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: First Results 

Report 

Leslie Eudy

National Renewable Energy Laboratory

Kevin Chandler

Battelle

Technical Report

NREL/TP-5600-50500

March 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: First Results 

Report 

Leslie Eudy

National Renewable Energy Laboratory

Kevin Chandler

Battelle

Prepared under Task No. H270.8150 

Technical Report

NREL/TP-5600-50500

March 2011
NOTICE

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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 

Credit for all photos in the report: Leslie 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 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). SunLine 

provides public transit services to the Coachella Valley area of California. 

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

been evaluating alternative fuel and advanced propulsion equipped transit buses since the early 

1990s. This fuel cell bus at SunLine is being evaluated 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. This protocol 

was documented in a joint evaluation plan (with the Federal Transit Administration) for transit 

bus evaluations.1

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. The AT fuel cell bus started revenue service on May 27, 2010. 

During the data period for this report (May 2010 to November 2010), the fuel cell bus operated 

9,687 miles and 818 fuel cell system hours (for an average operating speed of 11.8 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. 

 

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 May – Nov 

2010

May – Nov 

2010

Number of months 7 7

Total mileage in period 9,687 158,172

Average monthly mileage per bus 1,384 4,519

Availability (85% is target) 59% 90%

Fuel economy (miles/kg or GGE) 5.75 2.88

Miles between roadcalls (MBRC) – all 4,844 79,086

MBRC – propulsion only 4,844 79,086

Total maintenance, $/mile 0.47 0.38

Maintenance – propulsion only, $/mile 0.23 0.10

This NREL evaluation is planned to include at least 12 months of operation. The next evaluation 

report is expected toward the end of calendar year 2011. 

 

1 Fuel Cell Transit Bus Evaluations: Joint Evaluation Plan for the U.S. Department of Energy and the Federal 

Transit Administration, NREL/MP-560-49342-1, November 2010, www.nrel.gov/hydrogen/pdfs/49342-1.pdf. 
vi

Table of Contents

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

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

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

Fuel Cell Bus Evaluation at SunLine .......................................................................................... 3

Bus Technology Descriptions ......................................................................................................... 5

Advanced Technology Fuel Cell Bus .......................................................................................... 6

Hybrid Fuel Cell System ............................................................................................................. 7

Hydrogen and CNG Fueling ........................................................................................................... 7

Evaluation Results ........................................................................................................................ 10

Route Assignments .................................................................................................................... 10

Bus Use and Availability ........................................................................................................... 10

Fuel Economy and Cost ............................................................................................................ 12

Maintenance Analysis ............................................................................................................... 13

Roadcall Analysis ...................................................................................................................... 17

What’s Next for SunLine .............................................................................................................. 18

Contacts......................................................................................................................................... 19

References and Related Reports ................................................................................................... 20

SunLine ..................................................................................................................................... 20

General ...................................................................................................................................... 21

AC Transit ................................................................................................................................. 21

BurbankBus ............................................................................................................................... 21

Connecticut Transit ................................................................................................................... 22

Santa Clara Valley Transportation Authority ............................................................................ 22

Appendix A: Fleet Summary Statistics ......................................................................................... 23

Appendix B: Fleet Summary Statistics – SI Units ........................................................................ 29
1

Introduction

SunLine Transit Agency has demonstrated hydrogen and fuel cell bus technologies for more than 

10 years. In May 2010, the agency began operating its sixth-generation hydrogen fueled bus, 

which it unveiled in February 2010 during the 3rd Annual State of Public Transit Luncheon. This 

Advanced Technology (AT) fuel cell bus 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. This report provides the early data results and implementation experience 

of the fuel cell bus since it was placed in service. 

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

Host Site Profile: SunLine

 

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

Valley (including Palm Springs). SunLine’s headquarters are in Thousand Palms, California (see 

Figure 1), and its service area of more than 1,100 square miles includes nine member cities and a 

portion of Riverside County (Figure 2). 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. 

Figure 1. SunLine's headquarters, located in Thousand Palms, California

 

2 Fuel Cell Transit Bus Evaluations: Joint Evaluation Plan for the U.S. Department of Energy and the Federal 

Transit Administration, NREL/MP-560-49342-1, November 2010, www.nrel.gov/hydrogen/pdfs/49342-1.pdf. 
2

Figure 2. SunLine operating area in the Coachella Valley, California

SunLine operates 11 fixed routes (SunBus) and provides paratransit services (SunDial). Table 1

outlines SunLine’s current bus fleet including the newest fuel cell bus. In addition to the 69 

fixed-route buses, the agency’s fleet includes 31 CNG paratransit vehicles. Its non-revenue 

vehicle fleet consists of 39 light- and medium-duty CNG vehicles and one hybrid light-duty 

vehicle.

