Time-dependent plug-in hybrid electric vehicle charging based on national driving patterns and demographics Jarod C. Kelly ⇑ , Jason S. MacDonald, Gregory A. Keoleian Center for Sustainable Systems, University of Michigan, 3012 Dana Bldg., 440 Church St., Ann Arbor, MI 48109, USA article info Article history: Received 21 March 2011 Received in revised form 28 January 2012 Accepted 2 February 2012 Available online 3 March 2012 Keywords: PHEV Charging Utility factor Travel patterns Electric range Demographics abstract Plug-in hybrid electric vehicles (PHEVs) are one promising technology for addressing concerns around petroleum consumption, energy security and greenhouse gas emissions. However, there is much uncer- tainty in the impact that PHEVs can have on energy consumption and related emissions, as they are dependent on vehicle technology, driving patterns, and charging behavior. A methodology is used to sim- ulate PHEV charging and gasoline consumption based on driving pattern data in USDOT’s National House- hold Travel Survey. The method uses information from each trip taken by approximately 170,000 vehicles to track their battery state of charge throughout the day, and to determine the timing and quantity of electricity and gasoline consumption for a fleet of PHEVs. Scenarios were developed to examine the effects of charging location, charging rate, time of charging and battery size. Additionally, demographic information was examined to see how driver and household characteristics influence consumption pat- terns. Results showed that a compact vehicle with a 10.4 kW h useable battery (approximately a 42 mile [68 km] all electric range) travels between 62.5% and 75.7% on battery electricity, depending on charging scenario. The percent of travel driven electrically (Utility Factor, UF) in a baseline charging scenario increased from 64.3% using 2001 NHTS data to 66.7% using 2009 data. The average UF was 63.5% for males and 72.9% for females and in both cases they are highly sensitive to age. Vehicle charging load pro- files across charging scenarios and demographics show a varying effect on summertime peak load, which can be useful for PHEV market segmentation and electric utility planning. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction The transportation sector accounts for 28% of energy consump- tion and 33% of carbon dioxide emissions; light duty vehicles com- prise 57% of that energy consumption [1]. Vehicle electrification has been identified as an important strategy to address these environ- mental challenges and Plug-in Hybrid Electric Vehicles (PHEVs) represent a promising electrification technology because they maintain conventional vehicle range. PHEVs give drivers the range of a gasoline-powered vehicle, while allowing the environmental benefits of electrically propelled travel for short distances [2–10]. In addition, significant PHEV market penetration is expected to require only small changes to electricity generating capacity [6,7,10–14]. However, consumer driving and charging patterns will determine changes to electrical demand and the potential environ- mental impact reduction [5,15]. Sioshansi and Denholm have used a sample of real world driving data (227 vehicles) from the St. Louis area and applied the trip profile and drive cycle information to sim- ulate on-road PHEV energy consumption, PHEV charging, and elec- trical grid dispatch for several regions of the United States [16,17]. Weiller used the Federal Highway Administration’s National Household Travel Survey (NHTS) [18] to explore vehicle impacts on the grid on a trip-by-trip basis. This article extends that method- ology by investigating how demographics influence use pattern and total energy consumption, as well as how those consumption pat- terns impact current grid loads. PHEVs shift a portion of the emissions burden of automobile travel from on-road fossil fuel combustion to electricity generation at stationary power plants. The impacts of this shift depend on the amount of electricity demanded and the mix of generators used to supply the PHEV electrical demand. Understanding the effects of this coupling on the electrical grid system requires a representa- tion of both vehicle energy consumption, and the time and magni- tude of vehicle charging. In most energy and environmental analyses of PHEVs, vehicle energy consumption has been modeled using daily driving dis- tance but daily travel patterns have been ignored. These studies as- sume consumption rates (kW h/mile) and all electric ranges (AERs) to calculate electricity use for a fixed ratio of the daily travel [2,3,6,8,13]. That ratio of electrically-powered travel, also referred to as the utility factor [19], is dependent on the distribution of total vehicle travel in the NHTS and several studies have evaluated this ratio by assuming a single full charging event per day [2,3,8,19]. 0306-2619/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.apenergy.2012.02.001 ⇑ Corresponding author. Tel.: +1 734 763 8564. E-mail address: jckelly@umich.edu (J.C. Kelly). Applied Energy 94 (2012) 395–405 Contents lists available at SciVerse ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy