NREL is a national laboratory of the U.S. Department of Energy, Office of Energy 

Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Contract No. DE-AC36-08GO28308

SunLine Transit Agency 

Advanced Technology Fuel Cell 

Bus Evaluation: Second Results 

Report 

Leslie Eudy

National Renewable Energy Laboratory

Kevin Chandler

Battelle Link to appendices

Technical Report

NREL/TP-5600-52349-1 

October 2011
NREL is a national laboratory of the U.S. Department of Energy, Office of Energy 

Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. 

National Renewable Energy Laboratory

1617 Cole Boulevard

Golden, Colorado 80401

303-275-3000 • www.nrel.gov

Contract No. DE-AC36-08GO28308

SunLine Transit Agency 

Advanced Technology Fuel Cell 

Bus Evaluation: Second Results 

Report 

Leslie Eudy

National Renewable Energy Laboratory

Kevin Chandler

Battelle

Prepared under Task No. H270.8150 

Technical Report

NREL/TP-5600-52349-1 

October 2011
NOTICE

This report was prepared as an account of work sponsored by an agency of the United States government. 

Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, 

express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of 

any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately 

owned rights. Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, 

or favoring by the United States government or any agency thereof. The views and opinions of authors 

expressed herein do not necessarily state or reflect those of the United States government or any agency thereof.

Available electronically at http://www.osti.gov/bridge

Available for a processing fee to U.S. Department of Energy

and its contractors, in paper, from:

U.S. Department of Energy

Office of Scientific and Technical Information

P.O. Box 62

Oak Ridge, TN 37831-0062

phone: 865.576.8401

fax: 865.576.5728

email: mailto:reports@adonis.osti.gov

Available for sale to the public, in paper, from:

U.S. Department of Commerce

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22161

phone: 800.553.6847

fax: 703.605.6900

email: orders@ntis.fedworld.gov

online ordering: http://www.ntis.gov/help/ordermethods.aspx

Cover Photos: (left to right) PIX 16416, PIX 17423, PIX 16560, PIX 17613, PIX 17436, PIX 17721. Bus photo 

courtesy of Leslie Eudy, NREL.

Printed on paper containing at least 50% wastepaper, including 10% post consumer waste.
iii

Acknowledgements 

This evaluation at SunLine Transit Agency would not have been possible without the support 

and cooperation of many people. The authors thank the following: 

U.S. Department of Energy 

John Garbak 

U.S. Federal Transit Administration

Walter Kulyk

Christina Gikakis

National Renewable Energy Laboratory 

Keith Wipke

George Sverdrup 

SunLine Transit Agency

C. Mikel Oglesby 

Tommy Edwards

Polo Del Toro 

Mike Hayes

Ballard Power Systems 

Jeff Grant

Daljit Bawa

Bluways 

Tavin Tyler 

Photo credit for all pictures in the report: L. Eudy, NREL
iv

Acronyms and Abbreviations

AQMD Air Quality Management District

AT advanced technology 

CARB California Air Resources Board

CNG compressed natural gas

DGE diesel gallon equivalent 

DOE U.S. Department of Energy 

FCB fuel cell bus

ft feet

FTA Federal Transit Administration

GGE gasoline gallon equivalent 

HHICE hydrogen hybrid internal combustion engine 

hp horsepower 

HVAC heating, ventilation, and air conditioning

in. inches 

kg kilograms 

kW kilowatts

lb pounds 

MBRC miles between roadcalls

mpDGE miles per diesel gallon equivalent 

mph miles per hour 

NFCBP National Fuel Cell Bus Program

NREL National Renewable Energy Laboratory 

PMI preventive maintenance inspection

psi pounds per square inch 

RC roadcall 
v

Executive Summary

SunLine Transit Agency provides public transit services to the Coachella Valley area of 

California. SunLine has demonstrated hydrogen and fuel cell bus technologies for more than 10 

years. This report describes operations at SunLine for their newest prototype fuel cell bus and 

five compressed natural gas (CNG) buses (with model year 2010-level emissions). 

In May 2010, SunLine began demonstrating the Advanced Technology (AT) bus—a newgeneration fuel cell bus developed by Bluways, Ballard Power Systems, and New Flyer. The AT 

fuel cell bus has a hybrid electric propulsion system based on the Siemens ELFA system, 

integrated by Bluways with Ballard’s newest version fuel cell power system, and lithium-based 

hybrid batteries. The design incorporates the latest improvements to reduce weight and increase 

reliability and performance. Since it first went into service in May 2010, the fuel cell bus has 

operated almost 21,000 miles and has accumulated 1,776 fuel cell system hours (for an average 

operating speed of 11.7 mph). The operation of this new fuel cell bus at SunLine has been 

limited by air conditioning issues during the hot desert summer, some fuel cell power system 

issues, and some bus body work. 

The U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) is 

working with SunLine to evaluate the bus in real-world service to document the results and help 

determine the progress toward technology readiness. NREL uses a standard data-collection and 

analysis protocol originally developed for DOE heavy-duty vehicle evaluations. NREL has 

previously published a report documenting the first seven months of operation. This report 

provides a summary of the results with a focus on the operation from December 2010 through 

June 2011. 

Table ES-1 provides a summary of results for several categories of data presented in this report.

