A national laboratory of the U.S. Department of Energy

Office of Energy Efficiency & Renewable Energy

National Renewable Energy Laboratory 

Innovation for Our Energy Future 

Technical Report 

NREL/TP-560-42249 

October 2007 

Alameda-Contra Costa Transit District 

(AC Transit) 

Fuel Cell Transit Buses: 

Evaluation Results Update 

Kevin Chandler, Battelle 

Leslie Eudy, National Renewable Energy Laboratory 

NREL is operated by Midwest Research Institute ● Battelle Contract No. DE-AC36-99-GO10337 
National Renewable Energy Laboratory

1617 Cole Boulevard, Golden, Colorado 80401-3393 

303-275-3000 • www.nrel.gov 

Operated for the U.S. Department of Energy 

Office of Energy Efficiency and Renewable Energy 

by Midwest Research Institute • Battelle 

Contract No. DE-AC36-99-GO10337

Alameda-Contra Costa Transit District 

(AC Transit) 

Fuel Cell Transit Buses: 

Evaluation Results Update 

Kevin Chandler, Battelle 

Leslie Eudy, National Renewable Energy Laboratory 

Prepared under Task Nos. H270.8200 

Technical Report 

NREL/TP-560-42249 

October 2007 
NOTICE

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Acknowledgements 

This evaluation at Alameda-Contra Costa Transit District (AC Transit) 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 

National Renewable Energy Laboratory 

Keith Wipke 

George Sverdrup 

AC Transit 

Jaimie Levin 

Mallory Nestor-Brush 

Doug Byrne 

Roland Fecteau 

Stuart Thompson 

Henry Chen 

Steve Montoya 

Steve Seliandin 

Steve Tracey 

Craig Michels 

Bruce Randall 

Dennis Butler 

Patricia Broadbent 

Huaqi Yuan 

Bob Bithell 

Christina Ebojo 

And many others 

UTC Power 

Mike Tosca 

Matthew Riley 

David Boudreau 

Sandra Lajewski 

ISE Corporation 

Paul Scott 

Neil Flemmer 

Tavin Tyler 

Chevron 

Puneet Verma 

Rick Zalesky 

Dan Casey 

GGT 

Gene Walker 

Van Hool 

Paul Jenné

 iii
Table of Contents 

Executive Summary........................................................................................................................ 1 

Hydrogen Fueling Experience – Update..................................................................................... 1 

Bus Experience – Update............................................................................................................ 1 

Evaluation Results – Update....................................................................................................... 2 

What’s Next for This Demonstration?........................................................................................ 3 

Overview......................................................................................................................................... 4 

Infrastructure and Facilities ............................................................................................................ 6 

Hydrogen Fueling Experience – Update..................................................................................... 8 

Fuel Cell and Diesel Buses........................................................................................................... 10 

Bus Experience - Update .......................................................................................................... 11 

Training and Public Awareness.................................................................................................... 13 

Evaluation Results ........................................................................................................................ 16 

Route Descriptions.................................................................................................................... 16 

Bus Use and Availability .......................................................................................................... 17 

Fuel Economy and Cost............................................................................................................ 20 

Maintenance Analysis............................................................................................................... 22 

Roadcall Analysis ..................................................................................................................... 26 

What’s next for This Demonstration?........................................................................................... 27 

Contacts......................................................................................................................................... 28 

Acronyms and Abbreviations ....................................................................................................... 30 

References and Related Reports ................................................................................................... 31 

Appendix A: Fleet Summary Statistics......................................................................................... 33 

Appendix B: Fleet Summary Statistics – SI Units........................................................................ 39 

 v
Executive Summary 

In early 2007, the National Renewable Energy Laboratory (NREL) published a preliminary 

evaluation results report1

 (April through November 2006) on hydrogen fuel cell and diesel buses 

operating at Alameda-Contra Costa Transit District (AC Transit) in Oakland, California. This 

report provides an update to the previous report and includes results and experience from 

December 2006 through August 2007. The evaluation covers three prototype fuel cell buses and 

six diesel baseline buses operating from the same AC Transit bus depot. The evaluation periods 

presented in this report are as follows: 

• Fuel Cell Buses – April 2006 through August 2007 (17 months of operation) 

• Diesel Buses – April 2006 through August 2007 (17 months of operation) 

In March 2006, AC Transit kicked off the demonstration of three prototype fuel cell buses. The 

development of the fuel cell buses is the result of collaboration between ISE Corporation, UTC 

Power, and Van Hool. The buses use the PureMotion2 120 Fuel Cell Power System 

manufactured by UTC Power in a hybrid electric drive system designed by ISE. The energy 

storage in this hybrid system consists of three ZEBRA (sodium/nickel chloride, high 

temperature) batteries. 

This evaluation of prototype fuel cell transit buses at AC Transit is part of the U.S. Department 

of Energy’s (DOE) Hydrogen, Fuel Cells & Infrastructure Technologies Program (HFCIT). This 

program integrates activities in hydrogen production, storage, and delivery with transportation 

and stationary fuel cell applications. The evaluation focuses on documenting progress and 

opportunities for improving the vehicles, infrastructure, and operating procedures. There is no 

intent to consider the implementation of these hydrogen-fueled fuel cell transit buses as 

commercial (or full revenue transit service). 

Hydrogen Fueling Experience – Update 

During the evaluation period, the Chevron-AC Transit hydrogen fueling station dispensed a total 

of 9,421 kg of hydrogen into buses. The station was used at least once per day to fill buses for 

75% of the calendar days during the period. The overall average daily usage was 31.7 kg per 

day. The buses were filled a total of 418 times during the evaluation period, with an average fill 

amount of 20.2 kg. The average fueling rate was 1.50 kg/min and an average fueling takes 14 

minutes. 

Bus Experience – Update 

In the preliminary evaluation results report for AC Transit, several issues were described for the 

fuel cell buses. The following discussion provides an update on those issues. 

1. ZEBRA batteries – These batteries have had significant problems in this application. 

The main challenges have been accommodating cell failures and optimizing the state of 

charge (SOC) algorithm. The issues with using the three ZEBRA batteries have 

 

1

 Alameda-Contra Costa Transit District, Fuel Cell Transit Buses: Preliminary Evaluation Results, March 2007, 

NREL/TP-560-41041, www.nrel.gov//hydrogen/pdfs/41041.pdf 2

 PureMotion is a trademark of UTC Power. 

 1
continued. AC Transit has started operating the fuel cell buses 14-16 hours per day. This 

has put excessive demands on these batteries. It has been difficult to keep the batteries 

charged and ready for service overnight between daily work assignments. ISE has been 

able to make more batteries available and ready for installation into a bus as needed. 

2. Air Conditioning – During the summer of 2006, the air conditioning system had 

problems with failed evaporator and condenser motors. Since then, the motors have been 

changed. The summer of 2007 was uneventful as far as air conditioning failures for 

motor problems. This problem appears to be resolved at this point. 

3. UTC Power PureMotion 120 Fuel Cell Power System – As reported in the preliminary 

evaluation results report, the cell stack assemblies (CSAs) for the fuel cell buses were 

replaced in late 2006 and early 2007. However, the CSA issues reported in the previous 

report have continued to impact each of the three buses in operation. Upgraded CSAs 

were provided by UTC Power and installed into FC13

 and FC2 during June and August 

2007 respectively. This has allowed AC Transit to start operating the fuel cell buses 14-

16 hours per day. FC3 still has the previous version CSAs and had been taken out of 

service by the end of this evaluation period. This bus is expected to have CSA 

replacement in December 2007 with upgrades beyond those recently installed into FC1 

and FC2. 

Evaluation Results – Update 

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

Note that fuel economy for the hydrogen-fueled buses is shown in miles per kilogram of 

hydrogen and in diesel gallon equivalent to compare with the diesel baseline buses. 

Table ES-1. Summary of Evaluation Results 

Data Item Fuel Cell Diesel 

Number of Buses 3 6 

Data Period 4/06-8/07 4/06-8/07 

Number of Months 17 17 

Total Mileage in Period 54,404 277,408 

Average Monthly Mileage per Bus 1,067 2,720 

Availability (85% is target) 61% N/A 

Fuel Economy (Miles/kg) 6.17 

Fuel Economy (Miles/diesel gallon) 6.97 4.03 

Miles between Roadcalls (MBRC) – All 1,395 4,474 

MBRC – Propulsion Only 1,649 10,670 

MBRC – Fuel Cell Related Only 5,440 

Total Maintenance, $/mile 0.59 0.44 

Maintenance – Propulsion Only, $/mile 0.08 0.10 

 

3

 AC Transit’s fuel cell buses have been assigned the numbers: FC1, FC2, and FC3. 

