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Potential Benefits of Utilizing Fuel Cell Auxiliary Power Units in Lieu of Heavy-Duty Truck Engine Idling


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Suggested Citation:
Brodrick, Christie-Joy, Timothy E. Lipman, Mohammad Farshchi, Harry A. Dwyer, S. W. Gouse, III, D. B. Harris, Foy G. King, Jr. (2001) Potential Benefits of Utilizing Fuel Cell Auxiliary Power Units in Lieu of Heavy-Duty Truck Engine Idling. Institute of Transportation Studies, University of California, Davis, Presentation Series UCD-ITS-RP-01-01

Presented at the 80th Annual Transportation Research Board Meeting, January 7 - 11, 2001

Truck manufacturers and vehicle component manufacturers are exploring using fuel cell auxiliary power units (APUs) in lieu of main engine idling. While fuel cell powertrains continue to face significant technical and economic barriers, the truck auxiliary power application may offer a viable near-term market for small (1 – 5 kW) fuel cells. The University of California, Davis Institute of Transportation Studies (ITS-Davis) has conducted a study to quantify the potential benefits of utilizing APUs in lieu of truck idling. ITS-Davis researchers estimated the potential reductions of (1) air pollutants and greenhouse gases and (2) heavy truck fuel and lubricant consumption through elimination of truck idling. For new tractors, idling is estimated to contribute 0.2 to 0.7 metric tons of nitrogen oxide emissions and 8 to 24 tons of carbon dioxide per vehicle per year. Thus, depending upon the emissions from fuel cell system production, fuel cell APUs in lieu of idling could substantially reduce pollution emissions and greenhouse gas emissions. The extent of cost saving that an APU could achieve depends upon the cost of diesel engine idling, the market cost of the APU, the APU fuel-type, and quantity of APU fuel consumed. Conservative estimates are that diesel engine idling uses 1818 gallons of fuel per year for an average late model truck that idles 6 hours per day, 303 days per year. The fuel cost per year is $3,127 (at a cost of $1.72 per gallon) in addition to preventative maintenance and engine overhaul costs. Potential costs of the fuel cell APU systems are speculative due to the early commercialization stage of the technologies and uncertainty with regard to architectures and production volumes. This paper concludes with a discussion of appropriate fuel cell architectures for truck auxiliary power applications and the costs considerations associated with each.