Table ES-1. Summary of Evaluation Results

Data Item Fuel Cell CNG

Number of buses 1 5

Data period 12/10 – 6/11 12/10 – 6/11

Number of months 7 7

Total mileage in period 11,164 161,833

Average monthly mileage per bus 1,595 4,624

Availability (85% is target) 64 88

Fuel economy (miles/kg or GGE) 6.18 3.04

Miles between roadcalls (MBRC) – All 5,582 9,520

MBRC – propulsion only 5,582 16,183

MBRC – fuel cell system only 11,164 N/A

Total maintenance, $/mile $1.16 $0.44

Maintenance – propulsion only, $/mile $0.35 $0.15
vi

Table of Contents

Introduction ..................................................................................................................................... 1

NREL Evaluations....................................................................................................................... 1

Host Site Profile: SunLine........................................................................................................... 1

Fuel Cell Bus Evaluation at SunLine .......................................................................................... 1

Hydrogen and CNG Fueling ........................................................................................................... 3

Evaluation Results .......................................................................................................................... 7

Route Assignments ...................................................................................................................... 7

Bus Use and Availability ............................................................................................................. 7

Fuel Economy and Cost .............................................................................................................. 9

Maintenance Analysis ............................................................................................................... 10

Roadcall Analysis ...................................................................................................................... 14

What’s Next for SunLine .............................................................................................................. 16

Contacts......................................................................................................................................... 17

References and Related Reports ................................................................................................... 18

SunLine ..................................................................................................................................... 18

General ...................................................................................................................................... 19

AC Transit ................................................................................................................................. 19

BurbankBus ............................................................................................................................... 20

Connecticut Transit ................................................................................................................... 20

Santa Clara Valley Transportation Authority ............................................................................ 20
1

Introduction

In May 2010, SunLine Transit Agency began operating its newest fuel cell bus in service. This 

advanced technology (AT) fuel cell bus, built by New Flyer with a Bluways hybrid system and 

Ballard fuel cell power system, incorporates the latest design improvements to reduce weight and 

increase reliability and performance. SunLine is collaborating with the U.S. Department of 

Energy’s (DOE) National Renewable Energy Laboratory (NREL) to evaluate the bus in revenue 

service. The first results report, which was published in March 2011,1 covered data through 

November 2010. This report provides an update to that report and is focused on data from 

December 2010 through June 2011. 

NREL Evaluations

NREL has been evaluating alternative fuel and advanced propulsion transit buses for DOE and 

the U.S. Department of Transportation’s Federal Transit Administration (FTA) since the early 

1990s. NREL’s first evaluation of hydrogen fuel cell transit buses for DOE was in 2000 and 

continued with a series of evaluations at five transit agencies. These evaluations focus on 

determining the status of hydrogen and fuel cell systems and the corresponding infrastructure in 

transit applications to help DOE and FTA assess the progress toward technology readiness. 

NREL uses a standard data-collection and analysis protocol originally developed for DOE 

heavy-duty vehicle evaluations. This protocol was documented in a joint evaluation plan for 

transit bus evaluations.

2

 Appendix A describes NREL’s transit bus evaluation activities for DOE 

and FTA. 

Host Site Profile: SunLine

SunLine Transit Agency provides public transit services to Southern California’s Coachella 

Valley (including Palm Springs). Headquartered in Thousand Palms, California, SunLine’s 

service area covers more than 1,100 square miles including nine member cities and a portion of 

Riverside County. SunLine has proactively adopted clean fuel technologies in its fleet, beginning 

with complete fleet implementation of compressed natural gas (CNG) buses in 1994. Since then, 

the agency has tested many advanced technologies, including buses that run on a blend of 

hydrogen and CNG, battery electric power, and fuel cells. Appendix B provides more 

information on SunLine. 

Fuel Cell Bus Evaluation at SunLine

SunLine continues to invest in advanced hydrogen and fuel cell bus technologies. The AT fuel 

cell bus represents a sixth generation of hydrogen-fueled buses operated by the agency. The bus 

is shown in Figure 1. This report describes SunLine’s operation of the AT fuel cell transit bus in 

revenue service. The AT bus is a low floor, 40-foot New Flyer model with the latest advances 

designed to improve performance, reliability, and durability. The bus was designed in 

collaboration between Bluways,3

 Ballard, and New Flyer. Five compressed natural gas (CNG) 

buses operating from the same SunLine location are being used as a baseline comparison. These 

buses are 2008 model year New Flyer CNG buses with Cummins Westport ISL G natural gas 

 

1 SunLine Transit Agency Advanced Technology Fuel Cell Bus Evaluation: First Results Report, NREL/TP-5600-

50500, March 2011, www.nrel.gov/hydrogen/pdfs/50500.pdf. 2 Fuel Cell Transit Bus Evaluations: Joint Evaluation Plan for the U.S. Department of Energy and the Federal 

Transit Administration, NREL/TP-560-49342-1, November 2010, www.nrel.gov/hydrogen/pdfs/49342-1.pdf. 3 In February, 2011, Bluways acquired substantial assets and technology from ISE Corporation.
2

engines that are designed to meet 2010 emission regulations (see Figure 2). Appendix C provides 

more detail about the bus technologies included in this evaluation. 

Figure 1. SunLine's Advanced Technology fuel cell bus

Figure 2. New Flyer CNG bus at SunLine
3

Hydrogen and CNG Fueling

Hydrogen fuel is supplied at SunLine by a HyRadix natural gas reformer. The fuel is compressed 

to 5,000 psi and dispensed into the buses. CNG is brought into the SunLine property via a highpressure natural gas line and then compressed to 3,600 psi for delivery into the vehicles. 

Appendix D provides general descriptions of SunLine’s hydrogen and CNG fueling 

infrastructure and of its maintenance facilities.

