Analysis of Connected and Automated Vehicle Technologies Highlights Uncertainty in Potential Effects on Fuel Use, Miles Traveled
December 13, 2016
A joint study from the U.S. Department of Energy's National Renewable Energy Laboratory (NREL), Argonne National Laboratory, and Oak Ridge National Laboratory revealed the potential effects of connected and automated vehicle (CAV) technologies on fuel use and efficiency, vehicle miles traveled, and consumer costs. The analysis focused on a range of light-duty CAV technologies in conventional powertrain vehicles-from partial automation with some connectivity to full automation with maximum connectivity, with and without ridesharing-compared to today's base-case scenario.
"Our analysis revealed widely disparate fuel use estimates for the various scenarios considered, ranging from a tripling of light-duty vehicle fuel use to decreasing it to below 40 percent of today's level," said NREL's Jeff Gonder, co-author of a new report—Estimated Bounds and Important Factors for Fuel Use and Consumer Costs of Connected and Automated Vehicles—detailing the study findings. "This wide range reflects uncertainties in the ways that CAV technologies can influence vehicle efficiency and use through changes in vehicle designs, driving habits, and travel behavior, and highlights the need for future studies."
The most significant contributing factors to increased fuel use in the upper-bound full-automation scenarios were increased vehicle operation induced by easier travel and empty-vehicle travel together with reduced efficiency from high-speed travel. For the lower-bound scenarios, the most significant factors for fuel savings included efficiency improvements from vehicle and powertrain downsizing together with smoother driving and only modest assumed increases in travel demand.
The multi-lab team also examined CAV ownership and operating costs, including vehicle purchase price, insurance, and the perceived value of travel time, among other costs. Analysis results indicated that, compared to today's base-case scenario, CAV technologies could lead to a 60 percent cost reduction (based on a full automation, multiple-occupant scenario), with perceived travel-time cost changes as the most significant factor for this reduction.
The team identified the need for future research in four key areas:
- Assessing potential changes in travel demand due to CAVs
- Estimating the level of future CAV adoption
- Analyzing the potential effects on vehicle efficiency and redesign
- Estimating future heavy-duty CAV impacts, such as those stemming from truck platooning.
This analysis considered CAVs with conventional gasoline-powered drivetrains, but synergistic interactions of CAV technologies and vehicle electrification could result in even lower energy usage than the bounds reported in this study.
"We expect the relative impact of various CAV features in advanced vehicles, such as plug-in electric vehicles, to differ from the corresponding impact in conventional vehicles," Gonder added. "Future work will more rigorously explore the combined impacts of advanced powertrains and CAV technologies."
This work was funded by the Vehicle Technologies Office in the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy.
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 the Energy Department by The Alliance for Sustainable Energy, LLC.