NREL Study: Hybrid Delivery Vans Show Nearly 20 Percent Higher Fuel Economy
September 28, 2012
The U.S. Department of Energy's (DOE)’s National Renewable Energy Laboratory (NREL)
recently completed a performance evaluation report that showed significant fuel economy
benefits of hybrid electric delivery vans compared to similar conventional vans.
“During the on-road portion of our study, the hybrid vans demonstrated a 13 to 20
percent higher fuel economy than the conventional vans,” said NREL Project Engineer
Michael Lammert. “During dynamometer testing, three standard drive cycles were chosen
to represent the range of delivery routes. The hybrids showed a 13 to 36 percent improvement
in fuel economy and up to a 45 percent improvement in ton-miles-per-gallon. This wide
range in fuel economy is largely dependent on drive cycle.”
The NREL team collected and analyzed in-service fuel economy, maintenance, and other
vehicle performance data on 11 hybrid and 11 conventional step vans operated by the
United Parcel Service (UPS) in Minneapolis. The team also performed dynamometer testing
at the Renewable Fuels and Lubricants (ReFUEL) Research Laboratory
“The reliability of the hybrids was slightly lower, 92.5 percent compared to 99.7
percent, in part due to troubleshooting and recalibration issues related to prototype
components,” Lammert added. “Differences in per-mile maintenance and operating costs
were not statistically significant.”
The hybrid vans feature hybrid propulsion systems: 44 kilowatt electric motors, lithium-ion
batteries and regenerative braking that captures energy normally lost during braking
to power the electric motor. The comparable conventional vans were approximately the
same age and were operated in similar conditions out of the same facility. The two
vehicle groups switched route assignments during the study period to provide a balanced
review of the vans on the same route.
NREL has been working in partnership with UPS for five years to track and evaluate
the performance of its hybrid vehicles. The first study, performed in 2008, focused
on first-generation hybrid vans operated by UPS in Phoenix. In 2010, UPS deployed
200 second-generation hybrid vans to eight U.S. cities, including the 11 under study
in Minneapolis. These second-generation hybrids feature more advanced control algorithms
and an “engine off at idle” feature that automatically stops and restarts the engine
at stoplights and during other short-stop conditions.
These evaluations are part of the Advanced Vehicle Testing Activity, which supports
the Energy Department’s Office of Energy Efficiency and Renewable Energy. Visit www.nrel.gov/transportation/fleettest
to learn more about NREL’s fleet test and evaluation projects.
NREL is the U.S. 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.