Following publication, we have become aware that the inventory for the drivetrain of the electric vehicle (EV) modeled in our article (Hawkins et al. 2012) warranted revision and an update. This corrigendum incorporates the necessary modifications and better aligns our inventory with the current technology. These corrections do not substantially alter our main findings and do not change our conclusions.
Although the study is not specific to the Nissan Leaf, we have used its characteristics to guide decisions regarding model parameters. The revised inventories for the motor, inverter, and charger now match the total masses of these components in the Leaf: 60 kilograms (kg), 20.2 kg, and 16.6 kg, respectively (Nissan Motor Co. LTD 2011).1 The material composition of the electric motor was estimated by linear interpolation on the basis of power rating (80 kilowatts [kW]; Nissan 2010) from the mass decomposition of three commercial EV motors (60–100 kW; Burress et al. 2011). The material composition of the inverter and charger were estimated based on the material breakdown of inverters with a wide range of power ratings. With this revision, the inventory process “battery passive cooling system” is updated and renamed “additional battery packaging for passively-cooled battery.” The new name better reflects the nature of this inventory process, as it accounts for the additional packaging required in addition to the core battery components adapted from work by Majeau-Bettez and colleagues (2011). The composition has been changed from aluminum to steel (Bunkley 2011; Nissan Motor Co. LTD 2012).
Implications for Results
The ranking of the different technologies is unaltered for the human toxicity, mineral depletion, freshwater eco-toxicity, freshwater eutrophication, photochemical oxidation formation, and global warming impact potentials (see figure 1). The distinction between EVs and internal combustion engine vehicles (ICEVs) is especially robust for the first four impact categories.
The ranking is not altered for global warming potential (GWP), but the advantage of an EV LiNCM-NG2 relative to ICEV-diesel grew from less than 1% to 7%. The present correction reduces our best estimate of the EV production impacts from 87–95 to 72–81 grams carbon dioxide equivalents per kilometer (g CO2-eq/km). When powered by a European electricity mix, this leads to life cycle impacts in the range of 180 to 190 g CO2-eq/km, an 8% reduction relative to our original estimate (197 to 206 g CO2-eq/km). We find that EVs powered by the European electricity mix reduce GWP by 26% to 30% relative to gasoline (originally 20% to 24%) and 17% to 21% relative to diesel (originally 10% to 14%).
This correction narrows the small differences between the life cycle terrestrial eco-toxicity potential of EVs and ICEVs. A similar pattern is observed for the small gap in the terrestrial acidification potential between EVs powered by the European electricity mix and ICEVs. In both cases, no significant difference was identified in our original results. An alteration in ranking occurs for fossil depletion potential, for which the case of EV LiNCM-NG went from being slightly worse than ICEV-diesel to incrementally better. Both before and after, these differences should be considered statistically insignificant.
The modified inventory reduces the life cycle particulate matter formation potential of EVs powered by the European electricity mix to a level roughly on par with that of ICEVs. The reduction occurs in the production-phase impact, for which all vehicles are now approximately equal.
This corrigendum further confirms the battery as the real driver of EV's production-phase impacts, with a share amounting to just under half of the cradle-to-gate GWP. Our updated results still demonstrate the significance of production-phase impacts and, as such, are well aligned with a recent comparative life cycle assessment of first-generation EVs by the industry (Daimler AG 2012).
The authors would like to thank Linda Ager-Wick Ellingsen, Christian Poon, Auke Hoekstra, Timothy Burress, Juan Mauel Micó Soler, and Constantine Samaras for their input as we made these corrections and adjustments.
The supporting information, available on the journal's Web site, has been revised to reflect the changes described in this corrigendum.
Electric vehicle with lithium-ion nickel-cobalt-manganese battery powered by natural gas.