SunLine provides both hydrogen and CNG for purchase at its public dispensing island. Because 

of this, SunLine is required to track all of its fueling events in gasoline gallon equivalent (GGE) 

units to comply with state fuel-sale regulations. In the case of hydrogen, the unit used is typically 

kilograms (kg)—one kg of hydrogen contains essentially the same energy as a GGE for fueleconomy calculations. This report presents both GGE (kg for hydrogen) and diesel gallon 

equivalent (DGE) for hydrogen and CNG fuel consumption. The end of Appendix E shows the 

energy-conversion calculations for GGE and DGE. 

Fueling Station Data Analysis – SunLine currently operates two fuel cell buses in its service 

area: the AT fuel cell bus and a Van Hool fuel cell bus. To show overall performance of the 

station, the fueling analysis figures include hydrogen data for both buses. Figure 3 shows the 

average hydrogen dispensed per day into SunLine’s fuel cell buses from May 2010 through June 

2011. The calculation for this rate includes only the days in which the station dispensed 

hydrogen. The station was used at least once per day to fill at least one of the two hydrogen 

buses for 81% of the calendar days during the period. In September, the buses were held out of 

service for several days because the station was low on fuel. The overall average daily use was 

21.1 kg per day. During this period, SunLine dispensed a total of 7,293 kg of hydrogen. Less fuel 

was dispensed during December because the AT bus was unavailable for service during that 

month. The low point in April occurred because the other fuel cell bus was down for 

maintenance. 

Figure 4 shows the distribution of hydrogen amounts dispensed per fill by bus. The buses were

filled a total of 208 times during the evaluation period for a total of 3,249 kg hydrogen.4 The 

average amount of hydrogen per fill was 15.6 kg per fill. Figure 5 shows a cumulative fueling 

rate histogram for the SunLine hydrogen station from December 2010 through June 2011. The 

overall average fueling rate was 0.96 kg per minute, and the average time for a fill was 16.3 

minutes. 

 

4 This total is slightly lower than discussed above. If the time for the fueling was not captured in data collection, that 

fueling data was excluded for this calculation.
4

Figure 3. Average hydrogen dispensed per day (excluding 0 kg days)

Figure 4. Histogram of fueling amounts by bus

0

5

10

15

20

25

30

Hydrogen (kg)

Average Daily Fuel Use
5

Figure 5. Histogram of fueling rates

Hydrogen fuel costs at SunLine consist of the cost of natural gas for the reformer, the cost for 

maintenance of the station equipment, and capital cost amortization. SunLine performs the 

maintenance of the station equipment, including parts and labor. The average cost for hydrogen 

during the evaluation period was $26.19 per kg (monthly costs ranged from a low of $6.65/kg to 

a high of $59.40/kg). Lower use of the station (when the buses were out of service) and higher 

maintenance costs contribute to higher monthly fuel costs. Figure 6 shows the monthly station 

use and hydrogen cost per kg since January 2010. DOE’s target for hydrogen cost is between $2 

and $4 per kg and is included on the chart. The figure shows the relationship between cost and 

station use. In most cases, the highest costs per kg occurred in months with the lowest station 

use. In February 2011, the station compressor failed and the added costs of repair led to the 

highest monthly cost during the data period. SunLine indicates that the best steady-state 

operating point for the reformer system would bring the average cost of hydrogen to around $8 

per kg. This cost estimate is used in the cost calculations for the data results in the next section.

SunLine supplies CNG fuel to users in its area, and the fueling station is accessible to the public. 

The high volume of natural gas use has allowed SunLine to command a low cost as a commodity 

user. During the evaluation period, the CNG price at the dispenser for SunLine (not the public 

price) was $0.97 per GGE. This price includes all costs—natural gas, maintenance, and station 

amortization. 
6

Figure 6. Comparison of monthly hydrogen use and cost per kg

$-

$10 

$20 

$30 

$40 

$50 

$60 

0

200

400

600

800

1000

1200

Jan-10

Feb-10

Mar-10

Apr-10

May-10

Jun-10

Jul-10

Aug-10Sep-10

Oct-10

Nov-10Dec-10

Jan-11

Feb-11

Mar-11

Apr-11

May-11

Cost in $/kg

Total Monthly kg

kg H2 $/kg DOE target
7

Evaluation Results

SunLine placed the AT fuel cell bus in service on May 27, 2010. The focus of this report is the 

operating data collected on the fuel cell and CNG buses from December 2010 through June 

2011. Appendix E provides a summary of all data. Appendix F provides a data summary in SI 

(metric) units. 

Route Assignments

In general, SunLine’s buses are randomly dispatched on its routes. The overall system average 

speed is 13.9 mph. The AT fuel cell bus was used exclusively on Line 53 (average speed of 12.9 

mph). The five CNG buses were randomly dispatched with the majority of time (74%) split 

between Line 111 (35% at 13.9 mph), Line 14 (14% at 14.6 mph), and Line 30 (25% at 10.8 

mph). 

Bus Use and Availability

Bus use and availability indicates reliability. Lower bus use may indicate downtime for 

maintenance or purposeful reduction of planned work for the buses. This section provides a 

summary of bus use and availability for the fuel cell and CNG buses. 

The AT fuel cell bus has planned service of up to seven days per week. For this bus, total 

mileage accumulation for the evaluation period was 11,164 miles, and the fuel cell system 

accumulated 957 hours, which indicates an average speed of 11.7 mph. This average speed is

lower than the overall 13.9-mph average speed for all SunLine routes and also lower than the 

average speed for the Line 53 operation to which the bus is assigned. This lower average speed 

has been caused by events and training where the bus was operated at a significantly lower 

speed. For in-service days during the evaluation period, the AT fuel cell bus averaged 7.5 hours 

per day with a maximum of 13.9 hours in one day. 