Table 1. SunLine Fixed-Route Bus Fleet

Number Description

41 New Flyer 40-ft, low floor, CNG

15 Orion V 40-ft, CNG

10 ElDorado 30-ft, CNG

1 New Flyer Hybrid Hydrogen ICE (HHICE)

1 Van Hool 40-ft, Fuel Cell Bus

1 New Flyer 40-ft, Advanced Technology Fuel Cell Bus

69 Total Bus Fleet
3

SunLine’s fixed routes in the Coachella Valley operate along State Highway 111 and Interstate 

10. In 2009, SunLine conducted a Comprehensive Operational Analysis3

Table 2

 to better understand the 

existing and future transit market in the area and to develop a plan for optimizing service to costeffectively meet those needs. The Preferred Service Plan outlined in the study recommended a 

variety of modifications to the route structure to increase ridership and lower operational costs. 

The changes included realignment of select routes, establishment of new routes, and increased 

frequencies and spans on most routes. SunLine began implementing this plan during 2010. 

shows a weekly summary of the updated bus use at SunLine and indicates that bus 

service operates at an average of 13.9 mph on the weekends and 14.0 mph during the week for an 

overall average of 13.9 mph. 

Table 2. Summary of Total Weekly Bus Use at SunLine

Day of Week Total Miles Hours Average Speed

Weekday 42,993.0 3,080.8 14.0

Weekend 11,388.6 820.9 13.9

Total 54,381.6 3,901.7 13.9

The weather in SunLine’s service area can have an effect on vehicle performance. The Coachella 

Valley is a hot, desert climate with an annual rainfall between 2 and 4 inches. Average high 

temperatures are usually over 80°F for eight months of the year and can get as high as 120°F. 

This plays a role in how the SunLine buses are operated. During the eight months in the year 

when the average high temperature is above 80°F, drivers typically idle on the shorter layovers to 

keep the buses cool for passengers. This causes the bus average speed to go down and the airconditioning load to go up, both of which have a significant impact on fuel efficiency.

Fuel Cell Bus Evaluation at SunLine

SunLine has successfully used its unique capabilities with gaseous fuels, small size, and hightemperature/low-humidity location to attract testing projects with government and manufacturer 

partners. Over the years, many projects have involved natural gas, hydrogen, fuel cells, and 

various combinations of these technologies. The objectives for these projects have been to 

advance clean transit bus propulsion systems and leverage project funding to afford SunLine 

additional equipment and infrastructure. 

In May 2010, SunLine began demonstrating the AT bus—a new-generation fuel cell bus 

developed by Bluways,

4 Ballard Power Systems, and New Flyer. This report describes 

SunLine’s operation of the AT fuel cell transit bus in revenue service. Five compressed natural 

gas (CNG) buses operating from the same SunLine location are being used as a baseline 

comparison. This evaluation report describes results and experiences with the AT fuel cell bus 

and CNG buses from May 2010 through November 2010. 

 

3 Link to SunLine’s Comprehensive Operational Analysis: http://www.sunline.org/pub/pdfs/COA_July2009.pdf. 4 Bluways (www.bluways.com) supplies hybrid electric drive systems and components for heavy-duty applications. 
4

SunLine’s Experiences with Hydrogen Buses

SunLine’s experience with hydrogen spans more than a decade of development and demonstration 

projects. 

Ballard P4 Bus: SunLine participated in a 

demonstration of the Phase 4 version of the 

ZeBus. The bus was tested in SunLine’s service 

area but was not used in actual revenue service.

ThunderPower FCB: This bus featured an ISE 

hybrid design powered by UTC Power’s 60 kW fuel 

cell power system. SunLine demonstrated this 30-

foot FCB in revenue service for six months. The 

bus accumulated more than 8,000 miles and 640 

hours on the fuel cell system. Fuel economy 

averaged 12 mpDGE. 

Cummins - Westport (CWI) engine 

development: SunLine worked with CWI to 

develop and demonstrate a natural gas engine 

capable of using hydrogen and CNG blended fuel. 

Using a blend of 20% hydrogen/80% CNG, the 

project demonstrated significant reductions of 

several pollutant emissions–including 50% lower 

oxides of nitrogen and 58% lower non-methane 

hydrocarbons–when compared to conventional 

CNG engines. 

Hydrogen Hybrid Internal Combustion Engine 

bus: SunLine demonstrated the HHICE bus in 

revenue service for several years. During that time, 

the bus accumulated more than 85,000 miles with 

an average fuel economy of 4.9 mpDGE. 

Van Hool/UTC Power FCB: SunLine’s first fullsize FCB went into service in late 2006. This bus, 

developed by UTC Power, ISE, and Van Hool, 

continues to operate in revenue service in the 

fleet. The bus has accumulated more than 115,000

miles and 8,800 fuel cell system hours (through 

November 2010).

New Flyer/Bluways/Ballard FCB: SunLine’s 

newest FCB, which is the subject of this report, 

has operated nearly 9,700 miles and accumulated 

818 hours on the fuel cell system since it was put 

in service. 
5

Bus Technology Descriptions

Table 3 provides bus system descriptions for the AT fuel cell bus and CNG buses that were 

studied in this evaluation. The AT bus is a low floor, 40-foot New Flyer model with the latest 

advances designed to improve performance, reliability, and durability. The fuel cell bus is 

pictured in Figure 3. 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 engines that are designed to meet 2010 

emission regulations (see Figure 4). 

