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Faced with tough emission standards, auto manufacturers have started looking into technologies that offer feasible alternatives to internal combustion engines. Fuel cells - especially proton exchanged membrane fuel cells (PEMFC) - offer many advantages including almost-zero emissions. However, fuel cells need hydrogen as a fuel to generate electricity. Epyx Corporation, a subsidiary of Arthur D. Little, Inc., has developed a fuel-processor design that reforms hydrocarbons such as gasoline and generates hydrogen - needed to run a fuel cell engine. The Epyx fuel processor is the first to be demonstrated for gasoline operation. In addition to its lightweight and compact configuration, the Epyx fuel processor operates on multiple fuels such as gasoline, ethanol, propane, methanol, and natural gas. This paper gives a brief description of the Epyx automotive fuel processor system coupled with a PEMFC system.

The Epyx multi-fuel processor provides the key to integrating fuel cell vehicles into existing fueling infrastructures while maintaining the advantages of using a fuel cell - low emissions and increased drive cycle efficiency. The fuel processor can convert various fuels such as gasoline, methanol, ethanol, or natural gas to a hydrogen rich stream that feeds a fuel cell. Development efforts have led to a fuel processor capable of providing high efficiency (76-82% with gasoline, 82-88% with methanol), a reliable CO clean-up device that maintains CO outlet concentrations under 10 ppm during steady state and transient operation, and a tailgas burner that reduces startup time and maintains low emissions. Results from integrated fuel processor/fuel cell system testing show system efficiencies of 32 - 37%, assuming an overall stack efficiency of 42%, well on the way to an overall fuel processor/fuel cell system peak efficiency goal of 40% (DOE targets).

To avoid degradation, the Proton Exchange Membrane (PEM) fuel cell requires less than 10 to 50 ppmv carbon monoxide (CO) in the reformate stream. A transient Preferential Oxidation (PrOx) system was developed for reformer operating powers between 5 kW and 60 kW thermal. Testing results show that steady state reformate CO concentration from the PrOx is less than 6 ppmv for a variety of inlet CO concentrations. Furthermore, the PrOx is capable of maintaining CO under 10 ppmv during reformer transient conditions such as power turn up and turn down.

Fuel processor / fuel cell systems promise to provide a means of powering automobiles with low emission levels. Prototype systems have already been built to demonstrate operation on automotive fuels including gasoline, methanol, and ethanol. As these systems evolve it becomes increasingly important to verify that the emission reduction potential is indeed possible. This paper outlines the basic components in a fuel processor / fuel cell system, highlights a few differences between emissions from fuel cell systems and IC engines, and describes the various operation modes which must eventually be considered when testing for emissions from fuel cell systems. In addition, steady state results are presented for a 10 kWe system operating at ¼, ½ and full power on gasoline. Key issues related to emissions from fuel cell systems are identified. The Tail Gas Combustor is identified as the critical component for controlling emissions.

Recent commitment from automotive manufacturers to manufacture prototype fuel cell vehicles in the near future has highlighted the need for fuel processing systems ready for automotive integration. Epyx Corporation (a subsidiary of Arthur D. Little) has developed an integrated fuel processing system designed for automotive load-following conditions. The system, a product of numerous design iterations and basic development, integrates a fuel processing assembly (FPA), CO clean-up device (PrOX), anode tailgas combustor (TGC), and a full control system. System development is ongoing to produce a fuel processing system ready for integration into automotive prototypes by the end of 2000. While continued fuel processor development is critical in creating a successful fuel cell system, issues such as air management, water recovery, hybridization, heat rejection, and turndown are major factors in system design.