Score one for diesel hybrids.
The National Renewable Energy Laboratory got its hands on six hybrid vans that United Parcel Service is using, and after testing them nine ways from Sunday found diesel-electric technology improved fuel economy more than 28 percent. What's more, it cost significantly less per mile to operate while delivering the same reliability and performance as conventional diesel vans.
The federal eggheads spent a year analyzing fuel economy, maintenance and vehicle performance data for six first-generation hybrid UPS vans developed by Eaton Corp. It's no surprise a delivery service would be eager to give diesel-electric tech a try -- UPS must spend money by the truckload on fuel -- and the NREL joined UPS in putting the trucks through their paces in Phoenix.
So why'd they team up for the research?
Because the Eaton parallel hybrid system was developed in part under a $7.5 million, 33-month contract from the Department of Energy's Advanced Heavy-Hybrid Propulsion System program. The feds like the technology because it increases fuel economy and reduces emissions, and they wanted to see what we got for the money.
“Having provided funding for the development of the Eaton hybrid system, DOE was eager to participate in testing the system in a commercial fleet,” Lee Slezak, manager of the advanced heavy-hybrid program, said in a statement. “Our goal is to help develop more efficient vehicle technologies and then document their on-road performance."
The feds compared six diesel-hybrid vans to six diesel vans. According to the lab's report, the hybrids delivered 28.9 percent better fuel economy, averaging 13.1 mpg to the diesels' 10.2 mpg. Maintenance costs were about the same, but the diesels showed slightly better reliability -- a factor the researchers chalk up to "troubleshooting and recalibration issues" associated with prototype components.
The hybrids were driven 15 percent fewer miles per day, which the feds attribute to the fact the diesel-electrics were assigned to urban routes where they made more stops per mile and spent more time at low speeds or idling. Overall, the hybrids delivered a 15 percent improvement in total cost per mile.
UPS is, as you'd expect, quite pleased with the results.
“NREL’s report on the performance of our hybrid delivery vehicles is helping make this type of energy-efficient vehicle a standard in the industry,” said Robert Hall, the company's director of maintenance and engineering. He's hoping the findings speed up market acceptance of the technology.
Eaton supplied the hybrid propulsion systems for the vans, which were manufactured by Freightliner. The system uses an Eaton automated transmission with an integrated motor-generator and lithium-ion batteries. The electric bits are mated to a four-cylinder Mercedes-Benz diesel engine -- the same one used in the conventional vans.
UPS must like what it sees, because the delivery company just ordered another 200 Eaton hybrid vans.
Photo: United Parcel Service