Table 1 summarizes the average monthly mileage accumulation by bus and study group for the 

evaluation period. Using the CNG buses as the baseline, the AT fuel cell bus had an average 

monthly mileage that was 34% that of the CNG buses. This low percentage is due to downtime 

of the fuel cell bus because of issues with the air conditioning, the fuel cell power system, and an 

accident that caused body damage. 

Table 1. Average Monthly Mileage (Evaluation Period)

Bus Starting 

Hubodometer

Ending 

Hubodometer

Total 

Mileage Months Monthly Average

AT FCB 21,846 33,010 11,164 7 1,595

603 CNG 127,214 161,166 33,952 7 4,850

604 CNG 114,908 141,107 26,199 7 3,743

605 CNG 123,453 155,704 32,251 7 4,607

606 CNG 115,209 149,283 34,074 7 4,868

608 CNG 119,160 154,547 35,357 7 5,051

Total CNG 161,833 35 4,624

Another measure of reliability is availability—the percentage of time that the buses are planned 

for operation compared with the time the buses are actually available for that planned operation. 
8

Figure 7 shows the monthly average availability for each of the study bus groups. As shown in 

the chart, the availability goal is 85% for all buses. Availability for all of NREL’s evaluations is 

calculated by including the planned service days, which is typically every weekday. Weekends 

and holidays are included in the calculation only if the bus operated in service on those days. If a 

bus does not operate on the weekend or a holiday, it is not counted as unavailable. This strategy 

applies to both the AT fuel cell bus and the CNG buses. 

Overall availability for the AT fuel cell bus was 64% of the time during the evaluation period. As 

mentioned earlier, this unavailability was caused by problems with the air conditioning, the fuel 

cell power system, and an accident causing body damage (December 2010). In April, the CNG 

buses experienced engine problems that caused significant downtime for repair. 

 

Figure 7. Availability for study bus groups

Table 2 provides a summary of the availability and unavailability reasons for each of the study 

bus groups. Overall, during the evaluation period, the average availability for the fuel cell bus 

was 64%, and availability for the CNG buses was 88%. As discussed, the primary issues that 

kept the fuel cell bus out of service were downtime for transit agency maintenance—primarily 

for air conditioning and body work (31%), fuel cell propulsion (42%), and hybrid system issues 

(16%). Issues that kept the CNG buses out of service were general maintenance and engine 

problems. 

0

10

20

30

40

50

60

70

80

90

100

AT FCB CNG

Evaluation data period

Availability Target 85%
9

Table 2. Summary of Reasons for Availability and Unavailability of Buses for Service

Category AT FCB CNG Buses

Number Percent Number Percent

Planned work days 187 1,000

Days available 120 64 877 88

Available 120 100 877 100

On-route 108 90 823 94

Event/demonstration 9 8 0 0

Training 3 3 4 0

Not used 0 0 50 6

Unavailable 67 100 123 100

Fuel cell propulsion 28 42

Hybrid propulsion 7 10

Traction batteries 4 6

SunLine maintenance 21 31 123 100

Fueling unavailable 7 10

Fuel Economy and Cost

Table 3 shows hydrogen and CNG fuel consumption and fuel economy for the study bus groups 

during the evaluation period. Using the GGE fuel economy and the CNG buses as a baseline, the 

AT fuel cell bus had a fuel economy two times higher than the CNG buses. Figure 8 shows 

average fuel economies for each of the study bus groups. 

The fuel costs per mile for the study bus groups for the evaluation period were $1.30 per mile for 

the fuel cell bus and $0.32 for the CNG buses. The fuel cost for CNG has been much lower than 

the cost for hydrogen production. And, the CNG fuel cost at $0.97 per GGE is much lower than 

the typical diesel fuel average cost per gallon.

Table 3. Fuel Use and Economy (Evaluation Period)

Bus Mileage

(Fuel Base)

Hydrogen (kg) 

or CNG (GGE)

Miles per 

kg or GGE

Diesel Equivalent 

Amount (Gallon)

Miles per 

Gallon (DGE)

AT FCB 11,164 1,806.7 6.18 1,598.8 6.98

603 CNG 33,952 11,444.1 2.97 10,242.4 3.31

604 CNG 26,199 8,885.3 2.95 7,952.3 3.29

605 CNG 32,251 10,615.6 3.04 9,501.0 3.39

606 CNG 34,074 11,045.5 3.08 9,885.7 3.45

608 CNG 35,357 11,263.0 3.15 10.080.4 3.51

CNG Total 161,833 53,253.5 3.04 47,661.9 3.40
10

Figure 8. Average fuel economy (miles per kg or GGE)

Maintenance Analysis

The maintenance cost analysis in this section is only for the evaluation period. Warranty costs 

are generally not included in the cost-per-mile calculations. All work orders for the study buses 

were collected and analyzed for this evaluation. For consistency, we set the maintenance labor 

rate at $50 per hour, which does not reflect an average rate for SunLine. This section covers total 

maintenance costs first and then maintenance costs separated by bus system.

Total Maintenance Costs – Total maintenance costs include the price of parts and hourly labor 

rates of $50 per hour. Cost per mile is calculated as follows:

Cost per mile = [(labor hours * 50) + parts cost] / mileage

Table 4 shows total maintenance costs for the AT fuel cell bus and CNG buses. The CNG buses

have total maintenance costs 62% lower than those of the AT fuel cell bus. The parts costs are 

low for the AT fuel cell bus because they typically are covered by the manufacturers for most of 

the propulsion system maintenance; however, SunLine’s mechanics do nearly all of the work. 

