronically by mechanics, capturing data on repair codes, parts, and labor hours.
Approach
Vehicle Selection
Fifteen identical buses are included in this evaluation project. Eight of the buses operate on B20
fuel and seven operate on ULSD to serve as a control group. Basic vehicle attributes are
presented in Table 1, and detailed vehicle specifications can be found in Appendix A. Operation
and maintenance data is collected during normal operation and analyzed to evaluate
performance.
Table 1. Metro B20 Transit Bus Basic Description
Vehicle Information Evaluation Buses
(Diesel and B20)
Number of Buses 7 Diesel (Bus #s 3401-3407)
8 B20 (Bus #s 3408-3415)
Chassis Manufacturer/Model Gillig
Chassis Model Year 2002
Engine Manufacturer/Model Cummins ISM
Engine Model Year 2002 (2004 emissions certification)
Engine Ratings
Max. Horsepower 280hp @ 2100 rpm
Max. Torque 900 lb-ft @ 1200 rpm
Fuel Capacity 125 gallons
Transmission Manufacturer/Model Voith DIWA 863
Curb Weight 29,000 lbs.
Gross Vehicle Weight 40,600 lbs.
Additional information regarding the study vehicles is presented in Table 2.
2

9. Table 2. Study Bus Information
Bus Unit Date of Evaluation
Number VIN ESN Acquisition Start Mileage Fuel
3401 15GCD211741112498 35088747 2/3/2004 110,990 ULSD
3402 15GCD211941112499 35088751 2/4/2004 98,042 ULSD
3403 15GCD211141112500 35088755 2/5/2004 113,496 ULSD
3404 15GCD211341112501 35088748 2/9/2004 87,056 ULSD
3405 15GCD211541112502 35088754 2/3/2004 110,583 ULSD
3406 15GCD211741112503 35088750 2/3/2004 103,929 ULSD
3407 15GCD211941112504 35088752 2/3/2004 129,510 ULSD
3408 15GCD211041112505 35088746 2/3/2004 127,467 B20
3409 15GCD211241112506 35090107 2/3/2004 125,630 B20
3410 15GCD211441112507 35090103 2/3/2004 127,825 B20
3411 15GCD211641112508 35090106 2/3/2004 123,374 B20
3412 15GCD211841112509 35090105 2/16/2004 133,231 B20
3413 15GCD211441112510 35090104 2/23/2004 129,086 B20
3414 15GCD211641112511 35088753 2/18/2004 125,081 B20
3415 15GCD211841112512 35088749 2/3/2004 129,530 B20
Route / Duty-Cycle Selection
Several comparative routes were considered to evaluate B20- and ULSD-fueled buses. Options
were limited in selecting routes of similar characteristics, from different garages, which are
specific to 40-foot transit buses. The B20-fueled study buses are driven on the 11 Chippewa
route out of the Brentwood garage, while the ULSD-fueled study buses are operated on the 32
Wellston route from the Debaliveire garage. Route duty-cycle characteristics are summarized in
Table 3. Average speed is a more accurate representation of real-world driving, and was
therefore the defining metric in selecting these two routes for comparison.
Table 3. Evaluation Duty-Cycle Descriptions
Route 11 Chippewa 32 Wellston
Garage (Fuel) Brentwood (B20) Debaliveire (ULSD)
Average Speed (mph) 13.75 14.57
Revenue Speed (mph) 12.32 14.18
Passengers/Mile 3.03 2.9
Passengers/Trip 47 56
Total Boardings/Day 5100 4932
3

10. Vehicle Fueling and Data Collection
Throughout this study, eight of the 15 study buses operate on B20, and seven on petroleum
ULSD as a control group. Fueling records are submitted to NREL by Metro, reviewed for
accuracy, and analyzed for fuel economy comparison of the B20 and diesel groups.
The fueling regime at both Brentwood and Debaliveire garages is very similar. Brentwood fuels
with B20 and Debaliveire with petroleum ULSD.
Fuel is generally delivered to each garage daily, to every four or five days. Rack-blended (in-line
proportional blending) B20 is delivered to Brentwood by Hartford Wood River Terminal
(HWRT). ULSD is delivered to Debaliveire by Energy Petroleum. Brentwood has four 20,000-
gallon underground storage tanks (USTs), which have been converted to B20 storage.
Debaliveire has tanks in equal number and relative location. All USTs are located behind the
garage, and are connected to three interior fuel dispensers by about 1,000 feet of underground
supply line. There is a 30 um filter downstream of the supply pump, and a 10 um filter at the fuel
dispenser. There are three dispensers, two are actively being used and one is kept as a spare. All
USTs are monitored by a leak- and water-detection system manufactured by Veeder-Root. In
addition, the Veeder-Root system performs a tank tightness test (pressure test) once a month.
Each bus is scheduled to fuel every other day. As the bus enters the fueling island area, a radio
frequency connection is established between the bus, the fueling dispenser, and Metro’s M5
electronic database. The bus is recognized and odometer reading, fueling volume, and lube oil
requirements are uploaded to M5. These fueling records are transferred to NREL for evaluation
and analysis.
Vehicle Reliability
A road call (RC) is defined as a call-in to dispatch reporting a mechanical problem. Depending
on the nature of the problem, dispatch may instruct operators to continue driving their routes.
However, an RC may stem from an issue that requires the bus to stop driving, allowing for
roadside mechanical repair or towing back to the maintenance facility. RCs and average miles
(driven) between road calls (MBRC) are important reliability indicators for the transit industry.
For the purposes of this analysis, data received from Metro indicating the occurrence of an RC
was recorded as such, regardless of its relative severity.
Vehicle Maintenance and Data Collection
For the B20 fueled buses in this evaluation, routine maintenance is performed identically to the
diesel buses. Scheduled maintenance is performed by Metro personnel at the Brentwood and
Debaliveire garages, and preventative maintenance (PM) events are conducted every 6,000 miles
of driving. The buses evaluated in this study had a 2-year/100,000 mile general warranty, with
emissions control systems warranted to 200,000 miles. Thus, all buses operated in this study
were outside their warranty or went out of warranty shortly after the start of the evaluation.
Maintenance events in the form of labor hours and parts costs are captured electronically by M5.
These events are separated by work order, and further by job line. Each job line is specific to the
vehicle subsystem under repair. Maintenance records are submitted electronically to NREL by
Metro, reviewed for accuracy, and analyzed for maintenance cost per mile comparison of the
B20 and diesel groups. For vehicle subsystems that may be impacted by B20 fuel use,
4

