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 

Alameda-Contra Costa Transit 

District (AC Transit) Fuel Cell 

Transit Buses 

Preliminary Evaluation Results 

K. Chandler 

Battelle 

L. Eudy 

National Renewable Energy Laboratory

Technical Report 

NREL/TP-560-41041 

March 2007 

NREL is operated by Midwest Research Institute ● Battelle Contract No. DE-AC36-99-GO10337 
Alameda-Contra Costa Transit 

District (AC Transit) Fuel Cell 

Transit Buses 

Preliminary Evaluation Results 

K. Chandler 

Battelle 

L. Eudy 

National Renewable Energy Laboratory

Prepared under Task No(s). HF65.8200, WO16.1000 

Technical Report 

NREL/TP-560-41041 

March 2007 

National Renewable Energy Laboratory

1617 Cole Boulevard, Golden, Colorado 80401-3393 

303-275-3000 • www.nrel.gov 

Operated for the U.S. Department of Energy 

Office of Energy Efficiency and Renewable Energy 

by Midwest Research Institute • Battelle 

Contract No. DE-AC36-99-GO10337
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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 

Sigmund Gronich 

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 Corp. 

Jayson Cannon 

Neil Flemmer 

Tavin Tyler 

Chevron 

Linda Gallaher 

Rick Zalesky 

Dan Casey 

GGT 

Gene Walker 

Van Hool 

Paul Jenné 

 iii
Table of Contents 

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

Infrastructure and Facilities ........................................................................................................ 1 

Evaluation Results ...................................................................................................................... 1 

What’s Next ................................................................................................................................ 4 

Overview......................................................................................................................................... 5 

Project Design and Data Collection............................................................................................ 6

Host Site Profile.......................................................................................................................... 7 

AC Transit Fuel Cell Bus Program............................................................................................. 9 

Infrastructure and Facilities .......................................................................................................... 11 

Richmond Station...................................................................................................................... 11 

Oakland Energy Station ............................................................................................................ 11 

Maintenance Facility Modifications ......................................................................................... 16 

Fuel Cell and Diesel Buses ........................................................................................................... 20 

Fuel Cell Bus Propulsion System Description.......................................................................... 21 

Early Bus Experience................................................................................................................ 22 

Training and Public Awareness .................................................................................................... 25 

Evaluation Results ........................................................................................................................ 28 

Route Descriptions.................................................................................................................... 28 

Bus Use and Availability .......................................................................................................... 29 

Fuel Economy and Cost............................................................................................................ 33 

Maintenance Analysis............................................................................................................... 35 

Roadcall Analysis ..................................................................................................................... 40 

What’s Next .................................................................................................................................. 41 

Contacts......................................................................................................................................... 43 

References and Related Reports ................................................................................................... 46 

Appendix: Fleet Summary Statistics............................................................................................. 47 

Appendix: Fleet Summary Statistics – SI Units ........................................................................... 53

 iv
Executive Summary 

This evaluation includes three prototype fuel cell-powered transit 

buses operating at AC Transit in Oakland, California, since March 20, 

2006 and six baseline diesel buses similar in design to the fuel cell 

buses. This report describes the equipment used (buses and 

infrastructure) and provides early experience details, lessons learned, 

and results from the operation of the buses (shown in Figure ES-1) and 

the supporting hydrogen fueling station through November 30, 2006. 

In this evaluation report, the fuel cell buses are considered prototype 

technology that is in the process of being commercialized. The analysis and comparisons with 

standard diesel buses were done to help baseline the status and 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). 

 Figure ES-1. AC Transit Van Hool buses – diesel (left) and fuel cell (right) 

Infrastructure and Facilities 

In March 2004, AC Transit joined in partnership with Chevron Technology Ventures to design 

and build a hydrogen energy station at the East Oakland Division. Construction on the station 

began in June 2005 and was operational by mid-December the same year. On March 13, 2006, 

AC Transit and local officials formally inaugurated the Chevron – AC Transit Hydrogen Energy 

Station, kicking-off the demonstration project. 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 

Chevron – AC Transit Hydrogen Energy Station is 366 kg of hydrogen. 

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. 

Evaluation Results 

The evaluation period includes operational results from April 2006 through November 2006. 

The three $3.2 million Van Hool fuel cell buses use hybrid-electric propulsion systems from ISE 

Corp. with ZEBRA® sodium/nickel chloride batteries and regenerative braking. The fuel cell 

 1
system (PureMotionTM 120) was manufactured by UTC Power. The diesel baseline buses are 

Van Hool buses with Cummins ISL diesel engines equipped with diesel oxidation catalysts. 

Route Descriptions – For this program, AC Transit developed two special blocks of work 

(planned daily bus assignments) on each of two routes (Route 50 and Route 57) for operation of 

the fuel cell and diesel baseline buses. The two special blocks of work on Route 50 have an 

average speed of 16 mph, while the special blocks on Route 57 have an average speed of 11.3 

mph. 

Bus Use and Availability – The fleet 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 three fuel cell buses may be included. During the evaluation period, the fuel 

cell buses operated 27,065 miles and 2,338 total fuel cell system hours. The usage of the fuel 

cell buses was approximately 53% of the diesel baseline buses in the same time frame. Overall 

availability for the fuel cell buses was 77%. 

Fuel Economy and Cost 

Monthly average fuel economy for the fuel cell buses is shown in Figure ES-2. The fuel cell 

buses averaged 5.50 miles per kg of hydrogen for the evaluation period, which equates to 6.22 

miles per diesel gallon equivalent. The diesel fuel consumption for the evaluation period is not 

available except for November 2006, because the fuel tracking system was not working properly 

until late October 2006. AC Transit reports that the diesel bus fleet typically has an average fuel 

economy of approximately 4.00 mpg, which indicates that the fuel cell buses have an average 

fuel economy 56% higher than that of the diesel buses. 

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

Apr-06 May-06 Jun-06 Jul-06 Aug-06 Sep-06 Oct-06 Nov-06

Miles per kg or DGE

Miles/kg Miles/DGE

Figure ES-2. Fuel cell bus monthly average fuel economy (evaluation period) 

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

at $8 per kg. This excludes capital expenses and has been generated using early data (not 

 2
optimized operation) and conservative maintenance and operating estimates. This equates to a 

cost per mile for the fuel cell buses of $1.45. The average diesel fuel cost per gallon during the 

evaluation period is $2.30 per gallon. If the 4.00 mpg diesel average fuel economy is used, this 

indicates a $0.58 per mile cost. 

Maintenance Analysis – 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 47% lower than the diesel buses 

• Parts Costs – The fuel cell buses are 44% lower than the diesel buses 

• Labor Hours – The fuel cell buses are 11% higher than the diesel buses 

• Cost per Mile (without warranty costs) – The fuel cell buses are 71% higher than the 

diesel buses 

This reflects the fact that the fuel cell buses are prototypes in the development stage for transit 

bus service. 

Specific Experience with Fuel Cell Buses – The first fuel cell bus was delivered in 

October 2005 and the other two fuel cell buses were delivered in December 2005. Before the 

buses went into service on March 20, 2006, the mechanics and drivers were trained on the 

general characteristics of hydrogen, hydrogen safety, and fuel cell bus operation. AC Transit 

mechanics also received more detailed training on system troubleshooting. 

Both ISE and UTC Power have on-site technical support available to AC Transit for warranty 

support of the fuel cell buses, and AC Transit reports that this support has been excellent. AC 

Transit is responsible for bus maintenance, and UTC Power and ISE are responsible for the 

propulsion and drive system. The parts for the fuel cell power system have been provided to AC 

Transit through the UTC Power technician on an as-needed basis. 

There have been a few significant issues with the fuel cell buses: 

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 algorithm. A cell failure in this serial string causes a short that decreases the 

overall voltage of a pack (in the group of three packs). ISE Corp. is working to better 

optimize the control software to alleviate this issue. 

2. Air conditioning – This hybrid design is unique because the air conditioning unit is 

driven electrically instead of mechanically (by belt) like most vehicles. In this 

application, the system has experienced problems with failed motors. Several changes 

and upgrades have been attempted and the problem seems to be resolved. 

3. UTC Power PureMotion 120 Fuel Cell Power System – UTC Power monitors the 

performance of the fuel cell power system remotely to analyze actual performance vs. 

predicted performance. In June 2006, UTC Power observed that the Cell Stack Assembly 

 3
(CSA) performance was decaying at high current densities at rates that were beyond what 

was predicted. 

With the SunLine bus accumulating the most hours early on, the issue was observed there 

first. An engineering investigation determined that contaminants were released from a 

material in the CSAs due to a supplier quality control problem with that material. As part 

of UTC Power’s ongoing development, UTC Power has incorporated corrective action 

into the CSAs thus eliminating this condition for all builds. 

UTC Power has begun the process of retrofitting all three of the AC Transit buses with 

upgraded units. A spare powerplant is being used to minimize downtime for the buses. 

As the upgraded fuel cell power systems are installed into the AC Transit buses, there is a 

desire to maximize/accelerate the use of the fuel cell buses. This accelerated testing is 

currently limited due to issues with the ZEBRA battery pack failures and charging the 

batteries up to a nearly full SOC overnight in time for the next day’s service. Until the 

charging regime issue can be resolved, the bus cannot meet the desired 14-16 hours of 

operation on a regular/daily basis. AC Transit is in the process of upgrading electrical 

service to the maintenance building at East Oakland so that more battery charging 

capacity can be added. 

The drivers of the fuel cell buses have been excited about and reportedly really like the buses; 

however, they have expressed some nervousness with potentially “hurting” the new buses. The 

buses offer smooth, quiet driving and comfortable driver seats with good access to controls. 

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 schedule. If the problem with the bus can be 

repaired during a layover and the schedule is kept, this is not considered a RC. 

The diesel study buses had an overall RC rate of 4,468 miles between RCs (MBRC) and the fuel 

cell buses had 773 MBRC. For propulsion-only RCs, the diesel buses had a rate of 8,563 MBRC 

and the fuel cell buses had 1,230 MBRC. 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. 

(Note: AC Transit reports the entire 40-ft Van Hool diesel fleet has a propulsion-related MBRC 

of 14,000.) 

What’s Next 

This preliminary data report includes an eight-month evaluation period (April 2006 through 

November 2006) of the prototype fuel cell buses in operation at AC Transit. The next evaluation 

report, planned for release at the end of 2007, will include at least another 6 months of operations 

data and experience from AC Transit. 

 4
Overview 

This report provides preliminary results from an evaluation of three prototype fuel cell transit 

buses operating at Alameda-Contra Costa Transportation District (AC Transit) in Oakland, 

California. The three fuel cell transit buses have been operating at AC Transit in passenger 

service since March 20, 2006. This report describes the equipment used (buses and 

infrastructure) and provides early experience details, lessons learned, and results from the 

operation of the buses and supporting hydrogen fueling station through November 30, 2006. 

