NREL has now analyzed data from almost three years of the five-year project with 92 vehicles having been deployed, 15 project refueling stations in use, and no fundamental safety issues identified. The authors have analyzed data from over 200 000 individual vehicle trips covering 1 100 000 miles traveled and over 40 000 kg hydrogen produced or dispensed. With additional hours of operation accumulated on the stacks, the fuel cell degradation projections have been updated and include an individual team-average high of over 1 900 hours with the four-team average projection at 1 200 hours. During 2008, NREL will improve the accuracy of its projections by adding a non-linear fit (or a segmented linear fit) to avoid overestimating the projected time as the accumulated hours continues to grow. To answer the question of what is causing the stacks to gradually degrade, NREL continues to characterize how each stack is used and perform multivariate analysis on this dataset to examine dominant variables affecting stack voltage degradation rates. Results to date indicate the authors are probably not going to be able to extract strong trends across all four teams due to differences among the teams, but that individual results may be useful to the teams individually and for feeding trends back into the R&D program. The authors have analyzed fuel cell system efficiency at 1/4-power and compared it to the DOE target of 60 %; system efficiency results from the four teams ranged between 52.5 % and 58.1 %. Using data on communication vs. non-communication fills, the authors found that communication fills demonstrated a higher rate of fill than non-communication fills while the slowest of the non-communication fill rates are being phased out. Finally, the authors have published a total of 47 CDPs to date and made them directly accessible to the public through the Hydrogen Technology Validation Web site (http://www.nrel.gov/hydrogen/proj_leaming_demo.html). In the future, the authors will further explore the correlations of real-world factors influencing fuel cell degradation and strive to separate their interwoven dependencies. The authors will semi-annually (spring/fall) compare technical progress to program objectives and targets and provide results to the public by participating in technical conferences and writing reports. For the second-generation vehicles introduced in 2008, the authors will begin evaluating improvements in fuel cell durability, range, fuel economy, and safety, and publish results when there are sufficient second-generation vehicles to mask the companies' identities. As an important part of the project, the authors will identify opportunities to feed project findings back into HFCIT Program R&D activities to maintain the project as a 'learning demonstration.'
Fuel cell vehicle and infrastructure learning demonstration status and results
Brennstoffzellenauto und Infrastruktur-Lerndemonstration-Status und Ergebnisse
2008
12 Seiten, 8 Bilder, 5 Quellen
Conference paper
English
Fuel cell electric vehicles and hydrogen infrastructure: status 2012
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