11. maintenance cost per mile figures were calculated specific to these subsystems. These
subsystems and specific components of interest include:
• Vehicle Subsystems
o Engine
o Fuel
• Components
o Fuel supply system—fuel tank, fuel pumps, fuel lines, fuel injectors, fittings, sensors, etc.
o Fuel filters and housings
Vehicle Warranty Repairs
Data on warranty repairs are collected in a similar manner as data on normal maintenance
actions. However, the cost data are not included in the operating cost calculation. Labor costs
may be included depending on the mechanic (operator or manufacturer) and whether those hours
were reimbursed under the warranty agreement. (Warranty maintenance information is collected
primarily for an indication of reliability and durability.)
Biodiesel Fuel Analysis
Collecting and analyzing samples of B100 and B20 is useful in establishing and recording fuel
quality. In addition, should equipment maintenance or reliability issues give reason to suspect
poor quality or off-spec fuel, retained samples can be analyzed for corroboration.
NREL coordinated with HWRT to obtain samples of B100 used to blend each new batch of B20
delivered to Metro. These samples were stored in a cool, dark location before they were shipped
to NREL. Fuel samples were analyzed by NREL and Southwest Research Institute (SwRI).
Analyses performed are presented in Table 4.
Table 4. Biodiesel Fuel Analyses
B100 Load Sample Analysis
Description Method Performed By
Free & Total Glycerin ASTM D6584 SwRI
Flash Point ASTM D93 SwRI
Na/K/Ca/Mg ASTM D5185 SwRI
B20 Load Sample Analysis
Description Method Performed By
Biodiesel Content FTIR in-house NREL
Cloud Point ASTM D2500 SwRI
Lube Oil Analysis
Seven ULSD and seven B20 buses were selected for lube oil analysis over the course of the
evaluation. Analyses included:
• TBN decay
5

12. • Soot content
• Wear metals (Fe, Cu, Cr)
• Evaporative metals (Ca, Zn, P)
• Other (Ba, Mg, Mo, Sn, Pb, Al, Si, Na)
Metro uses Chevron RPM 15W-40 lube oil in the evaluation buses. Oil is changed as a part of
Metro’s preventative maintenance (PM) schedule, every 6,000 miles. Metro maintenance staff
sampled lube oil from the Cummins ISM sampling port every 2,000 miles, sometimes more
frequently. Lube oil samples were collected in sampling containers, and mailed in pre-labeled
packing provided by Cummins. Cummins conducted analyses to compare performance of lube
oil samples of vehicles fueled with B20 and ULSD.
Evaluation Results
These final evaluation results are based on a 12-month evaluation period of October 2006 –
September 2007.
Bus Use
During the evaluation period, the B20 and ULSD study bus groups accumulated 394,116 and
325,407 miles, respectively. Table 5 presents the average monthly mileage per bus during the
evaluation period. The overall 12-month average monthly miles per bus for the B20 buses at BW
depot is about 6% higher than for the ULSD buses at DB. This is primarily a function of depot
size and routes served.
Table 5. Average Miles Driven per Month per Bus by Study Group
Bus Group Average Miles per Month
B20 4,105
ULSD 3,874
Figure 1 shows cumulative average monthly miles per bus for each study group. Bus average
usage declined slightly during the evaluation period.
6

13. Running Average Monthly Miles Per Bus
ULSD Group B20 Group
5,000
4,500
Miles
4,000
3,500
3,000
Oct-06 Dec-06 Feb-07 Apr-07 Jun-07 Aug-07
Figure 1. Cumulative Average Monthly Mileage per Bus
Fuel Economy and Cost
Metro’s implementation of ULSD (less than 15 ppm sulfur) fuel coincided with the start of this
evaluation in October 2006, and the start of B20 use at Metro. ULSD was required in most areas
of the United States beginning in October 2006.
The B20 and ULSD study fleet fuel consumption and economy data are presented in Table 6.
The calculated 12-month average fuel economy for the B20 buses is 1.7% lower than that of the
ULSD buses. This difference is expected due to the approximately 2% lower energy content in a
gallon of B20. The 12-month fuel economy for each bus was used to compare ULSD and B20
groups in a two-tailed, paired t-test. By conventional criteria, the difference between the two
groups is not statistically significant with a high degree of confidence (P = 0.3).
7