This evaluation is part of DOE’s Hydrogen, Fuel Cells & Infrastructure Technologies (HFCIT) 

Program, which integrates activities in hydrogen production, storage, and delivery with 

transportation and stationary fuel cell applications. DOE’s National Renewable Energy 

Laboratory (NREL) works with fleets and industry groups to test advanced technology, heavyduty vehicles in service and provides unbiased information resources for fleet managers 

considering these technologies. Information collected during vehicle performance and 

evaluations of vehicle operation are fed back to research programs to help shape future work. 

In early 2003, DOE initiated the Controlled Hydrogen Fleet and Infrastructure Demonstration 

and Validation Project, which focuses on light-duty fuel cell vehicles and supporting 

infrastructure. The purpose of the project is to examine the impact and performance of fuel cell 

vehicles and supporting hydrogen infrastructure in real-world applications. The data collected 

and analyzed during this “learning demonstration” is used to verify performance targets and 

assess technology readiness. To coordinate efforts, the fuel cell bus evaluation team is working 

closely with the light-duty demonstration project teams. The overall goal of this coordination is 

to ensure that similar data for heavy-duty fuel cell vehicles are collected to enable a more 

complete picture of fuel cell performance over a wider range of vehicle applications than just 

light-duty. 

In addition to the light-duty demonstration project, DOE and NREL are also working with the 

Federal Transit Administration (FTA), an agency of the U.S. Department of Transportation 

(DOT), and heavy vehicle operators (mostly transit agencies) to demonstrate heavy fuel cell and 

hydrogen vehicles and to collect operations experience data. This collaboration directly supports 

FTA’s National Fuel Cell Bus Program (NFCBP). This data collection and evaluation follows 

the DOE/NREL standardized evaluation protocol1

 and detailed data collection templates based 

on the light-duty demonstration. A customized version of the General Evaluation Plan, created 

for fuel cell bus evaluations, is described in the draft Fuel Cell Transit Bus Evaluation Protocol 

of June 2005. Current heavy fuel cell vehicle evaluation sites are shown in Table 1. More 

information is available at 

www.eere.energy.gov/hydrogenandfuelcells/tech_validation/ca_transit_agencies.html. 

 

1

 General Evaluation Plan, Fleet Test & Evaluation Projects, July 2002, NREL/BR-540-32392, 

www.nrel.gov/vehiclesandfuels/fleettest/pdfs/32392.pdf. 

 5
 

Table 1. DOE/NREL Heavy Vehicle Fuel Cell/Hydrogen Evaluations 

Fleet Vehicle/Technology Evaluation Status 

Shuttle bus: Hydrogenics and Enova, 

battery-dominant fuel cell hybrid (one 

bus) 

Shuttle bus in operation, data 

U.S. Air Force/Hickam Air Force Base collection started 

(Honolulu, Hawaii) Delivery van: Hydrogenics and Enova, 

fuel cell hybrid (one van) 

Van in operation, data collection 

started 

Alameda-Contra Costa Transit District 

(Oakland, California) 

Van Hool/UTC Power fuel cell hybrid 

transit bus integrated by ISE Corp. 

(three buses) 

Evaluation in process, all three 

buses in operation since March 

2006, full service started in April 

2006; preliminary evaluation results 

reported here 

New Flyer ISE Corp. hydrogen internal 

combustion engine transit bus (one 

bus-HHICE) 

Evaluation in process, preliminary 

evaluation results reported Feb 

SunLine Transit Agency 2007 

(Thousand Palms, California) Van Hool/UTC Power fuel cell hybrid 

transit bus integrated by ISE Corp. 

(one bus-FCB) 

Evaluation in process, preliminary 

evaluation results reported Feb 

2007 

VTA (San Jose, California) and 

SamTrans (San Carlos, California) 

Gillig/Ballard fuel cell transit bus (three 

buses) Complete and reported in 2006 

SunLine Transit Agency 

(Thousand Palms, California) 

ISE Corp./ UTC Power ThunderPower 

hybrid fuel cell transit bus (one bus) Complete and reported in 2003 

This preliminary data report examines evaluation results from 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 November 2006 (8 months of operation) 

• Diesel Buses – April 2006 through November 2006 (8 months of operation) 

Project Design and Data Collection 

DOE/NREL evaluation projects focus on using a standardized process for data collection and 

analysis, communicating results clearly, and providing an accurate and complete evaluation. The 

objectives of the data collection are to validate fuel cell and hydrogen technologies in bus 

applications to: 

• Determine the status of fuel cell systems for buses and corresponding hydrogen 

infrastructure 

• Provide feedback for DOE HFCIT Program research and development 

• Provide “lessons learned” on implementing next generation fuel cell systems into bus 

operations 

This evaluation includes three prototype fuel cell-powered transit buses (40-foot) operating at 

AC Transit in Oakland, California (bus shown in Figure 1). Six diesel buses (bus shown in 

Figure 2) were selected from AC Transit’s newest order of Van Hool diesel buses operating at 

the same depot (East Oakland Division). Data have been collected in parallel to the three 

prototype buses for the evaluation period, April 2006 through November 2006. The diesel 

baseline data were collected and analyzed along side the prototype fuel cell buses to assess the 

progress of the fuel cell propulsion development for heavy vehicles, specifically in this 

application at AC Transit. 

 6
 Figure 1. Fuel cell transit bus at AC Transit 

Figure 2. Diesel bus at AC Transit 

Data for this evaluation were taken from AC Transit’s data system. Data parameters included: 

• Diesel fuel consumption by vehicle and fill 

• Hydrogen fuel consumption by vehicle and fill 

• Mileage data and route assignments from every vehicle in the study 

• Preventive maintenance action work orders, parts lists, labor records, and related 

documents 

• Records of unscheduled maintenance, including roadcalls and warranty actions by 

vendors (when available in the data system) 

Additional information has been collected on the maintenance/operation experience, issues at the 

hydrogen fueling station and at AC Transit facilities, and lessons learned at the start-up and 

during operation of the study buses. 

Host Site Profile 

AC Transit (www.actransit.org) was created in 1956, but public transit in Oakland dates as far 

back as 1869. The district is governed by a seven-member board of directors elected by East 

Bay voters. Five of these board members represent geographic wards while two are elected atlarge. The AC Transit service area of 360 square miles includes 13 cities and adjacent 

unincorporated areas in Alameda and Contra Costa counties. AC Transit operates 538 transit 

buses in peak service (717 active buses in the fleet including paratransit) on more than 105 fixed 

routes and provides school bus service. In fiscal year 2005, annual ridership exceeded 68.9 

million. Figure 3 shows the AC Transit and Golden Gate Transit (GGT) operating areas. GGT 

 7
is a participant in the AC Transit fuel cell bus demonstration and intends to operate the fuel cell 

buses in its service later in the program. 

Golden Gate Transit (www.goldengate.org) 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 as well as the operation of the Golden Gate 

Bridge and the Golden Gate Ferry operation. GGT, which operates from San Rafael, California, 

a central location in its operating area, started fixed-route service in 1972 based on transportation 

planning aimed at reducing traffic congestion on the Golden Gate Bridge. GGT has 260 buses 

that operated 5.1 million miles in fiscal year 2005. 

Figure 3. AC Transit and Golden Gate Transit operating area in California 

 8
AC Transit Fuel Cell Bus Program 

AC Transit’s interest in fuel cell buses started in October 1999, following a successful one-week 

demonstration of the Ballard P4 ZEbus on scheduled routes in the AC Transit service area. This 

preceded Ballard operating the bus for a one-year test at SunLine in 2000. Soon after, the 

California Air Resources Board (CARB) established a new fleet rule in February 2000 to 

significantly reduce emissions of existing and new transit buses in California. The rule set more 

stringent emissions standards for new urban bus engines and promoted advancement of the 

cleanest propulsion technologies – specifically, zero emission buses (ZEBs). This ruling 

required transit agencies to choose a compliance path – alternative fuel or diesel. 

The deadline for choosing one of these compliance paths was later in 2000. AC Transit and 

GGT chose the diesel path. AC Transit reported that it did not choose the alternative fuel path 

because it worried about reliability and capital costs for operating an alternative fuel such as 

compressed natural gas (CNG). Fleets choosing the diesel path were required to reduce the fleet 

average emissions through methods such as purchasing the cleanest diesel engines and 

retrofitting existing diesel engines with emissions control devices such as diesel particulate filters 

(DPFs). All California transit agencies with 200 or more buses (including AC Transit and GGT) 

choosing the diesel path were subject to demonstrate (by 2003) and eventually procure ZEBs at a 

rate of 15% of all new bus purchases starting in model year 2008. 

AC Transit and GGT agreed in 2001 to partner in the training and operation of the fuel cell buses 

in order to meet the CARB requirements. AC Transit attempted to purchase fuel cell buses in 

2000 and early 2001. The agency received only one bid, which was eventually withdrawn by the 

vendor. AC Transit set out in 2001 to learn all that it could about fuel cell buses, including 

operating the Ballard P4/ZEbus for one week for testing, joining the California Fuel Cell 

Partnership (CaFCP), and operating the ISE/UTC Power ThunderPower 30-foot fuel cell bus 

during part of 2003 and 2004. 

During 2001-2002, AC Transit was looking for a new bus design to purchase for its planned 

Rapid Bus Rapid Transit (BRT) project. AC Transit’s next large purchase of diesel buses 

(approximately 190 buses) was supplied by Van Hool through its distributor in the U.S., ABC 

Companies. These new buses featured three doors for quick loading and unloading for the Rapid 

BRT service, which started in June 2003 with the San Pablo Rapid service. 

At the end of 2001, AC Transit started discussions with ISE Corp. about developing a new fuel 

cell bus design. In April 2002, negotiations were started for a sole source contract with ISE 

Corp. and UTC Power with plans to use the same Van Hool bus chassis as was used for the 

diesel buses; however, this project stalled during most of 2002. After a major meeting of the 

project partners coinciding with an American Public Transportation Association (APTA) 

meeting in Las Vegas in September 2002, the project was re-energized. The contract for the new 

fuel cell buses was revised in April 2003, and the project was back on track. This order included 

three new Van Hool fuel cell buses for AC Transit and one new Van Hool fuel cell bus for 

SunLine. Rather than using a standard diesel chassis, as was originally planned, Van Hool 

designed and constructed an entirely new chassis (based on the existing A330 bus design) that 

could more effectively accommodate fuel cell and hybrid system components. 

 9
This new contract had several changes and the delays now required that the CARB deadline for 

demonstrating fuel cell buses be postponed. The first fuel cell bus was delivered to AC Transit 

in October 2005, and the other two AC Transit buses arrived in December 2005. The on-site 

hydrogen fueling station from Chevron was commissioned on March 13, 2006, and the three fuel 

cell buses went into service on March 20, 2006. 

