Plug-in Hybrid Electric Vehicles (PHEVs) have recently entered the commercial market in the United States. PHEVs can operate primarily on battery power using electricity stored from the electric grid for distances of 10 or more miles, and subsequently operate like a hybrid electric vehicle (HEV) using gasoline thereafter. During 2013, nearly 50,000 PHEVs were sold in the U.S., and 2014 sales are likely to top those of the previous year. PHEVs typically have initial purchase costs higher than comparably sized conventional vehicles, but may offer benefits of improved energy economy, reduced emissions, and flexibility to use electricity as an energy source. The objectives of this research are to demonstrate a method for quantification of the real-world activity, energy use, and emissions of PHEVs and to apply the method to evaluate electricity use, gasoline use, and emissions. Emissions include directly released tailpipe exhaust and indirect releases associated with power generation for grid-electricity consumed by the vehicle. A 2013 Toyota Prius Plug-In was previously measured in the real world to quantify activity, fuel use, and emissions rates at 1 Hz. Real-world vehicle activity data were measured using an on-board diagnostic (OBD) scan tool and multiple global positioning system (GPS) receivers with barometric altimeters. Second-by-second tailpipe emissions were measured using a portable emissions measurement system (PEMS). In this work, Vehicle Specific Power (VSP) based modal average energy use and emission rates are inferred to assess trends in energy use and emissions with respect to engine load and for comparisons of charge depleting versus charge sustaining modes of operation. Charge depleting mode refers to operation during which electricity from the grid that is stored in the traction battery is discharged to provide either exclusive or a significant share of energy for vehicle propulsion. Charge sustaining mode refers to operation during which the traction battery state of charge is held between set points based on in situ recharging from regenerative braking and discharge for low power operation or to supplement the engine at higher power demand. This paper will focus on example results and insights from one day of field data.
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