What is Electric Vehicle?
A new study by consulting firm Arthur D. Little (ADL) claims that the benefits of electric cars, both environmental and economic, are lower than others, including UCS, have shown. However, the differences are largely due to questionable assumptions about battery replacements and the use of electric vehicles as a gasoline car replacement.
What they get right
EVs on average have lower overall greenhouse gas emissions and lower costs to fuel than gasoline cars now, and these benefits are likely to increase over time. This is the conclusion of our report and also the ADL analysis. In our report, “Cleaner Cars from Cradle to Grave”, we found that the average electric vehicle results in about half the climate changing emissions than a comparable gasoline car, even when the manufacturing emissions are included. The ADL study finds a lower benefit, about 20 percent, due to assumptions discussed below. However, they also note that the emissions savings will likely grow over time as electricity generation becomes cleaner, consistent with our findings.
What they get wrong about emissions
The ADL analysis and the UCS analysis of greenhouse gas emissions is largely the same except for two factors: battery replacement and the need for a replacement gasoline car to accompany the electric car. These two factors account for nearly 40 percent of the ADL estimate of emissions from a battery electric car and therefore are critical to understanding the benefits of electric vehicles.
The ADL study assumes that all EVs will need a replacement battery after seven to ten years of use. The study cites the fact that “this is consistent with the warranty that BEV manufacturers offer on their vehicles’ battery packs” to bolster this claim. However, by analogy, gasoline cars would be expected to need a new engine and/or transmission after the expiration of a five-year powertrain warranty. We don’t know what the true lifetime and failure rate for electric car batteries are, especially for today’s second generation battery systems since they’ve only been on the market for a few years. But assuming a battery replacement at 7-10 years is a 100 percent failure rate for the battery system. Making this assumption would require some proof, and yet there’s no evidence that this is the case for battery lifetime.
The largest factor inflating the ADL estimates of emissions is the assertion that drivers of electric vehicles would require a replacement gasoline car for about a quarter of all miles driven, because electric vehicles are driven fewer miles per year than gasoline cars. This questionable assumption is critical to the lower electric car benefits seen in the ADL report: it increases their emission estimates from an electric vehicle like the Nissan LEAF by 28 tons, while the baseline estimate of LEAF manufacturing and electricity use only totals 69 tons.