The HyRoad – Once the fuel cell buses were on order and being manufactured, AC Transit got 

to work putting together its hydrogen future and vision for its hydrogen fuel cell program. This 

comprehensive fuel cell program (HyRoad) aims to demonstrate the viability of an emission-free 

transit system and features: 

• Three zero-emission hybrid-electric, hydrogen fuel cell buses 

• A fleet of fuel cell passenger vehicles (part of DOE’s Controlled Hydrogen Fleet and 

Infrastructure Demonstration and Validation Project) 

• On-site hydrogen production and fueling 

• On-site fleet maintenance 

• Ongoing, outside evaluation (this report and future reports) 

• Public education and safety training 

The partners for the fuel cell bus program at AC Transit include: 

• Van Hool Bus – manufacturer of the bus bodies and chassis 

• UTC Power of Connecticut – maker of the fuel cell power systems 

• ISE Corporation of San Diego – integrator of the fuel cell power systems and hybridelectric drive systems 

• Chevron Technology Ventures (a division of Chevron USA) – builder of the hydrogen 

fueling station at AC Transit’s East Oakland Division 

Funding for this project included more than $21 million from public agencies and private sector 

companies, as follows: 

• State of California – $8 million 

• CARB – $2.8 million 

• Bay Area Air Quality Management District (BAAQMD) – $1 million 

• Federal Transit Administration – $1 million 

• California Energy Commission – $1 million 

• DOE – $700,000 plus partial funding for the hydrogen station construction and operating 

expenses 

• AC Transit matching funds – $1.2 million 

• CALSTART-WestStart – $200,000 

• Chevron Technology Ventures – $2 million (matching funds) plus additional funding for 

capital and operating expenses 

• Miscellaneous contributions of more than $3 million 

 10
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. As a diesel-path fleet, AC Transit had no 

prior experience with gaseous fuels. Joining the CaFCP provided an opportunity for the fleet to 

accelerate the learning curve and gain valuable hydrogen fuel experience before the FCBs were 

delivered. AC Transit’s first hydrogen-related project was in partnership with the CaFCP and 

Stuart Energy Systems (now Hydrogenics) to install an electrolyzer at the Richmond Division. 

This station was mainly intended as a satellite station for light-duty fuel cell vehicles (FCVs) 

being tested by the automotive partners of the CaFCP. This location, between Sacramento and 

San Francisco, was ideal to enable FCVs to travel between the two cities. In addition to the 

light-duty FCVs, AC Transit also used this station to fill the ThunderPower FCB during its 

demonstration. 

Richmond Station 

The station at the Richmond division produces hydrogen through the electrolysis of water. The 

electrolyzer is capable of producing up to 24 kg of hydrogen each day. The station was equipped 

with storage vessels that hold 47 kg. As many as 5 FCVs can be fueled to settled pressures 

between 3,600 and 5,000 psi in about 8 minutes. The station can be used to fuel buses; however, 

the storage capacity is not currently large enough for more than one bus to be operated from this 

site. The electrolyzer and dispenser are pictured in Figure 4. 

Figure 4. Electrolyzer (left) and dispenser (right) at Richmond Division

Oakland Energy Station2

AC Transit selected the East Oakland Division as the site for demonstrating its fleet of FCBs. 

This was due to its location in a light industrial area and because space was available for the 

added fueling infrastructure. AC Transit operates over 200 vehicles from this division, including 

 

2

 Information on the Chevron-AC Transit Hydrogen Energy Station was provided in part by Chevron Technology 

Ventures, a division of Chevron USA. 

 11
the 3 FCBs, 21 40-ft diesel Van Hool buses, 41 paratransit shuttles, and 6 UC Berkeley vans. Of 

the buses at the site, 138 are required for peak service. 

In March 2004, AC Transit joined in partnership with Chevron Technology Ventures to design 

and build a hydrogen energy station at the East Oakland Division. Plans for a station were 

already in process as part of the DOE light-duty FCV demonstration. Chevron leads one of the 

teams that is demonstrating FCVs and hydrogen infrastructure for the DOE project. AC Transit 

serves as one of the demonstration sites, operating a small fleet of Hyundai/Kia FCVs. 

As the FCB demonstration plans began to solidify, the project partners decided it would be cost 

effective to combine the needs for both demonstrations into one station. Construction on the 

station began in June 2005 and was completed by November. The station was operational by 

mid-December. On March 13, 2006, AC Transit and local officials formally inaugurated the 

Chevron - AC Transit Hydrogen Energy Station, kicking-off the demonstration project. All of 

the HyRoad project partners participated in the event, which included facility tours and a ribboncutting ceremony. 

Figure 5 illustrates the overall station layout. The energy station at the East Oakland Division 

generates hydrogen through steam methane reformation in a 3-step process: 

1. Hydrogen generation – Natural gas from a utility line is fed to a steam methane 

reformer that produces a hydrogen-rich output gas. This output gas, called reformate, is 

typically composed of 75% hydrogen and 20% carbon dioxide and other trace gases. 

2. Reformate compression – Hydrogen-rich reformate is compressed to approximately 125 

psi, as required for the purification step. 

3. Purification – A pressure swing absorption unit purifies the reformate stream to 99.99% 

hydrogen, which is acceptable for use in PEM fuel cells. Excess gas is returned to the 

reformer for combustion. 

The station design includes two reformers that are capable of producing a total of 150 kg 

hydrogen per day. One of the reformers is a standard design (Figure 6) and produces hydrogen 

through the 3-step process outlined above. This reformer is intended to be the primary 

production reformer for hydrogen at the station. 

Chevron is using the second reformer, which is an advanced technology design, to investigate 

ways to further refine production methods and increase efficiency. For that second reformer, 

steps 1 and 2 are reversed: the natural gas is compressed to about 150 psi, and the reformer then 

generates hydrogen at the higher pressure. An advantage of this is that compressing natural gas 

takes less energy than compressing the hydrogen-rich reformate stream. Producing a reformer 

capable of operating at the higher pressure, however, will potentially increase the cost of that 

equipment. This may be offset by the reduced cost for the natural gas vs. reformate compressor. 

The demonstration will help Chevron determine the trade-offs between the increased efficiency 

of compressing natural gas and the change in equipment cost. 

 12
Figure courtesy of Chevron Technology Ventures

Figure 5. Chevron – AC Transit (Oakland) Hydrogen Energy Station overall layout Photo courtesy of Chevron Technology Ventures

Figure 6. Reformer train #1 at Chevron – AC Transit Hydrogen Energy Station (75 kg/day) 

The purified hydrogen is then compressed to 6,250 psi and stored in a series of cascade pressure 

vessels (Figure 7). Total storage capacity at the station is 366 kg of hydrogen. The station is 

equipped with two dispensers that supply the compressed hydrogen to the buses and light-duty 

vehicles. The system connections monitor the tank-fill status and provide an appropriate fill at 

5,000 psi. The dispensing system is designed to enable simultaneous fills for two buses (or lightduty fuel cell vehicles). Figure 8 shows the hydrogen fueling dispensers at the station. AC 

Transit’s agreement with Chevron includes all operation and maintenance of the station for two 

years. Chevron technicians are also responsible for fueling the buses. AC Transit will assume 

fueling responsibility by mid-2007. 

 13
Photo courtesy of Chevron Technology Ventures

Figure 7. Cascade hydrogen storage vessels at AC Transit station Photo courtesy of Chevron Technology Ventures

Figure 8. One of two dispensers at the Chevron – AC Transit Hydrogen Energy Station

 14
The design of the station includes various safety devices to alert AC Transit and Chevron of any 

potential problems. These devices include hydrogen detectors, flame sensors, emergency stop 

buttons, and alarm indicator lights (Figure 9). The alarm indicators reflect the condition of the 

station as follows: 

• Green light – normal operating conditions 

• Yellow light – a problem is occurring or has occurred 

• Red light – hazardous condition exists, evacuation from area required 

• Strobe and siren – fire condition, fire department notified 

Early Experience with Hydrogen Fueling – AC Transit reports a relatively smooth process for 

permitting the hydrogen station in Oakland. The experience gained from the Richmond station 

gave them a good knowledge base of what was needed. The agency took a proactive approach to 

the process for permitting the new station in Oakland; this process began in early 2003. Agency 

representatives held an initial meeting with the local fire marshal to give an overview of the 

HyRoad program. They also prepared a flyer describing the project and hydrogen station plans, 

which was shared with the local community as a direct mail piece sent to more than 8,500 

residences and businesses within a quarter mile of the station. Several town hall meetings were 

held and AC Transit staff gave numerous presentations to community and civic groups. Because 

of the considerable work accomplished to educate the public and local officials early in the 

process, AC Transit reported no opposition to the station. This was considered an early success 

for the program, especially since this process has proven to be a major challenge for some other 

fuel cell and hydrogen demonstrations around the world. 

Even with the relative ease of permitting, the buses began to arrive before the station was 

operational. During the two-month lag time, the fleet used an on-site tube trailer to fuel the 

buses. The station was fully operational on December 2, 2005. During the initial period of use, 

Chevron held the fueling rate to that recommended for the light-duty FCVs. Because of this, bus 

fuelings sometimes took more than 2 hours. As Chevron developed data on the temperature rise 

during fueling of the buses, which have approximately ten times the on-board hydrogen volume 

compared to a light-duty FCV, the rate was increased. The buses can now be fueled in under 15 

minutes. 

As can be expected with any high pressure system that contains a small molecule such as 

hydrogen, there have been a small number of leaks in piping and process systems, but no safety 

incidents. The integrated safety system was designed to detect leaks and take the appropriate 

action. The safety systems have been functioning as designed. 

 15
Figure 9. Condition indicator lights (left) and hydrogen flame sensor (right) 

at the Chevron – AC Transit Hydrogen Energy Station

Maintenance Facility Modifications 

AC Transit chose to modify an existing facility to enable staff to safely maintain the hydrogenfueled buses. The required modifications (~$1.5 million) were completed and the bay was 

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

facility by a firewall. There is space for maintaining two buses simultaneously. Figure 10 shows 

the modified maintenance bay. Safety features include: 

• Hydrogen leak and fire detection (thermal) systems 

• Two-hour firewall 

• Ignition-free space heating system 

• Anti-static, non-skid, grounded floor covering 

• High Speed roll-up doors 

• Magnetic door release 

• Audiovisual strobe alarms 

• Three-fan ventilation system capable of providing up to four to six air exchanges per hour 

• Class 1 Division 2 electrical classification 

 16
Figure 10. Modified maintenance bay at AC Transit

The detection system in the maintenance bay is configured to trigger specific actions if a leak or 

fire is detected. At 20% lower flammability limit (LFL), the garage doors automatically open, 

ventilation fans are turned on, the heating system is shut down, and the magnetic doors release. 

