How Much Do Electric Drive Vehicles Matter to Future U.S. Emissions? Samaneh Babaee,* ,† Ajay S. Nagpure, ‡ and Joseph F. DeCarolis † † Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States ‡ Hubert H. Humphrey School of Public Affairs, University of Minnesota, Minneapolis, Minnesota 55455, United States * S Supporting Information ABSTRACT: Hybrid, plug-in hybrid, and battery electric vehiclesknown collectively as electric drive vehicles (EDVs) may represent a clean and affordable option to meet growing U.S. light duty vehicle (LDV) demand. The goal of this study is 2-fold: identify the conditions under which EDVs achieve high LDV market penetration in the U.S. and quantify the associated change in CO 2 , SO 2 , and NO X emissions through midcentury. We employ the Integrated MARKAL-EFOM System (TIMES), a bottom-up energy system model, along with a U.S. data set developed for this analysis. To characterize EDV deployment through 2050, varying assumptions related to crude oil and natural gas prices, a CO 2 policy, a federal renewable portfolio standard, and vehicle battery cost were combined to form 108 different scenarios. Across these scenarios, oil prices and battery cost have the biggest effect on EDV deployment. The model results do not demonstrate a clear and consistent trend toward lower system-wide emissions as EDV deployment increases. In addition to the trade-off between lower tailpipe and higher electric sector emissions associated with plug-in vehicles, the scenarios produce system-wide emissions effects that often mask the effect of EDV deployment. ■ INTRODUCTION Increasing concerns over U.S. oil imports, anthropogenic climate change, and urban air quality motivate interest in alternative fuels and vehicles. Among existing options, electric drive vehicles (EDVs)hybrid electric vehicles (HEVs), plug- in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs)are receiving increased attention from government, industry, and academia. Current U.S. policies designed to promote EDVs include President Obama’s pledge to deploy 1 million BEVs by 2015, 1 a $7500 federal tax credit for BEVs and PHEVs, 2 and numerous state-level incentives. 3 In addition, the recent passage of aggressive new Corporate Average Fuel Economy (CAFE) standards that will roughly double fuel economy and halve the greenhouse gas emissions produced by cars and light duty trucks in model year 2025 4 make the prospect for EDV deployment even more promising. EDVs offer three key benefits over competing vehicle technologies: (1) reduced consumption of petroleum-based fuels, 5 (2) lower refueling infrastructure costs compared to alternatives such as H 2 and compressed natural gas, 6 and (3) a shift in energy production from vehicles to the electricity grid, where emissions from large, centralized facilities are cheaper and easier to control. 7,8 While previous work has applied different methodologies and models to quantify the environ- mental benefits of EDVs, several consistent insights have emerged. First, HEVs produce less emissions than conventional vehicles. 9-11 Second, PHEVs with smaller battery packs are more likely to deliver emissions benefits and reduced gasoline consumption at lower lifetime cost compared to those with large battery packs in the short term. 12-15 Third, significant emissions benefits, particularly from vehicles with large battery packs, only begin to accrue with clean electricity. 9,11,12,16-18 Fourth, CO 2 prices as high as 100 $/t do not provide sufficient incentive for vehicle electrification. 9,10,12,14,16 While these studies (along with others 19-22 ) have made significant contributions to the literature, they only consider a single point in time or employ sector-specific models or calculations that ignore the interaction of EDVs with the rest of the energy system over time. Recent analyses based on energy system models mainly focus on CO 2 emissions and have been run with a limited set of scenarios, 6,23,24 which make it difficult to draw insight specific to EDVs. This paper employs an energy system model to meet the following objectives: (1) identify the conditions under which EDVs achieve high market penetration in the U.S. light duty vehicle (LDV) sector through 2050 and (2) quantify the system-wide changes in CO 2 , SO 2 , and NO X emissions at the Received: February 21, 2013 Revised: December 23, 2013 Accepted: January 3, 2014 Published: January 3, 2014 Policy Analysis pubs.acs.org/est © 2014 American Chemical Society 1382 dx.doi.org/10.1021/es4045677 | Environ. Sci. Technol. 2014, 48, 1382-1390