 2
What’s Next for This Demonstration? 

This report covers AC Transit operation of the fuel cell and diesel baseline buses through August 

2007. The next evaluation report for this site will include operational data through February 

2008 and is planned for release around May 2008. This next evaluation report will include 

operational experience of one of the fuel cell buses on routes at Golden Gate Transit as well. 

 3
Overview 

The Alameda-Contra Costa Transit District (AC Transit) provides public transit service in the 

East Bay area including Oakland, California. The AC Transit service area of 360 square miles 

includes 13 cities and adjacent unincorporated areas in Alameda and Contra Costa counties. 

Since 2000, AC Transit has developed and operates a fuel cell demonstration program called the 

HyRoad. With a goal of demonstrating the viability of an emission-free transit system, the 

HyRoad program includes operating fuel cell buses and passenger cars, on-site hydrogen 

production, fueling, and vehicle maintenance, and public education and safety training. 

In March 2006, AC Transit kicked-off the demonstration of three prototype fuel cell buses. The 

development of the fuel cell buses is the result of collaboration between ISE Corporation, UTC 

Power, and Van Hool. The buses use the PureMotion 120 Fuel Cell Power System manufactured 

by UTC Power in a hybrid electric drive system designed by ISE. The energy storage in this 

hybrid system consists of three ZEBRA (sodium/nickel chloride, high temperature) batteries. 

One of the fuel cell buses is pictured in Figure 1. 

Figure 1. AC Transit fuel cell bus 

Golden Gate Transit (GGT) is participating in the AC Transit fuel cell bus demonstration and 

intends to operate one of the fuel cell buses later in the program. GGT is a part of the Golden 

Gate Bridge, Highway, and Transportation District (GGBHTD), which is headquartered in San 

Francisco, California, and serves the North Bay area. GGBHTD includes GGT and operates the 

Golden Gate Bridge and the Golden Gate Ferry operation. Figure 2 shows the coverage area of 

both AC Transit and GGT. 

Demonstrations, such as the AC Transit HyRoad Program, are critical to understanding how 

these prototype systems and components perform in actual operation. The manufacturers use the 

data collected from demonstrations of this type to verify the results from controlled laboratory 

tests and to further optimize and improve their advanced propulsion systems for 

commercialization. 

 4
Figure 2. AC Transit and Golden Gate Transit operating area in California 

The Department of Energy’s (DOE) National Renewable Energy 

Laboratory (NREL) is evaluating these buses to help determine the 

status of hydrogen and fuel cell systems and corresponding 

hydrogen infrastructure in a transit application. A preliminary data 

report was published in March 20074

. This report included 

descriptions of the technology, details on the early experiences, 

lessons learned, and eight months of preliminary operations data on 

the fuel cell buses. Evaluation results were also provided for diesel 

transit buses (Figure 1) as a baseline comparison to the fuel cell 

buses. 

 

4

 Alameda-Contra Costa Transit District, Fuel Cell Transit Buses: Preliminary Evaluation Results, March 2007, 

NREL/TP-560-41041, www.nrel.gov//hydrogen/pdfs/41041.pdf 

 5
This evaluation results report provides results and experiences from December 2006 through 

August 2007, which is in addition to those provided in the preliminary evaluation results report. 

This data report includes results from the three prototype fuel cell buses and six similar diesel 

baseline buses operating from the same AC Transit bus depot. The evaluation periods presented 

in this report are as follows: 

• Fuel Cell Buses – April 2006 through August 2007 (17 months of operation) 

• Diesel Buses – April 2006 through August 2007 (17 months of operation) 

Figure 1. Diesel bus at AC Transit 

Infrastructure and Facilities 

AC Transit operates its bus fleet from four divisions – Richmond, Emeryville, East Oakland, and 

Hayward. To demonstrate fuel cell buses (FCBs), the fleet needed to install hydrogen fueling 

infrastructure at one of these bus operating divisions. In March 2004, AC Transit partnered with 

Chevron Technology Ventures to design and build a hydrogen energy station at the East Oakland 

Division. Construction began in June 2005 and the station was operational by mid-December the 

same year. The Chevron – AC Transit Hydrogen Energy Station produces hydrogen through 

steam methane reforming. The station design includes two reformers that are capable of 

producing a total of 150 kg of hydrogen per day. Total storage capacity at the station is 366 kg 

of hydrogen at up to 6,250 psi. The station was inaugurated in March 2006. Figure 4 provides 

pictures of the energy station including the reformer buildings, one of two dispensers, and the 

safety warning system. 

AC Transit chose to modify an existing facility to enable staff to maintain the hydrogen-fueled 

buses safely. The required modifications (~$1.5 million) were completed and the maintenance 

bay was cleared for use in January 2006. The selected bay was isolated from the rest of the 

facility by a firewall. There is space for servicing two buses at a time. Figure 5 shows the bay 

with and without a fuel cell bus. Because the specially equipped maintenance bay is co-located 

with the rest of the maintenance building (and local fire code), maintenance staff is required to 

depressurize the buses prior to entering the facility. To accomplish this depressurization, the 

hydrogen in the tanks is vented down to 600 psi. The hydrogen removed from the vehicle is 

ultimately vented to the atmosphere in a controlled and safe manner. The fuel economy 

calculations presented later in this report exclude the hydrogen vented from the buses for this 

purpose. 

 6
Figure 4. The Chevron – AC Transit energy station 

Figure 5. Modified maintenance bay at AC Transit East Oakland Division 

 7
Hydrogen Fueling Experience – Update: Figure 6 shows average daily hydrogen usage from 

the station during the evaluation period (April 2006 through August 2007) for buses only. AC 

Transit also has a fleet of seven light duty hydrogen vehicles that use the station as well, but that 

fuel consumption is not accounted for in this analysis and discussion. The overall average daily 

usage in this period was 31.7 kg/day for buses. The calculation for this rate only includes the 

days in which hydrogen was dispensed from the station for buses – 75% of the calendar days 

during the period. A total of 9,421 kg of hydrogen were dispensed into buses during this period. 

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

Apr-06

May-06

Jun-06

Jul-06

Aug-06

Sep-06

Oct-06

Nov-06

Dec-06

Jan-07

Feb-07

Mar-07

Apr-07

May-07

Jun-07

Jul-07

Aug-07

H2 Amount (kg) / Day

Figure 6. Average hydrogen use per day for the FCBs 

Figure 7 shows the distribution of hydrogen amounts per fill. The three buses were filled a total 

of 418 times during the evaluation period, with an average fill amount of 20.2 kg/fill. Figure 8 

shows the cumulative fueling rate histogram for the AC Transit station for the evaluation period. 

During this time, the overall average fueling rate was 1.50 kg/min. On average, it takes 

approximately 14 minutes to fuel a bus. 

Currently, all hydrogen fueling is conducted by a Chevron technician. However, Chevron and 

AC Transit are working on training and certification so that AC Transit employees can qualify to 

perform the fueling function themselves. AC Transit staff (approximately 40 employees so far) 

completed classroom familiarization training for the fueling station and operation during the 

summer. Certification requires that each staff member complete 10 supervised fuelings (with the 

Chevron technician) along with the classroom training before being certified to fuel hydrogen on 

their own (with notification of Chevron and AC Transit). So far, three AC Transit employees 

have completed the certification process including the project manager, a trainer, and a service 

worker. 

 8
0

20

40

60

80

100

120

0-10kg 10-15kg 15-20kg 20-25kg 25-30kg 30-35kg 35-40kg

Number of Occurrences

Figure 7. Distribution of average fill amounts 

Figure 8. Fueling rate histogram for the AC Transit Hydrogen Energy Station (bus only) 

 9
Fuel Cell and Diesel Buses 

Table 1 provides bus system descriptions for the fuel cell and diesel buses included in this 

evaluation. The buses began passenger service on March 20, 2006. For this evaluation, six Van 

Hool diesel buses were selected from buses of that type operating at the East Oakland Division. 

These six diesel buses are operated along side the fuel cell buses. 

The diesel and fuel cell buses at AC Transit are the same bus model, but the diesel buses are 

slightly older. The fuel cell bus is a little more than 8,000 lbs heavier than the diesel bus, and 

this has reduced the passenger capacity. The price of the fuel cell bus is essentially ten times 

more than the diesel bus. 