14. Table 6. Bus Fuel Use and Economy
Bus Fuel Mileage Total Fuel Used (gallons) Fuel Economy (mpg)
3401 Diesel 50,154 14,043 3.57
3402 Diesel 45,786 12,797 3.58
3403 Diesel 44,019 12,092 3.64
3404 Diesel 45,252 12,729 3.55
3405 Diesel 42,695 12,397 3.44
3406 Diesel 48,650 13,785 3.53
3407 Diesel 48,851 13,140 3.72
Total Diesel 325,407 90,983 3.58
3408 B20 55,456 15,638 3.55
3409 B20 57,531 15,742 3.65
3410 B20 50,588 14,785 3.42
3411 B20 47,881 14,176 3.38
3412 B20 46,514 12,918 3.60
3413 B20 48,695 14,264 3.41
3414 B20 45,312 12,457 3.64
3415 B20 42,139 12,136 3.47
Total B20 394,116 112,115 3.52
Figure 2 shows average monthly fuel economy for the two study groups for the 12-month
evaluation period. This trend exhibits a continuous slight decline in fuel economy.
Fuel Economy Comparison
ULSD Group B20 Group
5.0
4.0
3.0
MPG
2.0
1.0
0.0
Oct-06 Dec-06 Feb-07 Apr-07 Jun-07 Aug-07
Figure 2. Average Fuel Economy
Vehicle Reliability Analysis
Figure 3 shows the cumulative MBRC for all RCs for the ULSD and B20 groups. Average
MBRC values over the evaluation period were 2,375 and 2,627 for ULSD and B20 groups,
respectively.
8

15. Running Miles Between Road Calls (MBRC)
ULSD Group B20 Group
10,000
8,000
6,000
Miles
4,000
2,000
0
Oct-06 Dec-06 Feb-07 Apr-07 Jun-07 Aug-07
Figure 3. Cumulative MBRCs
In addition, reliability as measured in MBRCs is assessed for the engine and fuel systems. Figure 4 shows
the cumulative MBRC for all RCs for the ULSD and B20 groups. The ULSD group had a three month
run of exceptionally high MBRC numbers, but by the end of the 12-month evaluation the B20 buses
exhibited higher reliability, with engine and fuel system MBRC values of 6,924 and 8,211 for ULSD and
B20 groups, respectively.
Running Engine and Fuel System MBRCs
ULSD Group B20 Group
30,000
25,000
20,000
Miles
15,000
10,000
5,000
0
Oct-06 Dec-06 Feb-07 Apr-07 Jun-07 Aug-07
Figure 4: Cumulative MBRCs, Engine and Fuel System
Maintenance Cost Analysis
The maintenance costs have been collected in a similar way for each study group. The duty cycle
and maintenance practices at BR and DB depots are similar. All work orders and parts
information available were collected for the study buses.
9

16. Total Maintenance Costs
This cost category includes the costs of parts, assumes hourly labor costs of $50 per hour, but
does not include warranty costs. Cost per mile is calculated as follows:
Cost per mile = ((labor hours * 50) + parts cost)/mileage
The labor rate has been artificially set at a constant rate of $50 per hour so that other analysts can
change this rate to one more similar to their own. This rate does not directly reflect Metro’s
current hourly mechanic rate.
Table 7 shows total maintenance costs for the study buses during the evaluation period. The total
maintenance cost per mile was 0.32% higher for the B20 buses than the ULSD buses. The 12-
month total maintenance cost/mile for each bus was used to compare ULSD and B20 groups in a
two-tailed, paired t-test. By conventional criteria, the difference between the two groups is not
statistically significant with a high degree of confidence (P = 0.8).
Table 7. Total Maintenance Costs
Total Maintenance Cost Comparison
Bus Fuel Mileage Total Labor Hours Parts Cost Cost ($/mile)*
3401 Diesel 50,154 459 $ 12,923 $ 0.716
3402 Diesel 45,786 324 $ 5,842 $ 0.482
3403 Diesel 44,019 364 $ 8,361 $ 0.604
3404 Diesel 45,252 293 $ 7,876 $ 0.498
3405 Diesel 42,695 305 $ 4,283 $ 0.457
3406 Diesel 48,650 442 $ 9,498 $ 0.649
3407 Diesel 48,851 332 $ 9,430 $ 0.533
Total Diesel 325,407 2,520 $ 58,214 $ 0.566
3408 B20 55,456 501 $ 12,762 $ 0.682
3409 B20 57,531 440 $ 8,092 $ 0.523
3410 B20 50,588 423 $ 11,574 $ 0.647
3411 B20 47,881 398 $ 7,540 $ 0.574
3412 B20 46,514 404 $ 9,673 $ 0.642
3413 B20 48,695 317 $ 4,369 $ 0.415
3414 B20 45,312 316 $ 8,221 $ 0.530
3415 B20 42,139 318 $ 5,778 $ 0.514
Total B20 394,116 3,116 $ 68,010 $ 0.568
* Assumed labor cost of $50/hour
The monthly and running average of maintenance costs for the diesel and B20 groups are
compared in Figure 5. The running average or cumulative presentation of maintenance costs
shows the average of the costs up to a given month and smoothes occasional spikes in monthly
maintenance costs. Maintenance costs are initially higher for the B20 group, but ultimately gain
parity with the diesel group by the ninth month of the evaluation.
10

