Five Generations:  Hydrogen Buses Evolving

Through the efforts of forward-looking transit systems like SunLine Transit Agency, California is deploying some of the world's most sophisticated hydrogen demonstration projects in transit buses.  Sunline boasts no less than five generations of buses powered by various hydrogen fueled engine systems that are currently in or slated for revenue service.  The drive configurations range from a large fuel cell engine to a fuel-cell hybrid to a hydrogen internal combustion engine hybrid.  The latest generation of fuel cell platform, the American Fuel Cell Bus, is a modern vehicle designed with fuel cell propulsion in mind, featuring:

   •  Lower-weight materials
   •  High-efficiency electronics and accessories
   •  A new high-durability fuel cell
   •  Hybrid propulsion and
   •  Advanced energy storage technology.

A History of Five Generations
Starting in 2000, SunLine began operating their first ZE-bus or zero-emission fuel cell bus. During 2000-2001, an Xcellsis (now Ballard) ZE-bus began operations. The ZE-bus Phase VI test used compressed hydrogen to supply a 200-kW PEM fuel cell stack to power the 40' bus.

Later, in 2002-2003, SunLine began operating the ThunderPower 30-ft fuel cell bus, a Thor Industries 30' ElDorado National EZ Rider 2 chassis using compressed hydrogen and a 60-kW PEM fuel cell stack from UTC Fuel Cells, then moving on for service at Chula Vista Transit.

The ISE/New Flyer hybrid hydrogen internal combustion engine (HHICE) bus was introduced into service in late 2004 at SunLine. The HHICE combines an ISE integrated electric drive and energy storage with a hydrogen-fueled ICE. Performance in initial testing at Sunline exceeded expectations in areas from fuel consumption to customer and driver experience.  Soon after arriving at SunLine, the HHICE bus was shipped to Manitoba, Canada for cold weather testing in February and March 2005. The winter testing included a survey of riders done by the University of Manitoba Vehicle Technology Centre.  According to a report issued by the Air Quality Management District, "Riders reported significant advantages of the bus: Its quiet operation was appreciated, 69% of the respondents reported improved temperature comfort, and 80% of respondents considered the HHICE bus to be superior in terms of smooth acceleration".

During 2004-2006 and continuing, a demonstration project of four fuel cell buses using UTC fuel cell stacks and compressed hydrogen in 40-ft Van Hool buses was conducted for AC Transit and SunLine. Developed and integrated by ISE, Van Hool, and UTC Power, SunLine operates one of these buses in daily rigorous service focused on providing data to UTC Power for engineering development of a next-generation, more durable and reliable fuel cell for public transit.

This leads to a project just getting underway at SunLine. The American Fuel Cell Bus (AFCB) development, part of the FTA National Fuel Cell Bus Program, will use an advanced 40-foot reduced-weight bus chassis by New Flyer, a 120 kW fuel cell from UTC Power, and an ISE improved electric traction drive subsystem, featuring a reduced weight power electronics suite, improved gearing to reduce weight and noise, and a lithium-ion battery energy storage subsystem. With these five generations of hydrogen buses, Sunline - known for its commitment to advancing alternative fuels - is proving to be a leader in hydrogen technology in transit.  Sunline Transit has signed on as co-leader of the newly formed Transit Users Group (TUG) along with Los Angeles County MTA. CALSTART, on behalf of the Federal Transit Administration, formed the TUG to help Transit Agencies on the Alternative Fuels Path to satisfy the California Zero-Emissions Bus Rule in 2012.

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