Table 3. Fuel Cell and CNG Bus System Descriptions 

Vehicle System AT Fuel Cell Bus CNG Bus

Number of buses 1 5

Bus manufacturer and model New Flyer, H40LFR New Flyer

Model year 2009 2008

Length/width/height 40 ft/102 in./137 in. 40 ft/102 in./130.8 in.

Gross vehicle weight rating 44,530 lb 42,540 lb

Passenger capacity 37 seated with no wheelchairs 39 seated with no 

wheelchairs

Hybrid system

Bluways hybrid-electric drive 

system incorporating Siemens 

ELFA components

N/A

Fuel cell or engine Ballard Power Systems 

FCvelocity HD6, 150 kW

Cummins Westport ISL G,

280 hp @ 2,200 rpm

Propulsion motor Two Siemens AC induction 

motors, 85 kW each N/A

Energy storage

Valence, phosphate based 

lithium ion batteries, 

rated energy: 47 kWh

N/A

Accessories Electric Mechanical

Fuel/storage

Gaseous hydrogen, 43 kg at 

5,000 psi, 6 Dynetek, Type 3 

tanks

125 diesel gallon 

equivalent

Bus purchase cost $1,200,0005 $402,900

 

 

5 The purchase price for the AT bus was prorated based on the fact it was previously demonstrated at BC Transit.
6

Figure 3. SunLine's Advanced Technology fuel cell bus

Figure 4. New Flyer CNG bus at SunLine

Advanced Technology Fuel Cell Bus

This AT fuel cell bus was designed in collaboration between Bluways,

6

 Ballard, and New Flyer. 

The bus was originally developed as the pilot for an order of 20 buses to be operated in British 

Columbia, Canada, beginning with the 2010 Winter Olympic Games. The transit operator, BC 

Transit, put the bus through a series of acceptance tests over a period of about six months. The 

data results from those tests enabled the manufacturers to make changes and optimize the design 

prior to building the larger fleet. Once this bus completed its pilot testing in Canada, it was 

returned to Bluways where it was upgraded to match the final design of the rest of the BC Transit

fleet. With funding from California and federal government agencies, SunLine was able to 

purchase the bus for operation in its service area. The data gathered on the bus at SunLine will 

help the manufacturers determine how the system performs in a hot, dry climate. 

 

6 In February 2011, Bluways acquired substantial assets and technology from ISE Corporation.
7

Hybrid Fuel Cell System 

The design is a next-generation system based on experiences with early hybrid and fuel cell bus 

demonstrations conducted by the manufacturers. Each partner brings a unique perspective and 

set of experiences to creating a fuel cell bus designed to compete in the market. For Ballard, the 

new fuel cell module included improvements and upgrades based on lessons learned with 

projects such as the CUTE and HyFLEET:CUTE programs. As part of these and other 

demonstrations, Ballard gathered data from fuel cell buses operating for more than 1.2 million 

miles of revenue service. The data collected during these demonstrations were used to refine and 

optimize the fuel cell and system components for higher efficiency and increased durability. 

Ballard now offers a 5-year, 12,000-hour warranty on the HD6 fuel cell module. 

The Bluways hybrid system was designed as a plug-and-play architecture, which enables a 

variety of power sources or energy storage solutions to be easily incorporated. For this AT bus, 

Bluways integrated Ballard’s 150-kW fuel cell module and lithium-ion batteries from Valence. 

The hybrid electric propulsion system is based on the Siemens ELFA system. The company’s 

experience with early version fuel cell buses and a fleet of gasoline hybrids provided in-service 

data to aid in the development process. 

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. 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 A shows 

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 from both buses. Figure 5 shows the 

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

November 2010. 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 83% 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 22.2 kg per day. During this period, SunLine dispensed a total of 3,924 kg of 

hydrogen. At times during the summer, one or the other fuel cell bus was out of service for 

maintenance issues. This resulted in lower hydrogen use during those months. 
8

Figure 6 shows the distribution of hydrogen amounts dispensed per fill by bus. The buses were

filled a total of 224 times during the evaluation period for a total of 3,675 kg.7

Figure 7

The average 

amount of hydrogen per fill was 16.4 kg per fill. shows a cumulative fueling rate 

histogram for the SunLine hydrogen station from May 2010 through November 2010. The 

overall average fueling rate was 1.0 kg per minute, and the average time for a fill was 15.8 

minutes. 

Figure 5. Average hydrogen dispensed per day (excluding 0 kg days)

Figure 6. Histogram of fueling amounts by bus

 

7 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. 