17. Total Maintenance Cost per Mile
ULSD Group B20 Group
ULSD Cumulative Avg B20 Cumulative Avg
1.20
1.00
0.80
$/mile
0.60
0.40
0.20
0.00
Oct-06 Dec-06 Feb-07 Apr-07 Jun-07 Aug-07
Figure 5. Total Maintenance Costs
Engine and Fuel System Maintenance Costs
The impact of B20 on the vehicle fuel delivery system is of considerable interest to NBB, OEMs,
and end users. Consequently, this analysis also includes a maintenance cost comparison specific
to the engine and fuel system.
Metro codes and categorizes labor events and parts replacements according to vehicle subsystem
or maintenance activity. For example, maintenance performed on the engine, fuel system, or as
part of a preventative maintenance program is coded differently. Using these codes, the
maintenance and repair data were analyzed in more detail to assess differences at the engine and
fuel system level—the systems that B20 use might be expected to impact.
Bus maintenance costs during the evaluation period related to the engine and fuel system are
presented in Table 8. The engine and fuel system maintenance cost per mile was 35% higher for
the B20 buses than the ULSD buses. These higher costs for the B20 study group were driven
primarily by an elevated number of fuel injector replacements (see Fuel System Component
Replacements). Nevertheless, the bus to bus variability is so high that this difference is not
statistically significant. The 12-month engine and fuel system maintenance cost/mile for each
bus was used to compare ULSD and B20 groups in a paired t-test. The difference between the
two groups is not statistically significant with a high degree of confidence (P = 0.21).
11

18. Table 8. Engine and Fuel System Maintenance Costs
Engine and Fuel Systems Maintenance Cost Comparison
Bus Fuel Mileage Total Labor Hours Parts Cost Cost ($/mile)*
3401 Diesel 50,154 36 $ 448 $ 0.045
3402 Diesel 45,786 59 $ 108 $ 0.067
3403 Diesel 44,019 59 $ 356 $ 0.075
3404 Diesel 45,252 54 $ 342 $ 0.067
3405 Diesel 42,695 27 $ 15 $ 0.032
3406 Diesel 48,650 21 $ 11 $ 0.022
3407 Diesel 48,851 66 $ - $ 0.067
Total Diesel 325,407 322 $ 1,281 $ 0.053
3408 B20 55,456 84 $ 657 $ 0.088
3409 B20 57,531 28 $ 459 $ 0.032
3410 B20 50,588 67 $ 1,740 $ 0.101
3411 B20 47,881 50 $ 608 $ 0.065
3412 B20 46,514 74 $ 1,696 $ 0.116
3413 B20 48,695 21 $ 862 $ 0.039
3414 B20 45,312 48 $ 882 $ 0.073
3415 B20 42,139 49 $ 455 $ 0.069
Total B20 394,116 421 $ 7,360 $ 0.072
* Assumed labor cost of $50/hour
The monthly and running average of engine and fuel system maintenance costs for the diesel and
B20 groups are compared in Figure 6. The running average or cumulative presentation of
maintenance costs shows the average of the costs up to a given month and smoothes occasional
spikes in the monthly maintenance costs. These engine and fuel system maintenance costs are
higher through the first several months for the B20 group, driven by the elevated number of fuel
filter and fuel injector replacements. Although the B20 group engine and fuel system related
maintenance cost is $0.02/mile higher than the ULSD group, the B20 group total maintenance
cost is only $0.002/mile higher. Thus, engine and fuel system related maintenance was not a
significant driver in total maintenance costs.
12

19. Engine, Fuel System Maintenance Cost per Mile
ULSD Group B20 Group
ULSD Cumulative Avg B20 Cumulative Avg
$0.25
$0.20
$0.15
$/mile
$0.10
$0.05
$0.00
Oct-06 Dec-06 Feb-07 Apr-07 Jun-07 Aug-07
Figure 6. Engine and Fuel System Maintenance Costs
Fuel System Component Replacements
Looking specifically at fuel system parts that may be considered potentially susceptible to B20
use, maintenance items found in the data include the following:
• Fuel filter
• Fuel injector
• Fuel pump
• Fuel system flush.
The fuel filter and fuel system flush are grouped with a suite of preventative maintenance repair
checks and part replacements. A fuel system flush is performed every 50,000 miles. The
occurrence of a fuel system flush outside of this interval could indicate fuel system diagnostic
activities to be further investigated. Fuel filters are replaced at 6,000 mile intervals, but Metro
changed B20 bus fuel filters every 2,000 miles for the first two months to avoid RCs caused by
fuel filter plugging. This is a common practice by fleets switching over to a biodiesel blend, but
we are not aware of data to support this change in practice.
Table 9 presents fuel system part replacement frequency for the ULSD and B20 groups over the
evaluation period. Fuel filter replacements listed are those that occurred outside of PM activities,
and may indicate a fuel-related issue. All fuel system flush events occurred as part of 50,000-
mile PM events.
13

