Fuel Cell IntegrationA Study of the Impacts of Gas Quality and Impurities

NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. 2 EXECUTIVE SUMMARY This report is a review of the recent literature exploring the issues of integrating fuel cells with various sources of fuel gas, with particular attention to the fuel-processing step of a fuel cell system. A brief discussion of the available fuel cell technologies is presented highlighting the tolerances of fuel cell systems to impurities in the fuel gases. For a more comprehensive description of fuel cell systems, please consult the Fuel Cell Handbook (5 th edition, 2000). This report also outlines a description of several sources of fuels and their compositions followed by a discussion how these fuel sources might be integrated with fuel cell systems for distributed and centralized power production. Ancillary components in a fuel cell power plant account for only half of the size of a fuel cell system yet account for nearly all of the unscheduled outages in hydrocarbon-fueled fuel cell systems. Components that require considerable attention are the fuel processing system, acid gas removal systems, and halogen guard beds. Acid gas removal systems will be required in all hydrocarbon reforming fuel cell systems because both fuel cells and steam reforming catalysts do not tolerate sulfur. They will be necessary even for natural gas, the simplest hydrocarbon fuel. Halogen guard beds will likely be required for all fuel cell power systems as well to minimize long term, high temperature corrosion. Molten Carbonate Fuel Cells (MCFC) and Solid Oxide Fuel Cells (SOFC) operate at high temperatures and therefore offer the best opportunity for thermal integration with coal and biomass gasification systems. The technical challenge will be to design a fuel processing system …