Table 1. Fuel Cell and Diesel Bus System Descriptions 

Operation from East Oakland Division Vehicle System Fuel Cell Bus Diesel Bus 

Number of Buses 3 6 

Bus Manufacturer and Model Van Hool A330 Low Floor Van Hool A330 Low Floor 

Model Year 2005 2003 

Length/Width/Height 40 ft/102 in/139 in 40 ft/102 in/121 in 

GVWR/Curb Weight 43,240 lb/36,000 lb 40,800 lb/27,800 lb 

Wheelbase 228 in 235 in 

Passenger Capacity 

30 seated or 26 seated 

and two wheelchairs 

15 standing 

32 seated or 28 seated 

and two wheelchairs 

53 standing 

Engine Manufacturer and 

Model 

UTC Power 

PureMotion 120 Fuel Cell 

Power System 

Cummins ISL 

Rated Power 

Fuel cell power system: 

120 kW 

Two Electric Drive Motors: 

170 kW total (continuous) 

280 hp @ 2200 rpm 

Accessories Electrical Mechanical 

Emissions Equipment None Diesel Oxidation Catalyst 

Transmission/Retarder Gearbox/Flenders 

Regenerative braking 

Voith 

Integrated retarder 

Fuel Capacity 50 kg hydrogen 92 gal 

Bus Purchase Cost $3.2 million $323,000 

Table 2 provides a description of some of the electric propulsion systems for the fuel cell buses. 

Note that the diesel buses are not a hybrid configuration and do not have regenerative braking or 

energy storage for the drive system. 

 10
Table 2. Additional Electric Propulsion System Descriptions 

Propulsion Systems Fuel Cell Bus 

Manufacturer/Integrator ISE Corporation 

Hybrid Type Series, charge sustaining 

Drive System Siemens ELFA/ISE 

Propulsion Motor 2-AC induction, 85 kW each 

Energy Storage Battery – 3 modules/216 cells sodium/nickel chloride 

ZEBRA; 53 kWh capacity 

Fuel Storage Eight, roof mounted, SCI, type 3 tanks; 5,000 psi rated 

Regenerative Braking Yes 

Bus Experience – Update: In the preliminary evaluation results report for AC Transit, we 

described several issues for the fuel cell buses. The following discussion provides an update on 

those issues from the last report and an additional topic. 

1. ZEBRA batteries – These batteries have had significant problems in this application. 

The main challenges have been accommodating cell failures and optimizing the state of 

charge (SOC) algorithm. The issues with using the three ZEBRA batteries have 

continued. AC Transit has started operating the fuel cell buses 14-16 hours per day. This 

has put excessive demands on the batteries. It has been difficult to keep the batteries 

charged and ready for service overnight between daily work assignments. ISE has been 

able to make more of the batteries available and ready for installation into a bus as 

needed. 

2. Air Conditioning – During the summer of 2006, the air conditioning system experienced 

problems with failed evaporator and condenser motors. Since then, the motors have been 

changed. The summer of 2007 was uneventful as far as air conditioning failures for 

motor problems. This problem appears to be resolved at this point. 

3. UTC Power PureMotion 120 Fuel Cell Power System – As reported in the preliminary 

evaluation results report, the cell stack assemblies (CSAs) for the fuel cell buses were 

replaced in late 2006 and early 2007. However, the CSA issues reported in the previous 

report have continued to impact each of the three buses in operation. Upgraded CSAs 

were provided by UTC Power and installed into FC1 and FC2 during June and August 

2007 respectively. This has allowed AC Transit to operate the fuel cell buses 14-16 

hours per day. FC3 still has the previous version CSAs and was taken out of service by 

the end of this evaluation period. This bus is expected to have CSA replacement in 

December 2007 with upgrades beyond those recently installed into FC1 and FC2. 

4. Charging – In preparation for full-day fuel cell bus operation, AC Transit upgraded their 

electrical access for charging the ZEBRA batteries overnight to allow faster charging. 

These upgrades were completed in June 2007. Each fuel cell bus is plugged into a charge 

station (shown in Figure 9) overnight to balance the charge between batteries, top off the 

charge, and provide heat for the batteries and freeze protection for the fuel cell when 

temperatures are 20° C or less. 

 

 11
Figure 9. Fuel cell bus/battery charging station at AC Transit 

 12
Training and Public Awareness 

AC Transit is taking a proactive stance in its training program. The agency has provided 

hydrogen familiarization training to the majority of its staff. This training included information 

on the AC Transit HyRoad Fuel Cell Bus Program, general characteristics of hydrogen, and 

hydrogen safety. 

The training for maintenance workers and operators is more extensive. For this training, 

maintenance staff at AC Transit and GGT has been learning light diagnostics and preventative 

maintenance for the FCB powertrain. ISE provided training that included a basic introduction to 

the hybrid fuel cell bus, descriptions of the drive system and components, preventive 

maintenance procedures, and instructions on 

safety aspects for maintaining the buses. 

UTC Power provided training on the fuel 

cell power system that included an 

introduction to the fuel cell system, 

descriptions of the various interfaces, and 

the necessary safety precautions for 

maintenance. AC Transit is working with 

the College of the Desert (Palm Springs, 

California) to develop a maintenance 

training class that will be incorporated into 

its apprenticeship program. AC Transit has 

also held several special training sessions f

local fire fighters and emergency 

responders. 

Figure 10. AC Transit’s Fuel Cell Bus Tracking 

Center 

or 

Raising public awareness for hydrogen and 

fuel cell technology continues to be an 

important part of the HyRoad program. In 

addition to introducing thousands of transit 

riders to the fuel cell buses in daily service, 

the agency has developed a Web site that 

provides information on the program. 

Visitors to the site can get general 

information on fuel cells and hydrogen, 

specifics on the demonstration, and keep upto-date on the status of the project. The site 

also includes a Zero-Emission Hydrogen 

Fuel Cell Bus Operations Center, which 

provides near real-time tracking of the buses 

on-route. Displays include monitors for 

speed, power, emissions avoided, and a map 

pinpointing the location of the bus. The 

ISE-developed tracking center (Figure 10) 

uses global positioning system data from the 

buses to provide the second-by-second 

 13
status of the buses. The site allows the viewer to switch between any of four fuel cell buses. 

(Three at AC Transit and the fourth at SunLine in Thousand Palms, CA) 

AC Transit continues to accommodate frequent requests for tours from various individuals and 

groups. As resources allow, transit agency staff take the buses to outside events, provide on-site 

tours of the facility, and present information on the program. Since the beginning of the 

demonstration (January 2006 through August 2007), AC Transit estimates it has potentially 

reached over 342,000 people through various events and tours. International interest includes 

representatives from eight countries. Table 3 summarizes those events by category. 

Table 3. Public Awareness Events by Category 

Event Category Number of 

Events 

Number of 

People 

Academic 14 3,176 

General Public 44 337,965 

Industry 11 26 

International 17 100 

Government 11 385 

Partner Event 9 591 

Total 106 342,243 

Events, tours, and presentations since the last report was published include: 

• December 2006: AC Transit provided tours of the hydrogen station and fuel cell bus to 

A.P. Gianini Middle School and the Haas Energy Club. 

• January 2007: AC Transit provided fuel cell buses for several off-site events including 

the inaugurations of the California Governor and Oakland Mayor, Berkeley’s Ecopass 

Program event, a UTC Power event, and the Lawrence Hall of Science sponsored Bay 

Area Environmental Education Resource (BAEER) fair. Tours of the hydrogen station 

and bus were provided to representatives from DaimlerChrysler, EMCOR Group, and 

Chevron Technology Ventures. 

• February 2007: AC Transit provided a fuel cell bus for a Climate Change event in 

Oakland, and hosted a meeting with representatives from the Weather Channel to discuss 

a study on climate change. 

• March 2007: During the month, AC Transit hosted tours of the hydrogen facility and 

fuel cell bus to several groups including delegations from the U.S. – China Exchange 

Council and the Japan Gas Association. A fuel cell bus was provided for local events 

such as a Good Neighbor Breakfast, 2007 Sustainability Conference, and a 

Transportation and Land Use Choices Annual Summit. 

• April 2007: AC Transit participated in several off-site events including the City of 

Oakland's Earth Day Celebration, the Cal Sustainable Transportation Fair, and Cal State 

East Bay Earth Day Event. Also during the month, AC Transit provided tours of the fuel 

cell bus and facilities to representatives from the California Transportation Commission, 

Bay Area Student Chapter of the Electrochemical Society, and Pacific Partners. 

 14
• May 2007: AC Transit provided a fuel cell bus for Keep Hayward Clean and Green 

event. Tours of the AC Transit facility and fuel cell bus were provided for several groups 

including Santa Clara Valley Transportation Authority, CalTrans, and the Indian 

government. 

• June 2007: During the month, AC Transit hosted tours for Chevron’s Mentoring 

Excellence in Technology program and representatives from SRI International. 

• July 2007: AC Transit participated in 4th of July parades for Alameda and Freemont, as 

well as the Port of Oakland World Music Festival. A tour of the station and bus were 

provided to the mayor of San Leandro and staff and to a group of teachers for the HyTech 

program. A fuel cell bus was used in filming for an episode of DooF Kitchen, a PBS 

program aimed at teaching children about making healthy food choices. 

