DELIVERING FUEL SAVINGS UPS tests diesel-electric hybrids vs. diesel-powered trucks in real-world service
BY BILL SIURU The Department of Energy’s National Renewable Energy Laboratory (NREL) conducted a 12-month long evaluation to help determine the fuel savings, emissions reductions and maintenance costs of hybrid trucks compared to diesel trucks. The NREL has been tracking and evaluating new propulsion sys- tems in transit buses and trucks for more than 10 years as part of its Advanced Vehicle Testing Activity. Six Freightliner-manufactured P70H diesel-electric hybrid-packaged deliv- ery vans and comparable P70D diesel delivery vans were evaluated under real-world conditions. The United Par- cel Service (UPS) placed the diesel- electric hybrid delivery vans in service at two locations in Phoenix, Ariz. The P70H hybrid vans were equip- ped with Eaton Corp.’s diesel hybrid electric system. The Eaton hybrid sys- tem includes a Fuller automatic trans- mission integrated with a 26 k W contin- uous/44 k W peak motor/generator driv- en by a Mercedes-Benz MBE 904 four- cylinder diesel engine. Electrical ener- gy is stored in a 340 Vdc, 1. 8 k W/hr lithium-ion battery pack supplied by Hitachi. The P70D vans were also pow- ered by the MBE 904 diesel engines. NREL said the first-generation hy- brid delivery vans showed a 28.9% improvement in on-road fuel economy over the diesel versions — 13. 1 mpg vs. 10. 2 mpg for the diesels. UPS assigned the hybrid vans to more urban routes to make the best use of the hybrid drivetrain. This meant shorter distances traveled, more stops per mile, more time idling and slower speeds. The hybrid’s aver- age monthly mileage was estimated at about 20% less than that of the diesel vans, and miles per operational day were 15% lower, NREL said. More
56 DIESEL PROGRESS NORTH AMERICAN EDI TION April 2010
The United Parcel Service, with the Department of Energy’s National Renewable Energy Laboratory, put Freightliner-manufactured diesel-elec- tric vans equipped with an Eaton hybrid system in operating service to compare fuel, maintenance and emissions to diesel-powered vehicles.
Bill Siuru, PhD, PE, is a Diesel Progress field editor based in Temecula, Calif.