For this video podcast, I spoke to Dr. David Rapson, Associate Professor of Economics at the University of California at Davis about a study he and colleagues recently completed on electric vehicles (EVs), “Low Energy: Estimating Electric Vehicle Electricity Use” in which the team provided the first at-scale estimate of EV home charging by matching 12 billion observations of hourly electricity usage with EV registration data.
The team found the average EV increases overall household load by 2.9 kilowatt-hours (kWh) per day, less than half the amount assumed by state regulators. They then scaled this up to account for away-from-home charging to estimate annual eVMT. The results implied that plug-in hybrids travel 1,700 miles per year on electricity and battery electrics 6,700 miles per year, both far below miles traveled in gasoline cars.
Following are a couple of excerpts from our discussion, which you can view or download below, or listen to in ITunes, Spotify, Google Podcasts or TuneIn.
“Yes, we were surprised. We were. I mean, this is really a very low amount of electricity consumed for EVs. We thought that these dedicated meters were probably a little bit selected, that they were probably going to show higher electricity consumption than the average EV. But we didn’t expect it to be two to three times as high. So yes, we were definitely surprised by these results. And actually, that caused us to take several months of really making sure that this result is correct, doing tons of robustness checks and in the end, we’re very confident that this is an accurate measure in our sample of what people are using at home.”
“It really matters for the vision of transportation electrification whether EVs are seen by consumers as complements or substitutes. We’re actually testing this now in more recent data and we can see the entire vehicle portfolio that a household owns — whether this a situation where EVs are part of a big portfolio and taking just a small slice of the VMT, or whether they are replacing gasoline cars outright. We’re not quite there yet, but I think that early indications are that they are at least for some households compliments.
So yeah, what does this mean for policy? Well, again, I think that’s unclear. Eventually this vision requires that most of the VMT is displaced from gasoline to electric, and to the extent that’s not happening, I think we should all care why. Is it just because of battery range and range anxiety that might be associated with inadequate charging infrastructure? That might be the case. It might also be just a selection issue — that the people who are buying cars over this period are just different. They’re wealthier, which we have seen. They’ve got a big car portfolio and they’re just dipping their toe in the water. But maybe in a few years, the technology will be such that they’ll feel comfortable just buying an EV outright and getting rid of their gasoline cars. And I don’t think we know yet how that’s all going to play out.”
“I think that this highlights just one of the main points that I want to get across to anybody who has influence in forming these policies, or just cares about transportation emissions reductions. I think that we have two categories of policies. We’ve got carrots and we’ve got sticks. Because of the intransigence of the political opposition that has been facing people who want to get a carbon price in there, either through tax or through cap and trade, people who really care about this issue have become basically desperate. I can understand why because there has not been enough climate action.
So, the question has shifted from what should we do to what is feasible? And it turns out that what’s feasible is carrots. And this leaves us in a situation where, okay, that’s what can be done and I’m sure that will have some effect. If you pay people enough money, they’re going to adopt EVs. There’s no question about that. And if you clean up the electric grid, those EVs are going to pollute less than gasoline cars, and those are good things.
But there’s also a question of costs and incentives. My concern with going with the carrot-only approach is it doesn’t penalize people who are making polluting decisions. And I think we really need to do that, and the Norway example is a really great case study in penalizing the polluting good. That creates the right incentives. If all we do is subsidize the greener good, we’re still not making it more costly to pollute and my fear is that that policy is going to be less effective than people hope. That this might not end up leading to the carbon abatement that is pretty much the whole purpose of this exercise. Or at least it’s one of the main motivating factors.”