• August 2007: AC Transit held a dedication for the solar power installation at the East 

Bay Division and hosted the filming of a documentary featuring Dave O’Reilly. A fuel 

cell bus was included in the Festival of India Parade, which was attended by 

approximately 40,000 people. AC Transit staff also provided tours to several groups 

including international students from Stanford’s American Language and Cultural 

Program and delegations from Korea and Japan. 

 15
Evaluation Results 

The evaluation period for the fuel cell and diesel baseline buses for this report includes 17 

months of operation from April 2006 through August 2007. The fuel cell buses started in 

revenue service on March 20, 2006, but the March 2006 data have not been included in the 

evaluation period to remove any early implementation/logistical issues. The diesel Van Hool 

buses are older and have been in operation at AC Transit for some time. The study group of 

diesel buses started operation elsewhere in 2003-2004, but did not start operating at the East 

Oakland Division until July 2005. The evaluation period for the selected diesel buses is the same 

as that for the fuel cell buses. 

In this evaluation report, the fuel cell buses are considered to be a prototype technology that is in 

the process of being commercialized. The analysis and comparison discussions with standard 

diesel buses help baseline the progress of the fuel cell bus technology. The intent of this analysis 

is to determine the status of this implementation and document the improvements that have been 

made over time at AC Transit. There is no intent to consider this implementation of fuel cell 

buses as commercial (or full revenue transit service). This evaluation focuses on documenting 

progress and opportunities for improving the vehicles, infrastructure, and procedures. 

Route Descriptions 

Overall, AC Transit operates 107 fixed routes including 74 local, 27 transbay, and 6 all-nighter 

routes. In addition, there are 67 routes for school service in the East Bay area. AC Transit 

operates four bus divisions to serve these routes. The fuel cell and diesel baseline buses are 

operated only from the East Oakland Division, which operates 15 local, two all-nighter, 10 

transbay, and 14 school routes with 179 buses total (138 buses for peak service). For weekday 

service from the East Oakland Division, the average bus operating speed is 14.3 mph. 

For demonstrating the advanced technology fuel cell buses, the fleet operates the buses only 

during the week on two blocks of work that were created for testing the fuel cell and diesel 

baseline buses. In addition, operating the fuel cell buses only in weekday service helps ensure 

that trained drivers and mechanics (and the manufacturer technicians) will be available to work 

with the fuel cell buses. The agency has also decided to place only two of the three fuel cell 

buses into service on any given weekday to allow for maintenance, training, and special events in 

which one of the fuel cell buses may be included. 

AC Transit developed two special bus blocks of work on each of two routes (Route 50 and Route 

57) for operating the fuel cell and diesel baseline buses. These special bus blocks of work are 

shown in Table 5. The fuel cell buses were first operated on the two special blocks of work on 

Route 50 (Hegenberger) from March 20, 2006 to June 19, 2006 and again during March 2007 

through June 2007. During these same timeframes, two of the diesel baseline buses were 

operated on two special blocks of work on Route 57 (40th Street). Starting June 20, 2006 through 

March 2007, the fuel cell buses operated on Route 57 and the two baseline diesel buses operated 

on Route 50. This switch was done to ensure that fuel economy comparisons between the fuel 

cell and diesel baseline buses could eventually be made in the same duty cycle. AC Transit also 

operated the fuel cell buses for a short period of time during January 2007 on longer (15-hour) 

blocks on the Route 50 and 57. 

 16
Table 5. Route Blocks of Work Created for Fuel Cell Bus Evaluation 

Route 

Block 

Pull Out 

Time 

Pull In 

Time 

Total 

Time 

Total 

Miles 

Average 

Speed 

50-12 5:26 AM 1:15 PM 7.82 127 16.2 

50-21 12:55 PM 8:53 PM 7.97 127 15.9 

57-20 6:27 AM 1:11 PM 6.73 76 11.3 

57-21 1:02 PM 8:13 PM 7.18 82 11.4 

Starting with the June 2007 service change at AC Transit, the fuel cell and diesel buses operated 

on two new special blocks of work on the newly formed Route 18 and Route 51. These two 

routes and blocks of work are shown in Table 6. There have been issues with meeting the long 

operation of the Route 18 blocks because of the need to be able to charge the batteries overnight 

before the next pullout. Another issue continues to be the need for tree trimming on the routes to 

ensure that the tall fuel cell buses do not get scratches around the roof. 

Table 6. New Route Blocks of Work Created for Fuel Cell Bus Evaluation 

Route 

Block 

Pull Out 

Time 

Pull In 

Time 

Total 

Time 

Total 

Miles 

Average 

Speed 

18 6:11 AM 11:43 PM 17.53 171 9.8 

18 5:16 AM 12:23 AM 19.11 199 10.4 

51 5:10 AM 8:43 PM 15.55 148 9.5 

51 5:32 AM 9:22 PM 15.84 148 9.3 

The diesel buses are not restricted to just these special blocks of work. These buses are allowed 

to operate on other work blocks during the week and on weekends as well. This is indicated in 

the bus use that is discussed next. 

Bus Use and Availability 

Bus use and availability are indicators of reliability. Lower bus usage may indicate downtime 

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

summary of bus usage and availability for the two study groups of buses. 

Figure 11 shows mileage and fuel cell power system operating hour accumulation for all three 

fuel cell buses from the start of testing at AC Transit in October 2005 through August 2007. As 

expected, usage began to accumulate faster after the buses went into passenger service in late 

March 2006. Use of the fuel cell buses was limited generally to weekdays and service within 

one eight-hour shift until the end of June 2007 when the work blocks were expanded. Other 

limiting factors included maintenance issues, availability of trained drivers, and availability of 

hydrogen fueling. 

 17
0

10000

20000

30000

40000

50000

60000

70000

Oct-05

Nov-05

Dec-05

Jan-06

Feb-06

Mar-06

Apr-06

May-06

Jun-06

Jul-06

Aug-06

Sep-06

Oct-06

Nov-06

Dec-06

Jan-07

Feb-07

Mar-07

Apr-07

May-07

Jun-07

Jul-07

Aug-07

Total Miles

0

1000

2000

3000

4000

5000

6000

7000

Total FC System Hours

Total Miles FC System Hours

Figure 11. Cumulative mileage and fuel cell system hours for all three fuel cell buses 

Table 7 summarizes average monthly mileage accumulation by bus and study group for the 

evaluation period. Since the start of operation, the fuel cell buses have accumulated over 60,000 

miles. For the evaluation period (17 months), the fuel cell buses accumulated 54,404 miles and 

4,938 fuel cell power system hours (this indicates an average speed of 11.0 mph during the 

evaluation period). 

The diesel buses operated a monthly average of 2,720 miles each as compared to the fuel cell 

buses, which operated a monthly average of 1,067 miles each. This indicates that the fuel cell 

buses operated only 39% of the miles that the diesel buses did in the same period. The fuel cell 

buses were limited to only weekdays and one eight-hour shift per weekday for most of the 

evaluation period. The diesel buses were used in typical service up to seven days per week and 

16-20 hours per day. 

Figure 12 shows monthly availability for each of the three fuel cell buses and an overall average 

availability for the group for the evaluation period. For the first five months of the evaluation 

period, the availability for the group was between 80% and 90%. Starting in September 2006, 

the availability for the group dropped to around 60% due to problems with the ZEBRA batteries 

and changeouts of the fuel cell stack assemblies (CSAs), as described above. The ZEBRA 

batteries have continued to be an issue for availability and the CSAs were replaced again for all 

three of the buses. These problems are highlighted by the number of months that a bus had zero 

availability, especially during April through August 2007. 

 18
Table 7. Average Monthly Mileage (Evaluation Period) 

Bus Starting 

Hubodometer 

Ending 

Hubodometer 

Total 

Mileage Months Monthly Average Mileage 

Fuel Cell 

System Hours 

FC1 5,164 23,646 18,482 17 1,087 N/A 

FC2 778 16,616 15,838 17 932 N/A 

FC3 3,153 22,967 20,084 17 1,181 N/A 

Fuel Cell 54,404 51 1,067 4,938 

1043 91,534 136,883 45,349 17 2,668 N/A 

1044 108,346 158,880 50,534 17 2,973 N/A 

1045 125,972 170,293 44,321 17 2,607 N/A 

1046 125,685 172,272 46,587 17 2,740 N/A 

1047 108,336 155,502 47,166 17 2,774 N/A 

1048 94,092 137,543 43,451 17 2,556 N/A 

Diesel 277,408 102 2,720 N/A 

0

10

20

30

40

50

60

70

80

90

100

Apr-06

May-06

Jun-06

Jul-06

Aug-06

Sep-06

Oct-06

Nov-06

Dec-06

Jan-07

Feb-07

Mar-07

Apr-07

May-07

Jun-07

Jul-07

Aug-07

Availability (%)

Total/Average FCB1 FCB2 FCB3

Figure 12. Availability for all three fuel cell buses and overall average 

Table 8 summarizes the reasons for availability and unavailability for each of the three fuel cell 

buses. During the evaluation period, the average availability for the fuel cell buses was 61%. 