20. Table 9. Fuel System Part Replacements
Fuel Part Replaced Oct-06 Nov-06 Dec-06 Jan-07 Feb-07 Mar-07 Apr-07 May-07 Jun-07 Jul-07 Aug-07 Sep-07 Total
ULSD Fuel Filter 2 1 1 1 1 2 3 1 1 13
Fuel Injector 2 1 3
Fuel Pump 0
Fuel Sys Flush 2 2
B20 Fuel Filter 7 5 1 10 1 3 1 28
Fuel Injector 1 1 2 3 1 1 2 2 2 15
Fuel Pump 0
Fuel Sys Flush 1 2 1 4
The higher replacement frequency of fuel filters in the first two months of B20 use is due to
Metro’s implementation of a 3:1 change frequency. The reasons for the replacement of ten fuel
filters on B20 buses in February 2007 are not completely understood. During February 2007, St.
Louis experienced unseasonable cold temperatures dropping below the cloud point of their B20.
This could indicate that cold flow issues contributed to the increase in fuel filter changes that
month. Four of the ten are listed as part replacements during a PM event, but not all correspond
to a PM activity in Metro’s work order database. The other six fuel filter replacements are coded
as “test”, but Metro does not have record of conducting a test involving fuel filters during this
period. Data indicate there was one RC related to a plugged fuel filter during February 2007.
The bulk of this analysis focuses on the high incidence of fuel injector replacements with B20
use. Fuel injectors are a costly item, and their long-term durability with B20 use is unknown.
According to Metro, injectors on this order group of buses have been observed to fail as early as
100,000 miles. Table 10 presents the miles accrued on buses with injector replacements during
this evaluation. It is unknown how many miles had been driven on these injectors prior to the
start of the study. Of note is the wide range of miles driven on B20 prior to injector failure,
suggesting that total injector mileage may be a more important factor than exposure to a specific
fuel. Also note the higher evaluation starting mileage (by about 20,000 miles) of the B20 group.
Table 10. Fuel Injector Failure Mileages
Evaluation B20 Miles Evaluation ULSD Miles
Injectors Injectors
Unit No Fuel Start Before Unit No Fuel Start (Before
Replaced Replaced
Mileage Failure Mileage Failure )
3408 B20 127,467 55,355 2 3401 ULSD 110,990 45,072 1
3409 B20 125,630 47,270 1 3402 ULSD 98,042 45,786 0
3410 B20 127,825 3,865 1 3403 ULSD 113,496 44,019 0
3410 B20 127,825 18,635 2 3404 ULSD 87,056 19,101 1
3411 B20 123,374 10,364 1 3405 ULSD 110,583 14,128 1
3411 B20 123,374 12,332 1 3406 ULSD 103,929 48,650 0
3412 B20 131,582 13,180 1 3407 ULSD 129,510 48,851 0
3412 B20 131,582 33,403 1
3412 B20 131,582 40,406 1
3413 B20 128,805 35,542 1
3413 B20 128,805 40,444 1
3414 B20 124,923 20,950 1
3415 B20 129,530 38,204 1
Average Miles 127,392 29,596 Average Miles 107,658 26,100
Standard Deviation 2,664 16,717 Standard Deviation 13,305 16,617
Gateway Cummins, Inc. is the local Cummins supplier for Metro. According to Metro, fuel
injectors have been covered under warranty by this supplier for this particular bus group even
14

21. beyond the 100,000 miles normal warranty. Table 11 presents the labor and parts costs
associated with injector replacements for all study buses. Parts costs that are blank are indicative
of warranty replacements. Metro maintains a field in their maintenance database for “job
reason”, which sheds some light on why a repair occurred. The “job reason” can range from a
driver report of suspected malfunction or diminished performance, to a scheduled maintenance
event. Table 11 includes this information when known, which in some cases qualifies fuel
injector replacements.
Table 11. Fuel Injector Replacement Costs, Job Reasons
Injectors Labor Total
Unit No Fuel Part Cost Job Reason
Replaced Hours Cost
3408 B20 2 4.2 $ 480 $ 690 Unplanned visit
3409 B20 1 6.2 $ 452 $ 760 Unplanned visit
3410 B20 1 4.9 $ - $ 246 Yard Grief
3410 B20 2 5.7 $ 1,106 $ 1,392 Driver Report x2
3411 B20 1 2.5 $ 604 $ 728 Unplanned visit
3411 B20 1 0 $ - $ - Unplanned visit
3412 B20 1 7.7 $ - $ 383 Driver Report
3412 B20 1 4.2 $ - $ 209 Unplanned visit
3412 B20 1 2.7 $ - $ 137 Unplanned visit
3413 B20 1 2.8 $ 398 $ 539 Inspection Grief
3413 B20 1 0.2 $ 452 $ 464 Inspection Grief
3414 B20 1 8.4 $ 565 $ 983 Unplanned visit
3415 B20 1 0 $ 448 $ 448 Unplanned visit
3401 ULSD 1 0 $ 448 $ - Planned Visit
3404 ULSD 1 0 $ - $ - Driver Report
3405 ULSD 1 0 $ - $ - Not Listed
As presented above, the ULSD-fueled buses had one known scheduled fuel injector inspection
and replacement out of three. However, the B20-fueled buses had injectors replaced under
circumstances that suggest operational problems. Table 12 presents fuel filter replacements (10)
and fuel injector replacements (3) for B20 buses in February 2007. The two shaded regions show
date ranges in which fuel filter replacements were followed by fuel injector replacements.
At the onset of this project, NREL and Metro agreed to employ a “part retention program” for
fuel system parts, which would allow tear-down analysis and identification of the root cause of
failure. This effort was not executed by depot maintenance staff as planned. A retroactive
investigation into fuel injector replacements was initiated by NREL and led by Metro staff, but
did not yield any additional information as to the cause of these maintenance events. Given the
large number of buses in Metro’s garages undergoing engine repairs, replacing injectors without
significant analysis of the root cause of failure is not abnormal.
15

22. Table 12. Fuel Filter-Injector Successive Replacements, February 2007
Unit No Fuel Date Part Replaced
3408 B20 02/08/07 Fuel filter
3410 B20 02/13/07 Fuel filter
3410 B20 02/14/07 Fuel injector
3410 B20 02/14/07 Fuel injector
3410 B20 02/22/07 Fuel filter
3410 B20 02/23/07 Fuel filter
3411 B20 02/05/07 Fuel filter
3411 B20 02/25/07 Fuel filter
3412 B20 02/26/07 Fuel filter
3413 B20 02/26/07 Fuel filter
3414 B20 02/27/07 Fuel injector
3414 B20 02/27/07 Fuel filter
3415 B20 02/27/07 Fuel filter
Fuel analysis was conducted in part to determine if fuel system durability issues were connected
with poor fuel quality. Biodiesel fuel analysis and results are presented below.
Based on the available data, the cause of the higher rate of fuel injector replacement for the B20
buses cannot be determined with certainty. On the one hand, exposure to B20 may have been the
cause, but on the other hand, the higher mileage of the B20 buses might also have lead to a
higher number of injector failures. This is not atypical for a 12-month evaluation, as a
significantly longer time is generally required to fully understand fuel impacts on engine
durability and maintenance. Note that the evaluation is being continued for a second year, and
the additional data will hopefully clarify the situation.
Biodiesel Fuel Analysis and Results
Fifteen B100 and 19 B20 samples were analyzed by NREL or SwRI. These samples represented
fuel consumed by Metro from late January through July 2007.
B100 analysis results are summarized in Table 13. Only one sample was off-spec (flashpoint),
and two additional samples were borderline (flashpoint). A sample is off-spec if flashpoint is
<130C, but >93C and methanol content is >0.200% by mass; or if flashpoint is <93C. Generally,
a flashpoint result in the 93 to 130C range warrants methanol analysis to confirm if the sample
was off-spec. While free and total glycerin results are within specification, the absence of acid
number results does not allow decoupling of fuel quality and fuel injector failures in B20 buses.
16