40

50

60

70

80

90

100

110

120

0

1

2

3

4

5

6

7

8

Average High Temperature F

Miles per gasoline gallon equivalent

AT FCB CNG Avg High Temp (F)

Evaluation data period
11

Table 4. Total Maintenance Costs (Evaluation Period)

Bus Mileage Parts ($) Labor 

Hours

Cost ($) 

per Mile

AT FCB 11,164 $1,796.00 222.5 $1.16

603 CNG 33,952 $3,907.59 158.25 $0.35

604 CNG 26,199 $6,512.39 178.25 $0.59

605 CNG 32,251 $6,086.75 204.5 $0.51

606 CNG 34,074 $5,735.39 198.5 $0.46

608 CNG 35,357 $3,616.83 169 $0.34

Total CNG 161,833 $25,858.95 908.5 $0.44

Maintenance Costs Separated by System – Table 5 shows maintenance costs by vehicle 

system and bus study group (without warranty costs included). The vehicle systems shown in the 

table include the following: 

• Cab, body, and accessories – Includes body, glass, and paint repairs following 

accidents; cab and sheet metal repairs on seats and doors; and accessory repairs such 

as hubodometers and radios. 

• Propulsion-related systems – Repairs for exhaust, fuel, engine, electric motors, fuel 

cell modules, propulsion control, non-lighting electrical (charging, cranking, and 

ignition), air intake, cooling, and transmission. 

• Preventive maintenance inspections (PMI) – Labor for inspections during 

preventive maintenance.

• Brakes

• Frame, steering, and suspension 

• Heating, ventilation, and air conditioning (HVAC)

• Lighting

• Air system, general

• Axles, wheels, and drive shaft 

• Tires

For the AT fuel cell bus, the systems with the highest percentage of maintenance costs were cab, 

body, and accessories; propulsion-related; and PMI. The CNG buses had the same highest 

percentage of maintenance costs categories, but in a slightly different order – propulsion-related; 

cab, body, and accessories; and PMI.
12

Table 5. Vehicle System Maintenance Cost per Mile by System (Evaluation Period)

System

AT FCB CNG

Cost per 

Mile ($)

Percent of 

Total (%)

Cost per 

Mile ($)

Percent of 

Total (%)

Cab, body, and accessories 0.47 41 0.10 23

Propulsion-related 0.35 31 0.15 35

PMI 0.20 17 0.08 18

Brakes 0.00 0 0.06 12

Frame, steering, and suspension 0.03 2 0.01 2

HVAC 0.07 16 0.02 5

Lighting 0.02 2 0.01 3

Axles, wheels, and drive shaft 0.00 0 0.00 0

General air system repairs 0.02 1 0.00 0

Tires 0.01 1 0.01 2

Total 1.16 100 0.38 100

Propulsion-Related Maintenance Costs – The propulsion-related vehicle systems include the 

exhaust, fuel, engine, electric propulsion, air intake, cooling, non-lighting electrical, and 

transmission systems. Table 6 categorizes the propulsion-related system repairs for the study bus 

groups during the evaluation period (not including warranty). The fuel cell bus was under 

warranty during the entire evaluation period, and the CNG buses have continued to be under 

warranty for any engine issues. During the evaluation period of this report, the SunLine 

mechanics did nearly all of the maintenance on the AT fuel cell bus themselves, supported by the 

manufacturers; however, as mentioned above, the manufacturers generally supplied the parts 

under warranty for the propulsion system, so the costs for these parts are not included. 

• Total propulsion-related – The AT fuel cell bus had more than double the maintenance 

cost for propulsion-related maintenance compared with the CNG buses. The majority of 

this maintenance for the fuel cell bus has been labor. 

• Exhaust system – Costs for this system for the study bus groups were low or zero. 

• Fuel system – Costs for the fuel system were low for both bus groups. 

• Powerplant and electric propulsion – The AT fuel cell bus maintenance reported here 

involved almost exclusively SunLine mechanics supporting manufacturer work on the 

bus. The preventive maintenance for the CNG buses was almost exclusively in the 

powerplant category (with none for electric propulsion – the CNG buses are not hybrids).

• Non-lighting electrical (charging, cranking, and ignition) – The AT fuel cell bus had 

some minor costs in this category relating to 24-volt batteries. The CNG buses mostly 

had preventive maintenance repairs in this category for spark plugs at the 24,000-mile 

preventive-maintenance cycle (and the 48,000-mile cycle) for each bus. The cost per mile 

in this category was the same.

• Air intake – Costs for this system for the study bus groups were low or zero. 

• Cooling – The AT fuel cell bus had a few hours of maintenance on this system, and the 

CNG buses had low costs in this category. 

