Fuel Cell Vehicle Learning Demonstration: Study of Factors Affecting Fuel Cell Degradation

The 5 year "Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project" (or Fuel Cell Vehicle Learning Demonstration) was initiated by the U.S. Department of Energy (DOE) in 2004. The purpose of the project is to conduct an integrated field validation that simultaneously examines the performance of fuel cell vehicles and the supporting hydrogen infrastructure. Four industry teams are currently operating more than 92 vehicles and 14 refueling stations throughout the United States. More than 40 additional vehicles and several additional refueling stations will be added to the project through 2009. At the National Renewable Energy Laboratory (NREL), on-road driving and refueling data are analyzed to assess the technology status and progress, as well as to provide feedback to the hydrogen research and development community. A new/updated set of public results, in the form of composite data products (constructed to protect the intellectual property of the four teams), is released twice a year in the spring and fall. In addition to the public results, detailed analyses results are shared with each participating team. One of the analyses studies fuel cell degradation. The study includes following the fuel cell performance degradation trends, e.g. identifying fuel cell stacks that are decaying at a different rate than others of a similar design and in the same fleet, and explores connections between the real world data and fuel cell degradation. This study differs from other degradation studies in a lab setting or at the single cell level because this study uses full scale fuel cell stacks in vehicles with on-road driving and refueling. In the study, researchers investigate degradation factors by applying multivariate analyses for each individual team and for the combination of all four teams. Detailed results are reviewed with the individual teams in an effort to improve each analysis iteration and comprehension of the results. This paper will detail NREL's study of fuel cell degradation factors by describing the process, reviewing the latest public results, and reporting on any observed dominant factor groups affecting fuel cell degradation.