23. Table 13. Summary of B100 Fuel Analytical Results
Sample Date Free Glycerin Total Glycerin Na K Ca Mg P Flashpoint
(weight %) (weight %) (ppm) (ppm) (ppm) (ppm) (ppm) (degC)
01/29/07 <0.005 0.078 <5 <5 <1 <1 <1 117.8
02/05/07 <0.005 0.071 <5 <5 <1 <1 <1 160.6
02/12/07 <0.005 0.178 <5 <5 <1 <1 <1 143.9
02/19/07 <0.005 0.135 <5 <5 <1 <1 <1 160.6
02/26/07 <0.005 0.182 <5 <5 <1 <1 <1 162.8
03/05/07 <0.005 0.173 <5 <5 <1 <1 <1 157.8
03/12/07 <0.005 0.159 <5 <5 <1 <1 <1 163.3
05/07/07 <0.005 0.112 <5 <5 <1 <1 <1 138.9
05/14/07 <0.005 0.112 <5 <5 <1 <1 <1 73.3
05/21/07 <0.005 0.085 <5 <5 <1 <1 <1 147.2
06/04/07 <0.005 0.179 <5 <5 <1 <1 <1 146.1
06/11/07 <0.005 0.159 <5 <5 <1 <1 <1 145
06/18/07 <0.005 0.173 <5 <5 <1 <1 <1 99.4
07/02/07 <0.005 0.160 <5 <5 <1 <1 <1 145
07/09/07 <0.005 0.178 <5 <5 <1 <1 <1 155
: Off-spec
: Borderline off-spec; require methanol content (EN14110) to confirm.
B20 analysis results are summarized in Table 14. The B20 samples had consistent cloud point
results; however during February 2007, St. Louis experienced unseasonable cold temperatures
dropping below the cloud point of their B20. This could indicate that cold flow issues
contributed to the increase in fuel filter changes that month.
17

24. Table 14. Summary of B20 Fuel Analytical Results
Sample Date Blend Content Cloud Point
(% Biodiesel) (degC)
02/07/07 20.09 -14
02/08/07 17.17 -15
02/21/07 18.23 -13
02/22/07 20.97 -12
02/23/07 17.18 -13
03/09/07 18.35 -14
03/15/07 20.08 -14
05/09/07 24.50 -12
05/17/07 15.64 -12
06/05/07 17.08 -10
06/13/07 17.34 -11
06/19/07 17.50 -14
06/20/07 16.41 -14
06/22/07 NA -12
07/03/07 21.48 -11
07/06/07 22.89 -11
07/13/07 21.96 -11
07/18/07 17.82 -11
07/20/07 16.40 -13
NA: Not Analyzed
Lube Oil Analysis and Results
Sixty-four lube oil samples from ULSD and B20 buses were analyzed by Cummins. Samples had
a range of 833 to 6,477 oil miles. The figures below present results graphically.
Figure 7 presents weight percent soot in oil. Ideally, soot should be below 3.0% by weight. Both
ULSD and B20 groups exhibit very low soot; however the B20 group oil samples have lower
soot and soot level is increasing with mileage at a lower rate. Figure 8 presents the kinematic
viscosity of oil at 100C. Viscosity can be used as an indication of fuel dilution. 15W-40 oils, as
used by Metro, have a minimum value of 12.5 cSt, thus this viscosity value should be above 12.5
cSt. Viscosity remains "in-grade" throughout the oil drain period for both groups. Figure 9
presents total base number (TBN) of oil. Ideally, TBN should be above 2.5 mg KOH/g. TBN
appears slightly lower with B20, but both show sufficient TBN retention at end of drain. Figure
10 presents iron in oil; an indication of engine wear. Wear appears slightly lower with B20,
especially at high mileage. Figure 11 presents lead in oil; an indication of engine corrosion.
Corrosion appears slightly higher with B20, especially at high mileage. However, the oil is still
“in-grade” throughout the oil drain period.
In general, there appeared to be no harm to lube oil with B20 use, and some potential benefits.
Both soot in oil and wear metals were lower with B20 use as compared to ULSD. TBN,
kinematic viscosity, and corrosion were slightly compromised with B20 use, but oil was still “in-
grade” throughout the 6,000 mile oil interval.
18

25. Soot
ULSD B20 Linear (ULSD) Linear (B20)
1
0.9
0.8
0.7
% by Weight
0.6
0.5
0.4
0.3
0.2
0.1
0
0 1,000 2,000 3,000 4,000 5,000 6,000 7,000
Lube Oil Mileage
Figure 7. Soot in Lube Oil
100C Viscosity
ULSD B20 Linear (ULSD) Linear (B20)
15.00
14.50
14.00
cSt
13.50
13.00
12.50
0 1,000 2,000 3,000 4,000 5,000 6,000 7,000
Lube Oil Mileage
Figure 8. 100C Viscosity of Lube Oil
19