If a leak is detected at 40% LFL or a fire is detected, the fire department is automatically 

notified, all electrical power to the bay is disconnected (except for ventilation and emergency 

equipment), and a fire alarm is activated to signal evacuation of the building. These safety 

measures are all in place to ensure maximum protection for staff and facilities in case of a 

hydrogen-related incident. None have been recorded to date. 

Because the specially equipped maintenance bay is co-located with the rest of the maintenance 

building, maintenance staff are 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. This decision to lower the fuel pressure in the vehicle was made early in the design 

process to reduce the overall cost of the facility modifications. The safety requirements for a 

facility capable of maintaining buses with full hydrogen tanks are more costly. Although 

capturing the vented hydrogen for future use is possible, early investigation showed it was not 

cost-effective using available methods. For a fleet of only three buses, the amount of hydrogen 

vented was deemed not significant enough to warrant the cost of the equipment to capture and 

reuse the fuel. 

 17
Early Experience with Maintenance Facility – AC Transit reports that modifications and startup of the maintenance bay for the FCBs went relatively smoothly, with only a few challenges. 

The biggest issue was timing for the bay to be completed and certified by inspectors for fleet use. 

As with the infrastructure, the maintenance bay was not cleared for use by the time the FCBs 

began to arrive. The first bus was delivered in October 2005, but the bay did not get approval for 

use until January 2006. During this gap, maintenance workers had to do repairs or service prep 

on the buses outside. This resulted in some discomfort for the workers from winter weather 

conditions. 

AC Transit experienced some early issues in operation of the new bus lift system in the 

maintenance facility. At one point, one of the fuel cell buses was stuck up on the lift system and 

missed pull out. This problem has been corrected through documented operating procedures and 

experience. 

Hydrogen Fuel Dispensing Analysis – The buses were officially put into service in late March 

2006. Figure 11 shows the monthly amounts of fuel consumed by the three buses since the 

station was opened. During the early months, the buses were used on a limited basis for testing 

and training. Once service began, the hydrogen use increased, as expected. From April through 

November 2006, the station dispensed over 4,500 kg of hydrogen into the three buses. Figure 12 

shows the average daily hydrogen consumed by the buses. The overall average for the 

evaluation period is 33.3 kg per day (for days that hydrogen was dispensed into buses). 

0

100

200

300

400

500

600

700

800

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

Hydrogen (kg)

Figure 11. Total hydrogen consumption for the FCBs by month 

Figure 13 shows a histogram of the fueling rates during the evaluation period (April – November 

2006). Since the buses went into service, the hydrogen station provided 215 bus fueling events, 

with an overall average fill of 21.8 kg. The fueling rate has ranged between 0.08 and 3.01 kg per 

 18
minute with an average of 1.35 kg per minute. On average, it takes approximately 16 minutes to 

fuel a bus. 

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

Apr-06 May-06 Jun-06 Jul-06 Aug-06 Sep-06 Oct-06 Nov-06

H2 Amount (kg) / Day

Figure 12. Average hydrogen use per day for the FCBs 

Figure 13. Fueling rate histogram for the AC Transit Hydrogen Energy Station

 19
Fuel Cell and Diesel Buses 

Table 2 provides bus system descriptions for the fuel cell and diesel buses that were studied in 

this evaluation. AC Transit unveiled its hydrogen fuel station and hydrogen fuel cell buses on 

March 13, 2006. The buses started in passenger service on March 20, 2006. The purchase, 

manufacturing, and packaging of the Van Hool fuel cell buses took about two years and cost 

approximately $3.2 million each. 

The Van Hool diesel buses were ordered in 2002, with delivery in 2003 and 2004. For this 

evaluation, six of the diesel Van Hool buses were selected from the 21 buses of that type 

operating from the East Oakland Division. These six diesel buses are operated along side the 

fuel cell buses. The diesel buses cost $323,000 each. 

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 2. 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 

PureMotionTM 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 

 Rated Torque 220 Nm 860 lb-ft @ 1600 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 3 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. 

 20
Table 3. 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 

Fuel Cell Bus Propulsion System Description 

The prototype fuel cell buses in service at AC Transit are the result of a collaboration between 

ISE Corporation (www.isecorp.com), UTC Power (www.utcpower.com), and Van Hool 

(www.abc-companies.com/sales_vh.htm). The buses use the PureMotion 120 Fuel Cell Power 

System manufactured by UTC Power in a hybrid electric drive system designed by ISE. Van 

Hool redesigned the A330 transit bus chassis to integrate the fuel cell and hybrid systems. The 

buses have a low floor from front to back and three doors for easy passenger boarding. 

ISE’s hybrid system (shown in Figure 14) is a series configuration, meaning the fuel cell power 

system is not mechanically coupled to the drive axle. The fuel cell power system and energy 

storage system work together to provide power to two electric drive motors, which are coupled to 

the driveline through a combining gearbox. When the bus needs extra power, the fuel cell power 

system and energy storage provide power to the drive motors. When the power requirements of 

the bus are low, the fuel cell power system provides power and recharges the energy storage 

system. 

The hybrid system is also capable of regenerative braking, which captures the energy typically 

expended during braking and uses it to recharge the energy storage system. Each component of 

the propulsion system is carefully controlled through an ISE-developed operating system. 

ISE designed the system to be flexible. Depending on a client’s needs, a variety of powerplants 

and energy storage options can be integrated into the system. The buses at AC Transit have a 

fuel cell power system and three ZEBRA (sodium/nickel chloride) batteries (www.betard.co.uk/) 

as the energy storage system. 

The powerplant, which is the primary power source for the hybrid system is UTC Power’s 

PureMotion 120 Fuel Cell Power System, which produces 120 kW from its proton exchange 

membrane (PEM) fuel cell stacks. UTC Power’s fuel cells operate at near-ambient pressure, 

which eliminates the need for a compressor. This not only increases the efficiency of the system, 

but results in very quiet operation as well. 

 21
Figure 14. ISE’s hybrid propulsion system 

Early Bus Experience 

The diesel Van Hool 40-foot buses were delivered to AC Transit during 2003 and 2004. There 

have been a few issues and campaigns so far: 

1. Steering tie rod sleeve and steering defect 

2. Seat retrofit 

3. Wheelchair control cabinet change 

The buses have a shorter wheelbase compared to the older, existing bus fleet at AC Transit. This 

has proved to be the biggest issue with the diesel Van Hool buses. Drivers not used to the short 

wheelbase have damaged the rear corner of the bus body by hitting things close to the curb on 

the street and in the parking lots. As the drivers gained experience with the buses, this problem 

has essentially been eliminated. 

The first fuel cell bus was delivered in October 2005 and the other two fuel cell buses were 

delivered in December 2005. AC Transit had to add specific equipment to the buses, such as the 

Satcom system, fareboxes, and radios. Before the buses went into service on March 20, 2006, 

the mechanics and drivers were trained on the general characteristics of hydrogen, hydrogen 

safety, and fuel cell bus operation. AC Transit mechanics received more detailed training on 

system troubleshooting. The fleet also trained several groups of emergency and first responders 

during this time. 

Both ISE and UTC Power have on-site technical support available to AC Transit for warranty 

support of the fuel cell buses, and AC Transit reports that this support has been excellent. AC 

Transit is responsible for bus maintenance and UTC Power and ISE are responsible for the 

propulsion and drive system. The parts for the fuel cell power systems have been provided to 

 22
AC Transit through the UTC Power technician on an as-needed basis. This has not caused any 

significant delays in maintaining the buses. UTC Power has converted its fuel cell power system 

operating-hour based preventive maintenance schedule to miles, and in the AC Transit operation, 

this has translated into 3,000-mile intervals. The fuel cell power systems reportedly use 

significant amounts of de-ionized water. The main issues with the ISE drive system have been 

with belts; parts have been readily available. 

Some minor operational issues have arisen with the fuel cell buses: 

1. The fuel cell buses are significantly taller than the diesel bus fleet. This has caused a 

need to keep up with tree trimming on routes where the fuel cell buses are operated. 

2. Several roadcalls have been reported due to the fuel cell buses stalling on the road. These 

issues were the result of the driver not starting the fuel cell power system before 

operating the bus, mainly a factor of the quiet nature of UTC Power’s fuel cell power 

system and the fact that there are no audible indicators that the fuel cell is powered on. 

This would eventually cause the onboard traction batteries to run down, followed by bus 

shut down. A software change has addressed this issue. Now, when the bus senses the 

traction battery pack at 30% state of charge (SOC), it automatically starts up the fuel cell 

power system on its own. 

3. Non-propulsion-related issues on the fuel cell buses included securing wiring clamps and 

changing cable routing, and making some minor changes to the operation of the bus 

heating system. 

There have been a few significant issues with the fuel cell buses: 

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

The main challenges have been accommodating cell failures and optimizing the SOC 

algorithm. A cell failure in this serial string causes a short that decreases the overall 

voltage of a pack (in the group of three packs). The battery failures have been caused by 

several issues; including internal short circuits, internal isolation faults, and thermal 

isolation faults. Because these batteries operate at about 260° C, it has also been difficult 

to make sure that a spare battery is available and up to operating temperature for efficient 

replacement of another battery in the set of three batteries. This issue has led to 

significant down-time for the bus. ISE Corp. is working to better optimize the control 

software to alleviate this issue. 

2. Air conditioning – This hybrid design is unique because the air conditioning unit is 

driven electrically instead of mechanically (by belt) like most vehicles. In this 

application, the system has experienced problems with failed evaporator and condenser 

motors. Several changes and upgrades have been attempted, and the problem seems to be 

resolved. 

3. UTC Power PureMotion 120 Fuel Cell Power System – UTC Power monitors the 

performance of the fuel cell power system remotely to analyze actual performance vs. 

predicted performance. In June 2006, UTC Power observed that the cell stack assembly 

 23
(CSA) performance was decaying at high current densities at rates that were beyond what 

was predicted and required for a minimum 4,000-hour fuel cell life. 

This problem was first observed in the SunLine fuel cell bus, because it had the highest 

number of miles and hours accumulated. On June 30, 2006, the fuel cell power system in 

the SunLine bus (the unit had approximately 1,140 hours) was removed from the bus and 

sent to UTC Power in Connecticut for advanced testing that could not be accomplished in 

the field. To minimize down time, the SunLine bus was retrofitted with a spare, 

developmental UTC Power fuel cell power system on July 6, 2006. 

During testing, it became apparent to UTC Power that the problem was with the CSAs 

and not a boundary condition issue (such as bad fuel). An engineering investigation 

determined that contaminants were released from a CSA material due to a supplier 

quality control problem with that material, which resulted in decayed performance. It 

should be noted that the issue was performance-related only and did not pose any safety 

issues, nor was there a failure of the CSAs. 

