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Hybridization: Cost and Efficiency Comparisons for PEM Fuel Cell Vehicles
ISSN: 0148-7191, e-ISSN: 2688-3627
Published August 21, 2000 by SAE International in United States
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This paper primarily compares costs and fuel economies of load following direct-hydrogen fuel cell vehicles with battery hybrid variations of the same vehicle. Additional information is included regarding load-following indirect methanol fuel cell vehicles. The key points addressed are as follows: the tradeoff between fuel cell system efficiency and regenerative braking ability; transient effects; and component cost differences. The difference in energy use and costs can vary significantly depending on the assumptions and the hybrid configurations. The mass of the battery pack creates the largest impact in energy use, while system efficiency losses roughly balance out with regenerative braking. For the direct-hydrogen fuel cell system, transient effects are small. These effects are expected to be significant for steam reformer/indirect-methanol systems (analyzed only graphically herein). Cost values are very sensitive to uncertainties, but tend to show similar results to those for energy use: vehicles with larger battery packs and smaller fuel cell systems tend to cost more. A key variable is battery replacement over the life of the vehicle. More frequent replacement required for certain battery technologies evens out the cost differential in comparison to the more expensive but longer lasting battery choices for the hybrids.
- David J. Friedman - Fuel Cell Vehicle Modeling Program, University of California, Davis
- Timothy Lipman - Fuel Cell Vehicle Modeling Program, University of California, Davis
- Anthony Eggert - Fuel Cell Vehicle Modeling Program, University of California, Davis
- Sitaram Ramaswamy - Fuel Cell Vehicle Modeling Program, University of California, Davis
- Kar-Heinz Hauer - Fuel Cell Vehicle Modeling Program, University of California, Davis
CitationFriedman, D., Lipman, T., Eggert, A., Ramaswamy, S. et al., "Hybridization: Cost and Efficiency Comparisons for PEM Fuel Cell Vehicles," SAE Technical Paper 2000-01-3078, 2000, https://doi.org/10.4271/2000-01-3078.
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- The exact point where the efficiency curve begins to roll-over has uncertainty associated with it. If auxiliaries represent a greater load, this roll-over will begin at a higher level of normalized power and would show a small improvement in the final results for hybridization.
- The transient behavior herein is primarily determined by the steam reformation based fuel processor model developed by Dr. Ramaswamy and the vehicle control systems developed by Karl Hauer.
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- One driving cycle has been added to these results, the WFTP. This stands for the weighted federal test procedure. While showing the FUDS and US06 cycles provides some insight into the tradeoffs, neither one represents a “prototypical” urban drive cycle (assuming one even could exist). The WFTP is EPA's method of combining the newly introduced US06 with the standard FUDS cycle to represent general urban driving behavior. It is based on 78% FUDS and 28% US06 (40CFR86.164-00). It is interesting to compare the results for this weighted cycle with the results for the 1.25 FUDS cycle. While there are differences, they are not drastic and the overall pattern of results is quite similar.