1994 Diesel Engine

A = 1998 Urban Bus Federal Emission Standards B = 1977 Detroit Diesel 6V71N MUI Bus Engine C = 1995 Detroit Diesel Series 50 Bus Engine D = Methanol M100 Bus Engine E = Ethanol E95 Bus Engine F=Compressed Natural Gas Bus Engine G=Fuel Cell Bus Powetplant

Environmental, Safety & Health Issues

A report on the environmental, health and safety issues that may affect commercialization of the PAFC buses states that the in-use environmental impacts are insignificant compared to the diesel bus. Only minor amounts of air pollutants are produced during the steam-formation of methanol. The high noise level caused by vehicular traffic contributes considerably to urban stress and based on the initial test results, the fuel cell bus is projected to be much quieter than a diesel bus. In terms of the health and safety of bus maintenance personnel or passengers, the report concludes that the bus is as safe as a typical diesel bus. The intrinsic hazards include phosphoric acid, mineral oil, hydrogen gas, methanol,-cadmium, nickel, high-power batteries and high-temperature exhaust from the reformer. The risks from these constituents were minimized in the design features which include hydrogen sensors, a fireproof wall between the passenger compartment and fuel cell compartment, an automatic fire-suppression system, and fuel cell and battery compartment ventilation fans.

Future Plans for the Test Bed Buses

The current plan for the first test bed bus is to leverage current DOE efforts in PEM fuel cell research and ethanol reformer development by replacing the current system with an ethanol-fueled PEM system and operating the bus in a region of the U.S. where ethanol is readily available. SCAQMD is still in the process of formulating a demonstration plan for the second bus. DOT/ETA plans on maintaining the third bus at Georgetown University to take advantage of the existing fueling set up, low overhead, and experience base. The experience gained at Georgetown will be applied to the 40-foot bus commercialization program.


The fuel cell bus has met or exceeded expectations with lower emissions (100 times lower than 1998 Federal standards), higher engine efficiency (25% better than diesel), higher fuel economy (25% better than diesel), lower noise (two times quieter than diesel), and equivalent operating performance (same as current diesel buses). Hie higher weight and higher capital cost projections are issues that need to be addressed in the commercialization phase where components will be optimized for weight, performance, and manufacturing cost reduction. Overall, this program, is a success — fuel cell technology in an urban transit application was demonstrated and validated with very good results. Completion of the test and evaluation of the 30-foot buses will be invaluable in avoiding past mistakes. A great deal of hands-on systems experience has been gained about this complex, integrated electric vehicle. With such a strong basis to build upon, the development of the next generation fuel cell bus looks very promising.


"Research and Development of A Phosphoric Acid Fuel Cell/Battery Power Source Integrated in A Test-Bed Bus," Final Report written by H Power Corporation for DOE Contract No. DE-AC02-91CH10447, May 30,1996.

"Environmental, Health, and Safety Issues of Fuel Cells in Transportation, Volume 1: Phosphoric Acid Fuel-Cell Buses," Report written by Shan Ring of the National Renewable Energy Laboratory, December 1994.


R. Wimmer, J. Laikins and S. Romano Georgetown University

37th &0 Street Washington, D.C. 20057

Fourteen years ago, Georgetown University (GU) perceived the need for a clean, efficient power systems for transportation that could operate on non-petroleum based fuels. The transit bus application was selected to begin system development GU recognized the range and recharge constraints of a pure batteiy powered transit bus. A Fuel Cell power system would circumvent these limitations and, with an on board reformer, accommodate liquid fuel for rapid refueling.

Feasibility studies for Fuel Cell power systems for transit buses were conducted with the Los Alamos National Laboratory in 1983. Successful results of this investigation resulted in the DOT/DOE Fuel Cell transit bus development program. The first task was to prove that small Fuel Cell power plants were possible. This was achieved with the Phase I development of two 25 kW Phosphoric Acid Fuel Cell (PAFC) brassboard systems. A liquid cooled version was selected for the Phase II activity in which three 30-foot Fuel Cell powered Test Bed Buses (TBBs) were fabricated. The first of these TBBs was delivered in the spring of 1994. All three of these development vehicles are now in Phase III of the program to conduct testing and evaluation.

GU is conducting a thorough operational testing program on the Fuel Cell buses. This includes dynamic emission testing at West Virginia University, instrumented route operation in the Washington, DC area, and fuel efficiency monitoring. The results of this testing is being documented and is aiding the design decisions on the 40-foot bus commercialization project

To date, every major question about Fuel Cell powered buses has been addressed in a methodical and thorough manner within these activities. The Los Alamos study verified that the concept was feasible; the 25-kW brassboard units showed that the technology could be engineered to the size required for transit buses, and the three TBBs proved that Fuel Cells could indeed power these vehicles. The remaining issue is whether Fuel Cell powered transit buses can be commercialized

The Federal Transit Administration (FTA) awarded a Grant to GU in October of 1993 to commercialize a Fuel Cell powered transit bus. To achieve commercialization of the technology in the near term, the mature International Fuel Cells PAFC was selected for the initial program. The original FTA Grant has since been modified to accommodate a Proton Exchange Membrane Fuel Cell (PEMFC) manufactured by the Ballard Power Corporation. Two commercializable, liquid-fueled 40-foot transit buses are to be produced: one with each type of Fuel Cell. A team led by Booz-Allen & Hamilton (with Kaman and NovaBUS) was selected as the systems integration contractor. The Grant will also address the propulsion needs for FTA's Advanced Technology Transit Bus (ATTB).

This paper presents preliminary test results gained from the IBB testing program and how these are being applied to guide the 40-Foot Commercial Transit Bus Development Program. Of special interest is the high degree of interaction between the various subsystems of a true hybrid electric drive system. This is further complicated when the Fuel Cell must operate on reformed liquid fuel introducing a further degree of technical integration into the overall control scheme. It was only after the introduction of a detailed data acquisition package onboard TBB #3 that the problems introduced by this complexity could be properly understood and addressed

The TBB test results are presented to illustrate these technical issues. Voltage matching of the two electrical power sources is critical in the hybrid propulsion train. The difficulty lies in achieving this match with subsystems that have vastly different transient responses and constantly changing loads. The techniques used on the TBBs include reactant flow control to adjust fuel cell output power and "current limiting" to maintain the batteiy voltage within the desired range. This paper will discuss difficulties inherent with these techniques and changes being considered for the 40-foot program. Additional data will be presented on batteiy performance, system efficiency, and water recovery to be used in the reforming process.

The data collected from testing and operating the TBBs has been invaluable in developing the system design and control strategy for the 40-Foot Commercial Transit Bus Development Program. Many of the "lessons learned" apply to not only future fuel cell buses, but to hybrid vehicles in general.

The 30-Foot TBBs are performing as expected and meets all transit industry and Americans with Disabilities Act requirements. These fully functional heavy-duty transit buses are providing engineering experience to guide the 40-foot commercialization effort. Two 40-foot Fuel Cell powered transit buses will be delivered in the 1997/1998 time frame to meet the Congressional edict to commercialize this highly competitive, environmentally- beneficial technology.

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