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NREL Releases Hybrid Electric Fleet Study

March 29, 2011

WASHINGTON - The National Renewable Energy Laboratory (NREL), which recently completed a year-long technology evaluation of gasoline hybrid electric trucks in the FedEx fleet, has released its report on the project.

NREL, part of the U.S. Department of Energy, set out to determine the impact of hybridization on fleet vehicle performance, emissions and fuel economy. NREL's Fleet Test and Evaluation Team collected and analyzed data on three gasoline hybrid electric trucks and three conventional diesel trucks used for FedEx parcel delivery service in the Los Angeles area. The team also tested a hybrid and a conventional truck at NREL's Renewable Fuels and Lubricants Research Laboratory in Denver, Colo.

The gasoline hybrid electric trucks produced substantially reduced tailpipe emissions during all drive cycles tested in the laboratory when compared to conventional diesel vehicles. On a drive cycle representing routes with frequent stops and accelerations, the gasoline hybrid electric trucks exhibited a 20-percent improvement in fuel economy while drive cycles representing routes with fewer stops and accelerations demonstrated similar fuel economy to the diesels.

"We conducted this study to show how a gasoline hybrid might perform compared to a conventional diesel truck given that gasoline engines are less efficient than diesel engines and generally not used in heavier vehicles," said Lee Slezak, program manager for DOE's Advanced Vehicle Testing Activity.

Manufactured by Ford, the gasoline hybrid electric trucks feature 5.4L gasoline engines and hybrid propulsion systems produced by Azure Dynamics with 100kW electric motors, regenerative braking and nickel-metal-hydride batteries.

 "Southern California continues to experience the worst air quality in the nation, and transitioning heavy-duty vehicle fleets to cleaner-burning vehicle technology is an important element of our overall clean air goals," said Barry R. Wallerstein, executive officer of the South Coast Air Quality Management District.

FedEx Express operates more than 32,000 motorized vehicles in the United States, including 20 gasoline hybrid electric trucks on parcel delivery routes in Los Angeles and Sacramento, Calif. The FedEx Express hybrid fleet, which has driven more than 8 million miles in revenue service, includes an all-hybrid station in Bronx, N.Y., where nearly half of the vehicles are gasoline hybrid electric vehicles.

This evaluation was funded by DOE's Vehicle Technologies Program with additional funding from CALSTART and the South Coast Air Quality Management District.

NREL is the Department of Energy's primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for DOE by the Alliance for Sustainable Energy LLC.

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  1. 1. Shrum Diesel Repair [ March 30, 2011 @ 04:50PM ]

    What was the cost of the hybrids in comparison to the diesel trucks? With all taken into account, what will be the payback time in months for the hybrids versus the diesels? Air quality is a major concern, of course, but can it be justified, or is it currently being subsisdized by the government. What happens when these entitlement programs are no longer funded. We have heard that a diesel to complete CNG conversion costs approx. $80,000. No company can stay in business trying to take such measures unless the costs are passed on to the consumer, and the consumer has had about they can stand at this time. Just a thought. JRS

  2. 2. Dawn Fenton [ March 31, 2011 @ 05:32AM ]

    It's not surprising that the gasoline hybrids had lower emissions than the diesels since the test used older diesels which were manufacturered before the new 2007 and 2010 models with advanced engines and emissions control technologies were introduced (note the gas hybrids were from 2008). Assuming this study will be used to encourage the selection of the cleanest and most efficient vehicles in future purchase decisions, it would have been more helpful (and accurate) to test the latest gasoline hybrid and diesel models.

    The fact that hybrid electric models are more fuel efficient in city driving patterns is commonly recognized. It seems to me that the best performance would come from diesel electric hybrids which benefit from the hybrid technology and a diesel's greater fuel economy. And this doesn't even account for the longer life and higher residual value of diesel vehicles!


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