The overall availability percentage is highlighted in the table for each bus and the average. 

 19
Table 8. Summary of Reasons for Availability and Unavailability of Buses for Service 

FC1 FC2 FC3 Group Total Category Days % Days % Days % Days % 

Planned Work Days 361 359 367 1,087 

Days Available 231 64 190 53 244 66 665 61 

Available 231 100 190 100 244 100 665 100 

On Route 165 65 162 85 170 70 497 75 

Event/Demonstration 14 5 11 6 37 15 62 9 

No Driver Available 13 6 7 3 2 1 22 3 

Training 13 7 5 3 6 2 24 4 

Not Used 26 17 5 3 29 12 60 9 

Unavailable 130 100 169 100 123 100 422 100 

Fuel Cell Propulsion 81 62 92 54 52 42 225 53 

ISE Propulsion 1 1 4 2 3 2 8 2 

ZEBRA Battery 14 11 30 18 25 20 67 16 

Air Conditioning 3 2 3 2 2 1 8 2 

AC Transit Maintenance 23 18 33 20 29 23 84 20 

Event Preparation 3 2 5 3 10 8 18 4 

Fueling Unavailable 5 4 2 1 5 4 12 3 

Fuel Economy and Cost 

Hydrogen fuel is supplied by the Chevron–AC Transit Hydrogen Energy Station at the East 

Oakland Division. The hydrogen is available at up to 5,000 psi for the three fuel cell transit 

buses. During the evaluation period, Chevron employees provided all fueling services for the 

hydrogen-fueled vehicles and electronically reported the fueling amounts. 

Table 9 shows hydrogen and diesel fuel consumption and fuel economy for the study buses 

during the evaluation period. Overall, the three fuel cell buses averaged 6.17 miles per kg of 

hydrogen, which equates to 6.97 miles per diesel gallon equivalent. The energy conversion from 

kg of hydrogen to diesel gallon equivalent is provided in Appendix A. ISE also reported that the 

fuel cell buses had approximately 1,035 kg of hydrogen removed during the evaluation period so 

that the buses could be taken into the maintenance facility. This amount of hydrogen removed 

and vented equates to 10% of the hydrogen dispensed into the fuel cell buses. 

Table 9. Fuel Use and Economy (Evaluation Period) 

Bus Mileage 

(Fuel Base) Hydrogen (kg) Miles per kg 

Diesel Equivalent 

Amount (Gallon) 

Miles per 

Gallon 

FC1 18,482 2,969.3 6.22 2,627.7 7.03 

FC2 15,838 2,609.1 6.07 2,308.9 6.86 

FC3 20,084 3,245.2 6.19 2,871.9 6.99 

FCB Total 54,404 8,823.5 6.17 7,808.4 6.97 

1043 24,736 6,211.8 3.98 

1044 26,328 6,104.5 4.31 

1045 26,998 6,421.7 4.20 

1046 23,513 6,436.2 3.65 

1047 26,547 6,189.6 4.29 

1048 21,258 5,748.8 3.70 

Diesel Total 149,380 37,112.6 4.03 

 20
The diesel fuel consumption for the evaluation period is only available for January through 

August 2007. For this eight-month period, the six diesel baseline buses averaged 4.03 mpg, 

which indicates the fuel economy for the fuel cell buses is an overall 73% higher than that of the 

diesel buses. 

Figure 13 shows a two-month rolling average fuel economy in both miles per kg and miles per 

diesel gallon equivalent for the fuel cell buses as well as the diesel buses in miles per gallon. 

The chart shows a progression downward for the average fuel economy at the beginning of the 

period, indicating the first problems with the fuel cell systems. After the first change-out of the 

fuel cell systems, the fuel economy started back up again, but the problems reappeared. In the 

last four months of the evaluation period, the fuel cell fuel economy was back to the expected 

level. For those last four months, the fuel cell fuel economy was generally two times higher than 

the diesel buses on an energy equivalent basis. 

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

Apr-06

May-06

Jun-06

Jul-06

Aug-06

Sep-06

Oct-06

Nov-06

Dec-06

Jan-07

Feb-07

Mar-07

Apr-07

May-07

Jun-07

Jul-07

Aug-07

Fuel Economy (Miles/Kg) 2-Month Avg

0

10

20

30

40

50

60

70

80

Monthly Average High Temperature (F)

FCB Mi/kg FCB Mi/DGE Diesel MPG Avg. High Temp

Figure 13. Two-month average fuel economy (evaluation period) 

The operating cost for hydrogen production and dispensing for AC Transit is currently estimated 

at $8 per kg. This amount, which excludes capital expenses, was generated using early data (not 

optimized operation) and conservative maintenance and operating estimates. Using this cost 

estimate for hydrogen fuel indicates a cost per mile for the fuel cell buses of $1.30. The average 

diesel fuel cost per gallon during the evaluation period is $2.20 per gallon. This indicates a 

$0.55 per mile cost. The diesel cost per mile is about 42% of the fuel cell bus fuel cost per mile. 

In addition to overall fuel economy analysis, the study buses had fuel economy calculations by 

route as shown in Table 10. As the specific routes and blocks were operated by the two study 

 21
bus groups, the fuel consumption and economy were tracked. As shown in the table and 

depending on the route, the fuel economy for the fuel cell buses ranged from 60% up to nearly 

90% higher than the diesel buses on the same route blocks during the evaluation period. The fuel 

cell bus fuel economy for the Route 57 was lower than expected due to the problems with the 

fuel cell systems during that period. 

Table 10. Route-specific fuel economy analysis (evaluation period) 

Route Average Fuel Cell Diesel 

Speed Period Mi/kg Mi/DGE Period MPG 

FC/Diesel 

(%) 

50 16.0 3-6/06; 3-6/07 6.64 7.50 6/06-3/07 4.39 71 

57 11.3 6/06-3/07 5.69 6.43 3-6/06; 3-6/07 3.95 63 

18 19.2 6/07-8/07 6.83 7.72 6/07-8/07 4.09 89 

51 9.5 6/07-8/07 5.87 6.63 6/07-8/07 3.68 80 

Maintenance Analysis 

The maintenance cost analysis in this section is only for the evaluation period (April 2006 

through August 2007). Warranty costs are not included in the cost-per-mile calculations. All 

work orders for the study buses were collected and analyzed for this evaluation. For consistency, 

the maintenance labor rate was kept at a constant $50 per hour; this does not reflect an average 

rate for AC Transit. This section first covers total maintenance costs, then maintenance costs 

broken down by bus system. 

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

$50 per hour; they do not include warranty costs. Cost per mile is calculated as follows: 

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

Table 11 shows total maintenance costs for the fuel cell and diesel buses. Note that the fuel cell 

bus maintenance costs shown in the table are significantly lower because of the on-site warranty 

work done by the UTC Power and ISE technicians physically located at AC Transit. These 

technicians have done all unscheduled and scheduled maintenance on the fuel cell buses for the 

fuel cell power systems and hybrid drive systems up until the end of the evaluation period. The 

AC Transit mechanics have done mostly cleaning and maintenance on the bus body (inside and 

outside) and doors. Some support has been provided for responding to roadcalls and that effort 

is reflected in the maintenance discussion that follows. 

AC Transit has expressed a strong desire to have its mechanics get more involved in all 

maintenance activities for these buses so that they get the experience. AC Transit has assigned 

one project manager/supervisor, one bus mechanic, one body mechanic, and two service workers 

to work on the fuel cell buses. This addition of resources for fuel cell bus maintenance will also 

be necessary based on the desired increase in operation toward the end of this evaluation period 

and with the future plans for more fuel cell buses. 

Maintenance issues for the fuel cell buses centered around problems with the traction batteries 

and the fuel cell system CSAs being replaced twice for FC1, FC2, and FC3 (and awaiting the 

next replacement). In addition to those problems, there were two accidents that required 

 22
significant work by the AC Transit mechanics – one for FC2 during February and March 2007; 

and one for FC3 in May 2007. 