• Transmission – Costs for this system for the study bus groups were low or zero.
13

Table 6. Propulsion-Related Maintenance Costs by System (Evaluation Period)

Maintenance System Costs AT FCB CNG

Mileage 11,164 161,833

Total Propulsion-Related Systems (Roll-up)

Parts cost ($) 46.64 13,744.81

Labor hours 78.00 217.75

Total cost ($) 3,946.64 24,632.31

Total cost ($) per mile 0.35 0.15

Exhaust System Repairs

Parts cost ($) 0.00 168.95

Labor hours 0.0 2.0

Total cost ($) 0.00 268.95

Total cost ($) per mile 0.00 0.00

Fuel System Repairs

Parts cost ($) 4.45 331.92

Labor hours 0.0 0.5

Total cost ($) 4.45 356.92

Total cost ($) per mile 0.00 0.00

Powerplant System Repairs

Parts cost ($) 0.00 7,289.26

Labor hours 37.5 156.3

Total cost ($) 1,875.00 15,101.76

Total cost ($) per mile 0.17 0.09

Electric Propulsion System Repairs

Parts cost ($) 0.00 0.00

Labor hours 9.5 0.0

Total cost ($) 475.00 0.00

Total cost ($) per mile 0.04 0.00

Non-Lighting Electrical System Repairs (General Electrical, Charging, 

Cranking, Ignition)

Parts cost ($) 0.00 4,663.98

Labor hours 9.0 26.0

Total cost ($) 450.00 5,963.98

Total cost ($) per mile 0.04 0.04

Air Intake System Repairs

Parts cost ($) 0.00 331.62

Labor hours 0.0 0.0

Total cost ($) 0.00 331.62

Total cost ($) per mile 0.00 0.00

Cooling System Repairs

Parts cost ($) 42.19 583.32

Labor hours 22.0 33.0

Total cost ($) 1,142.19 2,233.32

Total cost ($) per mile 0.10 0.04

Transmission System Repairs

Parts cost ($) 0.00 112.49

Labor hours 0.0 0.0

Total cost ($) 0.00 112.49

Total cost ($) per mile 0.00 0.00
14

Roadcall Analysis

A roadcall (RC), or revenue vehicle system failure (as named in the National Transit Database5), 

is defined as a failure of an in-service bus that causes the bus to be replaced on route or causes a 

significant delay in schedule. If the problem with the bus can be repaired during a layover and 

the bus remains on schedule, this is not considered a RC. The analysis provided here includes 

only RCs caused by “chargeable” failures. Chargeable RCs include systems that can physically 

disable the bus from operating on route, such as interlocks (doors and wheelchair lift) and engine 

problems. Chargeable RCs do not include RCs for things such as radios or destination signs. 

Table 7 shows the RCs and miles between roadcalls (MBRC) for each study bus group in two 

categories: all RCs and propulsion-related-only RCs. 

Table 7. Roadcalls and MBRC (Evaluation Period)

Bus Mileage All 

Roadcalls All MBRC Propulsion Roadcalls

Propulsion 

MBRC

AT FCB 11,164 2 5,582 2 5,582

603 CNG 33,952 2 16,976 2 16,976

604 CNG 26,199 2 13,100 1 26,199

605 CNG 32,251 8 4,031 5 6,450

606 CNG 34,074 3 11,358 2 17,037

608 CNG 35,357 2 17,679 0

Total CNG 161,833 17 9,520 10 16,183

Summary of Experience to Date

The AT FCB has been in operation for more than a year and each of the partners feel positive 

about the project and the technology. SunLine is happy with how the project has progressed. 

Early issues have been resolved and the bus is operating well. Maintenance staff has come up to 

speed on the new bus systems and has learned to diagnose and repair most issues. The 

manufacturer partners–Ballard and Bluways–both feel the project is going well and that they 

have addressed the majority of the problems experienced in the early demonstration period. This 

section summarizes the challenges and achievements that the team has had so far in the 

demonstration. 

Pilot Bus – The AT FCB was originally designed as the pilot bus to a much larger project in 

British Columbia, Canada. The bus was delivered in 2009 and the transit operator, BC Transit, 

ran the bus through a series of acceptance and operational tests over a period of about six 

months. This performance testing enabled the manufacturers to further refine and optimize the 

system and gave the transit agency firsthand experience with the bus and the technology. At the 

end of the test period, the design for the larger fleet had been finalized and the pilot bus was 

returned to Bluways. Prior to that, SunLine had received funding from the state of California for 

a new project to upgrade an older fuel cell bus with a new system. This project had stalled 

because of issues with the older bus and difficulties with retrofitting an old bus with a new 

design system. When the project team learned the pilot bus was available, SunLine was able 

negotiate with the state to reconfigure the original project. Bluways upgraded the pilot bus to 

 

5 Federal Transit Administration’s National Transit Database website: www.ntdprogram.gov/ntdprogram/. 
15

match the final design of the BC Transit buses and it was put in service at SunLine. This was a 

win-win for the parties involved; SunLine and the project team were able to purchase an 

advanced technology fuel cell bus that met the intent of the original project awarded by the state

of California, and the manufacturers were able to further test this new fuel cell system in a hot 

dry climate.

Heat Exchanger Failure – A crack in the heat exchanger resulted in leaks. The component 

supplier updated and replaced the part, which appears to have solved the problem. This situation 

also occurred with the buses in Canada.

Fuel Cell Issues – Problems that caused downtime for the bus included a faulty motor controller 

cable and coolant flow sensor. The motor controller cable issue was intermittent, which made it 

more difficult and time-consuming to diagnose. Replacing the cable resolved the issue. 

Temperature Issues – The extreme high summer temperatures have resulted in problems with 

the air conditioning. This was the primary reason for downtime in the early stage of the 

demonstration. The hybrid system is configured to cool the batteries with air from the bus's air 

conditioning unit. This unit is a prototype electrically-driven air conditioner model. The summer 

heat in SunLine’s service area affects how well the air conditioning can keep up with demand for 

cooling passengers while keeping the batteries within proper operating temperature range. The 

air conditioner component manufacturer has upgraded the unit to more closely match the 

production unit configuration. SunLine continues to work with Bluways and the component 

manufacturer to address the issue. 
16

What’s Next for SunLine

This report covers SunLine’s operation of the fuel cell and CNG buses from December 2010 

through June 2011. The agency will continue working with DOE/NREL to collect data on the 

buses in service. The next report is expected to be published in early 2012. 