 

As part of UTC Power’s ongoing development, UTC Power has incorporated corrective 

action into the CSAs, thus eliminating this condition for all builds. On September 25, 

2006, the spare fuel cell power system was removed from the SunLine bus and replaced 

with a new fuel cell power system that incorporated the new CSA design. 

On September 21, 2006, the fuel cell power system in AC Transit FCB2 was removed 

and sent back to Connecticut for refurbishing and upgrading. The developmental UTC 

Power fuel cell power system was brought from SunLine to AC Transit and installed into 

FCB2. The installation of the fuel cell power system was completed in approximately 10 

hours and FCB2 went back into service on October 19, 2006. 

On November 27, 2006, the fuel cell power system in AC Transit FCB3 was removed 

and returned to UTC Power in Connecticut. The first refurbished and upgraded fuel cell 

power system was received at AC Transit and installed into FCB3 on January 2, 2007. 

The entire upgrade process should be completed by the end of the first quarter of 2007. 

As the upgraded fuel cell power systems are installed into the AC Transit buses, there is a 

desire to maximize/accelerate the use of the fuel cell buses. This accelerated testing is 

currently limited due to issues with the ZEBRA battery pack failures and charging the 

batteries up to a nearly full SOC overnight in time for the next day’s service. Until the 

charging regime issue can be resolved, the bus cannot meet the desired 14-16 hours of 

operation on a regular/daily basis. AC Transit is in the process of upgrading electrical 

service to the maintenance building at East Oakland so that more battery charging 

capacity can be added. 

The drivers of the fuel cell buses have been excited about and reportedly really like the buses; 

however, they have expressed some nervousness with potentially “hurting” the new buses. The 

buses offer smooth, quiet driving and comfortable driver seats with good access to controls. 

There have also been some concerns about hydrogen safety. 

 24
Training and Public Awareness 

AC Transit is taking a proactive stance in its training program. Since the start of the program, 

the fleet has provided hydrogen familiarization training to approximately 1,500 of its 2,300 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 Golden Gate Transit has been learning light diagnostics and 

preventative maintenance for the FCB powertrain. 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 for local fire fighters and emergency responders. A quick reference card was produced 

for emergency responders showing the locations of specific equipment and places where it would 

be dangerous to cut into the bus. 

AC Transit has produced several training videos for its staff, emergency responders, and the 

general public. Videos produced include: 

• Employee Training Video: In this short video (< 5 minutes), employees are provided 

with basic information on the characteristics and safety aspects of hydrogen gas as well 

as the benefits of using the fuel for transit. 

• First-Responder Safety: To facilitate training for a large number of first responders, AC 

Transit filmed an initial training session for Oakland firefighters. The video includes a 

classroom portion that outlines the general characteristics of hydrogen and related safety 

concerns and provides instruction for emergency responders should an incident occur 

with a fuel cell bus or the hydrogen facility. This portion also includes a question and 

answer period. The second part of the video provides a walk-through of the hydrogen 

fuel production and dispensing facility, the maintenance bay, and the fuel cell bus. 

Representatives from Chevron, ISE Corp., and Schatz Energy Research Center describe 

all safety devices, including locations and instructions on how to safely shut-down and 

disable electric power and fuel lines in case of emergency. 

• AC Transit Grand Opening, March 13, 2006: The video of the grand opening 

ceremony for the Chevron – AC Transit Energy Station at AC Transit’s Seminary 

Division provides a comprehensive outline of the HyRoad program. 

Raising public awareness for hydrogen and fuel cell technology is extremely important to AC 

Transit. Thousands of transit riders have been introduced to the fuel cell buses in daily service 

since March 2006 when the buses began service. The buses serve as mobile learning centers 

through on-board exhibits describing various aspects of the technology, such as the buses’ 

systems and how fuel cells work. AC Transit is also working in partnership with Lawrence Hall 

of Science at UC Berkeley and Schatz Energy Research Center at Humboldt State University to 

develop a 10-week science education curriculum for high schools around the country. The 

Hydrogen Technology and Education Curriculum (HyTEC) was funded in part by DOE to 

develop, test, and disseminate hydrogen and fuel cell curricula for high school students. AC 

 25
Transit is funding the implementation of this curriculum over the next two years in East Bay high 

schools served by AC Transit. The materials include hands-on kits to generate hydrogen from 

electrolysis, working fuel cells, and test equipment to measure results and efficiencies. Also 

included with the teaching materials are two videos. The first is a two-minute introductory film, 

and the second is an eight-minute piece that describes various applications and associated 

challenges. 

AC Transit receives frequent requests for tours from various individuals and groups. Staff 

accommodates these requests and brings the buses to outside events as time and resources allow. 

From January through November 2006, AC Transit estimates it reached a potential of over 

220,000 people through various events and tours. Table 4 summarizes those events by category. 

Table 4. Public Awareness Events by Category 

Event Category Number of 

Events 

Number of 

People 

Academic 6 2,284 

General Public 26 224,536 

Industry 4 7 

International 9 41 

Government 6 109 

Partner Event 3 360 

Total 54 227,337 

Such events, tours, and presentations include: 

• September 2005: AC Transit participated in the APTA Annual Meeting and Expo in 

Dallas, Texas. The fuel cell bus was officially unveiled to the transit industry at a press 

conference on the floor of the Dallas Convention Center. Other activities during the event 

included a fuel cell bus for static display as well as a fully functional bus for 

demonstration rides. The bus carried approximately 100 to 200 people over the course of 

three days on short trips around the Dallas Convention Center. 

• November 2005: AC Transit held training sessions for various fire battalions. 

• February 2006: AC Transit provided tours of the bus and facilities to the president of 

Protium Energy Technologies; French parliamentarians; and representatives from PG&E, 

the U.S. Fuel Cell Council, and the Science Club from St. Elizabeth School. 

• March 2006: AC Transit and Chevron held a grand opening event for the hydrogen 

station. Approximately 300 attendees participated in the event, which included 

presentations and remarks from all the demonstration project partners. Also during the 

month, AC Transit hosted tours of the hydrogen facility and fuel cell bus to six 

representatives from Tsinghua University (China), representatives from the Oakland 

Mayor’s office, an FTA representative, and about 50 science students from Martin Luther 

King Middle School in Berkeley. 

• April 2006: AC Transit participated in several off-site events including the 

Transportation and Land Use Choices Annual Summit, the City of Oakland's Earth Day 

Celebration, Lawrence Hall of Science's Earth Week Celebration, the El Cerrito Earth 

Week Celebration, a press event for the Transportation and Land Use Coalition, and an 

 26
event for UTC Power at the San Francisco Ritz Carlton Hotel. Also during the month, 

AC Transit provided tours of the fuel cell bus and facilities to representatives from DOE 

and the Korea Automotive Technology Institute. 

• May 2006: AC Transit provided a fuel cell bus for Oakland’s Bike to Work Day, the 

Capitol Bike Fest and Cal/EPA Transportation Fair at State Capitol Park, and a Spare the 

Air Kick-off Media Event at Great Lawn, Treasure Island. Tours of the AC Transit 

facility and fuel cell bus were provided for delegations from Japan and the China 

Academy of Urban Planning and Design. 

• June 2006: A fuel cell bus was provided for two Get on the Bus events, sponsored by 

City Space, the Juneteenth Parade in Richmond, California, and the Water Keepers 

Conference at San Francisco State. Tours of the fuel cell bus and facility were provided 

to a Chinese delegation from the China Academy of Urban Planning and Design and a 

group of visitors from Evobus. 

• July 2006: AC Transit provided a fuel cell bus for several area events including the 

Fremont City 4th of July Parade, the Piedmont City 4th of July Parade, the Alameda 

Mayor's 4th of July Parade, and the AAA Greenlight Rally from Santa Clara to Concord 

to Sacramento. The combined attendance at these events was estimated at over 42,000. 

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

several professors from Kent State University, Ohio, and a representative from the 

California Air Resources Board. A fuel cell bus participated in several events including 

the Alameda County's Road to Sustainability Event and the Festival of India Parade. AC 

Transit also operated a fuel cell mini bus in the Sistahs Steppin in the Oakland Gay Pride 

Parade. 

• September 2006: AC Transit provided a fuel cell bus and car for a meeting of the 

Newark Optimist Club, the Solano Stroll Parade, the Newark City Parade, and the Bay 

Area Healthy Neighborhood event. AC Transit hosted tours of the hydrogen station and 

fuel cell bus to representatives from the Oakland Tribune, the East Bay Business Times, 

and a representative from the Japanese Automotive Research Institute. 

• October 2006: AC Transit provided a fuel cell bus and car for the UC Berkeley 

Lawrence Hall of Science October Fair, a Columbus Club event, a Central County Policy 

Advisory Committee event at Hayward City Hall, and an event in San Francisco with 

State Senator Don Perata, U.S. Senator Diane Feinstein, and local Bay Area officials. AC 

Transit also provided a road demonstration of the fuel cell bus for Chevron’s 

Environmental Awards Program. 

• November 2006: AC Transit hosted tours of the facility and fuel cell bus to two 

representatives from the Beijing Non-Ferrous Metal Research Institute and a group from 

the South Carolina Hydrogen and Fuel Cell Alliance. AC Transit also hosted a visit by 

representatives of Weekend Weather TV, a local adolescent-run, Web-based news 

program. Off-site events included the Get on the Bus!-ES 24 Freshman Seminar at UC 

Berkeley on Transportation and Sustainability. Approximately 25 students participated 

in the seminar, which was held on the bus. 

 27
Evaluation Results 

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

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

revenue service on March 20, 2006, but the March 2006 data has 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. 

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

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

buses were done to 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). 

Route Descriptions 

Overall, AC Transit operates 105 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 for two eight-hour blocks on two routes 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 fleet 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. 

As mentioned above, 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. 

During this same timeframe, two of the diesel baseline buses were operated on two special 

blocks of work on Route 57 (40th Street). Starting June 20, 2006 through the end of the 

evaluation period (November 30, 2006), 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. 

 28
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 

Originally, the fuel cell and diesel baseline buses should have switched to the next set of test 

blocks of work around the end of September 2006. This was delayed because of delays in 

overall route changes at AC Transit. Currently, the next major service change at AC Transit has 

most likely been delayed until at least March 2007, and maybe as late as May 2007. 

In the meantime, there are plans to switch the diesel buses back to the two blocks of work on 

Route 57 starting in January 2007. This has been planned so that fuel economy data can be 

collected. During the three months that the diesel baseline buses were originally on the Route 57 

blocks, the diesel fuel data collection system at the depot was not operating properly and the fuel 

economy data was lost. 

At the same time, there is a desire to increase the amount of work that the fuel cell buses are 

assigned to accomplish, as discussed above in the Early Bus Experience section. AC Transit 

intends to create three 13- to 14-hour blocks of work for each of the three fuel cell buses. 