26. TBN
ULSD B20 Expon. (ULSD) Expon. (B20)
9
8
7
6
mg KOH/g
5
4
3
2
1
0
0 1,000 2,000 3,000 4,000 5,000 6,000 7,000
Lube Oil Mileage
Figure 9. TBN of Lube Oil
20

27. Iron
ULSD B20 Linear (ULSD) Linear (B20)
30
25
20
ppm
15
10
5
0
0 1,000 2,000 3,000 4,000 5,000 6,000 7,000
Lube Oil Mileage
Figure 10. Iron in Lube Oil
Lead
ULSD B20 Linear (ULSD) Linear (B20)
12
10
8
ppm
6
4
2
0
0 1,000 2,000 3,000 4,000 5,000 6,000 7,000
Lube Oil Mileage
Figure 11. Lead in Lube Oil
21

28. Conclusions
• With similar usage and duty cycle, the B20 study group exhibited a 1.7% lower fuel
economy than the ULSD study group. This difference is expected due to the lower energy
content of B20 fuel. However, this difference is considered to be not statistically significant
(P = 0.3).
• The B20 study group exhibited similar reliability (as measured in MBRC) to the ULSD study
group.
• There was no significant difference in total maintenance cost per mile between the two study
groups; engine and fuel system related maintenance was not a significant driver in total
maintenance costs.
• The engine and fuel system maintenance cost per mile was 35% (P = 0.21) higher for the B20
study group than the ULSD study group, but the difference is not statistically significant
because of high vehicle to vehicle variability in engine and fuel system maintenance costs.
• The B20 study group had a higher incidence of fuel filter replacements. Initially, fuel filters
were intentionally replaced at a 3:1 ratio on B20 buses, as a proactive effort to avoid filter
plugging due to loosening of fuel system deposits. The reason for the replacement of ten fuel
filters on B20 buses in February 2007 is unknown, but extremely cold temperatures (below
cloud point) could be to blame.
• The B20 study group experienced an elevated number of fuel injector replacements.
• Metro’s maintenance database indicates that operational problems led to fuel injector
replacements on B20 buses. No additional qualifying information is available. However the
bus group, which includes the study buses, is the subject of ongoing warranty replacement of
injectors by the local Cummins distributor. All fuel injector failures occurred within the
expected mileage range of failure for this group, and no obvious pattern exists in terms of
miles driven on B20 prior to injector replacement.
• Although analysis of B100 fuel samples did not indicate poor fuel quality as measured by
free and total glycerin, no fuel injectors were retained for tear-down analysis to determine
failure mode and cause.
• Lube oil analysis indicates no harm, and some potential benefits, with B20 use; notably, soot
and wear metals were lower with B20 use. Viscosity, total base number, and corrosive metals
were generally more positive with ULSD use, but these qualities were still “in-grade” for the
B20 buses throughout the oil drain interval.
22

29. Appendix
Evaluation and Vehicle Specifications
Evaluation Technology Biodiesel (B20)
Operating Company Metro St. Louis
Evaluation Period 10/1/06 - 9/30/07
Bus Unit Date of Evaluation Start
Number VIN Acquisition Mileage Fuel
3401 15GCD211741112498 2/3/2004 110,990 ULSD
3402 15GCD211941112499 2/4/2004 98,042 ULSD
3403 15GCD211141112500 2/5/2004 113,496 ULSD
3404 15GCD211341112501 2/9/2004 87,056 ULSD
3405 15GCD211541112502 2/3/2004 110,583 ULSD
3406 15GCD211741112503 2/3/2004 103,929 ULSD
3407 15GCD211941112504 2/3/2004 129,510 ULSD
3408 15GCD211041112505 2/3/2004 127,467 B20
3409 15GCD211241112506 2/3/2004 125,630 B20
3410 15GCD211441112507 2/3/2004 127,825 B20
3411 15GCD211641112508 2/3/2004 123,374 B20
3412 15GCD211841112509 2/16/2004 133,231 B20
3413 15GCD211441112510 2/23/2004 129,086 B20
3414 15GCD211641112511 2/18/2004 125,081 B20
3415 15GCD211841112512 2/3/2004 129,530 B20
23

30. Vehicle Dimensions
Manufacturer Gillig
Model Phantom 4102
Length, ft. 39' 10"
Width, in. 101.75"
Height, in. 121"
9" (at axles), 13" (excluding
Ground clearance, in. axles)
Wheel Base 280"
Front overhang (axle to vehicle front), in. 90.75"
Number of axles 2
Number of driven axles 1
Gross Vehicle Weight Rating, lb.
Front Axle 14,600
Total 40,600
Curb Weight, lb.
Front Axle 10,000
Rear Axle 18,800
Total 29,000
Seated Load Weight
Front Axle 12,407
Rear Axle 22,843
Total 35,250
Rear Axle 26,000
24

31. Passenger Seats
Number of Passenger Seats
with no Wheelchairs on Board 43
Number of Wheelchair Positions 2
Number of Passenger Seats
with all Wheelchair Positions Occupied 37
Maximum Number of Standees 30.41
Fuel
Type(s) ULSD, B20
Necessary Additives None reported
Power Plant
OEM or Retrofit? OEM
Power Plant Type (engine, turbine, fuel
cell) Engine
Manufacturer Cummins
Model Number ISM 280
Year of Manufacture 2002
2 Cycle or 4 Cycle? 4 Cycle
Compression Ratio 16.1:1
Power Plant, continued
Ignition Aids Used? (Yes/No) No
Type of Ignition Aid
(Spark Plug, Glow Plug, Pilot Ignition,
Other) NA
EPA Certified? (Yes/No) Yes
CARB Certified? (Yes/No)
Power Rating
Max. bhp 280 hp
RPM of Max. bhp 2100
25