Table 11. Total Maintenance Costs (Evaluation Period) 

Bus Mileage Parts ($) Labor 

Hours 

Cost per 

Mile ($) 

FC1 18,482 1,995.75 136.9 0.48 

FC2 15,848 3,100.01 138.8 0.63 

FC3 20,084 5,243.21 162.9 0.67 

Total Fuel Cell 54,404 10,338.97 438.6 0.59 

Avg. per Bus 18,135 3,446.32 146.2 -- 

1043 45,349 7,069.91 155.4 0.33 

1044 50,534 8,531.68 162.9 0.33 

1045 44,321 16,304.30 176.0 0.57 

1046 49,587 11,872.98 184.4 0.45 

1047 47,166 14,406.51 184.6 0.50 

1048 43,451 12,585.31 186.6 0.50 

Total Diesel 277,408 70,770.69 1,049.8 0.44 

Avg. per Bus 46,235 11,795.12 175.0 -- 

Maintenance issues for the diesel buses were mostly related to engine problems with the 

turbocharger (three buses) and ECM (three buses). The diesel buses also had significant brake 

repair costs for standard relining (five times). The other major maintenance cost issues were for 

accident repair and replacing seats and windows (three buses). 

The total maintenance costs, without warranty costs, are much lower for the diesel buses. The 

per-bus results for the fuel cell buses compared to the diesel buses are as follows: 

• Usage/Mileage – The fuel cell buses are 61% lower than the diesel buses 

• Parts Costs – The fuel cell buses are 71% lower than the diesel buses 

• Labor Hours – The fuel cell buses are 16% lower than the diesel buses 

• Cost per Mile (without warranty costs) – The fuel cell buses are 34% higher than the 

diesel buses 

Maintenance Costs Broken Down by System—Table 12 shows maintenance costs by vehicle 

system and bus study group (without warranty costs). 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 

 23
• Frame, Steering, and Suspension 

• Heating, Ventilation, and Air Conditioning (HVAC) 

• Lighting 

• Air System, General 

• Axles, Wheels, and Drive Shaft 

• Tires 

The systems with the highest percentage of maintenance costs for the fuel cell buses were 

propulsion-related; PMI; cab, body, and accessories; and brakes. These systems were also the 

highest maintenance cost systems for the diesel buses. 

Table 12. Breakdown of Vehicle System Maintenance Cost per Mile (Evaluation Period) 

Fuel Cell* Diesel 

System Cost per 

Mile ($) 

Percent of 

Total (%) 

Cost per 

Mile ($) 

Percent of 

Total (%) 

Cab, Body, and 

Accessories 0.30 51 0.18 41 

Propulsion-Related 0.08 13 0.10 23 

PMI 0.11 19 0.07 16 

Brakes 0.08 13 0.06 14 

Frame, Steering, and 

Suspension 0.00 0 0.02 4 

HVAC 0.01 2 0.00 0 

Lighting 0.01 2 0.00 0 

Air, General 0.00 0 0.00 0 

Axles, Wheels, and 

Drive Shaft 0.00 0 0.01 2 

Tires 0.00 0 0.00 0 

Total 0.59 100 0.44 100 

 * Excludes warranty work costs 

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 13 shows the propulsion-related system repairs by category for the 

two study groups during the evaluation period (no warranty costs). The fuel cell and diesel buses 

had similar maintenance costs overall; however, these costs do not include the work done by the 

ISE and UTC Power personnel, which was covered under warranty. 

 24
Table 13. Propulsion-Related Maintenance Costs by System (Evaluation Period) 

Maintenance System Costs Fuel Cell Diesel 

Mileage 54,404 277,408 

Total Propulsion-Related Systems (Roll-up) 

Parts cost ($) 644.25 15,394.42 

Labor hours 72.3 238.0 

Total cost ($) 4,278.25 27,293.42 

Total cost ($) per mile 0.08 0.10 

Exhaust System Repairs 

Parts cost ($) 0.00 625.82 

Labor hours 0.0 17.6 

Total cost ($) 0.00 1,503.32 

Total cost ($) per mile 0.00 0.01 

Fuel System Repairs 

Parts cost ($) 0.00 1,942.50 

Labor hours 11.4 44.8 

Total cost ($) 570.50 4,182.50 

Total cost ($) per mile 0.01 0.02 

Powerplant System Repairs 

Parts cost ($) 126.00 7,235.65 

Labor hours 15.0 80.8 

Total cost ($) 874.68 11,276.15 

Total cost ($) per mile 0.02 0.04 

Electric Motor and Propulsion Repairs 

Parts cost ($) 235.32 0.00 

Labor hours 41.9 0.0 

Total cost ($) 2,330.82 0.00 

Total cost ($) per mile 0.04 0.00 

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

Cranking, Ignition) 

Parts cost ($) 0.00 1,072.38 

Labor hours 2.0 30.6 

Total cost ($) 100.00 2,600.88 

Total cost ($) per mile 0.00 0.01 

Air Intake System Repairs 

Parts cost ($) 294.45 1,048.51 

Labor hours 0.0 0.0 

Total cost ($) 294.45 1,048.51 

Total cost ($) per mile 0.01 0.00 

Cooling System Repairs 

Parts cost ($) 7.80 2,992.15 

Labor hours 0.0 55.5 

Total cost ($) 7.80 5,767.15 

Total cost ($) per mile 0.00 0.02 

Transmission Repairs 

Parts cost ($) 0.00 342.65 

Labor hours 2.0 2.8 

Total cost ($) 100.00 480.15 

Total cost ($) per mile 0.00 0.00 

 25
Roadcall Analysis 

A roadcall (RC) or revenue vehicle system failure (as named in the National Transit Database) 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 schedule5

. If the problem with the bus can be repaired during a layover and 

the schedule is kept, this is not considered a RC. The analysis provided here only includes RCs 

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

disable the bus from operating on route, such as interlocks (doors, air system), engine, etc. or 

things that are deemed to be safety issues if operation of the bus continued. They do not include 

RCs for things such as problems with radios or destination signs. 

Table 14 shows the RCs and miles between roadcalls (MBRC) for each study bus categorized by 

all RCs and propulsion-related-only RCs. The diesel buses have much better MBRC rates for 

both categories. This is indicative of the low usage and prototype status of the fuel cell buses. 

Table 14. Roadcalls and MBRC (Evaluation Period) 

Bus Mileage All 

Roadcalls All MBRC Propulsion Roadcalls 

Propulsion 

MBRC 

Fuel Cell 

only MBRC 

FC1 18,482 15 1,232 13 1,422 4,621 

FC2 15,838 14 1,131 11 1,440 3,960 

FC3 20,084 10 2,008 9 2,232 10,042 

Total FCB 54,404 39 1,395 33 1,649 5,440 

1043 Diesel 45,349 7 6,478 2 22,675 

1044 Diesel 50,534 13 3,887 6 8,422 

1045 Diesel 44,321 12 3,693 4 11,080 

1046 Diesel 46,587 8 5,823 2 23,294 

1047 Diesel 47,166 11 4,288 8 5,896 

1048 Diesel 43,451 10 4,345 4 10,863 

Total Diesel 277,408 62 4,474 26 10,670 

 

5

 AC Transit defines a significant delay as six or more minutes. 

 26
What’s Next for This Demonstration? 

This report covers AC Transit operation of the fuel cell and diesel buses through August 2007. 

The next evaluation report for this site will include operational data through February 2008 and 

is planned for release around May 2008. The future evaluation report will include experiences 

from the operation of one of these fuel cell buses at GGT with planned operation starting in late 

October 2007 through November 2007. 

The Federal Transit Administration (FTA) announced the projects for its National Fuel Cell Bus 

Program on October 12, 2006. AC Transit received a grant for $3.575 million for “testing to 

failure” of the existing fuel cell buses. This grant project is just getting under way, and the 

implications will be discussed in the next evaluation report. 

In response to the updated California Air Resources Board (CARB) zero-emission bus 

regulations, AC Transit continues to work with regional transit agency partners and potential 

funding partners for an expanded fuel cell bus demonstration. This future demonstration should 

result in the addition of 12 new zero-emission buses with partner transit agencies. Details for 

this activity are still being developed. 