Starting in late January 2007, current planning involves having all three fuel cell buses on several 

existing routes operating out of its division, including Route 50. Although there is a desire to 

maximize the operation of the fuel cell buses, they need to be back at the division so that the 

batteries can be properly charged before starting service the next day. 

When AC Transit makes its next service change (sometime between March and May 2007), 

there are plans for six special blocks of work on two new routes (the newly created Route 18 and 

Route 51). There will be two blocks of work per weekday for each of the three fuel cell buses 

and for three of the six diesel baseline buses. There are also plans to try a new regime of 

switching the diesel and fuel cell buses each week instead of every three months. 

Bus Use and Availability 

Bus use and availability are indicators of reliability. The lack of bus usage may be an indication 

of 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 15 shows mileage and fuel cell power system operating hour accumulation from the start 

of testing at AC Transit in October 2005 through November 2006. 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. Other 

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

hydrogen fueling. 

 29
0

5000

10000

15000

20000

25000

30000

35000

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

Total Miles

0

500

1000

1500

2000

2500

3000

3500

Total FC System Hours

Total Miles FC System Hours

Figure 15. Cumulative mileage and fuel cell system hours for all three fuel cell buses 

Table 6 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 33,000 

miles. For the evaluation period (eight months), the fuel cell buses have accumulated 27,065 

miles and 2,338 fuel cell power system hours. The diesel buses operated a monthly average of 

2,141 miles each as compared to the fuel cell buses, which operated a monthly average of 1,128 

miles each. This indicates that the fuel cell buses operated just over half (53%) the miles that the 

diesel buses did in the same period. The fuel cell buses were controlled to only weekdays and 

one eight-hour shift per weekday. The diesel buses were used in typical service up to seven days 

per week and 16-20 hours per day. There is some indication that the study diesel buses were not 

used as much as typical diesel buses at the division. This will be investigated further in the next 

evaluation report. 

For the fuel cell buses, the average operating speed during the evaluation period was 11.6 mph. 

Figure 16 shows the average monthly operating speed for the fuel cell buses during the 

evaluation period. At the beginning of the evaluation period, the average speed was around 12-

13 mph, which is slightly lower than the average operating speed (shown above, 16 mph) for the 

special route blocks on Route 50. During the rest of the evaluation period, the fuel cell buses 

operated on Route 57 with a planned average speed of 11.3 mph. The actual average speed data 

from July through November 2006 was slightly lower at 10.7 mph. In both cases, the actual 

operating speeds were slightly lower than the planned operation average speed. This was caused 

by additional operation of the fuel cell buses during start-up inspection; events where the fuel 

 30
cell system is operating, but the bus does not move (or moves very little for demonstrations); and 

operation for testing and troubleshooting. 

Table 6. Average Monthly Mileage (Evaluation Period) 

Bus Starting 

Hubodometer 

Ending 

Hubodometer 

Total 

Mileage Months Monthly Average Mileage 

Fuel Cell 

System Hours 

FC1 5,164 15,032 9,868 8 1,234 N/A 

FC2 778 9,666 8,888 8 1,111 N/A 

FC3 3,153 11,192 8,309 8 1,039 N/A 

Fuel Cell 27,065 24 1,128 2,338 

1043 91,534 108,222 16,688 8 2,086 N/A 

1044 108,346 127,965 19,619 8 2,452 N/A 

1045 125,972 139,105 13,133 8 1,642 N/A 

1046 125,685 144,583 18,898 8 2,362 N/A 

1047 108,336 125,361 17,025 8 2,128 N/A 

1048 94,092 111,484 17,392 8 2,172 N/A 

Diesel 102,755 48 2,141 N/A 

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

Apr-06 May-06 Jun-06 Jul-06 Aug-06 Sep-06 Oct-06 Nov-06

Average Speed (mph)

Figure 16. Fuel cell bus monthly average speed (evaluation period) 

Figure 17 shows the planned monthly mileage for the fuel cell buses and the actual monthly 

mileage accumulation. The fuel cell buses operated at a mileage level within 80% of the planned 

mileage except for September and November 2006. Fuel cell bus usage was low in September 

2006 due to ZEBRA battery issues and the lack of hydrogen fuel at the end of the month. FCB2 

had the fuel cell stack assemblies changed in October 2006, and had issues with the ZEBRA 

batteries in September and November 2006. FCB3 had issues with the ZEBRA batteries and had 

the fuel cell stack assemblies removed in November 2006, causing a significant reduction in bus 

usage. 

 31
0

1000

2000

3000

4000

5000

6000

Apr-06 May-06 Jun-06 Jul-06 Aug-06 Sep-06 Oct-06 Nov-06

Monthly Mileage

Actual Mileage Planned Service

Figure 17. Planned versus actual mileage for fuel cell buses 

Figure 18 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, as described above. Problems with the air 

conditioning on the three fuel cell buses were also worked on during September 2006. 

Table 7 provides a summary of the availability and unavailability reasons for each of the three 

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

77%. Issues that kept the fuel cell buses out of service included the fuel cell power system 

(26%), ZEBRA batteries (37%), air conditioning (3%), AC Transit maintenance (14%), event 

preparation (11%), and hydrogen fuel unavailability (9%). Note that FCB1 had the best 

availability and that FCB2 and FCB3 had significant unavailability due to the fuel cell stack 

assemblies being removed and replaced during the evaluation period. FCB3 was the designated 

event bus during most of the evaluation period, and the availability for events accounted for 18% 

and related cleaning accounted for 17% of unavailable days. 

 32
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

Availability (%)

Total/Average FCB1 FCB2 FCB3

Figure 18. Availability for all three fuel cell buses and overall average 

Table 7. Summary of Reasons for Availability and Unavailability of Buses for Service 

FCB1 FCB2 FCB3 Group Total Category Days % Days % Days % Days % 

Planned Work Days 172 172 177 521 

Days Available 152 88 118 69 130 73 400 77 

Available 152 100 118 100 130 100 400 100 

On Route 99 65 100 85 74 57 273 68 

Event/Demonstration 7 5 4 3 24 18 35 9 

No Driver Available 9 6 7 6 1 1 17 4 

Training 11 7 3 3 5 4 19 5 

Not Used 26 17 4 3 26 20 56 14 

Unavailable 20 100 54 100 47 100 121 100 

Fuel Cell Propulsion 0 0 23 43 8 17 31 26 

ISE Propulsion 0 0 0 0 0 0 0 0 

ZEBRA Battery 4 20 23 42 17 36 44 37 

Air Conditioning 2 10 1 2 1 2 4 3 

AC Transit Maintenance 7 35 2 4 8 17 17 14 

Event Preparation 2 10 4 7 8 17 14 11 

Fueling Unavailable 5 25 1 2 5 11 11 9 

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 up to 5,000 psi for the three fuel cell transit buses 

and for light-duty FCVs. During the evaluation period, Chevron employees provided all fueling 

services for the hydrogen-fueled vehicles and electronically reported the fueling amounts. 

 33
Table 8 shows hydrogen fuel consumption and fuel economy for the three fuel cell buses during 

the evaluation period. Overall, the three fuel cell buses averaged 5.50 miles per kg of hydrogen, 

which equates to 6.22 miles per diesel gallon equivalent. The energy conversion from kg of 

hydrogen to diesel gallon equivalent is provided in the appendix. ISE also reported that the fuel 

cell buses had approximately 313 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 6% of the hydrogen dispensed into the fuel cell buses. If that fuel were 

removed from the fuel economy calculation, the result would be 5.88 miles per kg and 6.64 miles 

per diesel gallon equivalent (DGE). 

Table 8. Fuel Use and Economy (Evaluation Period) 

Bus Mileage 

(Fuel Base) Hydrogen (kg) Miles per kg 

Diesel Equivalent 

Amount (Gallon) 

Miles per 

Gallon 

FCB1 9,868 1,726.0 5.72 1,527.4 6.46 

FCB2 8,888 1,700.1 5.23 1,504.5 5.91 

FCB3 8,309 1.492.7 5.57 1,321.01 6.29 

FCB Total 27,065 4,918.7 5.50 4,352.9 6.22 

The diesel fuel consumption for the evaluation period is not available except for November 

2006, because the fuel tracking system was not working properly until late October 2006. For 

the month of November 2006, the six diesel baseline buses averaged 4.46 mpg, which indicates 

the fuel economy for the fuel cell buses is 39% higher than that of the diesel buses. AC Transit 

reports that the diesel bus fleet typically has an average fuel economy of approximately 4.00 

mpg. Using this number in the calculation, the fuel cell buses have a fuel economy 56% higher 

than the diesel buses. 

As mentioned earlier, there have been some key issues with the fuel cell buses that are in the 

process of being resolved. Figure 19 shows the average monthly fuel economy in both miles per 

kg and miles per diesel gallon equivalent. The chart shows a progression downward for the 

average fuel economy. Some of the fuel economy decrease, starting in June-July 2006, was 

caused by the fuel cell buses changing operating routes from an average speed around 16 mph 

down to 11.3 mph. The average fuel economy also decreased during summer operation because 

of increased air conditioning loading. However, the fuel economy continued down in the fall 

months as well. Once the UTC Power fuel cell power systems have been replaced and the buses 

are back in service, the fuel economy is expected to come back up. 

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. This cost for 

hydrogen fuel indicates a cost per mile for the fuel cell buses of $1.45. The average diesel fuel 

cost per gallon during the evaluation period is $2.30 per gallon. If the 4.00 mpg diesel average 

fuel economy is used, this indicates a $0.58 per mile cost. If the 4.46 mpg diesel average fuel 

economy is used, this indicates a $0.52 per mile cost. In either case, the diesel cost per mile is 

about one-third of the fuel cell bus fuel cost per mile. 

 34
0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

Apr-06 May-06 Jun-06 Jul-06 Aug-06 Sep-06 Oct-06 Nov-06

Miles per kg or DGE

Miles/kg Miles/DGE

Figure 19. Fuel cell bus monthly average fuel economy (evaluation period) 

Maintenance Analysis 

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

through November 2006). 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 is not reflective of 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 9 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 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. The AC Transit mechanics have only done 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. This will also be necessary based on the 

desired increase in operation of the fuel cell buses. 

 35
For the fuel cell buses, FCB2 has the lowest cost per mile and the other two have similar costs 

per mile. The AC Transit mechanics did start to participate on one of the preventive 

maintenance actions for FCB1 in September, with 48 hours of mechanic time charged, and for 

FCB3 in July, with 6 hours of mechanic time charged. FCB3 had some body damage repaired in 

August 2006, which significantly increased maintenance costs. The diesel buses had a few 

significant maintenance repairs, including two buses with turbocharger replacements and 

window replacements/repairs. 