0

5

10

15

20

25

30

May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10

Average Daily Hydrogen Use (kg)
9

Figure 7. Histogram of fueling rates

Hydrogen fuel costs at SunLine consist of the cost of natural gas for the reformer, 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 $18.45/kg (monthly costs ranged from a low of $6.65/kg to a high of 

$29.68/kg). Lower use of the station (when the buses were out of service) and higher 

maintenance for the reformer during March 2009 were contributors to higher monthly costs. 

Figure 8 shows the monthly station use and hydrogen cost per kilogram since January 2008. 

DOE’s target for hydrogen cost ($2–$4/kg) is also included. The figure illustrates the 

relationship between high hydrogen costs and low station use. Repair costs for the reformer are 

also factored into the total hydrogen costs, which causes spikes in the hydrogen cost for those 

months. Hydrogen costs for the months when less than 100 kg are produced are not 

representative and are shaded in grey on the graph. SunLine indicates that the best steady-state 

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

$8/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 $0.90 per GGE. This price includes all costs—natural gas, maintenance, and station 

amortization. 
10

Figure 8. Comparison of monthly hydrogen use and cost per kg

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 May 2010 through November 

2010. Appendix A provides a summary of all data. Appendix B provides a data summary in SI 

(metric) units. 

Route Assignments

In general, SunLine’s buses are randomly dispatched on its routes. As previously mentioned, the 

overall system average speed is 13.9 mph. When first placed in service, the AT fuel cell bus was 

used exclusively on Line 50, which had an average speed of 14.1 mph. When SunLine instituted 

the Preferred Service Plan in September 2010, Line 50 was realigned and became Line 53. At 

that time, 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 (75%) split evenly between 

Line 111 (13.9 mph), Line 14 (14.6 mph), and Line 30 (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 9,687 miles, and the fuel cell system 

accumulated 818 hours, which indicates an average speed of 11.8 mph. This average speed is 

$-

$10 

$20 

$30 

$40 

$50 

$60 

0

200

400

600

800

1000

1200

Jan-08

Mar-08

May-08

Jul-08

Sep-08

Nov-08

Jan-09

Mar-09

May-09

Jul-09

Sep-09

Nov-09

Jan-10

Mar-10

May-10

Jul-10

Sep-10

Nov-10

Cost in $/kg

Total Monthly kg

kg H2 $/kg DOE target
11

slower than the overall 13.9 mph average speed for all SunLine routes. For in-service days 

during the evaluation period, the AT fuel cell bus averaged 7.6 hours per day with a maximum of 

14.4 hours in one day. 

Table 4 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 31% that of the CNG buses. This percentage is partly due to downtime 

of the fuel cell bus because of issues with the air conditioning. 

Table 4. Average Monthly Mileage (Evaluation Period)

Bus Starting 

Hubodometer

Ending 

Hubodometer

Total 

Mileage Months Monthly Average

AT FCB 12,159 21,846 9,687 7 1,384

603 CNG 92,951 127,214 34,263 7 4,895

604 CNG 84,664 114,908 30,244 7 4,321

605 CNG 89,238 123,453 34,215 7 4,888

606 CNG 81,301 115,209 33,908 7 4,844

608 CNG 93,618 119,160 25,542 7 3,649

Total CNG 158,172 35 4,519

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. 

Figure 9 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 59% of the time during the evaluation period. 

During the summer months, the bus experienced problems with its air conditioning system, 

which resulted in significant downtime. Because of the high summer temperatures in the area, 

SunLine can’t operate a bus without air conditioning. Also, the cooling for the hybrid battery 

pack is provided as part of the bus cooling system, and some issues occurred with this cooling of 

the hybrid battery pack during the evaluation period. The chart shows that the CNG buses have 

consistently achieved availability above the 85% target. 

Table 5 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 59%, and availability for the CNG buses was 90%. 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 (58%), fuel cell propulsion (20%), and hybrid system issues

(14%). Issues that kept the CNG buses out of service were general maintenance.

 
12

Figure 9. Availability for study bus groups

Table 5. Summary of Reasons for Availability and Unavailability of Buses for Service

Category AT FCB CNG Buses

Number Percent Number Percent

Planned work days 159 1,010

Days available 94 59 909 90

Available 94 100 909 100

On-route 93 99 865 95

Event/demonstration 0 0 5 1

Training 0 0 0 0

Not used 1 1 39 4

Unavailable 65 100 96 100

Fuel cell propulsion 13 20

Hybrid propulsion 9 14

Traction batteries 0 0

SunLine maintenance 38 58 96 100

Fueling unavailable 5 8

Fuel Economy and Cost

Table 6 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 nearly two times higher than the CNG buses. Figure 10

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 $1.40 per mile for 

the fuel cell bus and $0.31 per mile for the CNG buses. The fuel cost for CNG has been much 

0

10

20

30

40

50

60

70

80

90

100

May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10

Percent Availability

AT FCB CNG

Availability Target 85%
13

lower than the cost for hydrogen production. And, the CNG fuel cost at $0.90 per GGE is much 

lower than the typical diesel fuel average cost per gallon.

