An article on SeekingAlpha, written by a self-confessed non-believer in Tesla (to the degree that he is even shorting their stock), attempts to make the case that a hybrid Toyota Camry has a lower CO2 emission per mile than a Tesla Model 3. There are several serious flaws in his argument however, resulting in a misleading conclusion.
Kudos for actually including the production and transportation of the gasoline in the calculations for the hybrids (many other places ignore that part), and while there are various numbers out there for this (and, to be fair, it varies a lot depending on the oil field and refinery you look at), the numbers in the article are close to other estimates I have seen for this. So, in terms of fuel consumption, the CO2 footprint of the XLE hybrid is 244.5 g/mile (I’m going to look at just the XLE since he chose to look only at the long range Model 3).
Manufacturing the EV
Most of the manufacturing process for the two cars is similar in terms of CO2 impact. Where they differ obviously is the battery packs. While the hybrid does have a small battery pack, it is so small that it can rightly be considered negligible in the overall calculations I believe. The Tesla Model 3 on the other hand comes with a moderately large 75 kWh lithium ion battery pack.
The best estimate I can find for the CO2 emissions relating to battery manufacturing (from the Union of Concerned Scientists Cleaner Cars From Cradle to Grave report) equates to 5443kg for an 85kWh battery (converting to metric units). The Model 3 is only 75kWh, so we will estimate 4800kg. The author of the SeekingAlpha article used 150,000 miles in 12 years as his baseline, so the manufacturing cost of the battery is just 32g per mile. Significantly lower than the 85g per mile in his estimate.
Note: That also fails to take into account the fact that Tesla & Panasonic manufacture the cells and batteries side-by-side in their Gigafactory in Nevada, which is moving towards being 100% renewable energy powered. That will further reduce the CO2 emissions impact from manufacturing.
The long range Model 3 has an EPA rating of 325 miles per charge, and, as noted previously, a 75 kWh battery. That is equivalent to 231 Wh per mile. Given the estimated 85% charging efficiency (using the number from his article, which I believe is a fair estimate), that equates to 272 Wh per mile at the wall. He further estimate 5% loss in transmission lines between the wall and the generating source, so that gets us to 286 Wh (or 0.286 kWh) per mile at the generator.
Next he makes some very dubious assumptions that lead to the conclusion that all EV charging is done using marginal power from natural gas generators. Despite the fact that there is power in the grid from nuclear, large scale hydroelectric and wind over night (all zero CO2 sources).
Of course, not all EVs are charged over night (many use super chargers during the day, or are connected at office parking lots, shopping malls etc). Many EV owners also have solar arrays on their own roofs, and even local batteries to store generated energy during the day and transfer it to the car at night.
Let’s assume he is correct however and all EV charging is somehow marginal and powered only by natural gas generators which would not be running were it not the for people plugging in their Tesla Model 3s over night. Giving us a worst case number. His number for CO2 per kWh from a gas generator was 599.8 grams. Our Model 3 uses 0.286 kWh per mile at the generator, so that is 172 grams per mile.
In California, the grid average CO2 emissions per kWh is 300 grams. In Vermont, it is just 3 grams per kWh. Using those numbers, our Tesla Model 3 running in California accounts for just 86 grams per mile and in Vermont is is less than 1 gram per mile!
Adding It Up
We have an estimated 32g/mile from amortizing the battery over 150,000 miles and an estimated 172g/mile using purely natural gas generated electricity) for a total of 204 grams per mile. That is 40 grams / mile less than the hybrid, or 6,000 kg less over the 150,000 mile lifetime. Using the worst case emissions number.
In California, a Tesla Model 3 charged from the grid based on the average emissions per kWh accounts for just 118 grams / mile, or almost 19kg less CO2 over the lifetime of the car. In Vermont, we’re talking about of 30 kg less CO2 in the 150,000 mile lifetime.
Cleaner Every Year
The difference between the states in the calculations above also highlights something else about the EV compared to the hybrid. Where you live makes a big difference, but in almost all cases the power mix where you live is getting cleaner every year. The amount of renewables on the grid, night and day, is increasing. Coal fired power stations are being used less and less, and natural gas ones are next in line to be scaled back.
That means, for EV drivers, without any changes to their vehicles, the CO2 emissions per mile attributed to it get lower every year. Not true for the hybrid driver.
Finally, another aspect that the author conveniently ignores in the article is the impact of recycling at the end of life. The battery in the Tesla can be recycled, recovering much of the metal content for use in new batteries. There is no way to recover anything from the burned gasoline. Some estimates suggest that as much as 70% of the CO2 attributed to manufacturing the battery will be recovered at the end of the car’s life by recycling the battery materials.
If you apply that 70% reduction in the initial CO2 cost, that reduces the per mile cost of manufacturing the battery by 22 grams. Giving the Tesla at least 62 grams per mile lower emissions than the hybrid.