Environmental impacts of hybrid and electric vehicles—a review

Abstract

Purpose A literature review is undertaken to understand how well existing studies of the environmental impacts of hybrid and electric vehicles (EV) address the full life cycle of these technologies. Results of studies are synthesized to compare the global warming potential (GWP) of different EV and internal combustion engine vehicle (ICEV) options. Other impacts are compared; however, data availability limits the extent to which this could be accomplished.Method We define what should be included in a complete, state-of-the-art environmental assessment of hybrid and electric vehicles considering components and life cycle stages, emission categories, impact categories, and resource use and compare the content of 51 environmental assessments of hybrid and electric vehicles to our definition. Impact assessment results associated with full life cycle inventories (LCI) are compared for GWP as well as emissions of other pollutants. GWP results by life cycle stage and key parameters are extracted and used to perform a meta-analysis quantifying the impacts of vehicle options. Results Few studies provide a full LCI for EVs together with assessment of multiple impacts. Research has focused on well to wheel studies comparing fossil fuel and electricity use as the use phase has been seen to dominate the life cycle of vehicles. Only very recently have studies begun to better address production impacts. Apart from batteries, very few studies provide transparent LCIs of other key EV drivetrain components. Estimates of EV energy use in the literature span a wide range, 0.10-0.24 kWh/km. Similarly, battery and vehicle lifetime plays an important role in results, yet lifetime assumptions range between 150,000-300,000 km. CO 2 and GWP are the most frequently reported results. Compiled results suggest the GWP of EVs powered by coal electricity falls between small and large conventional vehicles while EVs powered by natural gas or low-carbon energy sources perform better than the most efficient ICEVs. EV results in regions dependant on coal electricity demonstrated a trend toward increased SO x emissions compared to fuel use by ICEVs. Conclusions Moving forward research should focus on providing consensus around a transparent inventory for production of electric vehicles, appropriate electricity grid mix assumptions, the implications of EV adoption on the existing grid, and means of comparing vehicle on the basis of common driving and charging patterns. Although EVs appear to demonstrate decreases in GWP compared to conventional ICEVs, high efficiency ICEVs and grid-independent hybrid electric vehicles perform better than EVs using coalfired electricity.

Second life of electric vehicle batteries: relation between materials degradation and environmental impact

“…However, the GWP, expressed in kg of carbon dioxide equivalent (kg CO 2 e.), is the most common environmental indicator used for the LCA of EVs for its simplicity and overall impact comprehension (Hawkins et al 2012). The scarcity or critical reserves of determined materials, such as lithium, will have no impact on our analysis because only reused EV batteries are considered in this study.…”

“…While one uses crude oil derivatives stored in a tank, the other one converts the stored electrochemical energy into electrical energy. This change forces car manufacturers to adapt all the traction, control, security and refrigerating systems (Hawkins et al 2012). This results in a lighter traction system, because of a smaller electric motor and no gearbox, but an overall weight increase of around 25% due to the battery system and all the electric and electronic additional components.…”

Integration of alternative energy sources into digital micro‐grids

“…Battery and vehicle lifetime plays an important role. The lifetime of EVs is estimated in the range between 150,000-300,000 km [20]. A main motivation of the use of EVs is their low carbon footprint.…”

Can Next-Generation Vehicles Sustainably Survive in the Automobile Market? Evidence from Ex-Ante Market Simulation and Segmentation

“…Due to growing concerns about global air pollution and depleting fossil fuels, research developing and deploying vehicles operated with environment-friendly fuels have been accelerated to reduce dependency on fossil fuels in transportation sector, which accounted for 65% of the total oil consumed worldwide in 2015 [3]. These efforts have leaded to start releasing various types of AFVs (e.g., electric vehicles, vehicles fueled with biofuels) in the existing car market and necessitated in-depth examination of not only their environmental impact [4][5][6][7], but also how the existing car market will react to this change. Another emerging market segment is that of alternative fuel vehicles (AFVs, hereafter), such as hybrid and electric cars.…”