Researchers at the Norwegian University of Science and Technology (NTNU) have suggested that production impacts, greater for EVs than for conventional cars, can significantly reduce EVs’ global warming reduction potential.
In the abstract of their paper, Comparative Environmental Life Cycle Assessment of Conventional and Electric Vehicles, the paper’s authors Troy R Hawkins, Bhawna Singh, Guillaume Majeau-Bettez and Anders Hammer Strømman, in Yale University’s Journal of Industrial Ecology, confirm that EVs coupled with low-carbon electricity sources offer the potential for reducing greenhouse gas emissions and exposure to tailpipe emissions from personal transportation. But in considering these benefits, they say it is important to address concerns of “problem-shifting”. They add that while many studies have focused on the vehicle lifecycle use phase in comparing transportation options, production is also significant when comparing conventional vehicles and EVs.
“We develop and provide a transparent life cycle inventory of conventional and electric vehicles and apply our inventory to assess conventional and EVs over a range of impact categories,” say the authors. “We find that EVs powered by the present European electricity mix offer a 10% to 24% decrease in global warming potential (GWP) relative to conventional diesel or gasoline vehicles assuming lifetimes of 150,000km.
“However, EVs exhibit the potential for significant increases in human toxicity, freshwater eco-toxicity, freshwater eutrophication, and metal depletion impacts, largely emanating from the vehicle supply chain. Results are sensitive to assumptions regarding electricity source, use phase energy consumption, vehicle lifetime, and battery replacement schedules.
“Because production impacts are more significant for EVs than conventional vehicles, assuming a vehicle lifetime of 200,000km exaggerates the GWP benefits of EVs to 27% to 29% relative to gasoline vehicles or 17% to 20% relative to diesel. An assumption of 100,000km decreases the benefit of EVs to 9% to 14% with respect to gasoline vehicles and results in impacts indistinguishable from those of a diesel vehicle.
“Improving the environmental profile of EVs requires engagement around reducing vehicle production supply chain impacts and promoting clean electricity sources in decision making regarding electricity infrastructure.”