SunLine is also leading a team to develop a purpose-built fuel cell bus that meets FTA “Buy 

America” requirements. Funded under the FTA’s National Fuel Cell Bus Program, the 

American Fuel Cell Bus Project brings a new team of manufacturers to the fuel cell bus 

industry—ElDorado, BAE SYSTEMS, and Ballard. The design features a number of 

advancements that are expected to result in a highly efficient bus. Elements include advanced 

energy storage and new power electronics, high-efficiency accessories, and the newestgeneration fuel cell on a U.S.-built chassis. This bus is in development and is expected to be 

ready for demonstration in late 2011 or early 2012. 

Status of SunLine’s Van Hool Fuel Cell Bus

SunLine has been operating a second fuel cell bus since December 2005. Operation and 

evaluation of this bus has been reported in five previous NREL evaluation reports. This Van 

Hool 40-foot bus was integrated by ISE Corp. (now Bluways) with a Siemens hybrid propulsion 

system, Zebra hybrid batteries, and UTC Power’s fuel cell power system. This bus continues to 

operate in service with a total of 125,761 miles and 9,705 hours (an average operating speed of 

13.0 mph) through June 2011. The current fuel cell power plant in the bus has been in service 

since August 2009. SunLine and UTC Power continue to support the operation of this bus. 

Figure 9. SunLine’s Van Hool fuel cell bus
17

Contacts

DOE

1000 Independence Ave., SW 

Washington, DC 20585 

John Garbak, Technology Validation 

Manager, Vehicle Technologies Program

Phone: 202-586-1723 

E-mail: john.garbak@ee.doe.gov

NREL

1617 Cole Boulevard 

Golden, CO 80401 

Leslie Eudy, Senior Project Leader

Phone: 303-275-4412 

E-mail: leslie.eudy@nrel.gov 

Battelle

505 King Avenue 

Columbus, OH 43201 

Kevin Chandler, Program Manager 

Phone: 614-424-5127 

E-mail: chandlek@battelle.org 

SunLine

32-505 Harry Oliver Trail

Thousand Palms, CA 92276 

Tommy Edwards, Director of Maintenance

Phone: 760-343-3456 

E-mail: tedwards@sunline.org 

Ballard Power Systems

9000 Glenyon Parkway 

Burnaby, BC, Canada 

Daljit Bawa, Market Manager - Bus 

Segment

Phone: 604-412-3108 

E-mail: daljit.bawa@ballard.com 

Jeff Grant, Business Development Manager

Phone: 604-453-3578 

E-mail: jeff.grant@ballard.com 

Bluways USA, Inc.

12302 Kerran Street 

Poway, CA 92064 

Tavin Tyler, Director, Product Management 

Phone: 858- 413-1745 

E-mail: tavin.tyler@bluways.com 
18

References and Related Reports

All NREL hydrogen and fuel cell-related evaluation reports can be downloaded from the 

following website: www.nrel.gov/hydrogen/proj_fc_bus_eval.html.

SunLine

Eudy, L.; Chandler, K. (2011). SunLine Transit Agency Advanced Technology Fuel Cell Bus 

Evaluation: First Results Report. NREL/TP-5600-50500, Golden, CO: National Renewable 

Energy Laboratory. 

Eudy, L.; Chandler, K. (2009). SunLine Transit Agency, Fuel Cell Transit Bus: Fifth Evaluation 

Report and Appendices. NREL/TP-560-46346-1, NREL/TP-560-46346-2. Golden, CO: National 

Renewable Energy Laboratory.

Chandler, K.; Eudy, L. (2009). SunLine Transit Agency, Fuel Cell Transit Bus: Fourth 

Evaluation Report and Appendices. NREL/TP-560-44646-1, NREL/TP-560-44646-2. Golden, 

CO: National Renewable Energy Laboratory. 

Eudy, L. (2008). SunLine Begins Extended Testing of Hybrid Fuel Cell Bus. DOE/GO-102008-

2610. Golden, CO: National Renewable Energy Laboratory. 

Chandler, K.; Eudy, L. (2008). SunLine Transit Agency, Hydrogen-Powered Transit Buses: 

Third Evaluation Report and Appendices. NREL/TP-560-43741-1, NREL/TP-560-43741-2. 

Golden, CO: National Renewable Energy Laboratory. 

Chandler, K.; Eudy, L. (2007). SunLine Transit Agency, Hydrogen-Powered Transit Buses: 

Evaluation Results Update. NREL/TP-560-42080. Golden, CO: National Renewable Energy 

Laboratory. 

Chandler, K.; Eudy, L. (2007). SunLine Transit Agency, Hydrogen-Powered Transit Buses: 

Preliminary Evaluation Results. NREL/TP-560-41001. Golden, CO: National Renewable Energy 

Laboratory. 

Eudy, L. (2006). SunLine Expands Horizons with Fuel Cell Bus Demo. DOE/GO-102006-2287. 

Golden, CO: National Renewable Energy Laboratory. 

Eudy, L. (2006). SunLine Tests HHICE Bus in Desert Climate. DOE/GO-102006-2333. Golden, 

CO: National Renewable Energy Laboratory. 

Chandler, K. (2006). Ten Years of Compressed Natural Gas (CNG) Operations at SunLine 

Transit Agency. NREL/SR-540-39180. Golden, CO: National Renewable Energy Laboratory. 

