by Bill Schlesinger
With the increasing popularity of electric vehicles (EVs), several readers have asked me to evaluate the net benefit of EVs for the mitigation of climate change. I first addressed this in a blog five years ago (Life-time side-by-side comparison: Electric vs. gasoline automobiles – Translational Ecology (duke.edu)), concluding that despite the large carbon dioxide emissions associated with the production of lithium batteries, electric vehicles reduce carbon dioxide emissions to the atmosphere in those regions where coal-fired power plants are not the major source of electricity.
A recent analysis that compares the carbon dioxide emissions among vehicle types in China offers some new insight on this question. Comparing sport-utility vehicles (SUVs), with traditional internal combustion engines, hybrid systems, or electric/battery power, each driven for about 70000 miles over a ten-year period, the study found that internal combustion vehicle delivered 43 tons of carbon dioxide to the atmosphere, whereas hybrids and battery options, delivered about 30 tons each. The devil is in the details: for internal combustion vehicles 82% of the carbon dioxide emissions stem from the gasoline used to operate the vehicle. For hybrids, 72% of the emissions stem from operations over the 10-year period.
For the battery-operated vehicle, where the batteries are designed to deliver a 400-mile range of operation, only 31% of the carbon dioxide emissions stem from operations, whereas the rest stem from manufacture of the vehicle (28%), and its battery (25%), and disposal of the vehicle at the end of its lifetime (14%). Putting a larger lithium battery in the vehicle to extend its range dramatically increases carbon dioxide emissions associated with the fabrication of the battery. The emissions from operation are calculated using the proportional contribution of various fossil fuels used to generate electricity in China, which is about 58% (mostly coal), versus 59% in the United States (mostly natural gas).
So, the answer remains the same: Overall, electric vehicles are climate friendly. They will become more so as we improve the efficiency of mining, purifying, and production of lithium for batteries, and as we improve the efficiency of recycling lithium, cobalt, and other valuable metals from spent batteries for reuse. The emissions reduction from an electric vehicle will be greater in Maine, which generates almost no electricity from coal, than in West Virginia, where coal is still king.
References:
Harper, G. and 13 others. 2019 Recycling lithium-ion batteries from electric vehicles. Nature 575: 75-86
Zhang, H., F. Zhao, H. Hao, Z. Liu. 2023. Comparative analysis of life cycle greenhouse gas emission of passenger cars: A case study from China. Energy doi 10.1016/j.energy.2022.126282
