Since the current electric vehicle (EV) boom started, there have been arguments about how much cleaner EVs are in comparison to internal combustion engine vehicles (ICEV). The claims are, “Making the batteries is dirty!” or, “The electricity is made from burning coal!” This Treehugger has argued many times that if you account for the embodied carbon—or the upfront carbon emissions released from making the materials and building the vehicle—they still have a significant carbon footprint.
Now, a new study from the Yale School of the Environment published in Nature Communications looks at all the data, the full life cycle of EVs, and finds EVs have significantly lower life cycle carbon than ICEV—far lower than previously thought.
“The surprising element was how much lower the emissions of electric vehicles were,” said postdoctoral associate Stephanie Weber in the press release. “The supply chain for combustion vehicles is just so dirty that electric vehicles can’t surpass them, even when you factor in indirect emissions.”
I found Weber’s statement confusing: Both EVs and ICEVs are made from roughly the same materials, but she is referring to the full life cycle, including the fuels. In previous Treehugger posts, we have discussed research that looked at the full life cycle of EVs and concluded the total emissions from upfront and operating carbon were about half of those of an ICEV. But that was using the current American power mix and the assumption that the upfront emissions of the EV were about 15% higher than those of an ICEV.
But we have also noted—and as this table shows—that the electrical grid is getting cleaner every day, as is the production of batteries. Furthermore, the energy density of batteries is increasing and their weight is dropping. This study takes all of this into account. In the summary of the supplementary information (PDF here, far easier to understand than the study), the authors note:
The estimates of the upfront carbon emissions were significantly lower than ours which were based on previous studies published in Carbon Brief. After I questioned this, wondering if they were discounting the upfront carbon, lead author Paul Wolfram told Treehugger:
Given the value of the materials in the batteries of EVs and the amount of aluminum used in them, the recycling rate is likely to increase dramatically. I might argue about the time value of carbon, that what matters is what is going into the air right now as we get close to the carbon ceiling to stay under 1.5 degrees Celsius (2.7 degrees Fahrenheit) of heating, but Wolfram is persuasive about it making a big difference.
After I noted that using Carbon Brief data, I listed ICEV life cycle emissions at 240 grams of carbon dioxide per kilometer, and a Tesla Model 3 at 127 grams CO2/km, Wolfram provided his comparables for a vehicle close in size and weight to a Tesla,
This is the critical insight of this study: Just going electric isn’t enough. In chart A, the emissions from a battery electric vehicle (BEV) light truck are still pretty high. To get to where we have to go, we have to also include reuse, recycling, downsizing, sharing, and most importantly, decarbonizing the grid.
In one of the most controversial posts I have written, I noted if you take embodied carbon into account, a big electric pickup is worse for the climate than a small gasoline-powered car. (Don’t read the comments!) These data don’t quite confirm my math, showing the total for the BEV light truck still lower than the ICEV personal car, but reading this study, I feel vindicated. Wolfram concurred: “I do see use in the comparison of the BEV truck versus the ICE small car. It does highlight that some of the mitigation potential of EVs is lost if cars continue to become bigger.”
The results are summarized in the supplementary notes:
Indeed, unless all sources of emissions throughout the entire life cycle are taken into account, we will continue to be buried in giant pickup trucks with 40-ton footprints. I have noted before what I called my ironclad rule of carbon: “As we electrify everything and decarbonize the electricity supply, emissions from embodied carbon will increasingly dominate and approach 100% of emissions.” Policies, standards, and emission pricing schemes all have to recognize this.
