Research Publications

One promising technology to address peak oil, global warming, and energy security is the plug-in hybrid electric vehicle (PHEV); however, the impact of PHEVs on greenhouse gas emissions and the petroleum that they directly displace is uncertain. PHEV gasoline and electricity consumption are dependent on the technological characteristics of the vehicle and the user’s charging/driving behavior. Additionally, there is uncertainty in the emissions associated with the generation of electricity for PHEVs as the time of day and geographic region of vehicle charging impacts emissions per kilometer driven. The present study describes a method for estimating the gasoline and electricity consumption of a fleet of PHEVs by tracking the state of charge over a single day of approximately 170,000 vehicles taking nearly 700,000 trips from USDOT’s National Household Transportation Survey. This results in a scalable, time dependent, PHEV charging demand that indicates the additional load a utility may expect, as well as PHEV gasoline consumption. Over 40 scenarios were examined that account for variation in on-road energy consumption, battery size, charging power, where vehicles can charge, and time dependent charging behaviors, including minimum dwell time and charge onset delays. The scenarios determine the amount of energy consumed, the percent of travel driven electrically, and when charging occurs. Average vehicles with a 10.4 kWh useable battery size consume from 48 to 61 kWh per week, and from 10.2 to 14.8 liters of gasoline per week. This also indicates that the PHEV would drive between 56% and 70% of its kilometers on electricity. Fleet charging load is also compared to the current non-PHEV load in Michigan. Recommendations on vehicle design and charging for manufacturers, utilities, and consumers will be presented based on scenario analysis results.