Table 9. Total Maintenance Costs (Evaluation Period) 

Bus Mileage Parts ($) Labor 

Hours 

Cost per 

Mile ($) 

FCB1 9,868 1,837.01 98.8 0.69 

FCB2 8,888 98.64 69.4 0.40 

FCB3 8,309 2,192.00 72.2 0.70 

Total Fuel Cell 27,065 4,127.65 240.4 0.60 

Avg. per Bus 9,022 1,375.88 80.1 -- 

1043 16,688 3,137.64 89.2 0.46 

1044 19,619 2,911.93 55.9 0.29 

1045 13,133 1,729.76 66.9 0.39 

1046 18,898 3,564.22 64.2 0.36 

1047 17,025 2,470.96 84.2 0.39 

1048 17,392 831.93 70.9 0.25 

Total Diesel 102,755 14,646.47 431.3 0.35 

Avg. per Bus 17,126 2,441.08 71.9 -- 

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 47% lower than the diesel buses 

• Parts Costs – The fuel cell buses are 44% lower than the diesel buses 

• Labor Hours – The fuel cell buses are 11% higher than the diesel buses 

• Cost per Mile (without warranty costs) – The fuel cell buses are 71% higher than the 

diesel buses 

This reflects the fact that the fuel cell buses are in the prototype development stage for transit bus 

service. 

Maintenance Costs Broken Down by System—Table 10 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 

 36
• 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 

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

propulsion-related; PMI; and cab, body, and accessories. These three systems, along with the 

frame, steering, and suspension system, were also the highest maintenance cost systems for the 

diesel buses. The additional category of frame, steering, and suspension reflects the higher use 

of the older diesel buses compared to the fuel cell buses. 

Table 10. 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 0.38 63 0.11 31 

Propulsion-Related 0.06 10 0.12 34 

PMI 0.15 25 0.08 23 

Brakes 0.00 0 0.01 3 

Frame, Steering, and 

Suspension 0.00 0 0.02 6 

HVAC 0.00 0 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 3 

Tires 0.00 0 0.00 0 

Total 0.60 100 0.35 100 

 * Excludes warranty work costs 

The maintenance cost reported in the AC Transit system for the fuel cell buses was low because 

the warranty work was done by on-site manufacturer technicians. For maintenance work that has 

been done by the AC Transit mechanics, the reported costs appear large because of the low 

mileage of the fuel cell buses. The cab, body, and accessories category for the fuel cell buses is 

higher than the diesel buses in both cost per mile and percent of total maintenance. The 

propulsion-related maintenance for the fuel cell buses is significantly lower than for the diesel 

buses because nearly all of the work was done by the manufacturers. The PMI labor started to 

increase for the fuel cell buses during the evaluation period as the AC Transit mechanics 

participated more. However, all of the parts used during preventive maintenance and 

unscheduled maintenance for the fuel cell power systems and drive systems have been covered 

under warranty. 

Preventive maintenance activities for the fuel cell bus power system involve daily inspection of 

the bus including download of electronic data and diagnosis of any warnings provided by the on-

 37
board computer. On an as-needed basis, de-ionized water is added based on inspections at startup, after any shutdown or warning from the fuel cell power system, after movement by trailer or 

towing, and after loss of water from maintenance or leaks. UTC Power created a preventive 

maintenance schedule based on 6,000 miles, which is an equivalent of 500 fuel cell system 

hours. The 6,000-mile work is planned at 2.5 hours, the 12,000-mile work is planned at 5 hours, 

and the 24,000-mile work is planned at 7.5 hours. 

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 11 shows a breakdown of the propulsion-related system repairs for 

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

significantly higher maintenance costs for all of the systems shown in the table except for the 

exhaust and transmission systems. 

 38
Table 11. Propulsion-Related Maintenance Costs by System (Evaluation Period) 

Maintenance System Costs Fuel Cell Diesel 

Mileage 27,065 102,755 

Total Propulsion-Related Systems (Roll-up) 

Parts cost ($) 235.32 6,355.53 

Labor hours 27.2 127.5 

Total cost ($) 1,592.82 12,730.53 

Total cost ($) per mile 0.06 0.12 

Exhaust System Repairs 

Parts cost ($) 0.00 172.39 

Labor hours 0.0 4.6 

Total cost ($) 0.00 399.89 

Total cost ($) per mile 0.00 0.00 

Fuel System Repairs 

Parts cost ($) 0.00 661.50 

Labor hours 1.2 32.0 

Total cost ($) 61.00 2,261.50 

Total cost ($) per mile 0.00 0.02 

Powerplant System Repairs 

Parts cost ($) 0.00 4,109.26 

Labor hours 0.0 38.8 

Total cost ($) 0.00 6,049.26 

Total cost ($) per mile 0.00 0.06 

Electric Motor and Propulsion Repairs 

Parts cost ($) 0.00 0.00 

Labor hours 20.9 0.0 

Total cost ($) 1,046.50 0.00 

Total cost ($) per mile 0.04 0.00 

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

Cranking, Ignition) 

Parts cost ($) 235.32 79.04 

Labor hours 3.0 11.4 

Total cost ($) 385.32 649.04 

Total cost ($) per mile 0.01 0.01 

Air Intake System Repairs 

Parts cost ($) 0.00 448.42 

Labor hours 0.0 0.0 

Total cost ($) 0.00 448.42 

Total cost ($) per mile 0.00 0.00 

Cooling System Repairs 

Parts cost ($) 0.00 803.23 

Labor hours 0.0 40.5 

Total cost ($) 0.00 2,828.23 

Total cost ($) per mile 0.00 0.03 

Transmission Repairs 

Parts cost ($) 0.00 81.69 

Labor hours 2.0 0.3 

Total cost ($) 100.00 94.19 

Total cost ($) per mile 0.00 0.00 

 39
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 schedule. 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 12 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. 

(Note: AC Transit reports the entire 40-ft Van Hool diesel fleet has a propulsion-related MBRC 

of 14,000.) 

Table 12. Roadcalls and MBRC (Evaluation Period) 

Bus Mileage All 

Roadcalls All MBRC Propulsion Roadcalls 

Propulsion 

MBRC 

FCB1 9,868 10 987 7 1,410 

FCB2 8,888 15 593 9 988 

FCB3 8,309 10 831 6 1,385 

Total FCB 27,065 35 773 22 1,230 

1043 Diesel 16,688 4 4,172 2 8,344 

1044 Diesel 19,619 2 9,810 2 9,810 

1045 Diesel 13,133 5 2,627 3 4,378 

1046 Diesel 18,898 4 4,725 0 

1047 Diesel 17,025 5 3,405 5 3,405 

1048 Diesel 17,392 3 5,797 0 

Total Diesel 102,755 23 4,468 12 8,563 

 40
What’s Next 

This preliminary data report includes an eight-month evaluation period (April 2006 through 

November 2006) of the prototype fuel cell buses in operation at AC Transit. The next evaluation 

report, planned for release at the end of 2007, will include at least another 6 months of operations 

data and experience from AC Transit. 

For the next evaluation report, additional data collection will focus on the following existing and 

new topics: 

• Gain more experience with the new/upgraded/refurbished fuel cell power systems, 

specifically looking for fuel economy improvements from this preliminary evaluation 

report. 

• Track and document AC Transit’s efforts to maximize the use of the fuel cell buses, the 

use of the study buses on the next routes and special route blocks on Route 18 and Route 

51, and the planned weekly switching of the fuel cell and diesel buses between the two 

new routes. 

• Collect more information regarding standard diesel bus usage at AC Transit. One 

question that needs to be answered is what is typical diesel bus usage from the East 

Oakland Division? The next issue has to do with getting comparable fuel economy 

information from the diesel baseline buses. AC Transit has committed to fueling the 

diesel study buses before and after operation on one of the special route blocks. This is 

done to allow fuel economy comparisons between the diesel and fuel cell buses on the 

same route blocks. It also allows AC Transit to maximize the use of its diesel buses (AC 

Transit started this fuel procedure in December 2006). 

• Collect more information about fuel cell bus maintenance for the fuel cell power system 

and the hybrid drive system. Track and document increases in AC Transit mechanic 

inclusion in the maintenance of these fuel cell buses. 

• Attempt to collect more detailed information about the on-site hydrogen production and 

cost/price of hydrogen fuel from the Oakland Energy Station as cost estimates become 

available. 

• Track and document any fuel cell bus operation activities with GGT. 

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 accelerated 

“testing to failure” of the existing fuel cell buses. 

The California Air Resources Board has been working on updating its zero emission bus 

regulations. The current proposed program includes an advanced fuel cell bus demonstration for 

transit agencies on the diesel path by 2009. In this proposed regulation, a single transit agency 

would need to demonstrate six new zero emission buses or work within a multi-transit agency 

group to demonstrate at least 12 new zero emission buses. CARB has also required that existing 

fuel cell buses qualify as new zero emission buses as long as the fuel cell power systems are 

upgraded with newer design units. 

 41
Several transit agencies in the San Francisco Bay area have started working together as the Bay 

Area Working Group to put a plan together for implementing a multi-transit agency advanced 

demonstration to meet this proposed CARB regulation. The transit agencies included are AC 

Transit, Santa Clara VTA, Golden Gate Transit, SamTrans, and San Francisco MUNI. One of 

the major barriers to responding to CARB’s regulation is the amount of funding required to 

establish and operate this advanced demonstration. 