 27
Contacts 

DOE 

1000 Independence Ave., SW 

Washington, DC 20585 

John Garbak 

Technology Validation Manager 

Office of Hydrogen, Fuel Cells, and 

Infrastructure Technologies 

Phone: 202-586-1723 

E-mail: john.garbak@hq.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

AC Transit 

1700 Franklin Street 

Oakland, CA 94612 

Jaimie Levin 

Director of Marketing & Alternative Fuels 

Policy 

Phone: 510-891-7244 

E-mail: jlevin@actransit.org 

Mallory Nestor-Brush 

Project Director 

Phone: 510-891-7213 

E-mail: mnestor@actransit.org 

Doug Byrne 

ZEB Program Manager 

Phone: 510-577-8821 

E-mail: dbyrne@actransit.org 

UTC Power 

195 Governor’s Highway 

South Windsor, CT 06074 

Michael Tosca 

Senior Product Manager 

Phone: 860-727-7324 

E-mail: michael.tosca@utcpower.com

Matthew Riley 

Senior Systems Engineer 

Phone: 510-628-8252 

E-mail: matthew.riley@utcpower.com 

ISE Corp 

12302 Kerran Street 

Poway, CA 92064 

Tavin Tyler 

Director of Prototype Programs 

Phone: 858-413-1745 

E-mail: ttyler@isecorp.com 

Neil Flemmer 

Project Engineer 

Phone: 510-735-7579 

E-mail: nflemmer@isecorp.com 

 28
Chevron Technology Ventures – a 

Division of Chevron USA 

Van Hool 

Bernard Van Hoolstraat 58 

1254 Daleview Dr B-2500 Lier Koningshooikt 

McLean, VA 22102 Belgium 

Puneet Verma Paul Jenné 

Hydrogen Program Manager Automotive Relations 

Phone: 703-848-0419 Phone: +32 (3) 420 22 10 

E-Mail: pverma@chevron.com E-mail: paul.jenne@vanhool.be

 29
Acronyms and Abbreviations

AC alternating current 

AC Transit Alameda-Contra Costa Transit 

District 

APTA American Public 

Transportation Association 

BAAQMD Bay Area Air Quality 

Management District 

BRT Bus rapid transit 

C Celsius 

CaFCP California Fuel Cell 

Partnership 

CARB California Air Resources Board 

CNG compressed natural gas 

CSA cell stack assembly 

DC direct current 

DGE diesel gallon equivalent 

DOE U.S. Department of Energy 

DPF diesel particulate filter 

FC fuel cell 

FCB fuel cell bus 

FCV fuel cell vehicle 

ft feet 

FTA Federal Transit Administration 

GGBHTD Golden Gate Bridge, Highway, 

and Transportation District 

GGT Golden Gate Transit 

HFCIT Hydrogen, Fuel Cells, and 

Infrastructure Technology 

HHICE hydrogen hybrid internal 

combustion engine 

hp horsepower 

HVAC heating, ventilation, and air 

conditioning 

HyTEC Hydrogen Technology and 

Education Curriculum 

in inches 

kg kilogram 

kW kilowatts 

kWh kilowatt hour 

lb pounds 

LFL lower flammability limit 

MBRC miles between roadcalls 

mpg miles per gallon 

mph miles per hour 

NFCBP National Fuel Cell Bus 

Program 

Nm Newton meters 

NREL National Renewable Energy 

Laboratory 

PEM proton exchange membrane 

PMI preventive maintenance 

inspection 

psi pounds per square inch 

RC roadcall 

rpm revolutions per minute 

SOC state of charge 

VAC volts alternating current 

ZEB zero emission bus 

 30
References and Related Reports 

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

Evaluation Results Update, National Renewable Energy Laboratory, Golden, CO, NREL/TP560-42080 

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

Experiences and Current Status, National Renewable Energy Laboratory, Golden, CO, 

NREL/TP-560-41967 

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

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

ACT preliminary 

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

Preliminary Evaluation Results, National Renewable Energy Laboratory, Golden, CO, 

NREL/TP-560-41001 

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

County Transit District, Fuel Cell Transit Buses: Evaluation Results, National Renewable 

Energy Laboratory, Golden, CO, NREL/TP-560-40615 

NREL, 2006, SunLine Tests HHICE Bus in Desert Climate, National Renewable Energy 

Laboratory, Golden, CO, DOE/GO-102006-2333 

NREL, 2006, AC Transit Demos Three Prototype Fuel Cell Buses, National Renewable Energy 

Laboratory, Golden, CO, DOE/GO-102006-2286 

NREL, 2006, SunLine Expands Horizons with Fuel Cell Bus Demo, National Renewable Energy 

Laboratory, Golden, CO, DOE/GO-102006-2287 

NREL, 2005, VTA, SamTrans Look into Future with Bus Demo, National Renewable Energy 

Laboratory, Golden, CO, DOE/GO-102005-2147 

NREL, 2005, Draft Fuel Cell Transit Bus Evaluation Plan, National Renewable Energy 

Laboratory, Golden, CO 

EvoBus GmbH, 2004, Clean Urban Transport for Europe (CUTE), A Fuel Cell Bus Project in 

Nine European Cities, EvoBus, Ulm, Germany 

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

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

NREL, 2003, SunLine Test Drives Hydrogen Bus, National Renewable Energy Laboratory, 

Golden, CO, DOE/GO-102003-1768 

 31
NREL, 2002, General Evaluation Plan, Fleet Test & Evaluation Projects, National Renewable 

Energy Laboratory, Golden, CO, NREL/BR-540-32392 

College of the Desert, 2001, Hydrogen Fuel Cell Engines and Related Technologies (Course 

Materials, Modules 1-11), College of the Desert, Palm Desert, CA 

Reports from DOE/NREL evaluations can be downloaded via the following Web sites: 

Hydrogen and fuel cell related: www.nrel.gov/hydrogen/proj_fc_bus_eval.html

Hybrid and other technologies: www.nrel.gov/vehiclesandfuels/fleettest/publications_bus.html 

 32
Appendix A: Fleet Summary Statistics 

Fleet Summary Statistics: Alameda-Contra Costa Transit District (AC Transit)

Diesel and FCB Study Groups 

Fleet Operations and Economics

Fuel Cell Diesel 

Number of Vehicles 3 6

Period Used for Fuel and Oil Op Analysis 4/06-8/07 1/07-8/07

Total Number of Months in Period 17 8

Fuel and Oil Analysis Base Fleet Mileage 54,404 149,380

Period Used for Maintenance Op Analysis 4/06-8/07 4/06-8/07

Total Number of Months in Period 17 17

Maintenance Analysis Base Fleet Mileage 54,404 277,408

Average Monthly Mileage per Vehicle 1,067 2,720

Availability 61% N/A

Fleet Fuel Usage in Diesel Gal/H2 kg 8,824 37,113

Roadcalls 39 62

RCs MBRC 1,395 4,474

Propulsion Roadcalls 33 26

Propulsion MBRC 1,649 10,670

 

Fleet Miles/kg Hydrogen 6.17 

(1.13 kg H2/gal Diesel Fuel) 

Representative Fleet MPG (energy equiv.) 6.97 4.03

 

Hydrogen Cost per kg 8.00 

Diesel Cost per Gallon 2.20

Fuel Cost per Mile 1.30 0.55

 

Total Scheduled Repair Cost per Mile 0.21 0.10

Total Unscheduled Repair Cost per Mile 0.38 0.55

Total Maintenance Cost per Mile 0.59 0.44

 

Total Operating Cost per Mile 1.88 0.99

Maintenance Costs

 Fuel Cell Diesel 

Fleet Mileage 54,404 277,408

 

Total Parts Cost 10,036.14 70,770.71

Total Labor Hours 436.6 1049.8

Average Labor Cost (@ $50.00 per hour) 21,831.00 52,489.00

 

Total Maintenance Cost 31,867.14 123,259.71

Total Maintenance Cost per Bus 10,622.38 20,543.29

Total Maintenance Cost per Mile 0.59 0.44

 33
Breakdown of Maintenance Costs by Vehicle System

Fuel Cell Diesel 

Fleet Mileage 54,404 277,408

 

Total Propulsion-Related Systems (ATA VMRS 27, 30, 31, 32, 33, 41, 42, 43, 44, 45, 46, 65) 

Parts Cost 664.25 15,394.42

Labor Hours 72.3 238.0

Average Labor Cost 3,614.00 11,899.00

Total Cost (for system) 4,278.25 27,293.42

Total Cost (for system) per Bus 1,426.08 4,548.90

Total Cost (for system) per Mile 0.08 0.10

 

Exhaust System Repairs (ATA VMRS 43) 

Parts Cost 0.00 625.82

Labor Hours 0.0 17.6

Average Labor Cost 0.00 877.50

Total Cost (for system) 0.00 1,503.32

Total Cost (for system) per Bus 0.00 250.55

Total Cost (for system) per Mile 0.00 0.01

 

Fuel System Repairs (ATA VMRS 44) 

Parts Cost 0.00 1,942.50

Labor Hours 11.4 44.8

Average Labor Cost 575.50 2,240.00

Total Cost (for system) 575.50 4,182.50

Total Cost (for system) per Bus 190.17 697.08

Total Cost (for system) per Mile 0.01 0.02

 

Power Plant (Engine) Repairs (ATA VMRS 45) 

Parts Cost 126.68 7,235.65

Labor Hours 15.0 80.8

Average Labor Cost 748.00 4,040.50

Total Cost (for system) 874.68 11,276.15

Total Cost (for system) per Bus 291.56 1,879.36

Total Cost (for system) per Mile 0.02 0.04

 

Electric Propulsion Repairs (ATA VMRS 46) 

Parts Cost 235.32 0.00

Labor Hours 41.9 0.0

Average Labor Cost 2,095.50 0.00

Total Cost (for system) 2,330.82 0.00

Total Cost (for system) per Bus 776.94 0.00

Total Cost (for system) per Mile 0.04 0.00

 

