Well-to-Wheels Efficiency Analysis for Plug-in Hybrid Electricvehicles

Global warming and its impact on the environment has been gaining a lot of attention over the past few decades. As a result, different countries across the world began undertaking key measures to reduce the emission of greenhouse gases and have committed to a goal of keeping the global temperature rise below 1.5 degrees Celsius from pre-industrial levels. Transportation is one of the key contributors to global warming owing to the significant use of fossil fuels as source for energy for propulsion. As a result, automotive sector has been under thorough scrutiny and is facing increased pressure to cut down on greenhouse gas emissions. Following this demand to reduce carbon emissions, the automotive sector has seen a rise in more efficient cars being developed. This effort comprised the development of hybrid vehicles as well as electric vehicles. Although electric vehicles have gained a lot of popularity over the last few years, there is still a significant share of market which is owned by hybrid vehicles. And owing to the recent plateau in the growth of EV sales, we can expect very slight chances of decrease in the sales of hybrid vehicles anytime in the next few years. Thus, it makes sense to explore different avenues to make hybrid cars more environmentally friendly. Understanding the operational energy consumption and efficiency is always the first step in making critical decisions on improving the efficiency and making transportation more environmentally friendly. However, when looking at the environmental impact, it is also important to consider all the processes including the manufacturing of vehicle, sourcing of fuel and end of lifecycle processes along with the operational efficiency of the vehicle. This methodology of including all energy sources in the life cycle of the vehicle leads to the computation of a term known as well-to-wheels efficiency.

This study focuses on a comprehensive estimation of different energy-consuming processes that form a part of the lifecycle of a typical plug-in hybrid vehicle and computes the resulting well-to-wheels efficiency. Furthermore, an analysis of the computed well-to-wheels efficiency is made for different operating conditions of plug-in hybrids based on the data gathered from real-time usage patterns. The aim of this study is to use the computed well-to-wheels efficiency to demonstrate the strong dependency of this well-to-wheels metric on usage patterns (utility factor) of plug-in hybrid vehicles.