Table 6. 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 9,580 1,665.0 5.75 1,474.4 6.50

603 CNG 34,263 12,062.7 2.84 10,796.1 3.17

604 CNG 30,244 10,520.5 2.87 9,415.8 3.21

605 CNG 34,215 11,995.9 2.85 10,736.3 3.19

606 CNG 33,908 11,792.2 2.88 10,554.0 3.21

608 CNG 25,542 8,624.8 2.96 7,719.2 3.31

CNG Total 158,172 54,996.0 2.88 49,221.4 3.21

Figure 10. 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

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:

 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.

0

20

40

60

80

100

120

0

1

2

3

4

5

6

7

May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10

Average High Temperature F

Miles per gasoline gallon equivalent

AT FCB CNG Avg High Temp (F)
14

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

Table 7 shows total maintenance costs for the fuel cell bus and CNG buses. The CNG buses have 

total maintenance costs 27% lower than those of the fuel cell bus. The parts costs are low for the 

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

system maintenance; however, SunLine’s mechanics do most of the work. 

Table 7. Total Maintenance Costs (Evaluation Period)

Bus Mileage Parts ($) Labor 

Hours

Cost ($) 

per Mile

AT FCB 9,687 153.22 88.0 0.47

603 CNG 34,263 5,053.43 166.3 0.39

604 CNG 30,244 4,606.42 192.4 0.47

605 CNG 34,215 3,333.56 187.8 0.37

606 CNG 33,908 2,700.06 144.5 0.29

608 CNG 25,542 2,688.06 139.8 0.38

Total CNG 158,172 18,381.53 830.8 0.38

Maintenance Costs Separated by System – Table 8 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 

propulsion-related, PMI, and HVAC. The CNG buses had highest percentage of maintenance 

costs for cab, body, and accessories; propulsion-related; and PMI.
15

Table 8. 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 0.05 11 0.13 34

Propulsion-related 0.23 49 0.10 26

PMI 0.11 23 0.09 24

Brakes 0.00 0 0.00 0

Frame, steering, and suspension 0.00 0 0.02 4

HVAC 0.06 13 0.01 3

Lighting 0.02 4 0.01 3

Axles, wheels, and drive shaft 0.00 0 0.01 3

General air system repairs 0.00 0 0.00 0

Tires 0.00 0 0.01 3

Total 0.47 100 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 9 categorizes the propulsion-related system repairs for the study bus 

groups during the evaluation period (no 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 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 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 – There were no costs for this system for the study bus groups. 

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

• Powerplant and electric propulsion – The 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 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. 

• Air intake – The fuel cell bus had no costs in this category, and the CNG buses had only 

air filter changeouts. 

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

buses had low costs in this category. 

• Transmission – Only the CNG buses had costs in this category for filters under 

preventive maintenance.
16

Table 9. Propulsion-Related Maintenance Costs by System (Evaluation Period)

Maintenance System Costs AT FCB CNG

Mileage 9,687 158,172

Total Propulsion-Related Systems (Roll-up)

Parts cost ($) 13.00 9,005.83

Labor hours 44.75 128.75

Total cost ($) 2,250.50 15,443.33

Total cost ($) per mile 0.23 0.10

Exhaust System Repairs

Parts cost ($) 0.00 0.00

Labor hours 0.0 0.0

Total cost ($) 0.00 0.00

Total cost ($) per mile 0.00 0.00

Fuel System Repairs

Parts cost ($) 0.00 344.34

Labor hours 1.0 0.0

Total cost ($) 50.00 344.34

Total cost ($) per mile 0.01 0.00

Powerplant System Repairs

Parts cost ($) 13.00 2,650.34

Labor hours 20.5 64.5

Total cost ($) 1,038.00 5,875.34

Total cost ($) per mile 0.11 0.04

Electric Propulsion System Repairs

Parts cost ($) 0.00 0.00

Labor hours 13.5 0.0

Total cost ($) 675.00 0.00

Total cost ($) per mile 0.07 0.00

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

Cranking, Ignition)

Parts cost ($) 0.00 5,006.16

Labor hours 4.5 45.0

Total cost ($) 225.00 7,256.16

Total cost ($) per mile 0.02 0.05

Air Intake System Repairs

Parts cost ($) 0.00 420.35

Labor hours 0.0 0.0

Total cost ($) 0.00 420.35

Total cost ($) per mile 0.00 0.00

Cooling System Repairs

Parts cost ($) 0.00 257.16

Labor hours 5.3 16.8

Total cost ($) 262.50 1,094.66

Total cost ($) per mile 0.03 0.01

Transmission System Repairs

Parts cost ($) 0.00 133.96

Labor hours 0.0 2.5

Total cost ($) 0.00 258.96

Total cost ($) per mile 0.00 0.00
17

Roadcall Analysis

A roadcall (RC), or revenue vehicle system failure (as named in the National Transit Database8

Table 10

), 

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. 