 34
Breakdown of Maintenance Costs by Vehicle System (continued)

 Fuel Cell Diesel 

Electrical System Repairs (ATA VMRS 30-Electrical General, 31-Charging, 32-Cranking, 33-

Ignition)

Parts Cost 0.00 1,072.38

Labor Hours 2.0 30.6

Average Labor Cost 100.00 1,528.50

Total Cost (for system) 100.00 2,600.88

Total Cost (for system) per Bus 33.33 433.48

Total Cost (for system) per Mile 0.00 0.01

 

Air Intake System Repairs (ATA VMRS 41) 

Parts Cost 294.45 1,048.51

Labor Hours 0.0 0.0

Average Labor Cost 0.00 0.00

Total Cost (for system) 294.45 1,048.51

Total Cost (for system) per Bus 98.15 174.51

Total Cost (for system) per Mile 0.01 0.00

 

Cooling System Repairs (ATA VMRS 42) 

Parts Cost 7.80 2,992.15

Labor Hours 0.0 55.5

Average Labor Cost 0.00 2,775.00

Total Cost (for system) 7.80 5,767.15

Total Cost (for system) per Bus 2.60 961.19

Total Cost (for system) per Mile 0.00 0.02

 

Hydraulic System Repairs (ATA VMRS 65) 

Parts Cost 0.00 134.76

Labor Hours 0.0 6.0

Average Labor Cost 0.00 300.00

Total Cost (for system) 0.00 434.76

Total Cost (for system) per Bus 0.00 72.46

Total Cost (for system) per Mile 0.00 0.00

 

General Air System Repairs (ATA VMRS 10) 

Parts Cost 12.34 284.80

Labor Hours 0.0 13.6

Average Labor Cost 0.00 677.50

Total Cost (for system) 12.34 962.30

Total Cost (for system) per Bus 4.11 160.38

Total Cost (for system) per Mile 0.00 0.00

 

 35
Breakdown of Maintenance Costs by Vehicle System (continued)

 Fuel Cell Diesel 

Brake System Repairs (ATA VMRS 13)

Parts Cost 4,098.95 11,813.82

Labor Hours 2.0 90.7

Average Labor Cost 100.00 4,535.00

Total Cost (for system) 4,198.95 16,348.82

Total Cost (for system) per Bus 1,399.65 2,724.80

Total Cost (for system) per Mile 0.08 0.06

Transmission Repairs (ATA VMRS 27) 

Parts Cost 0.00 342.65

Labor Hours 2.0 2.8

Average Labor Cost 100.00 137.50

Total Cost (for system) 100.00 480.15

Total Cost (for system) per Bus 33.33 80.03

Total Cost (for system) per Mile 0.00 0.00

 

Inspections Only – No Parts Replacements (101) 

Parts Cost 0.00 0.00

Labor Hours 123.8 405.0

Average Labor Cost 6,187.50 20,249.00

Total Cost (for system) 6,187.50 20,249.00

Total Cost (for system) per Bus 2,062.50 3,374.83

Total Cost (for system) per Mile 0.11 0.07

 

Cab, Body, and Accessories Systems Repairs 

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

Parts Cost 4,754.85 38,808.54

Labor Hours 227.9 197.3

Average Labor Cost 11,394.00 9,866.00

Total Cost (for system) 16,148.85 48,674.54

Total Cost (for system) per Bus 5,382.95 8,112.42

Total Cost (for system) per Mile 0.30 0.18

 

HVAC System Repairs (ATA VMRS 01) 

Parts Cost 0.00 267.96

Labor Hours 7.6 3.4

Average Labor Cost 380.00 169.00

Total Cost (for system) 380.00 436.96

Total Cost (for system) per Bus 126.67 72.83

Total Cost (for system) per Mile 0.01 0.00

 

 36
Breakdown of Maintenance Costs by Vehicle System (continued)

 Fuel Cell Diesel 

Lighting System Repairs (ATA VMRS 34)

Parts Cost 178.24 336.96

Labor Hours 1.6 16.4

Average Labor Cost 80.50 822.00

Total Cost (for system) 258.74 1,158.96

Total Cost (for system) per Bus 86.25 193.16

Total Cost (for system) per Mile 0.00 0.00

 

Frame, Steering, and Suspension Repairs (ATA VMRS 14-Frame, 15-Steering, 16-Suspension) 

Parts Cost 138.88 2,866.60

Labor Hours 1.5 86.5

Average Labor Cost 75.00 3,424.00

Total Cost (for system) 213.88 6,290.60

Total Cost (for system) per Bus 71.29 1,048.43

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 188.62 188.62

Labor Hours 0.0 0.0

Average Labor Cost 0.00 0.00

Total Cost (for system) 188.62 188.62

Total Cost (for system) per Bus 62.87 62.87

Total Cost (for system) per Mile 0.00 0.00

 

Tire Repairs (ATA VMRS 17)

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

 37
Notes

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

was also converted into diesel energy equivalent gallons. The general energy conversions are as 

follows, actual energy content will vary by location: 

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/gallon / 113,628 Btu/kg = 1.13 kg/diesel gallon 

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

could be directly impacted 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 only included in the overall totals (not by 

system). 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. 

 38
Appendix B: Fleet Summary Statistics – SI Units 

Fleet Summary Statistics: Alameda-Contra Costa Transit District (AC Transit)

Diesel and FCB Study Groups 

Fleet Operations and Economics

Fuel Cell Diesel 

Number of Vehicles 3 6

Period Used for Fuel and Oil Op Analysis 4/06-8/07 1/07-8/07

Total Number of Months in Period 17 8

Fuel and Oil Analysis Base Fleet Kilometers 87,552 240,397

Period Used for Maintenance Op Analysis 4/06-8/07 4/06-8/07

Total Number of Months in Period 17 17

Maintenance Analysis Base Fleet Kilometers 87,552 446,433

Average Monthly Kilometers per Vehicle 1,717 4,377

Availability 61% N/A

Fleet Fuel Usage in Diesel L/H2 kg 8,824 140,473

Roadcalls 39 62

Kilometers between roadcalls (KBRC) 2,245 7,201

Propulsion Roadcalls 33 26

Propulsion KBRC 2,653 17,170

 

Fleet kg Hydrogen/100 km 10.08 

Representative Fleet MPG (L/100 km) 33.76 58.43

 

Hydrogen Cost per kg 8.00 

Diesel Cost per Liter 0.58

Fuel Cost per Kilometer 0.81 0.34

 

Total Scheduled Repair Cost per Kilometer 0.13 0.06

Total Unscheduled Repair Cost per Kilometer 0.23 0.22

Total Maintenance Cost per Kilometer 0.36 0.28

 

Total Operating Cost per Kilometer 1.17 0.62

Maintenance Costs

 Fuel Cell Diesel 

Fleet Kilometers 87,552 446,433

 

Total Parts Cost 10,036.14 70,770.71

Total Labor Hours 436.6 1049.8

Average Labor Cost (@ $50.00 per hour) 21,830.00 52,490.00

 

Total Maintenance Cost 31,866.14 123,260.71

Total Maintenance Cost per Bus 10,622.05 20,543.45

Total Maintenance Cost per Kilometer 0.36 0.28

 39
F1147-E(09/2007) 

REPORT DOCUMENTATION PAGE Form Approved 

OMB No. 0704-0188

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, 

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currently valid OMB control number. 

PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION.

1. REPORT DATE (DD-MM-YYYY)

October 2007 

2. REPORT TYPE

Technical Report 

3. DATES COVERED (From - To)

 

5a. CONTRACT NUMBER

DE-AC36-99-GO10337 

5b. GRANT NUMBER

4. TITLE AND SUBTITLE

Alameda-Contra Costa Transit District (AC Transit) Fuel Cell Transit 

Buses: Evaluation Results Update 

5c. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

NREL/TP-560-42249 

5e. TASK NUMBER

H2708200 

6. AUTHOR(S)

Kevin Chandler and Leslie Eudy 

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-560-42249 

10. SPONSOR/MONITOR'S ACRONYM(S)

NREL 

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

11. SPONSORING/MONITORING 

AGENCY REPORT NUMBER

12. DISTRIBUTION AVAILABILITY STATEMENT

National Technical Information Service 

U.S. Department of Commerce 

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Springfield, VA 22161 

13. SUPPLEMENTARY NOTES

14. ABSTRACT (Maximum 200 Words)

This report is an update to the 2007 preliminary results report on hydrogen fuel cell and diesel buses operating at 

Alameda-Contra Costa Transit District. 

15. SUBJECT TERMS

Alameda; Contra Costa; fuel cell evaluation; fuel cell bus; fuel cell buses 

16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE PERSON 

a. REPORT 

Unclassified 

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