Del Toro, A.; Frailey, M.; Lynch, F.; Munshi, S.; Wayne, S. (2005). Development and 

Demonstration of Hydrogen and Compressed Natural Gas (H/CNG) Blend Transit Buses: 

October 15, 2002--September 30, 2004. NREL/TP-540-38707. Golden, CO: National Renewable 

Energy Laboratory. 
19

Chandler, K.; Eudy, L. (2003). ThunderPower Bus Evaluation at SunLine Transit Agency.

DOE/GO-102003-1786. Golden, CO: National Renewable Energy Laboratory. 

Eudy, L. (2003). SunLine Test Drives Hydrogen Bus. DOE/GO-102003-1768. Golden, CO: 

National Renewable Energy Laboratory. 

General

Eudy, L. (2010). Fuel Cell Transit Bus Evaluations, Joint Evaluation Plan for the U.S. 

Department of Energy and the Federal Transit Administration. NREL/TP-560-49342. Golden, 

CO: National Renewable Energy Laboratory. 

Eudy, L.; Chandler, K.; Gikakis, C. (2010). Fuel Cell Buses in U.S. Transit Fleets: Current 

Status 2010. NREL/TP-560-49379. Golden, CO: National Renewable Energy Laboratory. 

Eudy, L.; Chandler, K.; Gikakis, C. (2009). Fuel Cell Buses in U.S. Transit Fleets: Current 

Status 2009. NREL/TP-560-46490. Golden, CO: National Renewable Energy Laboratory. 

Eudy, L.; Chandler, K.; Gikakis, C. (2008). Fuel Cell Buses in U.S. Transit Fleets: Current 

Status 2008. NREL/TP-560-44133. Golden, CO: National Renewable Energy Laboratory. 

Eudy, L.; Chandler, K.; Gikakis, C. (2007). Fuel Cell Buses in U.S. Transit Fleets: Summary of 

Experiences and Current Status. NREL/TP-560-41967. Golden, CO: National Renewable 

Energy Laboratory. 

AC Transit

Eudy, L. (2010). Bay Area Transit Agencies Propel Fuel Cell Buses Toward Commercialization.

DOE/GO-102010-3067. Golden, CO: National Renewable Energy Laboratory. 

Chandler, K.; Eudy, L. (2010). National Fuel Cell Bus Program: Accelerated Testing Evaluation 

Report #2 and Appendices. FTA-CO-26-7004-2010.1. Golden, CO: National Renewable Energy 

Laboratory. 

Chandler, K.; Eudy, L. (2009). National Fuel Cell Bus Program: Accelerated Testing Evaluation 

Report and Appendices. FTA-CO-26-7004-2009.1. Golden, CO: National Renewable Energy 

Laboratory. 

Chandler, K.; Eudy, L. (2007). Alameda-Contra Costa Transit District (AC Transit), Fuel Cell 

Transit Buses: Third Evaluation Report and Appendices. NREL/TP-560-43545-1, NREL/TP560-43545-2. Golden, CO: National Renewable Energy Laboratory. 

Chandler, K.; Eudy, L. (2007). Alameda-Contra Costa Transit District (AC Transit), Fuel Cell 

Transit Buses: Evaluation Results Update. NREL/TP-560-42249. Golden, CO: National 

Renewable Energy Laboratory.

Chandler, K.; Eudy, L. (2007). AC Transit, Fuel Cell Transit Buses: Preliminary Evaluation 

Results. NREL/TP-560-41041. Golden, CO: National Renewable Energy Laboratory. 
20

Eudy, L. (2006). AC Transit Demonstrates Three Prototype Fuel Cell Buses. DOE/GO-102006-

2286. Golden, CO: National Renewable Energy Laboratory. 

BurbankBus

Eudy, L. (2010). Fuel Cell Bus Takes a Starring Role in the BurbankBus Fleet. DOE/GO102010-3035. Golden, CO: National Renewable Energy Laboratory. 

Connecticut Transit

Chandler, K.; Eudy, L. (2010). Connecticut Transit (CTTRANSIT) Fuel Cell Transit Bus: Third 

Evaluation Report and Appendices. NREL/TP-560-47334-1, NREL/TP-560-47334-2. Golden, 

CO: National Renewable Energy Laboratory. 

Chandler, K.; Eudy, L. (2009). Connecticut Transit (CTTRANSIT) Fuel Cell Transit Bus: Second 

Evaluation Report and Appendices. NREL/TP-560-45670-1, NREL/TP-560-45670-2. Golden, 

CO: National Renewable Energy Laboratory. 

Chandler, K.; Eudy, L. (2008). Connecticut Transit (CTTRANSIT) Fuel Cell Transit Buses: 

Preliminary Evaluation Results. NREL/TP-560-43847. Golden, CO: National Renewable Energy 

Laboratory. 

Eudy, L. (2008). CTTRANSIT Operates New England’s First Fuel Cell Hybrid Bus. DOE/GO12008-2529. Golden, CO: National Renewable Energy Laboratory. 

Santa Clara Valley Transportation Authority

Chandler, K.; Eudy, L. (2006). Santa Clara Valley Transportation Authority and San Mateo 

County Transit District, Fuel Cell Transit Buses: Evaluation Results. NREL/TP-560-40615. 

Golden, CO: National Renewable Energy Laboratory. 

Eudy, L. (2005). VTA, SamTrans Look into Future with Bus Demo. DOE/GO-102005-2147. 

Golden, CO: National Renewable Energy Laboratory.