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

categories: all RCs and propulsion-related-only RCs. Only two RCs for each study group have 

been reported so far in the evaluation. 

Table 10. Roadcalls and MBRC (Evaluation Period)

Bus Mileage All 

Roadcalls All MBRC Propulsion Roadcalls

Propulsion 

MBRC

AT FCB 9,687 2 4,844 2 4,844

603 CNG 34,263 0 0

604 CNG 30,244 1 1

605 CNG 34,215 1 1

606 CNG 33,908 0 0

608 CNG 25,542 0 0

Total CNG 158,172 2 79,086 2 79,086

 

8 Federal Transit Administration’s National Transit Database website: www.ntdprogram.gov/ntdprogram/. 
18

What’s Next for SunLine

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

November 2010. The agency will continue working with DOE/NREL to collect data on the buses 

in service. The next report, which will include at least 12 months of data, is expected to be 

published in fall of 2011. 

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. 

Figure 11. Advanced Technology fuel cell bus in service

 
19

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 
20

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. (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. 

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. 
21

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. 

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. 
22

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. 

 
23

Appendix A: Fleet Summary Statistics

Fleet Summary Statistics: SunLine Transit Agency

Fuel Cell Bus (FCB) and Compressed Natural Gas (CNG) Study Groups

Fleet Operations and Economics

AT FCB CNG Buses

Number of vehicles 1 5

Period used for fuel and oil op analysis 5/10–11/10 5/10–11/10

Total number of months in period 7 7

Fuel and oil analysis base fleet mileage 9,580 158,172

Period used for maintenance op analysis 5/10–11/10 5/10–11/10

Total number of months in period 7 7

Maintenance analysis base fleet mileage 9,687 158,172

Average monthly mileage per vehicle 1,384 4,519

Availability 59% 90%

Fleet fuel usage in CNG GGE/H2 kg 1,665 54,996

Roadcalls 2 2

RCs MBRC 4,844 79,086

Propulsion roadcalls 2 2

Propulsion MBRC 4,844 79,086

Fleet miles/kg hydrogen or CNG GGE 5.75 2.88

(1.13 kg H2/gal diesel fuel)

Representative fleet MPG (energy equiv) 6.50 3.21

Hydrogen cost per kg 8.00

GGE cost 0.90

Fuel cost per mile 1.39 0.31

Total scheduled repair cost per mile 0.11 0.14

Total unscheduled repair cost per mile 0.36 0.24

Total maintenance cost per mile 0.47 0.38

Total operating cost per mile 1.86 0.69

Maintenance Costs

AT FCB CNG Buses

Fleet mileage 9,687 158,172

Total parts cost 153.22 18,381.53

Total labor hours 88.0 830.8

Average labor cost 4,400.00 41,537.50

(@ $50.00 per hour) 

Total maintenance cost 4,553.22 59,919.03

Total maintenance cost per bus 4,553.22 11,983.81

Total maintenance cost per mile 0.47 0.38
24

Maintenance Costs by Vehicle System

AT FCB CNG Buses

Fleet mileage 9,687 158,172

Total Engine/Fuel-Related Systems (ATA VMRS 27, 30, 31, 32, 33, 41, 42, 43, 44, 

45, 46, 65)

Parts cost 13.00 9,005.83

Labor hours 44.75 128.75

Average labor cost 2,237.50 6,437.50

Total cost (for system) 2,250.50 15,443.33

Total cost (for system) per bus 2,250.50 3,088.67

Total cost (for system) per mile 0.23 0.10

Exhaust System Repairs (ATA VMRS 43) 

Parts cost 0.00 0.00

Labor hours 0.0 0.0

Average labor cost 0.00 0.00

Total cost (for system) 0.00 0.00

Total cost (for system) per bus 0.00 0.00

Total cost (for system) per mile 0.00 0.00

Fuel System Repairs (ATA VMRS 44)

Parts cost 0.00 344.34

Labor hours 1.0 0.0

Average labor cost 50.00 0.00

Total cost (for system) 50.00 344.34

Total cost (for system) per bus 50.00 68.87

Total cost (for system) per mile 0.01 0.00

Power Plant (Engine) Repairs (ATA VMRS 45)

Parts cost 13.00 2,650.34

Labor hours 20.5 64.5

Average labor cost 1,025.00 3,225.00

Total cost (for system) 1,038.00 5,875.34

Total cost (for system) per bus 1,038.00 1,175.07

Total cost (for system) per mile 0.11 0.04

Electric Propulsion Repairs (ATA VMRS 46) 

Parts cost 0.00 0.00

Labor hours 13.5 0.0

Average labor cost 675.00 0.00

Total cost (for system) 675.00 0.00

Total cost (for system) per bus 675.00 0.00

Total cost (for system) per mile 0.07 0.00
25

Maintenance Costs by Vehicle System (continued)

AT FCB CNG Buses

Electrical System Repairs (ATA VMRS 30-Electrical General, 31-Charging, 32-

Cranking, 33-Ignition)