32. Power Plant (continued)
Max. Torque (ft. lbs.) 900
RPM of Max. Torque 1200
Displacement (L) 661 cu in
Engine Oil
Type(s) Used Chevron RPM 15W40
Necessary Additives Proprietary
Oil Capacity (qts.) 40
Blower? (Yes/No) No
Turbocharger? (Yes/No) Yes
Liquid Fuel Delivery Systems
Mechanical or Electronic Fuel Injectors? Electronic
Injector Manufacturer Cummins / ISM
Injector Model Number 3411756
Number of Fuel Filters 2
Fuel Filter Manufacturer Fleetguard, Davco
Fuel Filter Model FS1022, 382
Gaseous Fuel Delivery Systems NA
Direct Injection or Fumigation? NA
Throttle for Intake Air? (Yes/No) NA
OEM or Retrofit? NA
26

33. Power Plant Accessories
Mechanical or Electric Drive
Accessories? Mechanical
Generator Delco Remy
Output at Normal Idle 200A
Maximum Rating 270A
Starter Type (Electrical/Air)? Electrical
Manufacturer Nippondenso
Model 42800-070
Hydraulic Pump
Manufacturer Saugr Sundstrand
Model
Output (gpm @ psi)
Heating
Heating System Type Forced Air
Capacity, BTU/hr 120,000 BTU
Air Conditioning
Manufacturer Carrier
Model 68RM35-604-48
Capacity, BTU/hr 108,000 BTU
Air Compressor
Manufacturer WABCO
Model Number
Capacity, Cubic Ft./Min.
27

34. Drivetrain
Transmission/Gearbox
Manufacturer Voith
Model Number D.864.3
Model Year 2002
Manual or Automatic? Automatic
Number of forward speeds 4
Gear Ratios
Torque conversion ratio
Additional features
Retarder
Manufacturer Voith
Model Number
Drive Axle
Manufacturer Rockwell Meritor
Model Number 61153-WX
Axle ratio(s) 4.1
Tires
Manufacturer Goodyear
Model Number Metro Miler
Size
Torque converter
Manufacturer
Model Number
Type (hydraulic, other)
28

35. Fuel Storage System
Number of Tanks 1
Maximum Working Pressure (Gaseous
Fuels Only) NA
Total Useful Amount of Fuel 125 gallon
Tank Manufacturer Mancor Canada
Tank Model(s)
Total Empty Weight of Tank(s)
Safety Equipment
Fire Detection (Y/N)? Yes
Manufacturer
Model Number
Year of Manufacture
Sensor Type
Number of Sensors
Fire Suppression (Y/N)? No
Manufacturer
Model Number
Year of Manufacture
Amount of Agent
Type of Agent
Number of Discharge Points
Vapor Detection (Y/N)? NA
Manufacturer NA
Model Number NA
Year of Manufacture NA
Sensor Type NA
Number of Sensors NA
Alarm Threshold (% LEL) NA
29

36. Other Attributes or Features
(Wheelchair lifts, wheelchair position,
bicycle racks, any items that make
this bus different from the
other test or control buses) No differences
Emission Control
Catalytic Converter (Y/N)? No
Manufacturer
Model Number
Type
Length of pipe from engine to catalyst
Diesel Particulate Control Device (Y/N)? No
Manufacturer
Model Number
Type
Special Requirements
(Low sulfur diesel, specific regeneration
temperatures, etc.)
Power Plant Emissions Certification
Data
30

37. Form Approved
REPORT DOCUMENTATION PAGE OMB No. 0704-0188
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PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION.
1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED (From - To)
July 2008 Technical Report
4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER
St. Louis Metro Biodiesel (B20) Transit Bus Evaluation: 12–Month DE-AC36-99-GO10337
Final Report
5b. GRANT NUMBER
5c. PROGRAM ELEMENT NUMBER
6. AUTHOR(S) 5d. PROJECT NUMBER
R. Barnitt, R.L. McCormick, and M. Lammert NREL/TP-540-43486
5e. TASK NUMBER
FC08.9460
5f. WORK UNIT NUMBER
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION
National Renewable Energy Laboratory REPORT NUMBER
1617 Cole Blvd. NREL/TP-540-43486
Golden, CO 80401-3393
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)
NREL
11. SPONSORING/MONITORING
AGENCY REPORT NUMBER
12. DISTRIBUTION AVAILABILITY STATEMENT
National Technical Information Service
U.S. Department of Commerce
5285 Port Royal Road
Springfield, VA 22161
13. SUPPLEMENTARY NOTES
14. ABSTRACT (Maximum 200 Words)
The St. Louis Metro Biodiesel Transit Bus Evaluation project is being conducted under a Cooperative Research and
Development Agreement between NREL and the National Biodiesel Board to evaluate the extended in-use
performance of buses operating on B20 fuel. The objective of this research project is to compare B20 and ultra-low
sulfur diesel buses in terms of fuel economy, vehicles maintenance, engine performance, component wear, and lube
oil performance.
15. SUBJECT TERMS
transit bus; St. Louis Metro; CRADA; B20; biodiesel; diesel particulate filter; ultra-low sulfur diesel; ULSD
16. SECURITY CLASSIFICATION OF: 17. LIMITATION 18. NUMBER 19a. NAME OF RESPONSIBLE PERSON
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