Influence of User Preferences on the Revealed Utility Factor of Plug-In Hybrid Electric Vehicles

Seshadri Srinivasa Raghavan,Gil Tal

doi:10.3390/wevj11010006

Abstract

Plug-in hybrid electric vehicles (PHEVs) are an effective intermediate vehicle technology option in the long-term transition pathway towards light-duty vehicle electrification. Their net environmental impact is evaluated using the performance metric Utility Factor (UF), which quantifies the fraction of vehicle miles traveled (VMT) on electricity. There are concerns about the gap between Environmental Protection Agency (EPA) sticker label and real-world UF due to the inability of test cycles to represent actual driving conditions and assumptions about their driving and charging differing from their actual usage patterns. Using multi-year longitudinal data from 153 PHEVs (11–53 miles all-electric range) in California, this paper systematically evaluates how observed driving and charging, energy consumption, and UF differs from sticker label expectations. Principal Components Analysis and regression model results indicated that UF of short-range PHEVs (less than 20-mile range) was lower than label expectations mainly due to higher annual VMT and high-speed driving. Long-distance travel and high-speed driving were the major reasons for the lower UF of longer-range PHEVs (at least 35-mile range) compared to label values. Enhancing charging infrastructure access at both home and away locations, and increasing the frequency of home charging, improves the UF of short-range and longer-range PHEVs respectively.

Highlights

Climate change, air quality, and public health concerns have necessitated that governments across the world implement policies to promote battery electric (BEVs) and plug-in hybrid electric vehicles (PHEVs), collectively addressed as plug-in electric vehicles (PEVs)
Using year-long longitudinal data collected via on-board data loggers from 153 PHEVs (11–53 miles all-electric range (AER)) in California, this paper systematically examines the disparities between observed PHEV driving, charging behavior and generalized expectations about their usage patterns, and its implications on Utility Factor (UF) estimates encapsulated in existing PEV policies
To the best of our knowledge, compared to existing studies which limit their scope of analysis to either aggregate or daily levels [16,21,22,24,35], this paper focuses on explaining why real-world performance deviates from label expectations by methodically examining disparities at varying time-scales; incorporates locational aspects of charging infrastructure access and utilization and how it impacts the UF; and explores if the key driving and charging factors that introduces deviations in real-world UF from their label values are the same irrespective of the AER

Summary

Introduction

Air quality, and public health concerns have necessitated that governments across the world implement policies to promote battery electric (BEVs) and plug-in hybrid electric vehicles (PHEVs), collectively addressed as plug-in electric vehicles (PEVs). In the U.S, the transportation sector is responsible for 30% of total national greenhouse gas (GHG) emissions, and the light duty vehicle (LDV) segment alone contributed close to 60% of total transport GHGs in 2017 [1]. In the state of California, 40% of total GHGs comes from the transportation sector, and the contribution from the LDV segment was close to 70% of transport GHGs [2]. California and many other governments have implemented a suite of technology forcing mandates, performance standards for transportation fuels, GHG emissions, and incentive-based policies to increase the market penetration of PEVs [3,4,5].

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