 42
Contacts 

DOE 

1000 Independence Ave., SW 

Washington, DC 20585 

Sigmund Gronich 

Technology Validation Manager 

Office of Hydrogen, Fuel Cells, and 

Infrastructure Technologies 

Phone: 202-586-1623 

E-mail: sigmund.gronich@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 

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 

Chevron Technology Ventures – a 

Division of Chevron USA 

3901 Briarpark Dr. 

Houston, TX 77042 

Linda Gallaher 

DOE Hydrogen Project Manager 

Phone: 713-954-6288 

E-Mail: LIMG@chevron.com

 43
Van Hool Battelle 

Bernard Van Hoolstraat 58 505 King Avenue 

B-2500 Lier Koningshooikt Columbus, OH 43201 

Belgium 

Kevin Chandler 

Paul Jenné Program Manager 

Automotive Relations Phone: 614-424-5127 

Phone: +32 (3) 420 22 10 E-mail: chandlek@battelle.org

E-mail: paul.jenne@vanhool.be

 44
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 

 45
References and Related Reports 

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 

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 

 46
Appendix: Fleet Summary Statistics 

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

Diesel and FCB Study Groups 

Fleet Operations and Economics

Diesel Buses Fuel Cell Buses 

Number of Vehicles 6 3

Period Used for Fuel and Oil Op Analysis 4/06-11/06 4/06-11/06

Total Number of Months in Period 8 8

Fuel and Oil Analysis Base Fleet Mileage N/A 27,065

Period Used for Maintenance Op Analysis 4/06-11/06 4/06-11/06

Total Number of Months in Period 8 8

Maintenance Analysis Base Fleet Mileage 102,755 27,065

Average Monthly Mileage per Vehicle 2,141 809

Availability N/A 77%

Fleet Fuel Usage in Diesel Gal/H2 kg N/A 4,919

Roadcalls 23 35

RCs MBRC 4,468 773

Propulsion Roadcalls 12 22

Propulsion MBRC 8,563 1,230

 

Fleet Miles/kg Hydrogen 5.50

(1.13 kg H2/gal Diesel Fuel) 

Representative Fleet MPG (energy equiv.) 4.66 6.22

 

Hydrogen Cost per kg 8.00

Diesel Cost per Gallon 2.30 

Fuel Cost per Mile 0.52 1.45

 

Total Scheduled Repair Cost per Mile 0.12 0.37

Total Unscheduled Repair Cost per Mile 0.23 2.23

Total Maintenance Cost per Mile 0.35 0.60

 

Total Operating Cost per Mile 0.87 2.05

Maintenance Costs

 Diesel Buses Fuel Cell Buses 

Fleet Mileage 102,755 27,065

 

Total Parts Cost 14,646.48 4,127.65

Total Labor Hours 431.3 240.4

Average Labor Cost (@ $50.00 per hour) 21,565.00 12,020.00

 

Total Maintenance Cost 36,211.48 16,147.65

Total Maintenance Cost per Bus 6,035.25 5,382.55

Total Maintenance Cost per Mile 0.35 0.60

 47
Breakdown of Maintenance Costs by Vehicle System

Diesel Buses Fuel Cell Buses 

Fleet Mileage 102,755 27,065

 

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

Parts Cost 6,355.53 235.32

Labor Hours 127.5 27.2

Average Labor Cost 6,375.00 1,357.50

Total Cost (for system) 12,730.53 1,592.82

Total Cost (for system) per Bus 2,121.76 530.94

Total Cost (for system) per Mile 0.12 0.06

 

Exhaust System Repairs (ATA VMRS 43) 

Parts Cost 172.39 0.00

Labor Hours 4.6 0.0

Average Labor Cost 225.50 0.00

Total Cost (for system) 399.89 0.00

Total Cost (for system) per Bus 66.65 0.00

Total Cost (for system) per Mile 0.00 0.00

 

Fuel System Repairs (ATA VMRS 44) 

Parts Cost 661.50 0.00

Labor Hours 32.0 1.2

Average Labor Cost 1,600.00 61.00

Total Cost (for system) 2,261.50 61.00

Total Cost (for system) per Bus 376.92 20.33

Total Cost (for system) per Mile 0.02 0.00

 

Power Plant (Engine) Repairs (ATA VMRS 45) 

Parts Cost 4,109.26 0.00

Labor Hours 38.8 0.0

Average Labor Cost 1,940.00 0.00

Total Cost (for system) 6,049.26 0.00

Total Cost (for system) per Bus 1,008.21 0.00

Total Cost (for system) per Mile 0.06 0.00

 

Electric Propulsion Repairs (ATA VMRS 46) 

Parts Cost 0.00 0.00

Labor Hours 0.0 20.9

Average Labor Cost 0.00 1,046.50

Total Cost (for system) 0.00 1,046.50

Total Cost (for system) per Bus 0.00 348.83

Total Cost (for system) per Mile 0.00 0.04

 

 48
Breakdown of Maintenance Costs by Vehicle System (continued)

 Diesel Buses Fuel Cell Buses 

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

Ignition)

Parts Cost 79.04 235.32

Labor Hours 11.4 3.0

Average Labor Cost 570.00 150.00

Total Cost (for system) 649.04 385.32

Total Cost (for system) per Bus 108.17 128.44

Total Cost (for system) per Mile 0.01 0.01

 

Air Intake System Repairs (ATA VMRS 41) 

Parts Cost 448.42 0.00

Labor Hours 0.0 0.0

Average Labor Cost 0.00 0.00

Total Cost (for system) 448.42 0.00

Total Cost (for system) per Bus 74.74 0.00

Total Cost (for system) per Mile 0.00 0.00

 

Cooling System Repairs (ATA VMRS 42) 

Parts Cost 803.23 0.00

Labor Hours 40.5 0.0

Average Labor Cost 2,025.00 0.00

Total Cost (for system) 2,828.23 0.00

Total Cost (for system) per Bus 471.37 0.00

Total Cost (for system) per Mile 0.03 0.00

 

Hydraulic System Repairs (ATA VMRS 65) 

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

 

General Air System Repairs (ATA VMRS 10) 

Parts Cost 44.87 0.00

Labor Hours 1.6 0.0

Average Labor Cost 77.50 0.00

Total Cost (for system) 122.37 0.00

Total Cost (for system) per Bus 20.40 0.00

Total Cost (for system) per Mile 0.00 0.00

 

 49
Breakdown of Maintenance Costs by Vehicle System (continued)

 Diesel Buses Fuel Cell Buses 

Brake System Repairs (ATA VMRS 13)

Parts Cost 670.69 0.00

Labor Hours 5.0 0.0

Average Labor Cost 250.00 0.00

Total Cost (for system) 920.69 0.00

Total Cost (for system) per Bus 153.45 0.00

Total Cost (for system) per Mile 0.01 0.00

Transmission Repairs (ATA VMRS 27) 

Parts Cost 81.69 0.00

Labor Hours 0.3 2.0

Average Labor Cost 12.50 100.00

Total Cost (for system) 94.19 100.00

Total Cost (for system) per Bus 15.70 33.33

Total Cost (for system) per Mile 0.00 0.00

 

Inspections Only – No Parts Replacements (101) 

Parts Cost 0.00 0.00

Labor Hours 160.7 79.5

Average Labor Cost 8,032.50 3,975.00

Total Cost (for system) 8,032.50 3,975.00

Total Cost (for system) per Bus 1,338.75 1,325.00

Total Cost (for system) per Mile 0.08 0.15

 

Cab, Body, and Accessories Systems Repairs 

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

Parts Cost 6,626.72 3,777.83

Labor Hours 93.1 132.0

Average Labor Cost 4,656.00 6,600.50

Total Cost (for system) 11,282.72 10,378.33

Total Cost (for system) per Bus 1,880.45 3,459.44

Total Cost (for system) per Mile 0.11 0.38

 

HVAC System Repairs (ATA VMRS 01) 

Parts Cost 88.77 0.00

Labor Hours 2.4 0.1

Average Labor Cost 119.00 5.00

Total Cost (for system) 207.77 5.00

Total Cost (for system) per Bus 34.63 1.67

Total Cost (for system) per Mile 0.00 0.00

 

 50
Breakdown of Maintenance Costs by Vehicle System (continued)

 Diesel Buses Fuel Cell Buses 

Lighting System Repairs (ATA VMRS 34)

Parts Cost 117.33 114.50

Labor Hours 3.3 1.6

Average Labor Cost 162.50 80.50

Total Cost (for system) 279.83 195.00

Total Cost (for system) per Bus 46.64 65.00

Total Cost (for system) per Mile 0.00 0.01

 

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

Parts Cost 742.56 0.00

Labor Hours 30.9 0.0

Average Labor Cost 1,544.00 0.00

Total Cost (for system) 2,286.56 0.00

Total Cost (for system) per Bus 381.09 0.00

Total Cost (for system) per Mile 0.02 0.00

 

Axle, Wheel, and Drive Shaft Repairs (ATA VMRS 11-Front Axle, 18-Wheels, 22-Rear Axle, 24-

Drive Shaft) 

Parts Cost 0.00 0.00

Labor Hours 7.0 0.0

Average Labor Cost 347.50 0.00

Total Cost (for system) 347.50 0.00

Total Cost (for system) per Bus 57.92 0.00

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

 51
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. 

 52
Appendix: Fleet Summary Statistics – SI Units 

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

Diesel and FCB Study Groups 

Fleet Operations and Economics

Diesel Buses Fuel Cell Buses 

Number of Vehicles 6 3

Period Used for Fuel and Oil Op Analysis 4/06-11/06 4/06-11/06

Total Number of Months in Period 8 8

Fuel and Oil Analysis Base Fleet Kilometers N/A 43,548

Period Used for Maintenance Op Analysis 4/06-11/06 4/06-11/06

Total Number of Months in Period 8 8

Maintenance Analysis Base Fleet Kilometers 165,333 43,548

Average Monthly Kilometers per Vehicle 3,444 1,815

Availability N/A 77%

Fleet Fuel Usage in Diesel L/H2 kg N/A 4,919

Roadcalls 23 35

Kilometers between roadcalls (KBRC) 7,188 1,244

Propulsion Roadcalls 12 22

Propulsion KBRC 13,778 1,979

 

Fleet kg Hydrogen/100 km 11.30

Representative Fleet MPG (L/100 km) N/A 

 

Hydrogen Cost per kg 8.00

Diesel Cost per Liter 0.61 

Fuel Cost per Kilometer 0.32 0.90

 

Total Scheduled Repair Cost per Kilometer 0.08 0.23

Total Unscheduled Repair Cost per Kilometer 0.14 0.14

Total Maintenance Cost per Kilometer 0.22 0.37

 

Total Operating Cost per Kilometer 0.54 1.27

Maintenance Costs

 Diesel Buses Fuel Cell Buses 

Fleet Kilometers 165,333 43,548

 

Total Parts Cost 14,646.48 4,127.65

Total Labor Hours 431.3 240.4

Average Labor Cost (@ $50.00 per hour) 21,565.00 12,020.00

 

Total Maintenance Cost 36,211.48 16,147.65

Total Maintenance Cost per Bus 6,035.25 5,382.55

Total Maintenance Cost per Kilometer 0.22 0.37

 53
F1147-E(12/2004) 

REPORT DOCUMENTATION PAGE Form Approved 

OMB No. 0704-0188

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collection of information, including suggestions for reducing the burden, to Department of Defense, Executive Services and Communications Directorate (0704-0188). Respondents 

should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a 

currently valid OMB control number. 

PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION.

1. REPORT DATE (DD-MM-YYYY)

March 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: Preliminary Evaluation Results 

5c. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

NREL/TP-560-41041 

5e. TASK NUMBER

H2708200 

6. AUTHOR(S)

K. Chandler and L. 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-560-41041 

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NREL 

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13. SUPPLEMENTARY NOTES

14. ABSTRACT (Maximum 200 Words)

This evaluation includes three prototype fuel cell-powered transit buses operating at AC Transit in Oakland, 

California, and six baseline diesel buses similar in design to the fuel cell buses. This report describes the equipment 

used and provides early experience details, lessons learned, and results for the operation of the buses and 

supporting hydrogen fueling station. 

15. SUBJECT TERMS

hydrogen infrastructure; AC Transit; fuel cell bus; fuel cell transit bus; hydrogen technology validation 

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