Parts cost 0.00 5,006.16

Labor hours 4.5 45.0

Average labor cost 225.00 2,250.00

Total cost (for system) 225.00 7,256.16

Total cost (for system) per bus 225.00 1,451.23

Total cost (for system) per mile 0.02 0.05

Air Intake System Repairs (ATA VMRS 41)

Parts cost 0.00 420.35

Labor hours 0.0 0.0

Average labor cost 0.00 0.00

Total cost (for system) 0.00 420.35

Total cost (for system) per bus 0.00 84.07

Total cost (for system) per mile 0.00 0.00

Cooling System Repairs (ATA VMRS 42)

Parts cost 0.00 257.16

Labor hours 5.3 16.8

Average labor cost 262.50 837.50

Total cost (for system) 262.50 1,094.66

Total cost (for system) per bus 262.50 218.93

Total cost (for system) per mile 0.03 0.01

Hydraulic System Repairs (ATA VMRS 65)

Parts cost 0.00 193.52

Labor hours 0.0 0.0

Average labor cost 0.00 0.00

Total cost (for system) 0.00 193.52

Total cost (for system) per bus 0.00 38.70

Total cost (for system) per mile 0.00 0.00

General Air System Repairs (ATA VMRS 10)

Parts cost 0.00 0.00

Labor hours 1.0 14.0

Average labor cost 50.00 700.00

Total cost (for system) 50.00 700.00

Total cost (for system) per bus 50.00 140.00

Total cost (for system) per mile 0.01 0.00
26

Maintenance Costs by Vehicle System (continued)

AT FCB CNG Buses

Brake System Repairs (ATA VMRS 13)

Parts cost 0.00 31.61

Labor hours 0.0 1.5

Average labor cost 0.00 75.00

Total cost (for system) 0.00 106.61

Total cost (for system) per bus 0.00 21.32

Total cost (for system) per mile 0.00 0.00

Transmission Repairs (ATA VMRS 27)

Parts cost 0.00 133.96

Labor hours 0.0 2.5

Average labor cost 0.00 125.00

Total cost (for system) 0.00 258.96

Total cost (for system) per bus 0.00 51.79

Total cost (for system) per mile 0.00 0.00

Inspections Only - No Parts Replacements (101)

Parts cost 0.00 0.00

Labor hours 20.8 286.5

Average labor cost 1,037.50 14,325.00

Total cost (for system) 1,037.50 14,325.00

Total cost (for system) per bus 1,037.50 2,865.00

Total cost (for system) per mile 0.11 0.09

Cab, Body, and Accessories Systems Repairs

(ATA VMRS 02-Cab and Sheet Metal, 50-Accessories, 71-Body)

Parts cost 23.16 6,610.56

Labor hours 8.3 286.3

Average labor cost 412.50 14,312.50

Total cost (for system) 435.66 20,923.06

Total cost (for system) per bus 435.66 4,184.61

Total cost (for system) per mile 0.05 0.13

HVAC System Repairs (ATA VMRS 01)

Parts cost 0.00 297.41

Labor hours 11.5 27.5

Average labor cost 575.00 1,375.00

Total cost (for system) 575.00 1,672.41

Total cost (for system) per bus 575.00 334.48

Total cost (for system) per mile 0.06 0.01
27

Maintenance Costs by Vehicle System (continued)

AT FCB CNG Buses

Lighting System Repairs (ATA VMRS 34)

Parts cost 117.06 170.36

Labor hours 0.8 14.3

Average labor cost 37.50 712.50

Total cost (for system) 154.56 882.86

Total cost (for system) per bus 154.56 176.57

Total cost (for system) per mile 0.02 0.01

Frame, Steering, and Suspension Repairs (ATA VMRS 14-Frame, 

15-Steering, 16-Suspension)

Parts cost 0.00 2,012.65

Labor hours 0.8 23.3

Average labor cost 37.50 1,162.50

Total cost (for system) 37.50 3,175.15

Total cost (for system) per bus 37.50 635.03

Total cost (for system) per mile 0.00 0.02

Axle, Wheel, and Drive Shaft Repairs (ATA VMRS 11-Front Axle, 

18-Wheels, 22-Rear Axle, 24-Drive Shaft)

Parts cost 0.00 251.11

Labor hours 0.0 15.5

Average labor cost 0.00 775.00

Total cost (for system) 0.00 1,026.11

Total cost (for system) per bus 0.00 205.22

Total cost (for system) per mile 0.00 0.01

Tire Repairs (ATA VMRS 17)

Parts cost 0.00 0.00

Labor hours 0.3 33.3

Average labor cost 12.50 1,662.50

Total cost (for system) 12.50 1,662.50

Total cost (for system) per bus 12.50 332.50

Total cost (for system) per mile 0.00 0.01
28

Notes 

1. To compare the hydrogen fuel dispensed and fuel economy to diesel, the hydrogen dispensed was 

also converted into diesel energy equivalent gallons. Actual energy content will vary by locations, but the 

general energy conversions are as follows: 

Lower heating value (LHV) for hydrogen = 51,532 Btu/lb 

LHV for diesel = 128,400 Btu/lb 

1 kg = 2.205 * lb 

51,532 Btu/lb * 2.205 lb/kg = 113,628 Btu/kg 

Diesel/hydrogen = 128,400 Btu/gal /113,628 Btu/kg = 1.13 kg/diesel gal 

2. The propulsion-related systems were chosen to include only those systems of the vehicles that could 

be affected directly by the selection of a fuel/advanced technology. 

3. ATA VMRS coding is based on parts that were replaced. If there was no part replaced in a given repair, 

then the code was chosen by the system being worked on. 

4. In general, inspections (with no part replacements) were included only in the overall totals (not by 

system). Category 101 was created to track labor costs for PM inspections. 

5. ATA VMRS 02-Cab and Sheet Metal represents seats, doors, etc.; ATA VMRS 50-Accessories 

represents things like fire extinguishers, test kits, etc.; ATA VMRS 71-Body represents mostly windows 

and windshields. 

6. Average labor cost is assumed to be $50 per hour. 

7. Warranty costs are not included. 
29

Appendix B: Fleet Summary Statistics – SI Units

Fleet Summary Statistics: SunLine Transit Agency

Fuel Cell Bus (FCB) and Compressed Natural Gas (CNG) Study Groups

Fleet Operations and Economics

AT FCB CNG Buses

Number of vehicles 1 5

Period used for fuel and oil op analysis 5/10–11/10 5/10–11/10

Total number of months in period 7 7

Fuel and oil analysis base fleet kilometers 15,417 254,546

Period used for maintenance op analysis 5/10–11/10 5/10–11/10

Total number of months in period 7 7

Maintenance analysis base fleet kilometers 15,589 254,546

Average monthly kilometers per vehicle 2,210 7,273

Availability 59% 90%

Fleet fuel usage in CNG liter equiv/H2 kg 1,665 208,160

Roadcalls 2 2

RCs KMBRC 7,795 127,273

Propulsion roadcalls 2 2

Propulsion KMBRC 7,795 127,273

Fleet kg hydrogen/100 km 10.80 81.78

(1.13 kg H2/gal diesel fuel)

Rep. fleet fuel consumption (L/100 km) 36.17 73.19

Hydrogen cost per kg 8.00

GGE cost/liter 0.24

Fuel cost per kilometer 0.86 0.19

Total scheduled repair cost per kilometer 0.07 0.09

Total unscheduled repair cost per kilometer 0.22 0.15

Total maintenance cost per kilometer 0.29 0.24

Total operating cost per kilometer 1.16 0.43

Maintenance Costs

AT FCB CNG Buses

Fleet mileage 15,589 254,546

Total parts cost 153.22 18,381.53

Total labor hours 88.0 830.8

Average labor cost 4,400.00 41,537.50

(@ $50.00 per hour)

Total maintenance cost 4,553.22 59,919.03

Total maintenance cost per bus 4,553.22 11,983.81

Total maintenance cost per kilometer 0.29 0.24
F1147-E(10/2008) 

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1. REPORT DATE (DD-MM-YYYY)

March 2011

2. REPORT TYPE

Technical Report

3. DATES COVERED (From - To)

 

4. TITLE AND SUBTITLE

SunLine Transit Agency Advanced Technology Fuel Cell Bus 

Evaluation: First Results Report

5a. CONTRACT NUMBER

DE-AC36-08-GO28308

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

Leslie Eudy and Kevin Chandler

5d. PROJECT NUMBER

NREL/TP-5600-50500

5e. TASK NUMBER

H270.8150

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Renewable Energy Laboratory

1617 Cole Blvd.

Golden, CO 80401-3393

8. PERFORMING ORGANIZATION

REPORT NUMBER

NREL/TP-5600-50500

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NREL

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AGENCY REPORT NUMBER

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National Technical Information Service

U.S. Department of Commerce

5285 Port Royal Road

Springfield, VA 22161

13. SUPPLEMENTARY NOTES

14. ABSTRACT (Maximum 200 Words)

This report describes operations at SunLine Transit Agency for their newest prototype fuel cell bus and five 

compressed natural gas (CNG) buses. In May 2010, SunLine began operating its sixth-generation hydrogen fueled 

bus, an Advanced Technology (AT) fuel cell bus that incorporates the latest design improvements to reduce weight 

and increase reliability and performance. The agency is collaborating with the U.S. Department of Energy’s (DOE) 

National Renewable Energy Laboratory (NREL) to evaluate the bus in revenue service. This report provides the early 

data results and implementation experience of the AT fuel cell bus since it was placed in service. 

15. SUBJECT TERMS

SunLine; fuel cell bus; FCB; advanced technology; AT; hydrogen; transit; bus evaluations; Bluways; Ballard Power 

Systems; New Flyer.

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